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4N2. Description of the stadimeter transmission shaft packing gland assembly (spring type). Figure 4-30 shows this packing gland assembly. All bubble numbers in this section refer to Figure 4-30 unless otherwise specified.

a. Packing gland. The packing gland (2) is made of phosphor bronze and, is 0.937 inch in length. It is cylindrical with a reamed hole in its center axis. The external surface consists of an undercut section with a large shoulder a few thousandths-inch smaller than the bored diameter of the eyepiece box base stuffing box chamber. The undercut section is a loose fit in the packing gland spring (4). The reamed hole of the packing gland is a sliding fit on the stadimeter transmission shaft (22, Figure 4-27). The large shoulder is chamfered at 30 degrees from the reamed hole axis to contact sufficient flax packing, thus forcing the packing into the similarly chamfered shoulder seat in the bored diameter of the stuffing box chamber under tension of the packing gland spring (4). The compression of the packing between the two chamfered seats causes the packing to adhere around the stadimeter transmission shaft (22,

b. Packing gland spring. The packing gland spring (4) is made of chrome silicon manganese steel alloy, having a free length of 1.500 inches. The upper part of the spring fits loosely over the undercut section of the packing gland (2) and rests against its large shoulder lower face. The lower part is a loose fit on the small shoulder and rests on the medium shoulder face of the spring retainer (3). The external diameter of the spring is a loose fit in the bored stuffing box chamber in the eyepiece box base (11, Figure 4-29).

Figure 4-30. Stadimeter transmission shaft packing gland assembly (spring type).

c. Spring retainer. The spring retainer (3) is made of phosphor bronze and is 0.810-inch in length. It is undercut with a long section having a nominal wall thickness, and serves as a guide for the packing gland spring (4). The medium shoulder serves as the seat for the spring. The large shoulder periphery is threaded to screw into the internal threaded stuffing box chamber in the eyepiece box base (11, Figure 4-29).

Two holes are drilled in the threaded periphery along a diameter, and the wall has a narrow slot cut halfway through the shoulder to these

Upon the loading of this packing gland with 9 inches of 1/4-inch flax packing, there is an initial compression of 1/8-inch required of the packing gland spring (4) before the spring retainer threads engage in the internal threaded

Figure 4-31. Stadimeter transmission shaft packing gland assembly (modified hycar type).

4N3. Description of the stadimeter transmission shaft packing gland assembly (modified hycar type). Figure 4-31 shows this packing gland assembly. All bubble numbers in this section refer to Figure 4-31 unless otherwise specified.

a. Gland filler piece. The gland filler piece (3) is made of rolled brass rod and is 0.338-inch in width. It is cylindrical with the periphery several thousandths-inch smaller than the bored diameter of the eyepiece box base stuffing box chamber. The axis is provided with a reamed hole a sliding fit on the stadimeter transmission shaft (22, Figure 4-27). The upper face is chamfered at 30 degrees. This gland filler piece serves to fill the 30 degrees chamfered seat of the stuffing box section, and has a flat shoulder upon which the uppermost hycar packing spacer rests under tension.

b. Hycar packing spacers. The four hycar packing spacers (4) are made of 1/8-inch special synthetic rubber sheet. Each spacer is cut cylindrical, with the external diameter 0.007-inch larger than the bored diameter of the eyepiece box base stuffing box chamber, while the center hole is 0.007-inch smaller than the stadimeter transmission shaft (22, Figure 4-27).

c. Brass spacer washers. The three brass spacer washers (5) are made of 0.020-inch thick brass. The washers are cylindrical, having a 0.006-inch smaller diameter than the bored diameter of the eyepiece box base stuffing box,

d. Packing retainer brass washer. The packing retainer brass washer (6) is made of 0.060-inch rolled brass. It is cylindrical, having the same internal and external diameters as the three brass spacer washers (5). This washer is placed below the lower hycar packing spacer (4) and the upper face of the packing retainer (2). The flat face of this washer serves to protect the rubber gasket next to the face of the packing retainer from being disrupted when tightening the packing retainer for the compression of the hycar packing spacers to maintain the hermetical seal.

e. Packing retainer. The packing retainer (2) is made of rolled phosphor bronze and is 1.190 inches in length. It is undercut a sliding fit into the bored diameter of the stuffing box chamber in the eyepiece box base, with a large shoulder having a threaded periphery. The threaded periphery engages into the internal threaded section in the stuffing box shoulder of the eyepiece box base. The packing retainer has a reamed hole in the axis of the upper part, and a counterbored section intercepting the reamed hole. The reamed hole is a sliding fit over the stadimeter transmission shaft (22, Figure 4-27) while the counterbored section has sufficient clearance for the female tang coupling (68, Figure 4-24) of the stadimeter housing assembly, for its interconnection with the male tang section of the stadimeter transmission shaft. The undercut shoulder is of sufficient length, with an adequate wall above the counterbored section, to compress the four hycar packing spacers for maintaining the hermetical seal.

4N4. Description of the rayfilter drive packing gland assembly. Figure 4-32 shows this packing gland assembly. All bubble numbers in Sections 4N4, 5, and 6 refer to Figure 4-32 unless otherwise specified.

a. Stuffing box body. The stuffing box body (4) is made of phosphor bronze and is 1.485 inches in length. It consists of a body section undercut a distance of 0.785 inch, with a medium shoulder section a sliding fit in the bored hole in the eyepiece box front opening below and to the right of the eyepiece window assembly (27, Figure 4-29). It is provided with a large rectangular shoulder flange with rounded corners a sliding fit in the rectangular recess section

part of the same opening. The rectangular flange has four countersunk clearance holes for the insertion of lockscrews (13), and is secured in the rectangular recess in the eyepiece box on a rectangularly shaped gasket (9). The lockscrews extend into nominal depth tapped holes in the remaining rectangular recess front wall of the eyepiece box.

The stuffing box body center axis is reamed to accommodate the rayfilter drive actuating

The large counterbore, 0.282 inch deep, is threaded to receive the spring retainer threaded periphery against the shoulder seat of this counterbored section. The center section, located with its face a depth of 0.406 inch from the outer face of the rectangular flange, is counterbored a depth of 3/8 inch, having a chamfered seat of 30 degrees. This counterbored area serves as the stuffing box chamber to receive the flax packing and the undercut section and upper chamfered seat of the packing gland (7). The flax packing is compressed against the chamfered seat of the stuffing box chamber by the opposite chamfered seat of the packing gland, thus forcing the flax packing to adhere to the rayfilter drive actuating shaft (10).

The stuffing box body is counterbored in the lower part a depth of 0.484 inch to provide sufficient clearance for the rayfilter drive actuating shaft (10) shoulder male coupling section, the female coupling section (2), and its interconnection with the male coupling section (40, Figure 4-28) of the eyepiece skeleton assembly. This counterbore serves as an alignment support section for the interconnecting coupling sections mentioned above.

b. Rayfilter drive actuating shaft. The rayfilter drive actuating shaft (10) is made of corrosion-resisting steel and is 1 15/32 inches long. The flange section of the shaft has two projecting lugs to form a male coupling section with the assembled female coupling section (2) which provides interconnection with the male coupling section (40, Figure 4-28) of the eyepiece skeleton assembly. The main body of the shaft is a sliding fit in the reamed hole in the stuffing box body (4) and the reamed hole in the packing gland (7). The flax packing surrounds the main body of the shaft in the stuffing box chamber. The square section of the upper part of the shaft carries a rayfilter drive actuating gear (11).

c. Female coupling section. The female coupling section (2) is made of corrosion

d. Rayfilter drive actuating gear. The rayfilter drive actuating gear (11) is made of phosphor bronze with a square broached hole in its center axis, and is a push fit over the square section of the rayfilter drive actuating shaft (10). The large diameter is provided with 16 teeth of 32 diametral pitch which mesh with the rayfilter drive actuating gear rack (8, Figure 4-40) of the rayfilter assembly. The hub section of the gear is a sliding fit in the reamed hole axis of the packing gland (7). The rayfilter drive actuating gear (11), in mesh with the rayfilter drive actuating gear-rack (8, Figure 4-40) of the rayfilter assembly, provides the interconnection with the eyepiece drive mechanism located in the eyepiece skeleton assembly (Figure 4-28) to synchronize its vertical travel.

e. Packing gland spring. The packing gland spring (8) is made of chrome silicon manganese steel alloy and has a free length of 2 1/2 inches. The spring fits loosely over the undercut body and rests on the shoulder seat of the spring cylinder (6). The spring when compressed, has a length of 7/8-inch at its fully loaded position.

f. Spring retainer. The spring retainer (5) is made of phosphor bronze ands is 9/32 inch in width. It is cylindrical, having a threaded periphery to screw into the large threaded counterbored section and shoulder seat in the stuffing box body (4). The internal surface of

A dowel pin hole is provided in the threaded periphery for the insertion of a dowel pin (14) of a drive fit. The dowel pin projects inward from the counterbored wall a sufficient distance to engage in the axial slot of the spring cylinder upper part. Its protrusion in the axial slot serves only to restrict the movement of the spring cylinder when loading the packing gland, and does not interfere with the threaded periphery of the packing gland (7).

Two opposite radius grooves are cut in the inner bored shoulder to a depth of the counterbored wall to provide the repairman a visual determination of the loaded position of the spring cylinder (6) as it contacts the shoulder seat of the spring retainer.

Two holes are drilled in the threaded periphery along a diameter, and the wall has a narrow slot cut halfway through the shoulder to these drilled holes. In the center of the slotted section, a tapped hole is provided near the periphery for insertion of a lockscrew (1). This lockscrew when tightened spreads the narrower slotted half of the wall away from the heavier part, and secures the spring retainer in the internal threaded counterbored section in the stuffing box body. The face of the spring retainer is provided with four equally spaced shallow holes to accommodate the projecting prongs of a special wrench. The spring retainer compresses the packing gland spring (8) for its initial compressed length of 31/64 inch.

g. Spring cylinder. The spring cylinder (6) is made of phosphor bronze and is 1.200 inches in length. It is bored a sliding fit over the external shoulder surface of the stuffing box chamber. The external surface is undercut down to a narrow shoulder of nominal wall thickness to carry the packing gland spring (8) loosely in the cylinder area between the internal and external walls of the stuffing box body. The upper part of the spring cylinder has

h. Packing gland. The packing gland (7) is made of phosphor bronze and is 1/2 inch in length. It is cylindrical with a large shoulder having a threaded periphery to engage into the internal threaded section of the upper part of the spring cylinder (6).

The packing gland is provided with an undercut section a sliding fit in the counterbored section of the stuffing box chamber. The center axis has a reamed hole, a sliding fit on the upper part of the rayfilter drive actuating shaft (10). The lower internal surface of the undercut section is provided with a 30 degrees chamfered seat to compress the flax packing properly for its adherence around the rayfilter drive actuating shaft.

Two holes are drilled in the threaded periphery along a diameter, and the wall has a narrow slot cut halfway through the shoulder to these drilled holes. In the center of the slotted section, a perpendicular upped hole is provided near the periphery for the insertion of a lockscrew (12). This lockscrew, when tightened A, spreads the narrower slotted half of the wall away from the heavier part and secures the packing gland in the internal threaded section of the spring cylinder (6). The face of the packing gland (7) is provided with four equally spaced shallow

i. Stuffing box body rubber gasket. The stuffing box body rubber gasket (9) is made of synthetic rubber of rectangular shape, while the center hole is cylindrical. The rubber gasket fits between the rectangular flange of the stuffing box body, in the rectangular recess seat of the eyepiece box (11, Figure 4-29). Clearance holes are punched in the four corners to match with the clearance holes in the rectangular flange and the tapped holes in the rectangular recess face of the eyepiece box base.

4N5. Disassembly of the rayfilter drive packing gland assembly. The rayfilter drive packing gland assembly is disassembled in the following manner:

1. Remove the rayfilter drive actuating gear (11), pulling it off the square section of the rayfilter drive actuating shaft (10).

2. Remove the lockscrew (12) from the face of the packing gland (7).

3. Using a special wrench, insert the projecting prongs of the wrench in the four shallow holes in the packing gland face (7). Unscrew the packing gland from the spring cylinder (6), unloading the packing gland (7) and thus releasing the pressure on the flax packing. Remove the packing gland.

4. Remove the rayfilter drive actuating shaft (10), carrying it out from the lower part of the stuffing box body (4) with the assembled female coupling section (2) and its securing bronze wire (3).

5. Remove the lockscrew (1) from the spring retainer face (5).

6. Using a special spring-unloading wrench (Figure 4-34), run the wing nut out a sufficient distance on the guide plug integral shaft threads. Screw the guide plug threaded periphery into the internal threaded section in the spring cylinder (6). Insert the projecting prongs of the wrench body into the four shallow holes in the

7. Unscrew the spring retainer (5), carrying with it the packing gland spring (8) and the spring cylinder (6). The spring remains at its initial compressed position (Figure 4-33).

Figure 4-33. Special spring-unloading and loading wrench with spring fully loaded.

8. Unscrew the wing nut, carrying it outward on the guide plug shaft and thus releasing the spring tension (Figure 4-34).

9. Unscrew the spring cylinder (6) from the guide plug and integral shaft. Remove the spring cylinder (6), packing gland spring (8), and spring retainer (5).

10. Remove the old flax packing, and destroy it, leaning out the stuffing box chamber.

11. Clean all parts of this assembly in a clear cleaning solvent.

4N6. Reassembly of the rayfilter parking, gland assembly. The rayfilter packing gland assembly is reassembled in the following manner:

1. Using the special spring-loading wrench (Figure 4-34), run the wing nut out on the guide plug integral shaft threads.

2. Hole the wrench with the wing nut down, and place the spring retainer (5) over the guide plug. Engage the four shallow holes in its face on the projecting prongs of the wrench body.

3. Place the packing gland spring (8) over the guide plug, and screw the spring cylinder (6) on the threaded periphery of the guide plug.

Figure 4-34. Unloading of the packing gland spring with the special wrench.

until the dowel pin is in contact with the bottom of the axial slot. In this position, the spring is fully loaded.

5. Screw the spring retainer (5) with the assembly in its fully loaded position (Figure 4-33), into the internal threaded counterbore of the stuffing box body (4). When the spring retainer is tight against the counterbored shoulder face of the stuffing box body, unscrew the wing nut and remove the projecting prongs. Unscrew the guide plug from the spring cylinder (6). As the wing nut is released, the spring releases the spring cylinder from the loaded position, carrying it down to the initial compression position.

6. The use of the loading wrench and its guide plug integral shaft and wing nut permits an ease in disassembly and reassembly of the packing gland spring (8) and removes the excessive wear of the spring retainer threaded periphery (5) and the internal threaded section in the stuffing box body (4). This would prevail were any other procedure of assembly or disassembly followed.

7. Insert and secure the lockscrew (1) in the tapped hole of the spring retainer face (5) locking the spring retainer in the stuffing box body (4) threads.

9. Using 1/4-inch flax packing, cut a length of 3 1/4 inches, and insert it in the stuffing box chamber around the rayfilter drive actuating shaft (10).

10. Place the packing gland (7) over the shaft and in the stuffing box chamber, and press downward, using a special wrench. Place the projecting prongs of the wrench in the four shallow holes in the packing gland face. Engage the packing gland threaded periphery in the internal threads of the spring cylinder (6). Check the entrance of the packing gland in the stuffing box chamber to insure that there are no loose ends of the flax packing overlapping the shoulder of the stuffing box chamber.

11. After setting up the flax packing the first time, repeat Steps 9 and 10 the second time. Allow the packing to set 30 minutes before screwing the packing gland face flush with the face of the spring retainer (5). In this final setting up of the packing gland, the spring cylinder (6) should be observed by viewing its position through the opposite radius slots of the spring retainer (5). Note its position, as it should be in contact with the counterbored face of the spring retainer.

12. Insert and secure the lockscrew (12) in the tapped hole in the packing gland face (7), locking the packing gland in the threads of the spring cylinder (6).

13. Place the rayfilter drive actuating gear (11) on the square section of the rayfilter drive actuating shaft (10). Carry the hub section of the gear into the upper part of the reamed hole in the packing gland (7). Check the reference punched marks of the gear and shaft for proper coincidence.

14. This rayfilter packing gland assembly is pressure tested as described under Section 4N13.

4N7. Description of the eyepiece drive packing gland assembly. Figure 4-35 shows the eyepiece

a. Stuffing box body. The stuffing box body (6) is made of phosphor bronze and is 1.500 inches in length. It is cylindrical and consists of a small undercut shoulder section, a medium shoulder section, and a large shoulder flange in the upper part. The small shoulder section is a loose fit in the bored opening and counterbored recess in the eyepiece box (11, Figure 4-29) between the two air valve body assemblies. The medium shoulder is a sliding fit in the bored hole, while the large shoulder flange is a sliding fit in the counterbored recess.

The outer face of the large shoulder flange is chamfered at 30 degrees. The chamfered face projects above the recess 6f the eyepiece box and conforms to the contour of its periphery, setting slightly below it. They large shoulder flange rests on a stuffing box body rubber gasket (11) and is secured to maintain the hermetical seal of the stuffing box body with six lockscrews (3). These lockscrews are inserted into countersunk clearance holes in the large shoulder flange and screwed into tapped holes in the counterbored recess seat.

The stuffing box body axis is provided with two reamed holes in the lower part to receive

The internal surfaces of the stuffing box body are treated in comparison to the rayfilter drive packing gland assembly stuffing box body (4, Figure 4-32) as follows: The cylinder area for the spring cylinder (8) and the packing gland spring (10) is the same depth but smaller in diameter. The center section wall is smaller in diameter and length. The stuffing box chamber is smaller in diameter and longer in depth, while it has a chamfered packing gland seat of 45 degrees. The large threaded counterbored section is smaller in diameter and has the same depth to receive the spring retainer (7).

b. Eyepiece drive actuating shaft. The eyepiece drive actuating shaft (12) is made of corrosion-resisting steel and is 1 29/32 inches long. The stub section is provided with a recess keyway for the insertion of a key (2). The stub section carries the eyepiece drive mechanism bevel gear (1) with a keyseat over this section and is secured with a lockscrew (4). The main body is carried a sliding fit in the large reamed hole axis, while a portion of the stub section is carried a sliding fit in the small reamed, hole axis in the stuffing box body (6). The main body section protruding through the stuffing box chamber is surrounded by flax packing.

The square section of the outer part of the shaft forms a connection with the square broached hole in the female coupling section (3) of the focusing knob assembly (Figure 4-39).

c. Eyepiece drive mechanism bevel gear. The eyepiece drive mechanism bevel gear (1) is made of phosphor bronze, with a reamed hole in its center axis, and is provided with a keyseat. The large diameter is provided with 28 bevel teeth of 32 diametral pitch, and has a pitch cone line angle of 60 degrees. It meshes with an identical bevel gear called the eyepiece prism shift bevel gear (11, Figure 4-28) of the eyepiece skeleton assembly. The bevel gear is a push fit over the inserted key (2) and the stub section of the eyepiece drive actuating shaft (12). The hub section has a tapped hole for the insertion of a lockscrew (4) to secure the bevel gear from axial

Figure 4-35. Eyepiece drive packing gland assembly.

skeleton assembly by the rotation of the focusing knob (1, Figure 4-39).

d. Packing gland spring. The packing gland spring (10) is made of the same material and thickness as the rayfilter drive packing gland assembly packing gland spring (8, Figure 4-32) except that it is shorter in length and

e. Spring retainer. The spring retainer (7) is made of the same material and thickness as the rayfilter drive packing gland assembly spring retainer (5, Figure 4-32) except that it is smaller in proportion to the large threaded counterbored section of the stuffing box body (6). It is secured in the same manner with a lockscrew (5).

f. Spring cylinder. The spring cylinder (8) is of the same material and length as the rayfilter drive packing gland assembly spring cylinder (6, Figure 4-32) except that the diameter is smaller and the internal threaded section is longer. It is designed for the same purpose and functions.

g. Packing gland. The packing gland (9) is made of the same material and is smaller in diameter, having a longer threaded periphery than its corresponding part in the rayfilter drive packing gland assembly packing gland (7, Figure 4-32). It is provided with a smaller reamed hole in its center axis, for the eyepiece drive actuating shaft (12), with the lower internal surface of the undercut section provided with a 45 degrees chamfered seat. The upper part is counterbored a nominal depth to provide clearance for an external connection with the female coupling section (3, Figure 4-39) of the focusing knob assembly. It is secured in the spring cylinder threaded section with a lockscrew (13) in similar manner, and is designed for the same purpose and functions.

4N8. Disassembly of the eyepiece drive packing gland assembly. The eyepiece drive packing gland assembly is disassembled in the following manner:

1. Remove the lockscrew (4) from the hub section of the eyepiece drive mechanism bevel gear (1).

2. Remove the eyepiece drive mechanism bevel gear (1), pulling it off the stub section of the

3. Remove the inserted key (2) from the stub section of the eyepiece drive actuating shaft (12).

4. Remove the lockscrew (13) from the packing gland face (9).

5. Remove the packing gland (9) in the manner described under Section 4N5, Step 3.

6. Remove the eyepiece drive actuating shaft (12), carrying it out from the large shoulder flange end of the stuffing box body (6).

7. Remove the lockscrew (5) from the spring retainer face (7).

8. Using a special spring-unloading wrench of smaller design such as that used under Section 4N5, Step 6, unscrew the spring retainer (7), carrying with it the packing gland spring (10) and the spring cylinder (8), in similar manner to that stated in Section 4N5, Step 7, and Figure 4-33.

9. Unscrew the spring cylinder (8) from the guide plug and integral shaft. Remove the spring cylinder packing gland spring (10) and the spring retainer (7, Figure 4-34).

10. Follow the procedure outlined in Section 4N5, Steps 10 and 11.

4N9. Reassembly of the eyepiece drive packing gland assembly. The eyepiece drive packing gland assembly is reassembled in the following manner:

1. Using the special spring-loading wrench of smaller design, follow the procedure described in Section 4N6, Steps 1, 2, 3, 4, and 5, for the reassembly of the spring retainer (7), packing gland spring (10), and the spring cylinder (8) in the stuffing box body (6).

2. Insert and secure the lockscrew (5) in the tapped hole of the spring retainer face (7), locking the spring retainer in the stuffing box body threads (6).

4. Using 1/8-inch flax packing, cut a length 5 inches, and insert it in the stuffing box chamber around the eyepiece drive actuating shaft (12).

5. Place the packing gland (9) on the shaft in the stuffing box chamber, and press downward using a special wrench. Place the projecting prongs of the wrench in the four shallow holes of the packing gland face. Engage the packing gland threaded periphery in the internal threads in the spring cylinder (8). Follow the precautions listed under Section 4N6, Step 10.

6. Follow Section 4N6, Step 11, for the second length of packing and the setting up of the packing gland (9).

7. Insert and secure the lockscrew (13) in the tapped hole in the packing gland face (9), locking the packing gland in the threads of the spring cylinder (8).

8. Insert the key (2) in the stub section of the eyepiece drive actuating shaft (12).

9. Place the eyepiece drive mechanism bevel gear (1) over the inserted key (2) and on the stub section of the eyepiece drive actuating shaft (12). The hub section of the gear faces the stuffing box body lower face (6).

10. Insert and secure the lockscrew (4) in the hub section of the bevel gear (1) and the spotted recess in the stub section of the shaft (12).

11. This eyepiece drive packing gland assembly is pressure tested as described under Section 4N13.

4N10. Description of the left and right training handle packing gland assemblies. The left end right training handle packing gland assemblies are identical. Figure 4-36 shows this assembly. All bubble numbers in Sections 4N10, 11, and 12 refer to Figure 4-36 unless otherwise specified.

a. Stuffing box body. The stuffing box body (5) corresponds to the eyepiece drive packing gland assembly stuffing box body (6, Figure 4-35) except that it has a single axis reamed hole, and a chamfered lower end. This reamed hole carries the actuating shaft (11). The stuffing box body fits on either side of the eyepiece box (11, Figure 4-29) in a bored hole and countersunk recess seat on a stuffing box body rubber gasket (10). This rubber gasket maintains the hermetical seal of the stuffing box body when secured with six lockscrews (1). These lockscrews are inserted into countersunk clearance holes in the stuffing box large shoulder flange and screwed into tapped holes in the counterbored recess seat in the eyepiece box (11, Figure 4-29).

b. Actuating shaft. The actuating shaft (11) is almost identical to the rayfilter drive actuating shaft (10, Figure 4-32) except in diameter and length. The square section is larger in diameter and length. The main body is smaller in diameter and longer. The flange sections of the shafts with two projecting lugs forming the male coupling section are identical. When assembled with the female coupling section (3), it provides interconnection with the male coupling section of the training handle rack gear and integral shaft (39, Figure 4-28) in either side of the eyepiece skeleton assembly. The square section of the shaft engages into the square broached hole in the inner bevel gear clutches (14 and 16, Figures 4-43 and

c. Female coupling section. The female coupling section (3) is almost identical to the female coupling section (2, Figure 4-32) of the

Figure 4-36. Left and right training handle packing gland assemblies.

rayfilter drive Backing gland assembly, with an exception in the outer diameter The coupling section is assembled with a bronze wire (4) in the same manner.

d. Packing gland spring. The packing gland spring (9) is identical to the packing

e. Spring retainer. The spring retainer (6) is identical to the spring retainer (7, Figure 4-35) of the eyepiece drive packing gland assembly, and is locked in the stuffing box body (5) in the same manner with a lockscrew (2).

f. Spring cylinder. The spring cylinder (7) is identical to the spring cylinder (8, Figure 4-35) of the eyepiece drive packing gland assembly.

g. Packing gland. The packing gland (8) is identical to the packing gland (9, Figure 4-35) of the eyepiece drive packing gland assembly. The counterbore receives the inner bevel gear clutches (14 or 16, Figures 4-43 and 4-44 respectively) of the left and fight training handle assemblies. It is secured in the spring cylinder (7) with a lockscrew (12) in the same manner.

4N11. Disassembly of the left or right training handle packing gland assembly. The left or right training handle packing gland assembly is disassembled in the following manner:

1. Remove the lockscrew (12) from the packing gland (8).

2. Remove the packing gland (8) in the manner described under Section 4N5, Step 3.

3. Remove the actuating shaft (11), carrying it out from the lower part of the stuffing box body (5).

4. Remove the lockscrew (2) from the spring retainer face (6).

5. Follow Section 4N8, Step 7, and Section 4N5, for the removal of the spring retainer (6), packing gland spring (9), and spring cylinder (7).

6. Unscrew the spring cylinder (7) carrying with it the packing gland spring (9) and the spring retainer (6). The spring remains in the initial loaded position (Figure 4-33).

7. Follow Section 4N5, Steps 10 and 11; see Figure 4-34.

1. Follow the procedure stated in Section 4N9, Step 1, and Section 4N6, Steps 1, 2, 3, 4, and 5 for reassembly of the spring retainer (6), packing gland spring (9), and the spring cylinder (7) in the stuffing box, body (5) see Figures 4-33 and 4-34.

2. Insert and secure the lockscrew (2) in the tapped hole in the spring retainer face (6), locking the spring retainer in the stuffing box body (5).

3. Place the training handle actuating shaft (11) in the reamed hole axis of the stuffing box body (5), carrying it in from the lower end.

4. Follow the procedure outlined in Section 4N9, Steps 4, 5, and 6 for insertion of the flax packing and the reassembly of the packing gland (8) on the actuating shaft (11) and its engagement in the spring cylinder (7).

5. Insert and secure the lockscrew (12) in the tapped hole in the packing gland face (8), locking the packing gland in the threads of the spring cylinder (7).

6. The left and right training handle packing gland assemblies are pressure tested as described under Section 4N13.

4N13. Care of packing gland assemblies. a. General. During any general overhaul all packing gland assemblies on the instrument should be tightened, repacked if necessary, and pressure tested. All packing gland assemblies except the stadimeter transmission shaft packing gland assembly (Figures 4-30 and 4-31) can be removed with the operating shaft in place in the gland.

If repacking is necessary, it is advisable to disassemble the packing gland assembly to clean out worn particles of packing and to insure free spring action. This is done by removing the packing gland and the spring retainer. The spring retainer should be removed with care, as

Before being reassembled to the eyepiece box (11, Figure 4-29), packing gland assemblies of this type should be tested individually in a fixture (Figure 4-37) prepared for this purpose, using 100 psi air pressure. The glands are immersed in water. No leaks should be discernible in a half-hour test. The stadimeter transmission shaft packing gland assembly (Figure 4-30 or 4-31) can be tested upon completion of reassembly, at which time an internal pressure test, using nitrogen at 100 psi, should be made. The test should be made with the periscope completely immersed in water and all glands, joints, and windows should be minutely examined for leaks.

b. Pressure test of the four springloaded type packing gland assemblies. The four spring-loaded type packing gland assemblies are pressure tested as follows:

1. Place each stuffing box body (4, 6, and 5, Figures 4-32, 4-35, and 4-36 respectively), and their respective stuffing box rubber gaskets (9, 11, and 10) in the bored hole and rectangular or counterbored recess seats in the pressure testing fixture (Figure 4-37).

2. Secure the four packing gland assemblies with lockscrews (13, 3, and 1, Figures 4-32,

Figure 4-37. Packing gland pressure testing fixture.

3. Use 100-psi air pressure, immersing the fixture in water. Each actuating shaft of each individual packing gland assembly must be rotated several times during the half-hour test. No leaks should be discernible during this test.

5. Place the packing gland assemblies to one side until ready for their reassembly to the eyepiece box (11, Figure 4-29).

Figure 4-38. Eyepiece window assembly.

All bubble numbers in Sections 4O1, 2, and 3 refer to Figure 4-38 unless otherwise specified.

a. Eyepiece window. The eyepiece window (9) consists of one crown element with parallel surfaces, and has sufficient thickness to withstand

b. Frame. The frame (7) is made of cast phosphor bronze and is 0.843 inch in width. It is of such construction as to withstand an internal pressure test of 300 psi. The outer part above the recess groove section has a rectangular projection section with narrow flat sides serving as flanges and it projects outward from the eyepiece box (11, Figure 4-29) when assembled. Each side flange has a. shallow recess groove section for clearance to carry two rayfilter plate straps (3, Figure 4-40) when assembled in the shallow recess groove sections which have sufficient sliding clearance.

The frame has a large cylindrical shoulder flange, with its outer face flush with the shallow recess groove sections. The large cylindrical shoulder flange has four equally spaced countersunk clearance holes, while the rectangular flange has eight countersunk clearance holes. The large cylindrical shoulder flange is a sliding fit in the counterbored recess seat in the eyepiece window assembly opening of the eyepiece box (11, Figure 4-29) and rests on this counterbored recess seat above a frame rubber gasket (8). It is secured with four short and eight long lockscrews (2 and 3) which extend into tapped holes in the counterbored recess seat.

The lower part of the frame below the large cylindrical shoulder flange is undercut, and serves as an alignment support section. It is a

The inner surface of the frame is bored to provide a clear aperture to the emerging light rays, for all positions of plus and minus diopter settings. Two counterbores are provided with a 45 degrees beveled seat section. The beveled seat section serves as a bezel shoulder, and has a bezel rubber gasket (4) adhering to it with the tightened eyepiece window (9). The small counterbore provides clearance for the eyepiece window periphery, while the large counterbore is threaded to receive the eyepiece window clamp ring (1).

c. Metal protection washer. The metal protection washer (6) is a thin brass washer with nominal wall thickness. This washer is cylindrical, and offers a smooth face for the contact of the clamp ring (1) as it is screwed in to tighten the rubber gasket (5) which is located on the inner surface of the eyepiece window (9). The metal washer is placed between the clamp ring rubber gasket (5) and the clamp ring (1), and protects the clamp ring rubber gasket (5) from being disrupted when tightening the eyepiece window with the clamp ring to maintain the hermetical seal.

d. Clamp ring. The clamp rings (1) is made of brass tubing and is 0.285 inch in width. It is cylindrical and has a nominal wall thickness. The periphery is threaded to engage in the internal threaded section in the large counterbore of the frame (7). The internal wall is tapered, and is of nominal thickness to permit sufficient tension for sealing the eyepiece window (9). The narrow face has two opposite slots 180 degrees apart, to permit clamping, removal, and reassembly of the eyepiece window by means of a special wrench.

4O2. Disassembly of the eyepiece window assembly. The eyepiece window assembly is disassembled in the following manner:

1. Use a special wrench in the two opposite slots in the bottom face of the clamp ring (1). Unscrew the clamp ring from the frame (7).

2. Place a piece of lens tissue on the front face of the eyepiece window (9) with the alignment

3. The bezel rubber gasket (4) adheres to the bezel shoulder of the frame (7). This connection must be broken.

4O3. Reassembly of the eyepiece window assembly. The eyepiece window assembly is reassembled in the following manner:

1. Turn the rectangular section of the frame (7) so that it is lying on its outer face.

2. Clean the eyepiece window in similar manner to that prescribed for the lenses of the various other assemblies.

3. Place the new bezel rubber gasket (4) on the bezel shoulder seat in the frame (7).

4. Place the new clamp ring rubber gasket (5) on the inner face of the eyepiece window (9).

5. Place the metal protection washer (6) on the clamp ring rubber gasket (5).

6. Screw the clamp ring (1) in the internal threaded section in the frame (7). Use a special wrench to tighten the eyepiece window (9) sufficiently to compress both the bezel rubber gasket (4) and the clamp ring rubber gasket (5). The eyepiece window should not be tightened to such an extent as to cause any strain in the glass. Any strain causes the eyepiece window to crack in time, necessitating renewal.

7. Place the eyepiece window assembly in a special pressure testing jig, with the frame rubber gasket (8) assemble in the counterbored recess seat in the jig. Secure the frame with four short and eight long lockscrews (2 and 3).

8. A pressure test of 100 psi under water for 30 minutes insures the hermetical seal of the eyepiece window (9).

9. After a successful pressure test, remove the four short and eight long lockscrews (2 and 3) and remove the assembly and the frame rubber gasket (8). Place aside the assembly with its lockscrews until ready for reassembly in the eyepiece box (11, Figure 4-29).

Figure 4-39. Focusing knob assembly.

hand of the observer. Figure 4-29 shows the focusing knob assembly. All bubble numbers in Sections 4P1, 2 and 3 refer to Figure 4-39 unless otherwise specified.

b. Knob. The knob (1) is made of phosphor bronze and is 1 13/32 inches long. It is of sufficient diameter to permit easy operation of the focusing

c. Knob shaft. The knob shaft (2) is made of monel metal and is 1 7/8 inches in length. It forms a connection between the knob at one part and a female coupling section (3) at the other. The long section of the shaft carries the knob secured with a taper pin (4). The stub section of the shaft is undercut to carry the large hub section of the female coupling section (3) which is secured with a straight pin (5). When assembled, the shaft provides a rigid support for the knob between the female coupling section (3) and the reamed hole in the knob bracket (7) for manipulation of the focusing mechanism.

d. Female coupling section. The female coupling section (3) is made of bronze rod and is 3/4 inch in length. It consists of a large hub section and an undercut alignment support section. The hub section is provided with a reamed hole of sufficient depth to retain it to the knob shaft with a straight pin (5). The alignment support section has a square broached hole and is a sliding fit on the square section of the eyepiece drive actuating shaft (12, Figure 4-35) of the eyepiece drive packing gland assembly. The alignment support section is a sliding fit into the counterbored recess in the packing gland (9) of the same assembly. It fits simultaneously over the square section of the shaft and in the packing gland counter bored recess.

e. Knob bracket. The knob bracket (7) is made of cast phosphor bronze and is rectangular. It provides a rigid joint for interconnection between the eyepiece drive packing assembly and the female coupling section (3). The outer surface is filleted from the base of the knob bracket to the hub section. The base is counterbored with a 30 degrees chamfered section, extending from the small counterbore to the

The axis is provided with a reamed hole and counterbored section, with the reamed hole serving as a bearing, and the counterbored section allowing clearance for the large hub of the female coupling section (3). The two dowel pins (8) maintain the alignment of the knob bracket to the milled recess in the eyepiece box. The bracket is secured with four lockscrews (10). The lockscrews (10) are inserted into countersunk clearance holes in the rectangular bracket base wall and screwed in tapped holes in the eyepiece box (11, Figure 4-29).

f. Diopter ring. The diopter ring (9) is made of brass material and is cylindrical. It has a nominal width and wall thickness, and is a sliding fit on the turned shoulder of the knob section. The outer circumference is graduated from 0 to 3 minus and 0 to 1.5 plus diopters. The graduated lines are spaced equally for each diopter line, having a plus and minus engraved indication above and below the zero diopter line. The diopter ring is a visual indication of the diopter reading, as the eyepiece lens is focused, and is observed from its coincidence with the stationary zero reference line in the knob bracket (7). The diopter ring is set to zero diopter and is secured with a lockscrew (6) at the factory, after the periscope is charged with nitrogen at 7 1/2 psi, with the use of an auxiliary telescope:

4P2. Disassembly of the focusing knob assembly. The focusing knob assembly is disassembled in the following manner:

1. Remove the taper pin (4) from the knob (1) and the knob shaft (2).

2. Remove the knob (1) sliding it off the knob shaft (2).

4. Remove the knob bracket (7) from the long section of the knob shaft (2).

5. The straight pin (5) is not removed from the female coupling section (3) and the knob shaft (2) as it is riveted at assembly.

4P3. Reassembly of the focusing knob assembly. The focusing knob assembly is reassembled in the following manner.

1. Slide the large hub section of the female coupling section (3) on the stub section of the knob shaft (2). Check the straight pin holes of both for proper alignment.

2. Insert and secure the straight pin (5) in the lined up holes, securing the female coupling section (3) to the stub section of the knob shaft (2) and riveting the straight pin at assembly. (Steps 1 and 2 are included for information, as these pieces normally are not disassembled.)

3. Place the knob bracket (7) over the long section of the knob shaft (2). The counterbored section slides over the large hub section of the assembled female coupling section (3).

4. Place the diopter ring (9) on the turned shoulder of the knob bracket hub section (7). Check the graduations; the minus graduations should be located in the lower part, using the stationary reference line of the knob bracket. Rotate the diopter ring, to ascertain that the tapped hole lines up with the spot face in the turned shoulder of the knob (1), and insert and secure the lockscrew (6).

5. Place the knob (1) on the outer part of the knob shaft (2). Insert and secure the taper pin (4) in the lined up holes of the knob and the knob shaft.

b. Rayfilter plate. The rayfilter plate (2) is made of cast phosphor bronze and is rectangular. This plate serves as a foundation for the remaining parts of the assembly. The upper part is provided with a center male hinge projection section with a reamed hole in its axis to accommodate two spring actuated plunger rods (23) of the two female hinge projection sections of the rayfilter housing (21). The upper main inside section has a cast recess allowing a nominal main body thickness, with side shoulders and a narrow upper shoulder. The side shoulders are provided with recesses to carry the rayfilter plate straps (3) on each

The lower section has a cast inside recess with nominal body thickness with wider side shoulders and a narrow lower shoulder. The side shoulders allow the rayfilter plate a vertical movement of 1 inch and serve as stops. The left side, when viewed from the rear of the inside recess of the lower section, is provided with a rectangular raised boss section or a rayfilter drive actuating gear rack (8) secured with four lockscrews (19) and maintained in alignment with two dowel pins (20). This gear rack meshes with a rayfilter drive actuating gear (11, Figure 4-32), projecting externally from the rayfilter drive packing gland assembly. The rayfilter drive actuating gear (11) is synchronized to carry the rayfilter plate (2) vertically with the eyepiece drive mechanism of the eyepiece skeleton assembly (Figure 4-28) for the focusing movement of 1 1/2 plus and 3 minus diopters.

The exteriors of the side shoulders of the lower section are stepped with two spotted recesses in the center of each step. The spotted recesses of 120 degrees engage the ball bearing friction catches (26) to retain the lower swinging part of the rayfilter housing (21). Two rectangular projecting bosses on the lower part serve as stops to engage in slots in the lower part of the inner, wall of the rayfilter housing (21) as the ball bearing friction catches (26) engage in the spotted recesses.

The main body wall is provided with a 3-inch opening which has anti-reflection threads in the inner circumference. This opening permits free access to the field of the periscope for the observer. The inside recess of the main body is provided with sliding vertical clearance over the flat flanges of the eyepiece window frame (7, Figure 4-38).

c. Rayfilter plate straps. The two rayfilter plate straps (3) are made of brass and are 4.624 inches in length, having a nominal thickness and width. Each strap fits in a recess in each side shoulder of the rayfilter plate (2), and is secured to each recess with seven lockscrews (19). These lockscrews are inserted into countersunk clearance holes in the rayfilter plate (2) and screwed into tapped holes in each strap. The outer side of each strap is flush with

d. Rayfilter housing. The rayfilter housing (21) is made of cast phosphor bronze, and is rectangular. This housing serves as an apron foundation which can be removed, readily during the installation and removal of the periscope. It carries the rayfilter parts.

The upper part is provided with two female hinge projection sections, a sliding fit over the center male hinge projection section of the rayfilter plate (2). Both hinge projection sections are reamed in their axis to carry the spring-actuated plunger rods (23) which are moved axially against spring tension for removal or reassembly to the center male hinge projection of the rayfilter plate. Both female hinge projection sections have a threaded section located at each outer end to carry two plunger rod spring bushings (22).

The cylindrical raised boss has a tapped hole in its center axis and a shallow counterbored section. The counterbored section carries the housing disk shoulder washer (14), while the tapped hole receives a lockscrew (15) to secure the shoulder washer.

The lower part of the inner section has two rectangular shoulder projections on both sides, in the center of which two ball bearing friction catches are provided. These two shoulder projections are a sliding fit over the shoulder steps of the rayfilter plate (2). The center of each projection is provided with a 90 degrees spotted recess and a tapped section with a smaller

When the rayfilter housing (21) is swung to the closed position, the ball bearing friction catches (26) engage in the 120 degree spotted recesses in each shoulder stop of the rayfilter plate (2), thus retaining the rayfilter housing (21) in the closed position. The rectangular stops of the rayfilter plate (2) are also in contact in the milled slots in the rayfilter housing (21).

The upper right side of the inner main body is provided with a raised rectangular boss, on which a detent catch spring (7) is mounted and secured with two lockscrews (17). This detent catch spring engages into the V-groove notch of the housing disk periphery, thus retaining it in any of the four positions desired.

The side shoulders above the two lower rectangular projections are provided with a left and right side bar (4 and 5) on the inner face of the rayfilter housing (21). These side bars are secured with five lockscrews (18) which are inserted in countersunk clearance holes in the side bars and screwed into tapped holes in the rayfilter housing sides shoulders. These side bars prevent foreign matter from being carried into the inner assembly of the rayfilter housing (21).

The outer face of the main body is provided with a large, flat, raised boss which has a bored hole and shallow counterfaced section. The bored hole is provided for light transmission and has anti-reflection threads on its inner circumference. The base of the eye blinder assembly and the variable density polaroid filter assembly is centered in this shallow counterfaced recess, and rests on the large flat raised boss. Either of the two assemblies is retained by two anchor screw pins (6), located with an appropriate center distance concentric with the bored hole and counterfaced shallow recess.

e. Housing disk. The housing disk (9) is made of cast phosphor bronze and is cylindrical. It has a diameter of 5.200 inches, with the periphery rough parallel knurled, and is provided with four equally spaced 90 degrees V-groove notches to engage a detent catch spring (7).

The housing disk axis is bored a sliding fit over the cylindrical raised boss of the inner body wall of the rayfilter housing (21). It has a shallow counterbored section to receive a shoulder washer (14) which is secured with a lockscrew (15). The inner face of the housing disk has a narrow projecting shoulder of 0.016 inch. This narrow shoulder contacts the inner body wall of the rayfilter housing (21, allowing the remaining wall of the housing disk clearance over the rayfilter housing inner body wall. Four equally spaced bored holes and threaded counterbored sections are provided in the same centerlines with the four periphery V-groove notches, for the insertion of red, green, and yellow rayfilters (16). The rayfilters rest on the counterbored seat in the counterbore of the clamp rings (13). The fourth opening remains clear.

f. Rayfilters. The three rayfilters (16) consist simply of cylindrical, colored filter glass with parallel surfaces. Three shades are used red, green, and yellow. These are provided for various conditions of observation. Each rayfilter is mounted in the counterbore of the clamp ring (13) and rests against the narrow shoulder seat of each threaded counterbored section in the housing disk (9).

g. Clamp rings. The three clamp rings (13) are made of seamless brass tubing, having a bored hole and counterbored section provision. The periphery is threaded and engages in the threaded counterbored section of any of the four

h. Shoulder washer. The shoulder washer (14) is made of rolled bronze and is cylindrical. The large diameter is a sliding fit in the counterbored section in the housing disk axis while the small shoulder is a sliding fit in the counterbored section in the raised boss on the inner body wall of the rayfilter housing (21). The small shoulder rests in the counterbored section seat in the raised boss, offering a nominal clearance to the housing disk (9). It is secured with a lockscrew (15) which is inserted in a countersunk clearance hole in the shoulder washer (14) and screwed into the tapped hole axis in the cylindrical raised boss.

i. Detent catch spring. The detent catch spring (7) is made of phosphor-bronze sheet and tempered. It has a developed length of 1.440 inches with a large rectangular section with two clearance holes as its securing part. This section is bent at 90 degrees and is secured to the raised rectangular boss section in the upper right side of the inner body wall of the rayfilter housing with two lockscrews (17). The projecting arm of this detent catch spring is provided with a 90 degrees detent bend conforming to the four 90 degrees V-groove notches in the housing disk periphery. The 90 degrees detent bend has a protruding depth of 0.093 inch, and when secured in the 90 degrees V-groove notch of the housing disk periphery, it holds the housing disk in the centerline under its spring tension.

j. Anchor screw pins. The two anchor screw pins (6) are made of corrosion-resisting steel and are 0.516 inch in length. The lower threaded part engages in the tapped holes in the flat raised boss section and main Wall of the rayfilter housing (21), up to its lower narrow shoulder and is soldered at assembly. The undercut section permits locking of the finger grip levers of the eye blinder assembly (Figure 4-42) and the variable density polaroid assembly (Figure 4-41).

k. Spring-actuated plunger rods. The two spring-actuated plunger rods (23) are made of corrosion-resisting steel material. The stub section is a sliding fit in the reamed hole located in the center male hinge projection section of the rayfilter plate (2). The stub section of each spring-actuated plunger rod assembled in each side of the female hinge projection sections of the rayfilter housing (21) form the hinge pins, to allow the rayfilter housing to swing upward when the lower part of the rayfilter housing is pulled clear of its engagement in the friction catch spotted recesses.

The shoulder section of the plunger rod slides axially in the reamed hole in each female hinge projection section against the spring tension, when pulled outward by the assembled plunger knobs. The plunger knobs are pulled outward only when removing or replacing the rayfilter housing (21).

The stem section of the plunger rods slides through each reamed hole in the plunger rod spring bushings (22), with the outer part of the stem section threaded to carry a plunger knob (24). The main body is slightly larger than the stem section in order to serve as a stop and to restrict the outward thrust of the plunger rod. A compression spring (25) fits over the main body up to the shoulder section, and is retained in the reamed hole in each female hinge projection section with a threaded plunger rod spring bushing (22).

l. Plunger rod spring bushings. The two plunger rod spring bushings (22) are made of phosphor bronze, The periphery is threaded to engage into tapped holes in the outer part of the female hinge projection sections of the rayfilter housing (21). The plunger bushings

m. Spring-actuated plunger knobs. The two spring-actuated plunger knobs (24) are made of phosphor bronze and are chromium plated. The periphery of each knob is fine diamond knurled to provide a firm finger grip. The center axis has a tapped hole to engage on the threaded part of the plunger rod stem section. The contour of the external surface is similar to an ordinary knob, with a hub section provided with a tapped hole to receive a lockscrew (1), thus securing the knob to the plunger rod. The knob offers the observer a firm grip projection and serves as a stop when the rayfilter housing (21) is removed.

4Q2. Disassembly of the rayfilter assembly. The rayfilter assembly is disassembled in the following manner:

1. Lift the lower swinging part of the rayfilter housing (21) by grasping the housing knob (10) and pulling it clear of its engagement in the friction catch spotted recesses of the rayfilter plate (2).

2. Grasp the two spring-actuated plunger knobs (24) pulling them outward as far as possible, thus removing the rayfilter housing (21) from the rayfilter plate (2).

3. Remove the rayfilter plate (2) by removing the seven lockscrews (19) and the rayfilter plate straps (3) from each side. This simulates the removal of the rayfilter plate from the eyepiece window frame (7, Figure 4-38).

4. Remove the five lockscrews (18) from the left and right side bars (4 and 5), and remove the side bars from the rear shoulders of the rayfilter housing (21).

5. Remove the lockscrews (15) from the housing disk shoulder washer (14).

6. Remove the housing disk (9), lifting it away from the rayfilter housing (21), carrying the shoulder washer (14) with it. Remove the shoulder washer (14) from the housing disk (9).

8. Remove the two lockscrews (1), unscrewing them from the hubs of the spring-actuated. plunger knobs (24).

9. Wrap a piece of emery cloth around the extended part of each spring-actuated plunger rod (23). Holding the emery cloth and rod firmly with a pair of parallel pliers, unscrew each spring-actuated plunger knob (24) from the threaded part of the spring-actuated plunger rods (23) one by one.

10. Remove each plunger rod spring bushing (22). Using a screwdriver of appropriate size, unscrew the plunger bushings from the outer parts of the two female hinge projection sections of the rayfilter housing (21).

11. Remove the spring-actuated plunger rods (23) and the plunger rod springs (2S) one by one from the reamed holes in the rayfilter housing two female hinge projection sections (21).

12. Remove the two friction catch spring retainers (11), unscrewing them from the outer two lower sides of the rayfilter housing (21), removing the two friction catch springs (12), and the two ball bearing friction catches (26).

13. Remove the two lockscrews (17) from the detent catch spring (7) and remove the detent catch spring from the rayfilter housing (21).

14. Remove the four lockscrews (19) from the front lower right side of the rayfilter plate (2), unscrewing the lockscrews from the rayfilter drive actuating gear rack (8). Remove the rayfilter drive actuating gear rack with the two dowel pins (20).

4Q3. Reassembly of the rayfilter assembly. The rayfilter assembly is reassembled in the following manner:

1. Place the rayfilter drive actuating ear rack (8) with its two dowel pins (20) on the lower right inner face of the rayfilter plate (2). Secure the gear rack with four lockscrews (19).

2. Focus the eyepiece lens to the center of the eyepiece window frame (7, Figure 4-38), making certain that the rayfilter drive actuating gear (11) is on the protruding square section of the rayfilter drive actuating shaft (10, Figure 4-32) of the rayfilter drive packing gland assembly. This central position is necessary for full focusing travel.

3. The rayfilter plate (2) is mounted only when the eyepiece lens is in the center of the eyepiece window frame to establish full synchronized movement. Place the rayfilter plate (2) over the flat sides of the eyepiece window frame (7, Figure 4-38); check the rayfilter drive actuating gear rack (8) to ascertain its engagement with the rayfilter drive actuating gear (11, Figure 4-32).

4. With the rayfilter plate (2) properly centered, and the gear rack in mesh with the rayfilter drive actuating gear, place both rayfilter plate straps (3) in each side shoulder recess of the rayfilter plate and the recess groove section of the eyepiece window frame (7, Figure 4-38). Secure the straps with seven lockscrews (19). These lockscrews are inserted in countersunk clearance holes in the rayfilter plate (2) and screwed in the tapped holes in the straps.

5. Place both ball bearing friction catches (26) in clearance holes in each rectangular side shoulder projection in the lower part of the rayfilter housing (21) with both friction catch springs (12), securing them with both friction catch spring retainers (11).

6. Place the two plunger rod spring bushings (22) in the outer threaded part of the female hinge projection sections of the rayfilter housing (21). Secure them with a screwdriver.

7. Place the plunger rod springs (25) on the spring-actuated plunger rods (3). Insert the spring and plunger rod in the reamed hole in each female hinge projection section, carrying them in from the center opening.

8. Place a piece of fine emery cloth around the stub section of the plunger rod and grasp

9. Insert the lockscrew (1) in the hub section of the spring-actuated plunger rod knobs (24), securing the knobs on the spring-actuated plunger rods (23).

10. Place the detent catch spring (7) on the raised rectangular boss located on the inner right side of the rayfilter housing (21), and secure it with two lockscrews (17),

11. Clean the three rayfilters (16) before reassembling them in the housing disk (9), placing them in the housing disk in a counterclockwise order of red, green, and yellow when viewed from the rear. Place each rayfilter in the counterbored recess in the clamp ring (13), and screw the clamp ring with the rayfilter in the housing disk (9). Secure each rayfilter snugly, using a special wrench inserted in the opposite slots of the clamp ring. Do not place any strain on the rayfilters while clamping, as this causes breakage.

12. Place the housing disk (9) on the raised cylindrical boss, tip the housing disk, and engage the periphery V-groove notch in the detent catch spring (7). A slight pressure against the detent catch spring permits the housing disk to slide easily over the cylindrical raised boss.

13. Place the housing disk shoulder washer (14) in the counterbored recess in the cylindrical raised boss of the rayfilter housing (21) and the housing disk (9), and secure the shoulder washer with a lockscrew (15). This lockscrew is inserted in a countersunk clearance hole in the shoulder washer (14) and screwed into a tapped hole in the raised cylindrical boss axis.

14. Place the left and right side bars (4 and 5) in the recess shoulders on each side of the rayfilter housing, and secure them with five lockscrews each (18). These lockscrews are inserted in the countersunk clearance holes in each side bar and screwed into tapped holes in the rayfilter housing recess shoulders.

a. Base plate. The base plate (9) is made of cast phosphor bronze, and holds the parts making up the assembly. The base plate follows a cylindrical pattern, except for the projecting upper and lower parts, which have a nominal thickness.

The outer part of the base plate is counterbored to carry the small shoulder of the knurled actuating sleeve (7). The bore is threaded to

The upper and lower projecting parts of the base plate are slotted to carry the right and left finger grip levers (1 and 2) and two tension springs (3). Two clearance holes are provided in the upper and lower centerline in these slotted sections. Each hole is concentric with the bore, with an appropriate center distance to slide over the anchor screw pins (6, Figure 4-40) projecting from the rayfilter housing (21). On opposite sides of each center clearance hole, clearance holes are provided in each outer slotted wall, while the inner wall has tapped holes in line with each clearance hole.

The large clearance holes receive the finger grip lever pivot screw pins (14), which are inserted in clearance holes in the outer slotted walls and screwed into tapped holes in the rear slotted walls. They extend through the reamed pivot holes in the finger grip levers (1 and 2) assembled in the slotted section between the outer and inner walls. The small clearance holes receive the finger grip lever thrust stop screw pins (13) which are inserted in clearance holes in the outer slotted walls, extend through a thrust hole in each finger grip lever (1 and 2), and are screwed into tapped holes in the inner slotted walls.

The finger grip lever pivot screw pins (14) are the hinge pivot pins for the right and left finger grip levers (1 and 2), while the finger grip lever thrust stop screw pins (13) extending through the thrust holes in the finger grip levers (1 and 2) restrict the movement of these levers for their unlocking and locking engagement

b. Finger grip levers. The right and left finger grip levers (1 and 2) are made of cast phosphor-bronze of duplicate design, except for the cast finger projection section. It consists of a narrow arm, which is a sliding fit in the upper and lower slotted sections in the base plate (9) between the outer and inner walls. Both projecting finger sections are right and left, and project outward, thus offering the observer a firm finger grip for removal or reattachment of the assembly. Three holes are provided in each lever. The center hole is a clearance hole for the anchor screw pins (6) and also serves as a catch in the undercut section of the anchor screw pins (6, Figure 4-40) when under tension by the finger grip lever springs (3).

The second hole toward the finger grip projection is a thrust hole, having sufficient clearance to contact the finger grip lever thrust stop screw pins (13) on opposite sides of its inner circumference. The reamed hole at the end of the arm serves as a pivot hole on the finger grip lever pivot screw pin (14). The inner side face of each arm has a narrow slot to carry the stub end of the finger grip lever springs (3). The stub end of each spring is a push fit in this narrow slot, while the remaining

When the finger grip levers (1 and 2) are gripped together, the spring is fully compressed. In this position the outer part of the thrust hole is resting on the finger grip lever thrust stop screw pin (13), and the center anchor screw pin clearance holes are in coincidence with the center clearance holes in the base plate (9). This position of the finger grip levers provides clearance for the removal of the base plate over the anchor screw pins (6, Figure 4-40) of the rayfilter housing (21). Reassembly of this base plate necessitates only centering the clearance holes over the anchor screw pins (6) and pressing inward until the snapping of both levers is noticeable.

c. Knurled actuating sleeve. The knurled actuating sleeve (7) is made of brass tubing and is chromium plated. It is cylindrical and has three external shoulders. The small shoulder is a sliding fit in the outer counterbored recess, resting on the recess seat in the base plate (9). The medium shoulder serves as the outer wall, while the large shoulder periphery is fine diamond knurled. It is bored and counterbored a sliding fit on the shoulder body and shoulder flange of the Polaroid socket housing (11) which, when secured, is stationary in the base plate (9).

d. Polaroid socket housing. The polaroid socket housing (11) is made of phosphor bronze and is cylindrical. The external surface is provided with three shoulders. The small shoulder is threaded to engage into the threaded section in the base plate (9). The medium, shoulder and the narrow shoulder flange are a sliding fit in the bored and counterbored section in the knurled actuating sleeve (7).

The internal part is bored for light transmission and is provided, with two counterbored sections in the outer section. The small counterbored section carries the assembled outer polaroid cradle (5), a polaroid filter (8), and a clamp ring (4). The cradle is a sliding fit in this counterbored section and the wall of this counterbored section is provided with a circumferential slot for the protrusion of an outer polaroid cradle actuating screw (6) to be carried through a 90 degrees rotation.

The large counterbored section is threaded to receive a face ring (10). The inner part of this polaroid socket housing has a threaded counterbored section to receive the inner polaroid filter (8) which is mounted in the counterbored section in the inner clamp ring (4). Two opposite drilled holes are provided in the rear face for the insertion of a special wrench to secure the housing in the base plate (9).

The medium shoulder periphery has a shallow 45 degrees radial recess slot for the insertion of a

e. Outer polaroid cradle. The outer polaroid cradle (5) is made of brass tubing and is cylindrical. It serves merely as a mount for the outer polaroid filter (8), having a bored hole for light transmission and a threaded counterbored section into which the outer polaroid filter (8) is secured by a clamp ring (4). A tapped hole in the wall carries the outer polaroid cradle actuating screw (6) for 90 degrees rotation.

f. Polaroid filters. The two polaroid filters are made of polaroid J glass of Bureau of Ordnance specification O.S. No. 1155. Each is shaped cylindrical with parallel surfaces.

Each polarizing filter is furnished in the form of a sheet of polarizing material bonded between two water-white glass plates.

Each filter is scribed with two short, permanent lines to indicate, within 1 degree, the diameter which is vertical when the filter is so oriented as to reduce to a minimum the intensity of the light reflected from a horizontal specular surface at the polarizing angle. These lines extend in from the edge of the filter for a distance of approximately 3 mm, and are placed on the side of the filter which is free from birefringent inclusions.

Polarizing filters without a bevel should have the side carrying the axis marks facing the source of polarized light.

g. Clamp rings. The two clamp rings (4) are made of brass tubing, having a bored hole and counterbored section, with the periphery of both threaded. One clamp ring carries the outer polaroid filter (8) in its counterbored section and screws into the threaded counterbored section in the outer polaroid cradle (5), securing the outer polaroid filter (8) snugly against the shoulder seat in the outer polaroid cradle.

They second clamp ring carries the inner polaroid filter (8) in the same manner, and secures it to the inner shoulder seat in the polaroid socket housing (11). The clamp ring

h. Face ring. The face ring (10) is made of brass tubing and is cylindrical. It is bored for light transmission and provided with a counterbored section leaving a narrow shoulder seat to carry the eyeguard mount (15). The periphery is threaded to engage in the large threaded counterbored section in the polaroid socket housing (11) and rests in contact with this counterbored section seat. The undercut shoulder of the inner face of this face ring comes within several thousandths inch to contact the outer polaroid cradle (5), allowing it sufficient free movement for its 90 degrees rotation. Two opposite slots are provided in the outer face for the insertion of a special wrench.

i. Eyeguard mount. The eyeguard mount (15) is made of brass rod and is cylindrical. It is bored for light transmission with a counterfaced cylindrical groove. The narrow remaining shoulder ring has 12 equally spaced slots which divide the inside narrow shoulder into 12 equally spaced clips, formed by shearing the narrow shoulder ring clips toward the rubber eyeguard (17).

The eyeguard mount has two shallow slots on opposite sides in the centerline that intercept the countersunk tapped holes, and two right angle slots intersecting the countersunk tapped holes and extending through the thickness of the mount. The two opposite countersunk tapped holes receive two eyeguard mount friction screws (16). These friction screws are inserted in countersunk tapped holes in the inner face of the eyeguard mount (15). The opposite side, or outer face, of each friction screw is slotted for a small screwdriver blade which can be tightened by turning the screwdriver counterclockwise. The slotted section of the eyeguard mount is thus spread by the upward tightening of the chamfered screw head in the countersunk angle, and the fixed position of the eyeguard for either the right or left eye of the observer is retained.

4R2. Disassembly of the variable density polaroid filter assembly. The variable density polaroid filter assembly is disassembled in the following manner.

1. With a small screwdriver, turn the two friction screws (16) in the outer face of the eyeguard mount (15) clockwise. Then remove the eyeguard mount.

2. Remove the polaroid socket housing (11) from the base plate (9) by inserting an adjustable wrench into the two shallow opposite holes in the inner face of the polaroid socket housing (11). Turn the wrench and housing clockwise, holding the base plate firmly in the left hand. When the housing is loosened, grip the knurled actuating sleeve (7) with the left hand and hold the base plate in the right hand; the remaining assembly can then be removed, by rotating it counterclockwise.

3. Remove the knurled actuating sleeve (7), lifting it evenly from the polaroid socket housing (11).

4. Remove the friction tension spring (12), lifting it out of the 45 degrees radial recess slot in the polaroid socket housing (11).

5 Turn the polaroid socket housing (11) so that its lower face is facing upward. Then insert an adjustable wrench in the slots in the clamp ring (4). Remove the clamp ring and the inner polaroid filter (8). Carefully check the opposite reference marks of the polaroid filter for reassembly.

6. Turn the polaroid socket housing (11) so that it is resting on its inner face. Then insert an adjustable wrench in the opposite slots in the face ring (10), holding the polaroid socket housing firmly. Unscrew the face ring by turning it counterclockwise.

7. Remove the outer polaroid cradle actuating screw (6), using a small screwdriver. Unscrew it from the tapped hole in the outer polaroid

8. Unscrew the clamp ring (4) from the outer polaroid cradle (5), inserting an adjustable wrench in the opposite slots in the clamp ring. Remove the clamp ring (4) and the outer polaroid (8). Carefully check the opposite reference marks of the polaroid filter for reassembly.

9. Using a small screwdriver, remove the finger grip lever thrust stop screw pins (13) and the finger grip lever pivot screw pins (14). Unscrew these screw pins from the tapped holes in the inner slotted walls of the base plate (9). Remove the right and left finger, grip levers (1 and 2) and their tension springs (3).

4R3. Reassembly of the variable density polaroid filter assembly. The variable density polaroid filter assembly is reassembled in the following manner:

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

2. Insert the right and left finger grip levers (1 and 2) with their tension springs (3) in the upper and lower slotted-sections in the base plate (9) between the outer and inner walls: Compress the tension springs (3) sufficiently to line up the outer pivot hole in each finger grip lever with the pivot hole in the base plate for the insertion of the finger grip lever pivot screw pins (14) one by one, securing each screw pin in the tapped holes in the inner slotted base plate walls.

3. Grasp both finger grip levers and compress them together, until near the limit of their travel. Insert the finger grip lever thrust stop screw pins (13) and secure them in the tapped holes in the inner slotted base plate walls (9).

4. Clean the two polaroid filters (8) and place them in each clamp ring (4) with their axis marks facing the source of polarized light.

5. Hold the polaroid socket housing (11) with the left hand and the inner clamp ring (4) and the polaroid filter (8) with the right

6. Hold the outer polaroid cradle (5) with its inner face upward with the left hand, and the outer clamp ring (4) and the polaroid filter (8) with the right hand. Screw the clamp ring into the threaded counterbored section in the outer polaroid cradle (5), using a special wrench to tighten the polaroid filter snugly against the counterbored seat.

7. Place the assembled outer polaroid cradle in the counterbored seat in the polaroid socket housing (11), carrying it in from the outer part with the clamp ring side facing upward.

8. Insert the outer polaroid cradle actuating screw (6) through the 90 degrees radial slot in the polaroid socket housing (11) and screw it into the tapped hole in the outer polaroid cradle (5), securing the actuating screw.

9. Place the friction tension spring (12) in the 45 degrees radial recess slot in the polaroid socket housing (11).

10. Place the polaroid socket housing (11) in the knurled actuating sleeve (7). This is done by engaging the protruding actuating screw (6) in the keyseat in the knurled actuating sleeve, and pressing the friction tension spring (12) inward while pressing the polaroid socket housing downward until flush with the inner face of the sleeve. Lift the knurled actuating sleeve upward until its outer face is flush with the polaroid socket housing (11).

11. Screw the polaroid socket housing (11) with the assembled knurled actuating sleeve (7) into the threaded section in the base plate (9). Secure the socket housing using a special wrench inserted in the opposite shallow holes in its lower face, screwing it counterclockwise.

12. Using a special wrench inserted in the opposite slots of the inner clamp ring (4), loosen the clamp ring and check the opposite reference marks of the inner polaroid filter (8). The opposite reference marks should be lying parallel to the vertical centerline of the base plate (9).

14. The clockwise rotation of the knurled actuating sleeve (7) controls the relation of one polarizing filter axis to the other, and therefore the density of the field. The light that passes through is plane-polarized in a direction that

15. Place the face ring (10) in the large threaded counterbored section in the polaroid socket housing (11), securing it with the use of an adjustable wrench inserted in opposite slots in the face ring.

16. Place the mounted eyeguard (17) and its mount (15) in the counterbored seat in the face ring (10). Secure the mount with the two friction screws (16), screwing them counterclockwise, and pressing down on the mount, setting the position of the eyeguard for either the right or left eye.

A suitable boss for attaching one of the eye buffers to the periscope when the eye buffer is not in use is provided on the eyepiece end of the periscope in such position as not to interfere with the observer. The eye buffers are supplied in the box containing spare parts and tools for the periscope.

A blinder for the unused eye of the observer is also furnished with each periscope. The blinder may be used in covering either eye of the observer. Suitable provision is made for the efficient use of the blinder by the observer with any probable interpupillary distance. Suitable arrangements are also provided for securing the blinder to the periscope in such position as not to interfere with the observer or with any of the other eyepiece end fittings when the blinder is not in use. The blinder is arranged so that it may be used when either the rayfilter or the stadimeter and course-angle device is in use. The part of the blinder in the line of vision

b. Rubber eyeguards. The two rubber eyeguards (1) are made of soft molded rubber. One eyeguard is mounted on the blinder plate (6) and the other is mounted on the base plate (2). They prevent injury, locate the eye at the proper

distance, and keep out stray light. Ventilating holes or slots should be provided in the eyeguard at any point as near as possible to the base to prevent external fogging of the eyepiece window (9, Figure 4-38).

c. Base plate. The base plate (2) is made of cast phosphor bronze. The main section is similar to the base plate of the variable density polaroid filter assembly (Figure 4-41), except that it is provided with an extended boss for the attachment of the blinder plate (6).

The main section has a cylindrical groove which is undercut to allow the small flange section to fit into the inside recess in the eyeguard (1). The Cylindrical shoulder flange section allows the eyeguard to be rotated and prevents it from dropping off. The eyeguard is stretched over the shoulder flange section and grips in the undercut part of the cylindrical groove, while the inside recess of the eyeguard also grips over the cylindrical shoulder flange section. The center axis is bored to provide a clear aperture for the emerging light rays of the periscope.

The upper and lower parts of the main section are slotted in similar manner to the base plate (9) of the variable density polaroid filter assembly, for the right and left finer grip levers (3 and 4), their tension springs (5), finger grip lever pivot screw pins (11), and the finger grip lever thrust stop screw pins (10).

The blinder plate projection boss forms the stem section and is bent at an approximate

d. Finger grip levers. The right and left finger grip levers (3 and 4) are identical to the finger grip levers (1 and 2, Figure 4-41) of the variable density polaroid filter assembly. Their purpose and function are identical. Refer to the variable density polaroid filter assembly for parts (3, 4, 5, 10, and 11).

e. Blinder plate. The blinder plate (6) is made of brass rod and is cylindrical. The outer surface is provided with a large shoulder flange and an undercut shoulder section. It carries an eyeguard (1) in similar manner to the main section of the base plate (2). The lower face has a small projection with two flat sides, which is a sliding fit in the wide shallow keyway in the stem projection boss in the base plate (2). A counterbored shallow recess chamfered at 30 degrees is provided in the outer face. This part of the blinder is in line with the observer's unused eye. When the blinder is in use, it is a dull nonreflecting black. The fitted eyeguard excludes light from the unused eye of the observer. A clearance hole offset from the center axis with a counterbored recess is provided for the blinder adjusting screw (7). The offset provides sufficient interpupillary distance.

f. Blinder adjusting screw. The blinder adjusting screw (7) is made of bronze rod. It has a large shoulder section, with the main body provided with two flat shoulders. It is a push fit in the offset clearance hole and counterbored recess in the blinder plate (6). The two flat shoulders are a sliding fit in the elongated hole An the stem projection boss of the base plate (2). The stub section is threaded to carry the blinder adjusting nut (8), with a tapped hole in the center axis in this section to carry the blinder adjusting screw nut lockscrew (9).

g. Blinder adjusting screw nut. The blinder adjusting screw nut (8) is made of bronze

4S2. Disassembly of the eye buffer and eye blinder assembly. The eye buffer and eye blinder assembly is disassembled in the following manner:

1. By pulling outward with two fingers, one from each hand placed inside near the base of the eyeguard, remove both eyeguards (1), one from the blinder plate (6) and the other from the base plate (2).

2. Follow Section 4R2, Step 9 for the removal of the right and, left, finger grip levers (3 and 4), their tension springs (5), the finger grip lever thrust stop screw pins (10), and the finger grip lever pivot screw pins (11) from the base plate (2) in similar manner to that followed for the variable density Polaroid filter assembly (Figure 4-41).

3. Remove the blinder adjusting screw nut lockscrew (9), unscrewing it from the tapped hole in the center axis in the blinder adjusting screw (7).and the counterbored recess in the blinder adjusting screw nut (8).

4. Remove the Minder adjusting screw nut (8), unscrewing it from the threaded stub section in the blinder adjusting screw (7).

5. Remove the blinder plate (6) with the blinder adjusting screw (7). Remove the blinder adjusting screw (7) from the blinder plate (6).

1. Place the blinder adjusting screw (7) in the offset counterbored clearance hole in the blinder plate (6). Line up the flat shoulders of the adjusting screw with the flat shoulders of the blinder plate rear small projection, by turning the adjusting screw.

2. With the left thumb pressed against the blinder adjusting screw head (7), place the raised projection section part of the blinder plate (6) in the wide shallow keyway in the base plate projection boss and the protruding part of the adjusting screw in the elongated axial slot. Check to ascertain that the offset hole in the blinder plate is located outward.

3. Screw the blinder adjusting screw nut (8) on the threaded stub section of the blinder adjusting screw (7), turning it clockwise until tight. The counterbored recess side should face inward.

4. Insert the blinder adjusting screw nut lockscrew (9) in the threaded axis in the blinder adjusting screw (7). The head of the lockscrew comes in contact with the inner face of the blinder adjusting screw while the lockscrew head enters the blinder adjusting screwnut (8) counterbored section. Sufficient distance of this counterbored section remains to allow the nut to be released 1/4 turn for the interpupillary adjustment of the blinder plate (6).

5. Insert the right and left finger grip levers (3 and 4) with their tension springs (5) in the base plate (2) in the same manner as that stated in Section 4R3, Step 2, and secure them in the same manner with finger grip lever pivot screw pins (11).

6. Follow Section 4R3, Steps 2 and 3 for the insertion of the finger grip lever thrust stop screw pins (10).

7. Reassemble the two eyeguards (1), one to the blinder plate (6) and the other to the base plate (2). Rotate the two low portions of the outer flared-out sections of the eyeguards so that they line up centrally.