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The upper telescope system is divided principally to permit familiarization as to nomenclature, description, disassembly, and reassembly. It is composed of 3 lenses, namely: a positive upper eyepiece lens doublet, a plano convex telemeter lens, and an air space upper objective lens doublet. This system is used in reverse to decrease the lower telescope system to a 6-power magnification. Figure 6-5 shows the upper telescope system assembly Part I. All bubble numbers in Section 6F1 refer to Figure 6-5 unless otherwise specified.

a. Fifth reduced tube section. The fifth reduced tube section (1) is made of brass rod, and is 5 1/4 niches in length. It serves to provide the necessary distance between the skeleton head assembly and the fourth reduced tube section (2).

The upper part is smooth turned, to serve as an alignment support section, and has a threaded periphery section. The alignment support and threaded periphery sections receive the internal threaded and counterbored alignment support sections in the lower part of the skeleton head

A bearing flange of nominal width immediately follows the threaded periphery section, and has a diameter coinciding with the skeleton head periphery, a sliding fit in the straight bored 1.99 external section of the outer taper section (1, Figure 6-2). The bearing flange in the lower part is the same thickness and diameter and is also a sliding fit in the straight bored 1.99 external section of the outer taper section. It coincides with the periphery wall of the fourth reduced tube section (2).

The external body of this section between both bearing flanges is tapered outward from the upper bearing flange down to the lower bearing flange. The inner circumference of the tapered section is counterbored with a uniform tapered wall thickness of 3/32 inch, commencing from the lower counterbored section and ending at the upper bored section for light transmission, and is threaded for antireflection. The upper part is bored straight a distance of 1 inch, with a straight counterbored section of 1.110 inch in length in the lower part.

The lower part is smooth turned, serves as an alignment support section, and has a threaded periphery section preceding it. The alignment support and threaded periphery sections receive the internal threaded and alignment support sections in the upper part of the fourth reduced tube section, and are secured together with two opposite lockscrews (5). These lockscrews are inserted in countersunk clearance holes in the fourth reduced tube section (2 and screwed into tapped holes in the fifth reduced tube section lower alignment support section.

At assembly, four shallow vertical slots are provided in both bearing flanges, two opposite the others to provide clearance for the prism tilt and change of power shifting wire tapes (38, Figure 4-28).

b. Fourth reduced tube section. The fourth reduced tube section (2) is made of brass tubing, and is 6.450 inches in length. The external diameter coincides with the bearing flange diameter of the fifth reduced tube section (1) and is a sliding fit in the straight bored 1.99 external section of the outer taper section.

The upper part is counterbored a short distance, serving as an alignment support section with an additional counterbored threaded section to receive the alignment support section of a sliding fit and the threaded periphery section of the fifth reduced tube section lower part (1).

The lower part is provided with three counterbored sections. The small counterbored section 2 inches long carries the mounted upper eyepiece lens (8) and its mount (3). Two opposite axial slots of appropriate length are provided in the wall near the lower part of this counterbored section for the insertion of two opposite special screws into tapped holes in the upper eyepiece lens mount (3). These two special inserted screws serve to carry the upper eyepiece lens (8) and its mount (3) vertically during collimation of the upper telescope system.

The medium diameter counterbored section is threaded to engage on the upper threaded periphery section of the third reduced tube section (9), while the large counterbored section serves as an alignment support of a sliding fit over the upper alignment support section of the third reduced tube section, and are secured together with two lockscrews (7). These lockscrews are inserted in countersunk clearance holes in the lower part of the fourth reduced tube section and screwed into tapped holes in the upper alignment support section of the third reduced tube section (9).

At assembly, four vertical shallow slots are provided in this reduced tube section, two opposite the others, to provide clearance for the prism tilt and change of power shifting wire tapes (38, Figure 4-28).

c. Upper eyepiece lens, mount, and clamp ring. 1. Upper eyepiece lens. The upper eyepiece lens (8) is made of two optical elements. It consists of a piano concave flint element cemented to a double convex crown element, forming a positive doublet. It is mounted in the upper eyepiece lens mount (3) with the crown element resting in the seat of

2. Upper eyepiece lens mount. The upper eyepiece lens mount (3) is made of brass tubing, and is 1 1/4 inch in length. It is bored for light transmission and has two counterbored sections. The small counterbored section carries the upper eyepiece lens doublet (8), while the large counterbored section is threaded to carry the threaded periphery of the upper eyepiece lens clamp ring (4). The lower face is chamfered from the bore at an angle of 15 degrees outward. Two opposite clearance holes are located in the wall of this chamfered section for the insertion of a special pair of calipers in order that, the assembled mount can be carried out of the lower part of the fourth reduced tube section (2). The mount is an axial sliding fit in the small counterbored section in the lower part of the fourth reduced tube section.

The mount is moved axially during collimation by the two special screws inserted in the opposite axial slots in the fourth reduced tube section and screwed into opposite tapped holes in the mount. This axial movement is necessary to obtain correct adjustment for definition and the elimination of parallax in the upper and lower telescope systems during collimation. The mount is secured in the fourth reduced tube section (2) with two lockscrews (5) after, collimation. These lockscrews are inserted in countersunk clearance holes in the fourth T educed tube section (2) and screwed into tapped holes in the mount.

Two opposite narrow air channel slots are provided in the periphery of the mount to allow sufficient clearance for the passage of nitrogen.

3. Upper eyepiece lens clamp ring. The upper eyepiece lens clamp ring (4) is made of brass tubing, and is of nominal thickness and width. The periphery is threaded for engagement in the counterbored threaded section in the upper part of the eyepiece lens mount (3) to secure the lens doublet. The clamp ring is bored for light transmission, and is threaded for antireflection. Two opposite slots are provided in the face of the clamp ring for the insertion of a special wrench. The clamp ring is secured with a lockscrew (6) which is inserted in a countersunk clearance hole in the mount (3) and screwed into the tapped hole in the clamp ring.

The external diameter is turned straight 2 inches below the alignment support section. From this point the wall is tapered outward down to the 5/8-inch straight section.

The lower part is provided with two counterbored sections. The small counterbored section carries the telemeter lens mount (10) of a sliding fit, and is provided with two opposite vertical air channel slots for the passage of nitrogen. These two channel slots extend vertically inch above the small counterbored shoulder.

A circumferential slot of appropriate length with an additional similar recess is provided in the wall and located in the center of this small counterbored section, to accommodate an angular alignment lockscrew (12). It is used to permit angular adjustment of the telemeter lens mount (10) during collimation, so that the telemeter lens line will lie in a true vertical plane. The angular alignment lockscrew is inserted in the circumferential slot and screwed in a tapped hole in the telemeter lens mount (10), while the head of the lockscrew rests on the circumferential recess face.

The large counterbored section is threaded and serves as an alignment support section to receive the upper threaded periphery alignment support section of the second reduced tube section (17) to which it is secured with two opposite lockscrews (13).

The inner surface of this reduced tube section is bored tapered, commencing from a diameter of 1.420 inch in the upper part to a diameter of 1.590 inch, in a length of 3 21/32 inches, and is threaded for antireflection starting from the upper end for a distance of 3.152 inches. The remainder of the inner surface is counterbored tapered from the small straight counterbored

At assembly, four vertical shallow slots are provided in both shoulder flanges, to provide clearance for the prism tilt and change of power shifting wire tapes (38, Figure 4-28).

e. Telemeter lens, mount, and clamp ring. 1. Telemeter lens. The telemeter lens (15) is made of one ordinary crown piano convex element. The piano surface is etched with vertical and horizontal calibrations in degrees of true field, and provides a means of measuring the angular size of a target. Refer to Section 4U7, Paragraph a, for further detail.

The telemeter lens is placed in the image plane of the upper telescope and first real image plane of the periscope, so that the graduations appear to vibrate in unison with the image, and observation is easier.

The telemeter lens periphery is provided with a vertically stoned groove. A lockscrew (16) in the telemeter lens mount (10) fits in this groove, thus permitting the lens to be reassembled in its original position, and preventing any angular shift of the telemeter lens in the mount. The piano surface of the lens is placed toward the seat of the mount, and is secured with a clamp ring (11) and lockscrew (14).

2. Telemeter lens mount. The telemeter lens mount (10) is made of brass tubing and is 1/2 inch in width. Its inside diameter is bored for light transmission. The mount is a sliding fit into the counterbored section in the lower part of the third reduced tube section (9), and is secured after collimation with an angular alignment lockscrew (12). The mount is counterbored to carry the telemeter lens (15) and telemeter lens clamp ring (11). The mount is provided with a small lockscrew (16) located as a permanent fitting and filed off so that the protruding section of the lockscrew will allow the free disassembly and reassembly of the telemeter lens in the mount. This protruding section of the lockscrew when engaged in the stoned vertical groove in the telemeter lens periphery, prevents it from shifting angularly in the mount and also provides the original reassembly of the lens in the mount.

f. Second reduced tube section. The second reduced tube section (17) is made of phosphor bronze and is 22 1/2 inches in length. It serves to enclose the light rays to their designed clear aperture area for its length and provides a partial assembly of the upper telescope system.

The upper part has a threaded periphery alignment support section to receive the internal threaded section of the lower part of the third reduced tube section (9) and is secured together with two lockscrews (13). These lockscrews are inserted in countersunk clearance holes in the third reduced tube section (9) and screwed in tapped holes in the upper threaded periphery alignment support section of the second reduced tube section.

The external circumference is tapered from the upper alignment support section downward to the straight turned shoulder section. The inner surface is bored tapered for light transmission and threaded for antireflection, commencing from the small straight counterbored section in the lower part.

The straight turned shoulder 1 1/4 inches long in the lower part provides sufficient wall area for the small counterbored and larger counterbored threaded sections. The small counterbored section serves as an alignment support section, a sliding fit over the upper alignment support section of the first reduced tube section (23). The large counterbored threaded section engages on the upper threaded periphery of the first reduced tube section (23) and is secured to it with four lockscrews (18).

Two opposite tape straps (19) are soldered to the upper periphery wall of this reduced tube section, located 2 3/4 inches from the upper end, and retain the prism tilt and change of power shifting wire tapes (38, Figure 4-28) at their required vertical centerline position.

g. Air line adapter. The air line adapter (20) consists of a piece of flat brass air line with the upper end closed, and is provided with a 1/8-inch diameter drilled hole located 7/64 inch from the upper end. The adapter is soldered to the periphery of the upper part of the second reduced tube section (17) with both 1/8-inch holes in coincidence. The lower opening of the adapter receives the air line section (22).

h. First reduced tube section. The first reduced tube section (23) is made of cast phosphor bronze, and is 22.646 inches in length. It serves to enclose the light rays to their designed clear aperture area for this, length and provides partial assembly of the upper telescope system.

The upper part is smooth turned, to serve as an alignment support section, and has threaded periphery section. The alignment support and threaded periphery sections receive the internal threaded and counterbored alignment support sections of the lower part of the second reduced tube section (17) and are secured together with four lockscrews (18). These lockscrews are inserted in countersunk clearance holes in the second reduced tube section (17) and screwed into tapped holes in 4 the upper alignment support section of the first reduced tube section.

A shoulder flange of nominal width immediately follows the threaded periphery section, and has a diameter coinciding with the lower part of the second reduced tube section (17).

The external body of this section between the upper shoulder flange and lower bearing flange is tapered outward and downward. The inner circumference of this reduced tube section is bored tapered its entire length with a uniform wall thickness of 7/64 inch between the flanges for light transmission. It is threaded for antireflection.

The lower part is smooth turned and serves as an alignment support section in the bored diameter of the sixth inner tube section upper end coupling (30). The threaded periphery section preceding this alignment support section engages in the internal threaded section in the sixth inner tube section upper end coupling (30) and is secured with four lockscrews (33). These lockscrews are inserted in countersunk clearance holes in the upper part of the sixth inner tube section (28) with clearance holes in its upper end coupling (30) and screwed in tapped holes in the lower alignment support section of the first reduced tube section (23).

The central part of this reduced tube section is provided with a removable air line strap (26) to retain the air line section continuation (25). It is secured with two lockscrews (27) which are inserted in clearance holes in the air line strap and screwed into tapped holes in the periphery wall of this reduced tube section. The air line continuation (25) is the extension of the air line section (22) of the second reduced tube section (17), and extends the entire length of this reduced tube section.

Four tape slots are provided in both flanges, two opposite the others to provide free movement of the prism tilt and change of power shifting wire tapes (38, Figure 4-28), Two tape straps (24) are soldered to opposite sides on the periphery, located 2 1/8 inches from the upper shoulder flange to provide vertical guidance to the shifting wire tapes.

One air port is provided in the lower part, and is located 1 inch from the lower bearing flange. A wire screen is placed in the countersunk

i. Sixth inner tube section. The sixth inner tube section (28) is made of brass tubing and is 31 1/4 inches in length. Its inner and outer diameter are uniform the entire length. The upper part is a push fit and is soldered on the lower alignment support section of the sixth inner tube section upper end coupling (30) with four lockscrews (32). These lockscrews are inserted in soldered countersunk clearance holes in the upper part of the sixth inner tube section and screwed into soldered tapped holes in the lower alignment support section of the sixth inner tube section upper coupling (30), to form a permanent joint.

The lower part of this inner tube section is a push fit and is soldered on the upper alignment support section of the sixth inner tube section lower end coupling (31) with eight lockscrews (29). These lockscrews are inserted in soldered countersunk clearance holes in the lower part of the sixth inner tube section, and screwed into soldered tapped holes in the upper alignment support section of the sixth inner tube section lower end coupling (31) to form a permanent joint.

The aid line section, continuation (35) of this inner tube section extending downward from the airline section continuation (25) of the first reduced tube section (23) and the air line section (22) of the second reduced tube section (17), ends in the lower part of this inner tube section. An air line coupling (36) is soldered in the lower end of the air line section continuation (35). The upper part of this continuation (35) is retained by two soldered air line straps (39) to the periphery wall of this inner tube section.

The air line section (37) located in the lower part of this inner tube section, connects to the soldered air line coupling (36) and is retained in place with a removable air line strap (38) which is secured with two lockscrews (40). These lockscrews are inserted in clearance holes in the air line strap (38) and screwed into

Two opposite tape straps (34) are soldered to the lower part of this inner tube section periphery wall, to provide vertical guidance to the prism tilt and change of power shifting wire tapes (38, Figure 4-28).

j. Sixth inner tube section upper and lower end couplings. 1. Sixth inner tube section upper end coupling. The sixth inner tube section upper end coupling (30) is identical to the sixth inner tube section upper end coupling (26, Figure 4-20) Type II periscope. Refer to Section 4I1.

At assembly it is provided with a vertical air line slot to allow for clearance of the air line section continuation (25) extending downward from the first reduced tube section (23).

There are no air ports in this coupling as there are in the Type II periscope.

2. Sixth inner tube section lower end coupling. The sixth inner tube section lower end coupling (31) is identical to the sixth inner tube section lower end coupling (27, Figure 4-20) of the Type II periscope. Refer to Section 4I1.

At assembly it is provided with a vertical air line slot to provide clearance for the air line section (37) extending downward from the lower part of the sixth inner tube section (28).

k. Fifth inner tube section. The fifth inner tube section (41) is identical to the fifth inner tube section (34, Figure 4-20) of the Type II periscope. Refer to Section 411.

At assembly it is provided with a vertical air line slot to allow for clearance of the air line section continuation (47) of this section extending downward from the air line section (37) of the sixth inner tube section (28).

l. Upper objective lens, mount, spacer ring, and clamp ring. 1. Upper objective lens. The upper objective lens is made of two optical elements. It consists of a plano concave flint element (48) separated from the crown element with a spacer ring (50). The second is a double convex crown element (49) forming an air space doublet. The doublet is

2. Upper objective lens mount. The upper objective lens mount (45) is identical to the upper objective lens mount (38, Figure 4-20 of the Type II periscope. Refer to Section 4I1.

3. Upper objective lens spacer ring. The upper objective lens spacer ring (50) is identical to the upper objective lens spacer ring (40 Figure 4-20) of the Type II periscope. Refer to Section 4I1.

4. Upper objective lens clamp ring. The upper objective lens clamp ring (46) is identical to the upper objective lens clamp ring (39 Figure 4-20) of the Type II periscope. Refer to Section 4I1.

6F2. Description of the upper telescope system assembly Part II: second, third, and fourth inner tube sections. These three inner tube sections have new lenses, but form the necessary inner tube bodies to enclose the inter-objective parallel light ray that are deflected downward to the magnifying lower telescope system. Figure 6-6 shows the upper telescope system assembly Part II. All bubble numbers in Section 6F2 refer to Figure 6-6 unless otherwise specified.

a. Fourth inner tube section. The fourth inner tube section (1) is identical to the fourth inner tube section (1, Figure 4-21) of the Type II periscope. Refer to Section 4I2.

Two tape straps (8) are soldered to opposite sides of the periphery in the lower part to provide the vertical guidance to the prism tilt and change of power shifting wire tapes (38, Figure 4-28).

The internal diameter of this inner tube section carries a diaphragm (6) which is located in the central part and is secured with three lockscrews (7).

The upper part of this inner tube section is a push fit and is soldered on the lower alignment support section of the fourth inner tube section upper end coupling (4) with eight lockscrews (2). These lockscrews are inserted in soldered countersunk clearance holes in the upper part of the fourth inner tube section and screwed into

The lower part of this inner tube section is a push fit and is soldered on the upper alignment support section of the fourth inner tube section lower end coupling (5) with eight lockscrews (3). These lockscrews are inserted in soldered countersunk clearance holes in the lower part of the fourth inner tube section and screwed into soldered tapped holes in the upper alignment support section of the fourth inner tube section lower end coupling (5).

The air line section continuation (9) extends the entire length of this inner tube section, and is part of the air line section continuation (47, Figure 6-5) of the fifth inner tube section (41) and the air line section (37) of the sixth inner tube section (28). It is retained to this inner tube section with seven air line straps (10), which are soldered to the periphery wall.

b. Fourth inner tube section upper end coupling, diaphragm, and lower end coupling. 1. Fourth inner tube section upper end coupling. The fourth inner tube section upper end coupling (4) is identical to the fourth inner tube section upper end coupling (5, Figure 4-21) of the Type II periscope. Refer to Section 4I2.

At assembly it is provided with a vertical air line slot to allow for clearance of the air line section continuation (47, Figure. 6-5) extending downward from the fifth inner tube section (41).

2. Diaphragm. The diaphragm (6) is identical to the diaphragm (7, Figure 4-21) of the Type II periscope. Refer to Section 4I2.

3. Fourth inner tube section lower end coupling. The fourth inner tube section lower end coupling (5) is identical to the fourth inner tube section lower end coupling (6, Figure 4-21) of the Type II periscope. Refer to Section 4I2.

At assembly it is provided with a vertical air line slot to allow for clearance of the air line section continuation (9) extending downward from the fourth inner tube section (1).

Two tape straps (18) are soldered to opposite sides on the periphery wall in the lower part to provide vertical guidance to the prism tilt and change of power shifting wire tapes (38, Figure 4-28).

The upper part of the third inner tube section (11) is a push fit and is soldered on the lower alignment support section of the third inner tube section upper end coupling (16) with eight lockscrews (12). These lockscrews are inserted in soldered countersunk clearance holes in the upper part of the third inner tube section and screwed into soldered tapped holes in the lower alignment support section of the third inner tube section upper end coupling (16) to form a permanent joint.

The lower part of this inner tube section is a push fit and is soldered on the upper alignment support section of the third inner tube section lower end coupling (15) with eight lockscrews (12). These lockscrews are inserted in soldered countersunk clearance holes in the lower part of the third inner tube section and screwed into soldered tapped holes in the upper alignment support section of the third inner tube section lower end coupling (15).

The air line section continuation (21) extending downward on this inner tube section, ends in its upper part and is retained to the periphery wall of the third inner tube section with two soldered air line straps (22). An air line coupling (20) is soldered in the lower end of the air line section continuation (21).

The air line section (19) located in the upper part of this inner tube section, connects to the soldered air line coupling (20) and is retained in place with four air line straps (22) soldered on the periphery wall of this inner tube section.

d. Third inner tube section upper end coupling, diaphragms, and lower end coupling. 1. Third inner tube section upper end coupling. The third inner tube section upper end coupling (16) is identical to the third inner tube section upper end coupling (17, Figure

At assembly it is provided with a vertical air line slot to allow for clearance of the air line section continuation (9) extending downward from the fourth inner tube section (1).

2. Diaphragms. The two diaphragms (17) are identical to the two diaphragms (18, Figure 4-21) of the Type II periscope. Refer to Section 4I2.

One is secured in the bore in the lower part of the third inner tube section upper end coupling (16) with its side wall facing downward. It is secured with three lockscrews (14), which are inserted in countersunk clearance holes in the upper part of the third inner tube section (11) in clearance holes in its upper end coupling (16) and screwed into tapped holes in the diaphragm (17).

The second diaphragm (17) is secured with three lockscrews (14) which are inserted in countersunk clearance holes in the lower part of the third inner tube section (11) in clearance holes in its lower end coupling (15) and screwed into tapped holes in the diaphragm (17).

3. Third inner tube section lower end coupling. The third inner tube section lower end coupling (15) is identical to the third inner tube section lower end coupling (16, Figure 4-21) of the Type II periscope. Refer to Section 4I2.

At assembly it is provided with a vertical air line slot to allow for clearance of the air line section (19) of the third inner tube section (11).

e. Second inner tube section. The second inner tube section (23) is made of brass tubing and is 96.400 inches in length. The inner and outer diameters are uniform throughout the entire length.

The upper part of this inner tube section is a push fit and is soldered on the lower alignment support section of the second inner tube section upper end coupling (25) with four lockscrews (24). These lockscrews are inserted in soldered countersunk clearance holes in the upper part of the second inner tube section and screwed into soldered tapped holes in the lower alignment

The lower part of this inner tube section is a push fit and is soldered on the upper alignment support section of the second inner tube section lower end coupling (26) with four lockscrews (24). These lockscrews are inserted in soldered countersunk clearance holes in the lower part of the second inner tube section (23) and screwed into soldered tapped holes in the upper Alignment support section of the second inner tube section lower end coupling (26) to form a permanent joint.

Two tape straps (29) are soldered on opposite sides of the periphery in the lower part to provide vertical guidance for the prism tilt and change of power shifting wire tapes (38, Figure 4-28).

The air line section continuation (30) extends the entire length of this inner tube section from the air line section (19) of the third inner tube section (11). This air line section continuation (30) is retained to the periphery wall of this inner tube section with six soldered air line straps (32) and a removable air line strap (31) secured with two lockscrews (33). These lockscrews are inserted in clearance holes in the air line strap (31) and screwed into tapped holes in the periphery wall of this inner tube section.

The internal diameter of this inner tube section carries three diaphragms (27). The upper diaphragm is located 42 13/16 inches from its upper end. The second diaphragm is located 18 inches from the upper diaphragm, while the lower diaphragm is located 9 1/2 inches from the center diaphragm. Each diaphragm is located with its side wall facing upward and is secured with three lockscrews (28), which are inserted in countersunk clearance holes in this inner tube section and screwed into tapped holes in each diaphragm.

f. Second inner tube section, upper end coupling, diaphragms, and lower end coupling. 1. Second inner tube section upper end coupling. The second inner tube section upper end coupling (25) is identical to the second inner tube section upper end coupling (25, Figure 4-21) of the Type II periscope. Refer to Section 4I2.

2. Diaphragms. The three diaphragms (27) are identical to the diaphragm (7, Figure 4-21) of the Type II periscope. Refer to Section 4I2.

3. Second inner tube section lower end coupling. The second inner tube section lower end coupling (26) is identical to the second inner tube section lower end coupling (26, Figure 4-21) of the Type II periscope. Refer to Section 4I2.

6F3. Disassembly of Part I. The first, second, third, fourth, and fifth reduced tube sections and the fifth and sixth inner tube sections are disassembled in the following manner. (All bubble numbers in Sections 6F3 and 4 refer to Figure 6-5 unless otherwise specified.)

1. Separation of the lower part of the fifth reduced tube section (1) from the upper part of the fourth reduced tube section (2) proceeds as follows:

2. Remove the two lockscrews (5) from the upper part of the fourth reduced tube section (2). These lockscrews are unscrewed from tapped holes in the fifth reduced tube section (1).

3. Unscrew the fifth reduced tube section (1) from the upper part of the fourth reduced tube section (2).

4. Separation of the lower part of the fourth reduced tube section (2) from the upper part of the third reduced tube section }(9 degrees) proceeds as follows:

5. Remove the two lockscrews (7) from the lower part of the fourth reduced tube section (2). These lockscrews are unscrewed from tapped holes in the third reduced tube section

6. Unscrew the fourth reduced tube section (2) from the upper part of the third reduced tube section (9).

7. Remove the two lockscrews (5) from the upper eyepiece lens mount (3). These lockscrews are unscrewed from the tapped holes in the mount, and are carried out of countersunk clearance holes in the lower part of the fourth reduced tube section (2).

9. Remove the lockscrew (6) from the upper eyepiece lens mount (3) and its clamp ring (4). This lockscrew is unscrewed from the tapped hole in the clamp ring (4).

10. Using a special wrench, unscrew the upper eyepiece lens clamp ring (4) and remove it from the upper eyepiece lens mount (3).

11. Place the upper eyepiece lens mount (3) on a piece of lens tissue, resting it on its upper face. Using a piece of lens tissue on the lower face, press downward on the lens tissue and the upper eyepiece lens (8) for its removal. Wrap the lens doublet in clean lens tissue and store it in a box to prevent scratches and breakage.

12. Separation of the third reduced tube section (9) from the upper part of the second reduced tube section (17) proceeds as follows:

13. Remove the two lockscrews (13) from the lower part of the third reduced tube section (9). These lockscrews are unscrewed from tapped holes in the second reduced tube section (17).

14. Unscrew the third reduced tube section (9) from the upper part of the second reduced tube section (17).

15. Remove the angular alignment lockscrew (12) from the circumferential slot in the lower part of the third reduced tube section. This lockscrew is unscrewed from the tapped hole in the telemeter lens mount (10) and is carried out of the circumferential slot.

16. Remove the assembled telemeter lens mount (10) from the lower part of the third reduced tube section. This is done by means of a special pair of calipers inserted in opposite holes in the telemeter lens clamp ring (11). Slide the telemeter lens mount out of the lower part of the third reduced tube section, removing the mount, telemeter lens (15), its clamp ring (11), and its lockscrews (14).

18. Turn the telemeter lens mount (10), resting it on its lower face on a piece of lens tissue. If necessary, using a piece of lens tissue, press downward on the plano surface of the telemeter lens (15), removing the lens and the clamp ring (11). Wrap the lens in clean lens tissue and store it in a box to prevent scratches and breakage.

19. Separation of the second reduced tube section (17) from the upper part of the first reduced tube section (23) proceeds as follows:

20. Remove the four lockscrews (18) from the lower part of the second reduced tube section (17). These lockscrews are unscrewed from tapped holes in the first reduced tube section (23).

21. Unscrew the second reduced tube section (17) from the upper part of the first reduced tube section (23).

22. Separation of the first reduced tube section (23) from the sixth inner tube section upper end coupling (30) proceeds as fellows:

23. Remove the four lockscrews (33) from the upper part of the sixth inner tube section (28). These lockscrews are unscrewed from tapped holes in the first reduced tube section (23).

24. Unscrew the first reduced tube section (23) from the 6th inner tube section upper end coupling (30).

25. Separation of the fifth inner tube section (41) from the sixth inner tube section lower end coupling (31) proceeds as follows:

26. Remove the four lockscrews (42) from the fifth inner tube section (41). These lockscrews are unscrewed from tapped holes in the lower alignment support section of the sixth inner tube section lower end coupling (31).

27. Unscrew the fifth inner tube section (41) from the sixth inner tube section lower end coupling (31). Carry the mounted upper objective lens (48 and 49), its mount (45), spacer

28. Remove the four lockscrews (43), unscrewing them from tapped holes in the upper objective lens mount (45), and carrying their out of countersunk clearance holes in the fifth inner tube section (41).

29. Remove the assembled upper objective lens mount (45) from the fifth inner tube section (41). The mount can be slid out from either end. Remove the assembled mount (45) with the upper objective lens (48 and 49), upper objective lens spacer ring (50), upper objective lens clamp ring (46), and its lockscrew (44).

30. Remove the lockscrew (44) from the upper objective lens mount (45). This lockscrew is unscrewed from the tapped hole in the upper objective lens clamp ring (46).

31. Using a special wrench, unscrew the upper objective lens clamp ring (46) from the upper part of the upper objective lens mount (45).

32. Place the lower part of the upper objective lens mount (45) over a special padded wooden block. The mount will slide down over the block, with the upper objective lens elements (48 and 49) and the upper objective lens spacer ring (50) remaining on the padded part of the wooden block.

33. Wrap the flint and crown elements of the upper objective lens air-space doublet (48 and 49) with lens tissue and store them in a box or place them to one side to prevent scratches and breakage.

6F4. Reassembly of Part I. The first, second, third, fourth, and fifth reduced tube sections and the fifth and sixth inner tube sections are reassembled in the following manner:

1. Using an air hose, blow out the internal surfaces of the reduced and inner tube sections. If various sized circular brushes are available, they should be used first. This procedure should be carried out with the clamp rings and lens mounts.

2. Clean the upper eyepiece lens (8) with clean lens tissue. Surface dust can be removed

3. Place the upper eyepiece lens (8) in the upper eyepiece lens mount (3). The crown element of this doublet is placed toward the seat of the mount.

4. Place the upper eyepiece lens clamp ring (4) in the internal threaded section in the upper part of the upper eyepiece lens mount (3). Screw this clamp ring tight against the plano face of the upper eyepiece lens doublet. The lockscrew holes should coincide when the lens doublet is tightened sufficiently.

5. Insert and secure the lockscrew (6), inserting it in the countersunk clearance hole in the mount (3) and screwing it into the tapped hole in the upper eyepiece lens clamp ring (4).

6. Reassemble the assembled upper eyepiece lens mount (3) sliding it in the lower part of the fourth reduced tube section (2). The clamp ring side of the assembled mount should be located upward.

7. Secure the upper eyepiece lens mount (3) temporarily with two lockscrews (5). These lockscrews are inserted into countersunk clearance holes in the fourth reduced tube section (2) and screwed into tapped holes in the mount.

8. The connection of the lower part of the fifth reduced tube section (1) in the upper part of the fourth reduced tube section proceeds as follows: Screw the lower part of the fifth reduced tube section (1) into the upper part of the fourth reduced tube section (2) until the lockscrew holes coincide.

9. Insert and secure the two opposite lockscrews (5), inserting them in countersunk clearance holes in the fourth reduced tube section (2), screwing them into tapped holes in the fifth reduced tube section (1), thus securing the fourth and fifth reduced tube sections together.

10. The connection of the lower pat of the fourth reduced tube section (2) on the upper part of the third reduced tube section (9) proceeds as follows: Screw the lower part of the fourth reduced tube section (2) on the upper part of the third reduced tube section (9) until the lockscrew holes coincide.

12. Clean the telemeter lens (15), in similar manner to that outlined in Step 2 of this section for the upper eyepiece lens (8).

13. Place the telemeter lens in the telemeter lens mount (10). The etched graduations on the piano side of the lens are placed toward the seat in the mount, with the stoned vertical slot meshing with the inward projecting lockscrew (16) in the mount.

14. Slide the telemeter lens clamp ring (11) in the telemeter lens mount (10) to the convex face of the telemeter lens (15) so that opposite lockscrew holes of the mount and clamp ring coincide.

15. Insert and secure the two lockscrews (14). These lockscrews are inserted in countersunk clearance holes in the telemeter lens mount (10) and screwed into tapped holes in the telemeter lens clamp ring (11).

16. Slide the telemeter lens (15) with its mount (10) into the lower part of the third reduced tube section (9), with the clamp ring side of the assembled mount facing downward.

17. Insert and secure the angular alignment lockscrew (12) in the circumferential slot in the lower part of the third reduced tube section (9). This lockscrew is screwed into the tapped hole in the telemeter lens mount (10).

18. The connection of the lower part of the third reduced tube section (9) on the upper part of the second reduced tube section (17) proceeds as follows: Screw the lower part of the third reduced tube section (9) on the upper part of the second reduced tube section (17), until the lockscrew holes coincide.

19. Insert and secure the two lockscrews (13). These lockscrews are inserted in countersunk clearance holes in the third reduced tube section (9) and screwed into tapped holes in the second reduced tube section (17). This secures the second and third reduced tube sections together.

21. Insert and secure the four lockscrews (18). These lockscrews are inserted in countersunk clearance holes in the second reduced tube section (17) and screwed into tapped holes in the first reduced tube section (23). This secures the first and second reduced tube sections together.

22. The connection of the lower part of the first reduced tube section (23) in the sixth inner tube section upper end coupling (30) proceeds as follows: Screw the lower part of the first reduced tube section (23) in the sixth inner tube section upper end coupling (30), supporting the assembled reduced tube sections during this connection procedure, until the lockscrew holes coincide.

23. Insert and secure the four lockscrews (33). These lockscrews are inserted in countersunk clearance holes in the sixth inner tube section (28) into clearance: holes in the sixth inner tube section upper end coupling (30) and screwed in tapped holes in the first reduced tube section (23). This secures the first reduced tube section and sixth inner tube section upper end coupling together.

24. Clean the upper objective lens flint element (48) and the crown element (49) in similar manner to the procedure described in Step 2, of this section for the upper eyepiece lens (8).

25. Place the plano side of the flint element (48) on the padded part of a special wooden block. Place the upper objective lens spacer ring (50) on the concave surface of the flint element (48). Place the longest radius of the double convex crown element (49) on the spacer ring. Line up the periphery of both, elements and the spacer ring.

26. Place the upper objective lens mount (45) with the clamp ring side facing downward, over the assembled upper objective lens doublet and the padded wooden block. Turn the complete assembly with the padded block over, so

27. Place the upper objective lens clamp ring (46) in the threaded section in the upper part of the upper objective lens mount (45). Using a special wrench, screw this clamp ring tightly against the plano side of the flint element (48) until the lockscrew holes coincide.

28. Insert and secure the lockscrew (44). This lockscrew is inserted in a countersunk clearance hole in the upper objective lens mount (45) and screwed into the tapped hole in the upper objective lens clamp ring (46).

29. Slide the assembled upper objective lens mount (45) into the fifth inner tube section (41). The clamp ring side of the assembled mount should face upward.

30. Secure the upper objective lens mount (45) temporarily with four lockscrews (43). These lockscrews are inserted in countersunk clearance holes in the fifth inner tube section (41) and screwed into tapped holes in the upper objective lens mount (45).

31. The connection of the upper part of the fifth inner tube section (41) on the sixth inner tube section lower end coupling (31) proceeds as follows: Screw the upper part of the fifth inner tube section (41) on the lower alignment support section of the sixth inner tube section lower end coupling (31) until the lockscrew holes coincide.

32. Insert and secure the four lockscrews (42). These lockscrews are inserted in countersunk clearance holes in the fifth inner tube section (41), and screwed into tapped holes in the sixth inner tube section lower end coupling (31), securing the fifth inner tube section and the sixth inner tube section lower end coupling together.

33. Place a canvas boot over the upper end of the fifth reduced tube section (1) and the lower end of the fifth inner tube section (41) to prevent foreign matter entering and adhering to the cleaned lenses.

6F5. Disassembly of Part II. The second, third, and fourth inner tube sections are disassembled in the following manner (all bubble numbers in Sections 6F5 and 6 refer to Figure 6-6 unless otherwise specified):

2. Remove the four lockscrews (3) from the fourth inner tube section lower end coupling (5). These lockscrews are unscrewed from tapped holes in the upper alignment support section of the third inner tube section upper end coupling (16).

3. Unscrew the fourth inner tube section lower end coupling (5) from the third inner tube section upper end coupling (16). This removes the fourth inner tube section (1) and its lower end coupling (5) from its connection with the third inner tube section (11) and its upper end coupling (16). The diaphragm (6) should of be removed from the central part of the fourth inner tube section (1) unless the periscope is known to be flooded with sea water. To remove it would require the removal of either the upper or lower end couplings which are soldered to form a permanent joint.

4. Separation of the third inner tube section lower end coupling (15) from the second inner tube section upper end coupling (25) proceeds as follows:

5. Remove the four lockscrews (13) from the third inner tube section lower end coupling (15). These lockscrews are unscrewed from the tapped holes in the upper alignment support section of the second inner tube section upper end coupling (25).

6. Unscrew the third inner tube section lower end coupling (15) from the second inner tube section upper end coupling (25). This removes the third inner tube section (11) and its lower end coupling (15) from its connection with the second inner tube section (23) and its upper end coupling (25).

7. If it is necessary to remove the two diaphragms (17) from the third inner tube section upper and lower end couplings (16 and 15), remove the three lockscrews (14) each from the upper} and lower parts of the third inner tube section (11). These lockscrews are unscrewed from tapped holes in each diaphragm (17). The diaphragms can be pulled out easily, as they are a push fit into these two couplings.

6F6. Reassembly of Part (I. The second, third, and fourth inner tube sections are reassembled in the following manner:

1. Using an air hose, blow out the internal surfaces of the second inner tube section. If a circular brush is available, it should be used first. This procedure is also carried out with each succeeding inner tube section and couplings.

2. Place the two diaphragms (17) in the third inner tube section upper and lower end couplings (16 and 15). The side wall of each diaphragm should face inward toward the inner part of this inner tube section.

3. Insert and secure the three lockscrews each (14) into each diaphragm (17). These lockscrews are inserted into countersunk clearance holes in the upper and lower part of the third inner tube section (11), further into clearance holes in their respective couplings, and screwed into tapped holes in the diaphragms.

4. The connection of the third inner tube section lower end coupling (15) on the second inner tube section upper end coupling (25) proceeds as follows: Screw the third inner tube section lower end coupling (15) on the second inner tube section upper end coupling (25).

5. Insert and secure the four lockscrews (13). These lockscrews are inserted in countersunk clearance holes in the third inner tube section lower end coupling (15) and screwed in tapped holes in the upper alignment support section of the second inner tube section upper end coupling (25). This secures the third inner tube section lower end coupling and second inner tube section upper end coupling together.

6. The connection of the fourth inner tube section lower end coupling (5) on the third inner tube section upper end coupling (16) proceeds as follows: Screw the fourth inner tube section lower end coupling (5) on the third inner tube section upper end coupling (16).

8. Place a canvas boot over each end of this assembly to prevent dust and foreign matter from entering the cleaned inner tube sections.

6G2. Description of the objective operating mechanism assembly. This mechanism consists of the necessary parts which transmit the displacement of the lower (split) objective lens and mount assembly, and is described as follows. Figure 6-7 shows this assembly. All bubble numbers in Sections 6G2, 3, and 4 refer to Figure 6-7 unless otherwise specified.

a. Sliding track. The sliding track (19) is made of cast/ phosphor bronze and is 7 7/8 inches in length. It is machined cylindrical, with a large shoulder flange of nominal thickness at the upper part. Its internal diameter is machined for light transmission and is threaded for anti-reflection.

A brass plate spacer 1/16 inch thick and 1/4 inch wide is inserted and soldered in the slots cut directly in the centerline in each side of the bore in the large shoulder flange. The spacer when assembled is flush with the face of the large shoulder flange. It prevents stray light from entering the gap between the two split lens

Two longitudinal T-slots are milled parallel to the centerline, at an appropriate center distance from the vertical centerline on each side; there are two more 180 degrees apart on the opposite side in the large shoulder flange. These longitudinal T-slots project inward on each side, to correspond to an appropriate center distance from the vertical centerline, to receive two

The sliding track has a cylindrical tube section 7 1/2 inches in length below the large shoulder flange. Next to the large shoulder flange is a small shoulder to receive the shallow centerbored section in the operating gear (22). An undercut section 3 3/16 inches in length is provided to allow a bearing shoulder thickness of 7/64 inch in the upper and lower part, for the upper and lower remaining shoulders of the operating gear bore.

The lower bearing section carries the operating gear retaining ring (21) secured to the sliding track with six lockscrews (27), while the remainder of this lower bearing section serves as an alignment support section for the track sleeve (18).

b. Operating gear. The operating gear (22) is made of cast phosphor bronze and is 4 11/16 inches in length. It is machined cylindrical with a large shoulder flange in the upper part. It is counterbored in the center part of the bore to provide only sufficient bearing surface over the bearing section shoulders of the sliding track (19). The large shoulder flange is counterbored a shallow depth and is a sliding fit over the small shoulder next to the large, shoulder flange of the sliding track (19).

The large shoulder flange has two cam grooves of appropriate depth and width in its face, which extend 1 degree beyond the vertical centerline. This 1 degree extension provides sufficient clearance for the cam shoes (26) which have centers in the vertical centerline of the operating gear (22) at zero displacement of the lower (split) objective lens (8A and 8B). Using the vertical centerline as a reference, these two cam grooves are machined 153 degrees circumferentially on opposite sides starting 180 degrees apart.

The operating gear fits over the two bearings of the sliding track (19) with its large shoulder flange face a metal-to-metal bearing contact with the lower face of the sliding track large shoulder flange. It is retained from axial displacement on the sliding track (19) by an

The outer surface below the large shoulder flange has two shoulders, one near the center, 5/8 inch wide, and the other at the lower end. The center shoulder has 160 teeth of 32 diametral pitch cut in its periphery, which engage with an assembled operating gear pinion (2) that projects upward from the rectangular bearing projection of the track sleeve (18) assembled on the operating gear pinion shaft (20).

The operating gear stop (23) is assembled in a shallow circumferential slot 0.047 inch deep and 1 1/8 inch long, located in the lower shoulder of this operating gear. The stop is secured in the shallow slot with four lockscrews (29). These lockscrews are inserted in countersunk clearance holes in the stop and screwed into tapped holes in the operating gear shoulder. The centerline of the assembled operating gear stop in the shallow slot is the vertical reference line of the operating gear, the stop covering a distance of 26 degrees.

The observation position stop (24) and the maximum displacement stop (25) have a predetermined location on the operating gear retaining ring (21) of approximately 166 degrees between their contacting surfaces, thus providing the operating gear stop (23) a travel of approximately 140 degrees with the operating gear.

c. Operating gear retaining ring. The operating gear retaining ring (21) is made of cast phosphor bronze and is 3/4 inch in width. It is cylindrical with an undercut shoulder and a large shoulder flange. It is bored a push fit over the lower bearing section of the sliding track (19), and is secured with six lockscrews (27). These lockscrews are inserted in countersunk clearance holes in the undercut shoulder and screwed into tapped holes in the sliding track tube section periphery wall.

The large shoulder flange has a rectangular slot to provide clearance for the rectangular cast bearing projection of the track sleeve (18) extending upward from the lower face of this . flange a distance of 21 11/32 inches.

The undercut shoulder and large shoulder flange are provided with two rectangular 90 degrees

The large shoulder flange has six equally spaced countersunk clearance holes to receive lockscrews (28) which extend into tapped holes in the upper face of the track sleeve (18). The retaining ring serves to retain the operating gear (22) axially and also serves as a stationary support for the track sleeve (18).

d. Track sleeve. The track sleeve (18) is made of cast phosphor bronze and is 5 31/32 inches in length. The upper part has a cast rectangular bearing projection that extends upward from its upper face through the rectangular slot in the operating gear retaining ring (21) a sufficient distance for the support of the operating gear pinion (2). It is provided with a reamed hole in its center axis which serves as a bearing for the operating gear pinion shaft (20).

It is bored a push fit on the lower bearing alignment support section of the sliding track (19). The rectangular bearing projection is counterbored for clearance over the undercut shoulder and in the rectangular slot of the operating gear retaining ring (21). The lower part is counterbored to serve as an alignment support section with a threaded section in the lower part to receive the upper alignment support and threaded periphery section of the first inner tube section upper end coupling (23) which is secured with four lockscrews (9).

The lower part of the track sleeve is cored a depth of 2 inches, leaving an inner body wall and an outer body wall with four inter-connecting webs. One web is larger below the rectangular bearing projection which has a reamed hole for the operating gear pinion shaft (20). The outer body wall of smaller diameter extends downward a short distance from the bearing flange face and tapers inward. It serves to provide sufficient body wall for attachment to the first inner tube section upper end coupling (23, Figure 6-10).

Four tape slots are provided in the bearing flange of this track sleeve, two opposite the others, for the prism tilt and change of power shifting wire tapes (38, Figure 4-28). A vertical air line slot is provided at assembly in the bearing for the air line section continuation (16) extending downward from the air line section continuation (30, Figure 6-6) of the second inner tube section (23, figure 6-6).

e. Mounting plates, guide keys, and integral shafts, and guides. 1. Mounting plates. The mounting plate halves left and right (1) are identical to the mounting plate halves left and right (5, Figure 4-23) used in the Type II periscope. Refer to Section 4J5.

2. Mounting date guide keys and integral shafts. The two mounting plate guide keys and integral shafts (4) are identical to the mounting plate guide keys and integral shafts (15, Figure 4-23) used in the Type II periscope. Refer to Section 4J5.

3. Mounting plate guide keys. The two mounting plate guide keys (5) are identical to the mounting plate guide keys (17, Figure 4-23) used in the Type II periscope. Refer to Section 4J5.

f. Cam shoes. The two cam shoes (26) are identical to the cam shoes (4, Figure 4-23) used in the Type II periscope. Refer to Section 4J5. The factory detail numbers differ between the two periscopes, but their construction is identical.

g. Maximum displacement stop. The maximum displacement stop (25) is made of cold rolled steel and is a rectangular circumferential design. It conforms to the contour of the rectangular circumferential recess in the undercut shoulder of the operating gear retaining ring (21) and is provided with two countersunk clearance holes for lockscrews (29) to secure it in the recess.

It serves to restrict the operating gear stop (23) from displacing the lower (split) objective lens (8A and 8B, Figure 6-13) beyond its required maximum displacement. It also relieves the torque of the cam shoes (26) so that they do not contact the ends of the cam grooves in the operating gear (22) at this position.

h. Observation position stop. The observation stop (24) is identical to the maximum displacement stop (25), and is located in the rectangular circumferential recess in the opposite side of the operating gear retaining ring (21) in the undercut shoulder section. It serves to relieve the torque from the cam shoes (26) so that they do not contact the ends of the cam grooves in the operating gear (22) in the observing position. It also serves as a stop to restrict the lower (split) objective lens (8A and 8B, Figure 6-13) for the single image or whole lens position.

i. Operating gear stop. The operating gear stop (23) is made of cold rolled steel and is shaped rectangular. It covers are length of 26 degrees of a circumferential step design, with the seat of the stop conforming to the shallow circumferential slot in the lower shoulder of the operating gear (22) and is secured with four lockscrews (29). These lockscrews are inserted in countersunk clearance holes in the stop and screwed into tapped holes in the shallow circumferential slot in the operating gear lower shoulder (22).

j. Operating gear pinion. The operating gear pinion (2) is identical to the operating gear pinion (12, Figure 4-23) used in the Type II periscope. Refer to Section 4J5.

k. Operating gear pinion shaft. The operating gear pinion shaft (20) is almost identical to the operating gear pinion shaft (13, Figure 4-23) used in the Type II periscope, except that it is 2 inches shorter. Refer to Section 4J5.

1. Stadimeter transmission shaft coupling. The stadimeter transmission shaft coupling (3) is identical to the stadimeter transmission shaft coupling (14, Figure 4-23) used in the Type II periscope. Refer to Section 4J5.

m. Coupling sleeve. The coupling sleeve (17) is identical to the coupling sleeve (34, Figure 4-23) used in the Type II periscope, except that it is 4 inches shorter. Refer to Section 4J5. At assembly it is provided with a vertical slot for the air line section continuation (16) Which extends its entire length from the air line section continuation (30, Figure 6-6) of the second inner tube section (23).

A counterbored section 0.020 inch deep, commencing 1 7/8 inch from the upper end for the same distance, provides clearance for the assembled parallel moving lower (split) objective lens mount half, in case it is collimated beyond the approximate clearance allowed.

6G3. Disassembly. The objective operating mechanism assembly is disassembled in the following manner:

1. Remove the six lockscrews (28) from the operating gear retaining ring (21). These

2. Turn the complete assembly, allowing it to rest on the mounting plates (1). A helper should hold downward on the operating gear (22) large shoulder flange as the track sleeve (18) is slowly carried off the sliding track (19). The operating gear pinion (2) rests on the lower face of the operating gear large shoulder flange lower face as the track sleeve (18) is removed. The operating gear pinion (2) and its shaft (20) are carried off with it.

3. Remove the operating gear pinion (2) with its shaft (20), carrying the shaft out of the rectangular bearing projection of the track sleeve through the upper end.

4. Remove the two lockscrews (10) from opposite sides of the operating gear pinion (2). Pull the operating gear pinion off the operating gear pinion shaft (20). The woodruff key (7) remains in the shaft.

5. Remove the six lockscrews (27) from the operating gear retaining ring (21), unscrewing them from tapped holes in the sliding track (19).

6. Slowly carry the operating gear retaining ring (21) off the lower end of the sliding track.

7. Remove the four lockscrews (29), unscrewing two each from the observation position and maximum displacement stops (24 and 25) from tapped holes in the operating guar retaining ring milled recesses (21). Apply reference marks to both stops and the undercut shoulder section of the operating gear retaining ring (21) for proper reassembly. Remove the observation position and maximum displacement stops (24 and 25).

8. Remove the operating gear (22) from the tube section of the sliding track (19).

9. Remove the four lockscrews (29) from the operating gear stop (23). These lockscrews are unscrewed from the tapped holes in the lower shoulder circumferential slot of the operating gear (22).

11. Remove the three lockscrews (13) from each of the two mounting plate guides (6). These lockscrews are unscrewed from tapped holes in the large shoulder flange face on opposite sides of the sliding track (19). Remove the two mounting plate guides (6).

12. Remove the two lockscrews (12) from the two mounting plate guide keys (5). These lockscrews are unscrewed from the two mounting plate halves (1). Remove the two mounting plate guide keys from the T-slots in opposite sides of the sliding track (19).

13. Carefully slide out each mounting plate half (1) with the mounting plate guide keys and integral shafts (4), moving them outward in opposite directions.

14. Remove the two taper pins (14) from the large eccentric section of the two mounting plate halves (1). Drive out the two mounting plate guide keys and integral shafts (4) from both mounting plate halves.

6G4. Reassembly. The objective operating mechanism is reassembled in the following manner:

1. Apply Lubriplate No. 110 lightly to all rotating parts as the reassembly procedure is followed.

2. Assemble the mounting plate guide keys and integral shafts (4) in the reamed holes in the large eccentric part of the two mounting plate halves (1) checking their corresponding reference marks for proper reassembly. The long section of each integral shaft section is inserted from the lower face and secured with a taper pin (14).

3. Stand the sliding track (19) in a vertical position resting it on its lower end. Place one and then the other of the two mounting plate halves (1) on the large shoulder flange face of the sliding track (19). Carefully slide the mounting plate guide keys of the assembled integral shafts into the elongated T-slots in the sliding track in opposite directions, noting the reference marks for correct reassembly.

5. Place one and then the other of the two mounting plate guides (6) over the side shoulder of each mounting plate half, noting their reference marks on the sliding track large shoulder flange face (19). Secure each with three lockscrews (13), screwing them into tapped holes in the large shoulder flange on opposite sides. The mounting plate guides are placed 180 degrees apart.

6. Place the two earn shoes (26) on the two mounting plate guide keys and integral stub shafts (4), placing the thinner wall of the cam shoe outward on each side.

7. Place the operating gear (22) on the tube section of the sliding track (19). The upper face of the operating gear large shoulder flange (22) contacts the lower face of the sliding track large shoulder flange (19), and the cam shoes (26) are fitted into the cam grooves in the operating gear (22). The proper position of the operating gear (22) for its contact with the sliding track large shoulder flange (19) is obtained from corresponding reference marks on the sliding track.

8. Place the operating gear retaining ring (21) on the tube section of the sliding track (19). Check to ascertain that the scribed lines on the operating gear (22) lower shoulder and the operating gear retaining ring are in coincidence. These scribed lines represent the position of the cam shoes (26) in the ends of the cam grooves for the observing position. Insert the six lockscrews (27) in countersunk clearance holes in the operating gear retaining ring (21) and screw them into tapped holes in the sliding track tube section (19) for its securement.

9. Place the observation position and maximum displacement stops (24 and 25) in their respective rectangular circumferential slots in the operating gear retaining ring (21) and secure each with two lockscrews (29).

11. Place the operating gear pinion (2) on the operating gear pinion shaft (20), sliding it over the inserted woodruff key (7) located in the upper part of this shaft. Secure the pinion with two lockscrews (10), screwing them into tapped holes in opposite sides of the pinion and into spotted recesses in the shaft.

12. Place the operating gear pinion shaft (20) in the reamed hole axis in the track sleeve rectangular bearing projection.

13. Turn the complete assembly, allowing it to rest on the mounting plates (1). Place the track sleeve (18) with the assembled operating gear pinion (2) and its shaft (20) on the sliding track (19). Allow the pinion to rest on the operating gear large shoulder flange face (22) as the rectangular bearing projection is located in the rectangular circumferential slot in the operating gear retaining ring (21). When located properly, slowly push the track sleeve on the alignment support section of the sliding track (19) until it contacts the shoulder flange of the operating gear retaining ring (21). Insert and secure the six lockscrews (28), inserting them in countersunk clearance holes in the retaining ring and screwing them into tapped holes in the upper face of the track sleeve.

14. Wrap up both ends of the objective operating mechanism assembly until required for its connection to the first inner tube section upper end coupling (23) to preserve the cleanliness of this assembly.

6G5. Description of the stadimeter housing assembly. The stadimeter housing assembly is described in the following manner:

a. General. This assembly is similar to the stadimeter housing assembly used in the Type II periscope except that it contains the alterations required for computing the estimated range of the target and the deletion of the course angle mechanism. The scale housing mechanisms and the stadimeter housing are altered. Therefore, the variance alone will be described.

This assembly contains gearing which is connected to the internal mechanism of the

The stadimeter housing assembly is coupled to the operating gear pinion shaft (20, Figure 6-7) of the objective operating mechanism assembly by means of the stadimeter transmission shaft (12, Figure 6-10) and the stadimeter transmission shaft coupling (3). The stadimeter transmission shaft (12, Figure 6-10) extends through a bearing hole in the spider (2) where its thrust is maintained by two thrust collars (4) secured with taper pins (10). These thrust collars (4) maintain the axial thrust of the shaft on either side of the spider (2). The eyepiece skeleton (42, Figure 4-28) has a clearance hole in its large shoulder flange to accommodate the stadimeter transmission shaft (12, Figure 6-10).

The lower (split) objective lens and mount assembly is secured to the objective operating mechanism assembly by means of four stadimeter collimating screws (13, Figure 4-22). The stadimeter housing assembly is secured to the eyepiece box (11, Figure 4-29) by means of four housing bolts (30, Figure 4-24). The stadimeter housing assembly modifications are shown in Figure 6-8. Alt bubble numbers in Sections 6G5, 6, and 7 refer to Figure 6-8 unless otherwise specified.

b. Stadimeter housing. The stadimeter housing (8) is almost identical to the stadimeter housing (67, Figure 4-24) used in the Type II periscope, except for the construction of the front and rear scale housing sections. The center section which carries the transmission mechanism is identical, therefore, the scale housing sections and the scale housing mechanisms alone are described.

The front scale housing only will be described as the rear scale housing is of identical design. The internal part of this section is cored following the outer conical wall of the section a short distance, at which point it is cored inward to allow a stationary undercut shoulder section to serve as the height scale mount. It is bored to allow free actuation of the range scale mount (9). A counterbored section is provided in the outer part to allow sufficient area for the indicator mount (21) and its free actuation.

The lower inner wall of this section is provided with a reamed hole in its axis having a depth of 1/2 inch with a smaller tapped hole below it of 11/32-inch depth to receive the

The lower inner wall is machined smooth, serving as a contact face for the lower range scale mount housing ball bearing (2). The shallow counterbored section in the inner wall face serves as a grease cell for this ball bearing.

A tapped hole is provided in the lower conical wall of this section to receive the alemite fitting (82, Figure 4-24) for the introduction of grease. In the upper part of the conical wall and height scale mount section, it has a concave clearance provision for the range scale actuating bevel gear pinion (23).

c. Range scale actuating bevel gear pinion. The range scale actuating bevel gear pinion (23) replaces that used in the Type II periscope (10, Figure 4-24). It is made of phosphor bronze with a reamed hole in its center axis. The large diameter is provided with 26 bevel teeth of 32 diametral pitch, with a pitch cone line angle of 21 degrees 36 minutes, to mesh with 78 bevel teeth of a range scale actuating bevel gear (11) having a pitch cone line angle of 68 degrees 24 minutes. It is provided with a hub section which faces toward the assembled ball bearing (14, Figure 4-24) located in the wall of the scale housing section. Both, gear pinions are a push fit on the long and short transmission shafts (4 and 53, Figure 4-24) secured with a taper pin (5). Both pinions operate their respective range scale actuating bevel gears (11) for the front and roar scale housing mechanisms.

d. Indicator mount. The indicator mount (21) is made of bronze and is shape cylindrical. It has a width of 0.210 inch and is a sliding fit in the large counterbored section area, resting on the seat of this counterbored section.

An undercut groove is provided in its periphery for the protrusion of three retaining screws (22). These screws are inserted in three equally spaced countersunk taped holes in the outer wall of the scale housing section. Their protrusion in the indicator mount groove retains it in its seat, and permits free rotation of the mount. The face of this indicator mount is flush with the outer face of the scale housing section and the assembled height scale dial (13).

The mount face carries an indicator (20) separated with an indicator shim (19) to raise

e. Range scale actuating bevel gear. The range scale actuating bevel gear (11) is made of phosphor bronze. The large diameter has 78 teeth of 32 diametral pitch, with a pitch cone line angle of 68 degrees 24 minutes, to mesh with 26 bevel teeth of a range scale actuating bevel gear pinion (23) having a pitch cone line angle of 21 degrees 36 minutes.

The lower face has an undercut shoulder with its corner rounded off. It is bored to accommodate the range scale mount housing (10) and the range scale mount housing shaft (12). It is provided with two counterbored sections in the upper part. The small counterbored section is threaded to engage on the threaded periphery section of the range scale mount housing (10), while the large counterbored section receives the large shoulder of the above housing. The range scale mount housing (10) is secured in this bevel gear with four lockscrews (24). These lockscrews are inserted in four tapped holes in the hub section of the bevel gear and extend into the spotted recesses in the range scale mount housing (10). The axial height adjustment of this bevel gear in mesh with the range scale actuating bevel gear pinion (23) is maintained by the range scale mount housing (10) in this bevel gear, as it is not secured against the counterbored seat.

f. Range scale mount housing ball bearings. The two range scale mount housing ball bearings (2) are of a torque tube type. Both ball bearings are a push fit in the upper and lower counterbored section in the range scale mount housing (10), with the outer races resting against the seats in the counterbored sections. The range scale mount housing shaft (12)

g. Range scale mount housing. The range scale mount housing (10) is made of brass and is 31/32 inch in length. It is provided with three shoulder sections. The small undercut shoulder section is a sliding fit in the bore of the range scale actuating bevel gear (11). The medium shoulder section periphery is threaded to engage in the internal threaded section of the above bevel gear to maintain its height adjustment, while the large shoulder section is a sliding fit in the counterbored section and is secured with 4 lockscrews (24). These lockscrews, extending from tapped holes in the bevel gear hub, extend into spotted recesses in the large shoulder section.

The housing is bored to accommodate the range scale mount housing shaft (12) and is provided with two counterbored sections. The lower counterbored section of 1/4-inch depth, receives the lower ball bearing (2) of a push fit, with its outer race resting in the seat of this counterbored section. The upper counterbored section of 17/64-inch depth, receives the upper ball bearing (2) of a push fit, with its outer race resting in the seat of this counterbored section.

The range scale mount housing shaft (12) extending through both center ball bearing races and into the reamed hole and threaded axis in the scale housing section, maintains the axial thrust of the two mounted ball bearings. The lower ball bearing center race rests against the inner face of the scale housing section, while the upper ball bearing center race is in contact with the hexagon shoulder face of the above shaft. The lower face of the shaft above the undercut threaded periphery section contacts the seat of the scale housing section reamed hole axis and is secured with a lockscrew (3). This lockscrew extends into the spotted recess in the shaft from a tapped hole in the scale housing section lower outer wall.

The upper part of this housing receives the range scale mount (9) which is secured with four lockscrews (25). These lockscrews are inserted in countersunk clearance holes in

h. Range scale mount. The range scale mount (9) is made of brass and is shaped cylindrical. It is provided with a large shoulder flange and an undercut shoulder section. It has a clearance hole in its center axis to fit loosely over the hexagon section of the range-scale mount housing shaft (12). The undercut shoulder section has a shallow counterbored section which is a sliding fit and rests on the upper part of the range scale mount housing (10) which is secured with four lockscrews (25). These lockscrews are inserted in four equally spaced countersunk clearance holes in the mount and are screwed into tapped holes in the range scale mount housing (10).

The large shoulder flange is provided with a shallow undercut shoulder to allow clearance for the rotation of the large shoulder flange over the range scale actuating bevel gear pinion (23), while the outer diameter rotates freely in the large bored opening in the height scale mount section of the stadimeter housing (8). The outer face of the mount is provided with two dowel pins (6), a drive fit in opposite drilled holes, which are not both located in the centerline, for reassembly alignment of the range scale dial (14). This outer face carries the range scale dial (14) secured with 10 lockscrews (4). These lockscrews are inserted in countersunk clearance holes in the range scale dial and screwed into tapped holes in the range scale mount.

The range scale mount is actuated clockwise with the range scale actuating bevel gear (11), range scale mount housing (10), and the range scale dial (14) as the handwheel (12, Figure 4-24) is turned clockwise.

i. Range scale mount housing shaft. The range scale mount housing shaft (12) is made of corrosion resisting steel and is 2 7/64 inches in length. The lower stub section has a threaded periphery which screws into the tapped axis hole in the scale housing section. The body section is a push fit through both range scale mount housing ball bearing center races (2), and is a sliding fit, bottoming in the reamed axis hole in the scale housing section.

The axis of the outer part is provided with a tapped hole to receive the pointer shoulder screw (18).

The body section and threaded periphery section of the shaft assembled in the reamed hole axis and tapped hole axis in the scale housing section, is secured with a lockscrew (3). This lockscrew is inserted in the tapped hole from a screwdriver clearance provision in the lower outer wall of the scale housing section, and extends into the spotted recess in the body section of the shaft for its securement. The shaft serves as a stationary support for the scale housing mechanism, and maintains the axial thrust of the two range scale mount housing ball bearings (2).

j. Height scale dial. The height scale dial (13) is made of 1/16-inch bakelite, having an inside diameter of 3 3/16 inches and an outside diameter of 3.996 inches. It is attached to the undercut stationary shoulder provision of the scale housing section over two opposite inserted dowel pins (6) which reestablish its proper reassembly. It is secured with six lockscrews (4) which are inserted in countersunk clearance holes in the dial and screwed into tapped holes in the undercut stationary shoulder provision. The dial is graduated 15 to 130 feet and inscribed Height in Feet.

k. Range scale dial. The range scale dial (14) is made of 1/16-inch bakelite. It has an axis hole of 0.630 inches and an outside diameter of 3.180 inches. It is attached to the range scale mount (9) over two dowel pins (6) and is secured with 10 lockscrews (4). These lockscrews are inserted in countersunk clearance holes in the dial and screwed into tapped holes in the range scale mount (9). The dial is graduated from 220 to 11,000 yards and inscribed Range in Yards.

The height and range scale dials are graduated in a correct ratio of the target distance to the

1. Indicator. The indicator (20) is made of 1/16-inch clear Lucite sheet, and is 1 11/64 inch in length. It conforms to the contour and width of the indicator mount (21). The index line section of 1/4-inch width forms a concave junction on opposite sides with the main section of the indicator, with the outer index line section having a convex radius. The lower face of this section is provided with an engraved groove of shallow depth in the centerline, which projects inward toward the main section 5/16 inch, and is filled with red lacquer. The main section is provided with two countersunk clearance holes for the insertion of lockscrews (26), securing the indicator to its mount and separated with an indicator shim of 0.016-inch. The lockscrews extend into tapped holes in the mount.

m. Pointer. The pointer (15) is made of 1/16-inch clear Lucite sheet and is 1.590 inches in length. The wider part is 15/32 inch, with a clearance hole located in the center of a 5/16-inch radius. It is provided with three equally spaced countersunk clearance holes in the lower face for lockscrews (7). These lockscrews extend into tapped holes in the pointer knob (17) and secure it to the upper face of this pointer.

The pointer tapers from the wider part to 1/4 inch in width, with the corners rounded. This part has an engraved groove of shallow depth in the centerline located in the lower face, which projects inward 1/2 inch, and is filled with red lacquer.

The periphery of the pointer knob (17) is knurled to offer a firm grip. It has a countersunk clearance hole in its axis to receive a spring washer (16) and the pointer shoulder screw (18). This pointer serves to indicate the reference points of range setting, previously set up by the known silhouette chart of enemy ships for the particular type of ship encountered.

n. Pointer shoulder screw. The pointer shoulder screw (18) is made of bronze and is 19/32 inch in length. The large diameter forms

6G6. Disassembly. The stadimeter housing assembly is disassembled in the following manner:

1. Follow steps 1 to 19 inclusive of Section 4J9, as the parts removed are identical to those in the disassembly procedure of the Type II periscope stadimeter housing assembly.

2. Remove the pointer shoulder screw (18), unscrewing it from the tapped hole axis in the range scale mount housing shaft (12). Remove the pointer knob (17) and the pointer (15).

3. Remove the three lockscrews (22), unscrewing them from their protrusion in the indicator mount (21) from countersunk tapped holes in the scale housing section outer wall. Remove the indicator mount (21), lifting it out by grasping both of the indicator mount knobs (1).

4. Remove the two lockscrews (26) from the indicator (20), unscrewing them from tapped holes in the indicator mount (21). Remove the indicator (20), and indicator shim (19). Remove the two indicator, mount knobs (1), unscrewing them from tapped holes in the indicator mount (21).

5. Remove the six lockscew (4) from the height scale dial (13) and 10 from the range scale dial (14).

6. Remove the height scale dial (13) and range scale dial (14).

7. Removed the four lockscrews (25) from the range scale mount (9). These lockscrews are unscrewed from tapped holes in the range scale mount housing (10). Precaution must be taken to observe reference marks on all these parts upon disassembly in order to reassemble them correctly later. Remove the range scale mount (9).

9. Remove the range scale mount housing shaft (12), carrying it out with the assembly consisting of the range scale actuating bevel gear (11), range scale mount housing (10), and its two mounted ball bearings (2).

10. Remove the range scale mount housing shaft (12), pulling it out of the center races of the two mounted ball bearings (2).

11. Remove the four lockscrews (24), unscrewing them from tapped holes in the hub section of the range scale actuating bevel gear (11) and their contact in spotted recesses in the range scale mount housing (10).

12. The repairman should apply reference marks on the range scale mount housing (10) noting its position in the range scale actuating bevel gear (11) for proper reassembly. Using a special fibre wrench attached over the protruding outer circumference of the range scale mount housing (10), unscrew it from the hub section of the range scale actuating bevel gear (11), removing the housing.

13. Remove the two range scale mount housing ball bearings (2), pushing them out from opposite counterbored sections in the range-scale mount housing (10).

14. The removal of the rear scale housing mechanism is followed in similar manner to Steps 2 to 12 inclusive for the front scale housing mechanism.

15. Remove the taper pin (44, Figure 4-24) from the transmission gear pinion (2, Figure 4-24) and the inner part of the long transmission shaft (4, Figure 4-24), and remove the transmission gear pinion (2, Figure 4-24).

16. Remove the long transmission shaft (4, Figure 4-24) carrying it out of the mounted ball bearing (14, Figure 4-24) of the scale transmission ball bearing housing (8). The range scale actuating bevel gear pinion (23) is carried out

17. Remove the taper pin (5) from the front range scale actuating bevel gear pinion (23) and the outer part of the long transmission shaft (4, Figure 4-24) and remove the gear pinion (23) from the shaft.

18. Remove the lockscrew (55, Figure 4-24) by the insertion of a long screw driver blade extending through the ball bearing center races (14, Figure 4-24). The lockscrew is unscrewed from the tapped hole axis in the inner end of the short transmission shaft (53, Figure 4-24). Remove the transmission gear pinion (54, Figure 4-24).

19. Remove the key (56, Figure 4-24) from the inner end of the short transmission shaft (53, Figure 4-24).

20. Remove the short transmission shaft (53, Figure 4-24) carrying it out of the mounted ball bearing (14, Figure 4-24) in the scale ball bearing housing (8). It is further carried out of the ball bearing (14, Figure 4-24) mounted in the rear scale housing section, carrying with it the rear range scale actuating bevel gear pinion (23).

21. Remove the taper pin (5) from the range scale actuating bevel gear pinion (23) and the outer end of they short transmission shaft (53 Figure 4-24) and remove the gear pinion (23) from the shaft.

22. Follow the procedures J stated in Steps 43 to 47 inclusive of Section 4J9 of the Type II periscope for the remainder of the disassembly of the stadimeter housing assembly, omitting Step 46.

6G7. Reassembly. The stadimeter housing assembly is reassembled as follows:

1. Apply Lubriplate No. 110 lightly to all rotating parts as the reassembly procedure is followed.

2. Various parts have reference numerals with mating numerals stamped in or on the various parts to establish coincidence of these parts for correct reassembly.

4. Place the rear range scale actuating bevel gear pinion (23) on the outer end of the short transmission shaft (53, Figure 4-24) and secure it by the insertion of a taper pin (5). The insertion of the taper pin should be done with the gear pinion hub held on a soft metal V-block.

5. Follow the reassembly procedure stated in Steps 8 to 10 inclusive of Section 4J10.

6. Place the front range scale actuating bevel gear pinion (23) on the outer end of the long transmission shaft (4, Figure 4-24) and secure it by the insertion of a taper pin (5). The insertion of the taper pin should be done with the gear pinion hub held on a soft metal V-block.

7. Follow the reassembly procedure stated in Steps 12 to 22 inclusive of Section 4J10.

8. Reassembly of the front scale housing mechanism proceeds as follows: Place both range scale mount housing ball bearings (2) in their respective counterbored sections in the range scale mount housing (10).

9. Place the range scale mount housing (10) in the range scale actuating bevel gear (11), screwing it in until its reference marks and the spotted recesses are in coincidence. Insert and secure the four lockscrews (24), screwing them into tapped holes in the bevel gear hub and extending them into the spotted recesses in the range scale mount housing (10).

10. Rotate the front range scale actuating bevel gear pinion (23) until its reference tooth is down, so that upon the assembly of the range scale actuating bevel gear (11) the reference tooth opening of this bevel gear is upward for its engagement with the reference tooth of the pinion gear (23).

11. Place the range scale actuating bevel gear (11) and the assembled range scale mount housing (10) with its two ball bearings (2) in the front scale housing section, and properly mesh it with the range scale actuating bevel gear pinion (23) as outlined in step 10. Holding the range scale actuating bevel gear (11) in

12. Place the range scale mount (9) over the hexagon section of the range scale mount housing shaft (12) and on the range scale mount housing (10). Insert and secure the four lockscrews (25). Insert these lockscrews in countersunk clearance holes in the range scale mount (9) and screw them into tapped holes in the range scale mount housing (10). The reference line on the range scale mount should be lined up vertically.

13. Reassembly of the rear range scale mechanism proceeds as follows (follow Steps 8 to 12 inclusive for the front scale housing mechanism):

14. Check the reference marks of the height and range scale mounts for the front and rear scale housing mechanisms and note their relation. Should both appear in unison, assemble the height and range scale dials (13 and 14) to their respective mounts in the front and rear scale housing mechanisms over the inserted dowel pins (6). Check the 220 numeral graduation on the range scale dial (14) for its coincidence with the 15 numeral graduation on the height scale dial (13). Refer to both sets of dials, noting their proper relation. Should both appear in unison, further, assembly is to be followed.

15. Follow the reassembly procedure stated in Steps 32 and 33 of Section 4J10.

16. Secure the front and rear height scale dials (13) with six lockscrews (4) each. These lockscrews are inserted in countersunk clearance holes in the dials and screwed into the tapped

17. Secure the front and rear range scale dials (14) with 10 lockscrews (4) each. These lockscrews are inserted in countersunk clearance holes in the dials and screwed into tapped holes in the range scale mounts (9).

18. Place the indicator shims, (19) and indicators (20) on their respective indicator mounts (21) and secure them with two lockscrews each (26). These lockscrews are inserted in countersunk clearance holes in each indicator (20) and screwed into tapped holes in each indicator mount (21).

19. Place the two indicator mount knobs (1) in opposite sides of each indicator mount (21). These knobs are screwed into tapped holes in the indicator mounts.

20. Place each indicator mount (21) in each counterbored section seat in the front and rear scale housing sections, and insert and secure them with three lockscrews (22) each. These lockscrews are screwed into tapped countersunk holes in the outer body wall of each scale housing section the extend further into each indicator mount undercut groove.

21. Reassembly of the front pointer assembly to the front scale housing mechanism proceeds as follows: Place the spring washer (16) over the medium shoulder of the pointer shoulder screw (18).

22. Secure the pointer (15) to the pointer knob (17) with three lockscrews (7).

23. Place the pointer shoulder screw (18) with the spring washer (16) in the counterbored section in the pointer knob (17).

24. Holding the pointer knob (17) with the assembled pointer (15) and the pointer shoulder screw (18) and its spring washer (16), screw the pointer shoulder screw (18) into the reamed axis hole in the range scale mount housing shaft (12) until its medium shoulder is tight against the outer face of the shaft.

25. Reassembly of the rear pointer assembly to the rear scale housing mechanism is followed in similar manner to that for the front scale housing mechanism.

6G8. Principles of the stadimeter. The stadimeter relies for its operation upon the formation of two identical images, capable of being vertically displaced with relation to each other, the amount of such displacement being controlled by the observer. For example, the waterline of a vessel in one image can be brought into apparent contact with the masthead as seen in the other image. The extent of displacement necessary to effect this is translated on the stadimeter dial to the range of the vessel as read against the known distance between the masthead and the waterline. The duplicate images are produced by two movable lens halves which travel in a plane normal to their axis and parallel to their dividing line. When so placed as to constitute a complete circle, they form only one image and in this condition are said to be in the observing position. The displacement of the lens halves is actuated by the handwheel (12, Figure 4-24) through transmission gears, to which the stadimeter dials are connected.

6G9. Operation of the stadimeter. See Figure 6-9 which illustrates the following problem: Given a target vessel whose height from waterline to masthead is known to be 60 degrees feet, find the range. Starting with the periscope in high power and the stadimeter in the observing position, i.e., with the handwheel (12, Figure 4-24). turned counterclockwise to the limit of its travel, the target is brought approximately into the center of the field of view. The observer rotates the handwheel clockwise, causing the duplicate images of the target to separate, until the masthead in one image coincides with the waterline in the other. At this point the scale dials are as shown in the illustration, and the range (2,300 yards) is read on the range scale dial opposite the known height (60 feet) on the height scale dial. The stadimeter is then restored to the observing position by rotating the handwheel counterclockwise to the limit of its travel.

The following hints may be of value:

a. Remember that the stadimeter measures only angles, and computes the range on the basis of the estimated height. Hence the range reading

will be no more accurate than the estimate of the heights.

b. The dimension selected for this observation should be one which is known, or which can be estimated with fair accuracy. The reference points should, as far as possible, be definite, easy to see, and widely spaced. The masthead and waterline, for instance, while affording the greatest vertical dimension, might both be invisible at long range.

c. The stadimeter is graduated up to 11,000 yards Longer ranges may be obtained by remembering, that the angle subtended by 80 feet, for instance, at 20,000 yards, is the same as that subtended by 40 feet at 10,000 yards. Thus an object 80 feet high may be set up at the 40-foot line, and the range obtained multiplied by 2.

d. The range scale dial is graduated for use with the periscope in high power. The stadimeter may also be used with the periscope in low power, by dividing the range, as read against the correct height of the object, by 4. In the case of high objects, the periscope should be placed in low power, and the object set up on the height scale dial at 1/4 its actual height. In this case the range reading will be correct.

A stadimeter range may be taken with a periscope exposure of a few seconds. It is assumed that the approximate bearing of the target is known, and that the reference points have been selected. The known or estimated height between the reference points should be set in advance on the height scale dial, using the pointer

Practice is essential to the efficient operation of the stadimeter.

Figure 6-10. First inner tube section assembly.

The upper part is bored a distance of 13/16 inch and threaded to engage on the lower threaded periphery section of the first inner tube section upper end coupling (23), and is secured with four lockscrews (6). These lockscrews ate inserted in countersunk clearance holes in the upper part of this inner tube section and screwed into tapped holes in the lower alignment support section of the first inner tube section upper end coupling (23).

The inner surface of this inner tube section supports a diaphragm (11) which is located in the center part and is secured with three lockscrews (8).

The lower part is a push fit on the upper alignment support section of the spider bearing (3), and is secured with eight lockscrews (5). These lockscrews are inserted in countersunk clearance holes in the lower part of this inner tube section and screwed into tapped holes in the upper alignment support section of the spider bearing (3).

The air line section continuation (16) of the objective operating mechanism assembly extends downward from the, coupling sleeve (17, Figure 6-7) and forms the airline section continuation (17) of this inner tube section ending in the upper part. It is retained in the periphery wall of this inner tube section in the upper part with a removable air line snap (18) secured with two lockscrews (22). These lockscrews are inserted in clearance holes in the air line strap (18) and screwed into tapped holes in the periphery wall of this inner tube section. The air line section continuation (17) has an air line coupling (15), soldered in its lower end.

The air line section (16) located in the upper part of this inner tube section, connects to the soldered air line coupling (15) and is retained in place with an air line strap (19) soldered to the periphery wall of this inner tube section in the central part. The lower end of this air line section (16) has an air line coupling (15) soldered in its lower end, which receives the bent air line (14).

b. First inner tube section upper end coupling. The first inner tube section upper end coupling (23) is made of cast phosphor bronze and is 3 1/4 inches in length. It forms a joint between the track sleeve (18, Figure 6-7) of the objective operating mechanism assembly and the upper part of the first inner tube section (1).

In the upper part it is smooth turned and serves as an alignment support section in the counterbored alignment support section in the lower part of the track sleeve (18, Figure 6-7). The threaded periphery section following the alignment support section engages in the internal threaded section in the track sleeve (18, Figure 6-7) and is secured with four lockscrews (9, Figure 6-7). These lockscrews are inserted in countersunk clearance holes in the track sleeve (18, Figure. 6-7) and screwed into tapped holes in the upper alignment support section of this coupling.

The center part is provided with a narrow shoulder 1/4 inch wide, and its diameter coincides with the diameter of the lower part of the track sleeve (18, Figure 6-7).

The inner diameter is bored for light transmission and threaded for anti-reflection.

The lower part is similar to the upper part, having a threaded periphery and alignment support sections. The alignment support section is carried in the first inner tube section, while

At assembly the narrow shoulder is provided with a vertical slot to provide clearance for the air line section continuation (17).

c. Diaphragm. The diaphragm (11) is identical to the diaphragm (12, Figure 4-27) used in the first inner tube section (1) of the Type II periscope. Refer to Section 4K1.

d. Spider bearing and spider. 1. Spider bearing. The spider bearing (3) is identical to the spider bearing (3, Figure 4-27) used in the Type II periscope. Refer to Section 4K1.

2. Spider. The spider (2) is identical to the spider (2, Figure 4-27) used in the Type II periscope. Refer to Section 4K1.

e. Stadimeter transmission shaft thrust collars. The two stadimeter transmission shaft thrust collars (4) are identical to the two stadimeter transmission shaft thrust collars (4, Figure 4-27) used in the Type 11 periscope. Refer to Section 4K1.

f. Stadimeter transmission shaft bracket. The stadimeter transmission shaft bracket (21) is identical to the stadimeter transmission shaft bracket (23, Figure 4-27) used in the Type II periscope. Refer to Section 4K1.

g. Stadimeter transmission shaft. The stadimeter transmission shaft (12) is identical to the stadimeter transmission shaft (22, Figure 4-27) used if the Type II periscope. Refer to Section 4K1. This shaft however, is slightly longer to make up for the variance in length of the first inner tube section (1).

6H2. Disassembly of the first inner tube section assembly. The first inner tube section assembly is disassembled in the following manner:

1. All airline sections and continuations, air line straps, thrust collars, and the stadimeter transmission shaft (12), pertaining to this assembly were removed previously for the separation of the various telescope systems and their individual assemblies.

2. Remove the four lockscrews (6) from the upper part of the first inner tube section (1).

3. Unscrew the lower part of the first inner tube section upper end coupling (23) from the upper part of the first inner tube section (1). Remove the first inner tube section upper end coupling from the first inner tube section.

4. Remove the eight lockscrews (5) from the lower part of the first inner tube section (1). These lockscrews are unscrewed from tapped holes in the upper alignment support section of the spider bearing (3).

5. Remove the spider bearing (3) from the lower part of the first inner tube section (1). Tap the spider bearing from the lower end of the first inner tube section.

6. Remove the four lockscrews (7) unscrewing two from opposite side flanges of the spider halves (2). Remove the taper pin (9) from the spider half, and remove both spider halves from the spider bearing (3).

7. Remove the three lockscrews (8) from the central part of the first inner tube section (1). These lockscrews are unscrewed from tapped holes in each soldered strip in the inner diaphragm wall (11).

8. Tap the diaphragm (11) out through the lower part of the first inner tube section (1).

6H3. Reassembly of the first inner tube section assembly. The first inner tube section assembly is reassembled in the following manners:

1. Check all reference marks in the reassembly of and part to prevent incorrect reassembly.

2. Using an air hose, blow out the internal surfaces of the first inner tube section. If a circular brush is available, it should be used first. This procedure should be carried out also with the couplings and the diaphragm.

3. Place the diaphragm (11) in the central part of the first inner tube section from the lower end. The diaphragm side wall faces upward toward the first inner tube section upper end coupling (23). Tap the diaphragm in until the

4. Insert and secure three lockscrews (8). The lockscrews are inserted in countersunk clearance holes in the first inner tube section (1) and screwed into tapped holes in the diaphragm soldered inner wall strips.

5. Screw the lower threaded periphery section of the first inner tube section upper end coupling (23) into the upper part of the first inner tube section (1).

6. Insert and secure the four lockscrews (6). These lockscrews are inserted in countersunk clearance holes in and screwed into tapped holes in the upper part of the first inner tube section of the first inner tube section upper end coupling (23).

7. Place the upper alignment support section of the spider bearing (3) in the lower part of the first inner tube section (1). Using a rawhide maul and a block of wood, tap the spider bearing

8. Insert and secure the eight lockscrews (5). These are inserted in countersunk clearance holes in the first inner tube section and screwed into tapped holes in the upper alignment support section of the spider bearing (3).

9. Place both halves of the spider (2) over the spider bearing (3) between its two narrow shoulders.

10. Insert and secure each flange half of the spider with two lockscrews (7). Insert the lockscrews in clearance holes in one flange half and screw them into tapped holes in the other flange half of both sets of opposite flanges.

11. Insert the taper pin (9) in one spider half (2) and the spider bearing (3).

12. The air line sections and the air line continuation, air line straps, thrust collars, and the stadimeter transmission shaft (12) are assembled later, upon the connection of individual assemblies of this lower telescope system.