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SOURCES OF HYDRAULIC POWER
 
A. INTRODUCTION
 
2A1. Hydraulic motors. The pressures required to operate the hydraulic equipment are developed by electric motor-driven pumps.

Hydraulic motors, such as actuating cylinders, are generally regarded as the power units. Like other motors, they do not actually create their own power. They merely convert hydraulic power which has been built up elsewhere into mechanical energy. Pumps, therefore, act as the central power supply for the entire hydraulic system by creating pressure in the system.

B. IMO PUMPS

2B1. General description. The IMO pump (see Figure 2-1) is a power-driven rotary pump, consisting essentially of a cylindrical casing, horizontally mounted, and containing three threaded rotors which rotate inside a close-fitting sleeve, drawing in oil at one end of the sleeve and driving it out at the other.

2B2. Detailed description. a. The rotors. The rotors of the IMO pump, which resemble worm gears, are shown in Figure 2-2. The inside diameters of the spiral "threaded portions" of the rotors are known as the troughs of the thread; the outside diameters, or crests, are known as the lands. The troughs and lands of the adjacent rotors are so closely intermeshed that, as they rotate, the meshing surfaces push the oil ahead of them through the sleeve, forming, in effect, a continuous seal, so that only a negligible fraction of the oil trapped between the lands can leak back in the direction opposite to the flow.

A cutaway view of the, pump is shown in Figure 2-3. The center rotor, (5) is

 

Figure 2-1. IMO pump.
Figure 2-1. IMO pump.

power-driven; its shaft is direct-coupled to an 18-horsepower electric motor which drives it at 1750 revolutions per minute. The other two rotors (6), known as idlers, are driven by the center rotor which, through the intermeshing of its threads with those of the idlers, communicates the shaft power to the idlers and forces them to rotate in a direction opposite to that of the center rotor. The rotation of the center rotor is clockwise as viewed from the motor end of the coupling shaft, while the rotation of the two idler rotors is counter-clockwise.

The end of the power rotor nearest the motor rotates in the guide bushing (9); the rotor shaft extends out through the end-plate, where it couples to the shaft of the electric motor which drives it. Leakage around the shaft is prevented by five rings of 3/8-inch

Figure 2-2. IMO rotors.
Figure 2-2. IMO rotors.
 
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square flexible metallic packing (8) which is held in place by a packing gland (7). Any oil which does leak through the packing falls into the drip cup (13).

b. The sleeve. It should be emphasized that the rotors are not housed directly within the casing itself (1), but within a removable two-piece sleeve (4) which fits snugly inside the casing proper and can be quickly removed and replaced as soon as it shows signs of wear. The two pieces of which the sleeve consists are bolted together near the center of the casing, as shown, by the sleeve bolts (14). The sleeve is secured against longitudinal drift by the two adjusting bolts, one of which (10) is shown in the cutaway. Rotary motion is prevented by three taper pins (not shown in the cutaway) which project into the sleeve and bearing block from the casing.

  The casing contains two ports, the suction port (15), which receives oil from the supply tank at a pressure of from 10 to 25 pounds per square inch, and the discharge port (16) from which it is discharged into the system.

c. Elimination of axial thrust; the balancing connection. It must be remembered that the function of a pump is merely to displace fluid by mechanical action. This displacement will of in itself create any pressure throughout the fluid being pumped unless the movement of the fluid encounters resistance somewhere in the system beyond the point at which it is discharged from the pump. The working pressure of the main hydraulic system, of which the two IMO pumps are the power supply units, runs between 600 and 700

 Figure 2-3. Cutaway of IMO pump.
1) Casing; 2) end cover; 3) end cover; 4) rotor housing; 5) power rotor; 6) idler rotors; 7) packing gland;
8) packing; 9) guide bushing; 10) adjusting bolts; 11) jam screw; 12) bearing block; 13) drip cup; 14) sleeve
bolts; 15) suction port; 16) discharge port; 17) equalizing channel; 18) collars; 19) bearing journal.
Figure 2-3. Cutaway of IMO pump. 1) Casing; 2) end cover; 3) end cover; 4) rotor housing; 5) power rotor; 6) idler rotors; 7) packing gland; 8) packing; 9) guide bushing; 10) adjusting bolts; 11) jam screw; 12) bearing block; 13) drip cup; 14) sleeve bolts; 15) suction port; 16) discharge port; 17) equalizing channel; 18) collars; 19) bearing journal.
 
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pounds per square inch. It is prevented from exceeding this value by relief valves and an automatic bypass, or unloading, valve (see Chapter 1, page 15). But it will not reach this working pressure, or in fact any pressure above the 10- to 25-pound "back-pressure" at which the oil enters the suction side of the pump from the supply tank, unless the oil being driven out of the discharge side of the pump encounters a corresponding resistance somewhere else in the system. In short, when the hand bypass valve is open, the oil circulates at no-load, that is, at the same pressure as the pressure existing in the supply tank or reservoir.

Since pressure existing anywhere in an enclosed liquid is transmitted equally in all direction's (see Chapter 1, page 5), it follows that any pressure which the intermeshed rotors have developed in the oil by the time it reaches the discharge end of the sleeve will be exerted against every surface with which this oil is in contact, including the threads of the rotors themselves. In other words, if the full working pressure of from 600 to 700 pounds per square inch is developed at the discharge port, a pressure equal to 600 to 700 pounds per square inch would necessarily be exerted against the rotors in the direction

Figure 2-4. IMO pump showing pipe plugs and
balancing connection.
Figure 2-4. IMO pump showing pipe plugs and balancing connection.

opposite to which the oil was being moved by the rotors. This pressure would then express itself as an axial, or longitudinal, thrust tending to force the rotors against the bearing block (12, Figure 2-3). This would naturally result in excessively high friction, with consequent rapid wear of all moving parts

  involved. Therefore this axial thrust must be equalized or balanced in some way.

To supply this balancing or equalizing force, a small pipe, called the balancing connection is provided. This connection permits oil from the discharge end of the pump to flow into the equalizing channel (17, Figure 2-3) in the end-plate at the suction side of the pump. Figure 2-4 shows the balancing connection.

The cutaway, Figure 2-3, shows the equalizing channel (17) in the end-plate. A study of the cutaway will show that from the equalizing channel, three lines open from the endplate into the bearing block at the points where the ends of the rotor shafts extend into it. The function of this equalizing channel is to allow the oil to bear against the ends of the rotor shafts at the suction side of the pump with the same pressure which it is exerting against them at the discharge end. In effect, the three rotors are floated between equal oil pressures exerted against their opposite ends, thus eliminating axial thrust. The ends of the shafts of the idler rotors (6) are fitted with collars (18) to locate the axial position of the rotors. Another compensating area for elimination of axial thrust against the center rotor is seen at the bearing journal (19), which forms a shoulder on the shaft just at the point where the journal enters the guide bushing.

The IMO pump is ideally adapted for continuous, long-term service. It is quiet and efficient in performance, requiring a minimum of attention.

2B3. Operating instructions. Before an IMO pump is started for the first time, the motor wiring should be checked for proper rotation as indicated by the arrow on the pump casing. To start the pump, open the quick-throw valve at the supply tank, and the-quick-throw valve and hand bypass valve on the main supply manifold. Then turn the motor switch to ON. If the pump is unusually noisy when started, it should be shut down immediately and the system investigated for a clogged line, dirty strainers, or a closed valve which prevents the flow of hydraulic fluid.

 
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2B4. Maintenance. Once the pump is in service, it requires no attention other than an occasional inspection for leakage at the packing gland. If, however, excessive leakage occurs, the packing must be replaced.

To replace packing, remove the two packing-gland nuts as shown in Figure 2-5. Pull out packing gland and remove the packing.

After new packing has been assembled, the nuts should be tightened enough to seat the metallic packing rings, and then backed off and set up again without using a wrench. Excessive gland pressure on the packing causes scoring of the shaft as well as rapid deterioration of the packing. Adjust the gland nuts about finger tight. The final adjustment should be made with the pump running.

Figure 2-5. Removing packing gland nut.
Figure 2-5. Removing packing gland nut.

2B5. Disassembly and re-assembly. When it becomes necessary to overhaul the IMO pump, its disassembly is quite simple (see Figure 2-3). Proceed as follows:

a. Removing taper pins. On one side of the pump (see Figure 2-4), are three pipe plugs. Each one holds in place one of the taper pins mentioned in Section 2B2b, which must be removed as the first step in disassembly. These pins are individually fitted to their holes to insure correct alignment of the sleeve and bearing block. Before removal,

  their positions should be marked with a prick-punch so that they may be replaced in their original holes.

b. Removing end-plates. Taking off the two end-plates (2 and 3) then frees all of the inner parts for removal.

c. Removing sleeve. The two halves of the sleeve (4, Figure 2-3), which are shown bolted together in the illustration, are fitted together in a step joint. Mark the parts with a prick-punch so that they may be reassembled in their original arrangement. The sleeve is maintained in its correct longitudinal position within the casing by the adjusting bolts (10). The settings of the adjusting bolt should not be altered during disassembly.

d. Replacing guide bushing. When replacing the guide bushing (9), be sure it is firmly secured by the jam screw (11).

e. Renewing sleeve. When it is necessary to renew the sleeve, the two halves of the new sleeve must be carefully fitted so that the inner and outer surfaces of the one half line up with those of the other. They are then bolted together and installed in the pump, and aligned longitudinally by the adjusting bolts. These should be so adjusted that the shoulder on the discharge end of the sleeve fits tightly against the counterbore at that end of the casing. These adjusting bolts are necessary to correct for individual differences in longitudinal dimensions resulting from tolerances allowed in manufacture.

Also, the length of that portion of the adjusting bolt which protrudes from the tapped hole in the sleeve must be sufficient to bear tightly against the inner face of the end-plate. It must be tight enough to hold the sleeve in position, but not sufficient to prevent the end-plate from being bolted solidly to the casing. In practice, the proper adjustment of the adjusting bolt is determined by taking a trial setting. First, bolt on the end-plate, without the paper gasket; then estimate the additional clearance needed between the end-plate and the casing, allowing for the thickness of the gasket; screwing in the adjusting screws to the estimated clearance around in the trial setting will then bring the sleeve into longitudinal alignment.

 
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C. THE WATERBURY SPEED GEAR
 
2C1. Introduction. The actuation of the various hydraulically operated units on board a submarine often requires great precision of control, and transmission of power at variable speeds and pressures, without any sharp steps or gradations. The hydraulic machine used for many of these operations is the Waterbury speed gear, a quiet, efficient mechanism which furnishes instant, positive, and accurate hydraulic power transmission.

2C2. A-end pumps and B-end motors.The Waterbury speed gear may be used either as

Figure 2-6. Waterbury A-end.
Figure 2-6. Waterbury A-end.

a pump (converting rotary mechanical motion into hydraulic fluid displacement), or as a hydraulic motor (converting hydraulic fluid displacement into rotary mechanical motion).

The type of Waterbury speed gear generally used as a pump is designated as a Waterbury A-end speed gear (see Figure 2-6). The type generally used as a hydraulic motor is designated as a Waterbury B-end speed gear, or Waterbury B-end hydraulic motor (see Figure 2-7). In one special installation, the A-end type is used as a hydraulic motor, but since this is not generally the case, it will be convenient to describe the A-end type primarily as a hydraulic pump.

A-end and B-end speed gear are often used together to form a pair of power transmission units, separated by any required length of hydraulic piping to suit the needs of a particular installation. So used, they receive rotary mechanical motion from an electrical motor at one point and transmit it as

  a fluid displacement to any required point, where it is reconverted into rotary motion, with a positiveness and fineness of control which could not be achieved by the use of electric motors alone.

The size of the Waterbury A-end speed gear, used in the submarine hydraulic system. primarily as a pump, is designated as No. 5-A. The sizes of B-end motors used are designated as No. 5-B and No. 10-B.

Inasmuch as this chapter is devoted to sources of hydraulic power, we shall here

Figure 2-7. Waterbury B-end.
Figure 2-7. Waterbury B-end.

concern ourselves primarily with the Waterbury A-end speed gear in its use as a pump. It will then be convenient to consider briefly the operation of the Waterbury B-end speed gear as a hydraulic motor; this will be readily understood as a not very extensive departure from these principles.

2C3. The Waterbury A-end pump. a. Use of the Waterbury A-end pump in submarine hydraulic systems. The Waterbury A-end. pump is operated by a rotating shaft which may be driven either by an electric motor or by hand.

Three motor-driven and three hand-driven Waterbury A-end pumps are used in the submarine-one of each type in the steering system, stern plane system, and bow plane system. In operation by normal power, the two types are used in each system as team; the motor-driven unit transmits oil for the power actuation of the system, while the hand-driven unit fitted with a large handwheel

 
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and designated as a telemotor, or telemotor pump, transmits oil to a control cylinder to provide fine control of the output of the motor-driven unit. The hand-driven unit is also used, alternatively, to operate the system by hand whenever it is desired not to use the motor-driven pump.

b. Operating principle. Although the Waterbury A-end speed gear is actuated by rotary motion, in principle it is actually a reciprocating multiple-piston type of pump. It consists of a casing containing three basic elements:

Figure 2-8. Tilt-box at neutal.
Figure 2-8. Tilt-box at neutral.

Figure 2-9. Maximum tilt.
Figure 2-9. Maximum tilt.

1. A socket ring, which in ball sockets holds seven or nine piston connecting rods, arranged roughly in circle around the driving shaft as a center.

2. A cylinder barrel, in which are bored the seven or nine corresponding cylinders.

3. A tilt-box, which alters the angle and direction of the socket ring with respect to the cylinder barrel.

  The socket ring and cylinder barrel are mounted on the drive shaft so that they rotate together. The socket ring is so arranged that it can be made to rotate either parallel to the cylinder barrel or at an angle to it. Connected to the tilt-box is a control shaft extending through the pump casing. When the control shaft is pushed up or down, it determines the angle and direction of the tilt-box.

The diagrams, Figures 2-8 and 2-9, will help to clarify the manner in which pumping action is obtained. The socket ring rotates within the tilt-box on the radial and axial thrust bearings. As long as the tilt-box is maintained in the vertical position, as shown in Figure 2-8, the socket ring and cylinder barrel will rotate parallel to each other, and there will be no reciprocating motion of the pistons within the cylinder barrel.

However, when the tilt-box is tilted in either direction away from the vertical, as in Figure 2-9, the socket ring no longer rotates in the same plane as the cylinder barrel. This means that as a ball socket on the socket ring reaches that point in its rotation which is closest to the barrel, the piston belonging to it will be driven down into the corresponding cylinder, and then, as this same ball socket recedes to the point farthest away from the barrel, the piston will be withdrawn again.

Figures 2-10, 2-11, and 2-12 will help still further to clarify this action. They show the tilt-box tilted away from the vertical, and illustrate the course of a single piston, whose motion we are able to follow as the socket ring turns through a half-cycle (180 degrees).

As the piston rises to its uppermost position, as shown in Figure 2-10, it occupies a progressively smaller space in the cylinder, until it reaches the point at which the socket ring and barrel are farthest apart. The partial vacuum in the chamber, produced by the outward movement of the piston, causes the fluid to be forced into the cylinder.

In moving from its uppermost position to its intermediate position, Figure 2-11, the piston moves into the cylinder and begins to displace the fluid accumulated there. At its

 
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lowest point, Figure 2-12, the piston occupies almost the entire cylinder. The expulsion of the fluid through the discharge port is now complete. The piston again rises from this position for the suction stroke.

The repetition of these movements in sequence by all of the pistons results in a smooth, nonpulsating flow of hydraulic fluid.

Now that the pumping principle of the Waterbury A-end speed gear has been illustrated diagrammatically, we are ready to consider in detail the parts of which it is composed.

c. Basic differences between A-end and B-end. For the sake of simplicity and clarity of explanation, the mechanism of the speed gear is illustrated, in Figure 2-13, by a cutaway view of the B-end (hydraulic motor) type. The B-end motor has been selected for the cutaway view instead of the A-end pump because the actual appearance of the tilt-box and control shaft parts in such a view of the A-end pump would appear too complicated. Therefore, a word of explanation is needed here as to the basic structural difference between A-end and B-end speed gears.

In the A-end type, as already explained, the angle between the socket ring and the cylinder barrel-which determines the amount of displacement caused by the pistons in the cylinders as these elements rotate is determined by a tilt-box whose angle is, in turn, controlled by a control shaft. The A-end is therefore said to have variable displacement of the pistons.

In the B-end type, this tilt-box is replaced by an angle-box (see Figure 2-14), which may be loosely described as a "permanently tilted tilt-box." This angle-box is bolted solidly to the inside of the case, presenting its vertical side to the end of the case, and its slanted face to the socket ring which rotates against it. The important point is that, unlike the tilt-box, it is immovable, so that its direction and angle of tilt are fixed and permanent. Therefore it does not need a control shaft.

There is also a difference between the spacing of the sockets in the socket ring, and

  of the cylinders in the cylinder barrel, in the two types of speed gear, of which a detailed explanation is given in Section 2C4b.

Figure 2-10. Piston on top.
Figure 2-10. Piston on top.

Figure 2-11. Piston in middle.
Figure 2-11. Piston in middle.

Figure 2-12. Piston of bottom.
Figure 2-12. Piston of bottom.

However, the basic structural differences between an A-end pump and B-end motor may be summed up as follows:

1. The A-end has a variable tilt-box and a control shaft.

2. The B-end has fixed angle-box and no control shaft.

 
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Once this structural difference between A-end and B-end is clearly understood, the cutaway view, Figure 2-13, which shows the B-end with the angle-box can then be used to illustrate our discussions of the A-end pump with which it is identical in all other details.

2C4. Detailed description of parts. a. The case. The case, or casing (15, Figure 2-13), is a light metal casting tested to a pressure of 80 pounds per square inch and formed

  roughly into a square, boxlike shell with an opening at each end. As can be seen in Figure 2-13, the far end, in the view shown, is considerably smaller than the near end.

The inside surface of the case is rough machined.

The larger end is finish-machined to take the valve plate (16) which is held to the case by four heavy studs, or tie-bolts, called the case bolts (21). The case bolts extend all the way through the case beyond the squared

Figure 2-13. Cutaway of Waterbury B-end.
1) Main shaft; 2) socket ring; 3) angle-box; 4) cylinder barrel; 5) cylinder; 6) piston; 7) connecting rod; 8) universal joint; 9) pin; 10) axial thrust bearing; 11) roller bearing; 12) chaff keys; 13) oil seal; 14) ports;
15) case; 16) valve plate; 17) radial thrust bearing; 18) spring lock; 19) barrel spring; 20) end-plate; 21) case
bolt; 22) intershaft disk.
Figure 2-13. Cutaway of Waterbury B-end. 1) Main shaft; 2) socket ring; 3) angle-box; 4) cylinder barrel; 5) cylinder; 6) piston; 7) connecting rod; 8) universal joint; 9) pin; 10) axial thrust bearing; 11) roller bearing; 12) chaff keys; 13) oil seal; 14) ports; 15) case; 16) valve plate; 17) radial thrust bearing; 18) spring lock; 19) barrel spring; 20) end-plate; 21) case bolt; 22) intershaft disk.
 
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shoulder near the smaller end, where spot-faced surfaces are provided to serve as seats for the stud-ends.

The smaller end is finish-machined to take the end-plate (20) which is screwed to the case by six small Allen-head screws that fit down into countersunk holes in the endplate so that, when secured, they come down flush with the plate. This end also contains a finished surface to receive the main shaft roller bearing.

In the center of the case, as viewed from the top, is a tapped hole which receives a fitting from a vent and replenishing line. A similar tapped hole in the bottom of the case serves as a drain. When the pump is mounted bottom-side up, the functions of these two holes are reversed.

Cast integral with the case are tie mounting brackets. These have drilled and spot-faced mounting holes.

The smaller end of the A-end pump also has vertical holes drilled through the top and bottom, 1 3/4 inches to the right of the center line of the shaft as viewed from the shaft end, machined and tapped to take the control shaft bearing and guides (not shown in Figure 2-13). Either the top or bottom hole may be used to provide a passage for the control shaft, depending on which way the pump is mounted, and on other installation limitations. Whichever hole is used for the control shaft the opposite one is generally, though not necessarily, used for the shaft which operates a centering device mounted over it. When the second hole is not used, it is closed by a plug.

b. The main shaft. The main shaft (1, Figure 2-13) is direct-coupled to the electric driving motor. It is rotated clockwise as viewed from the motor end of the shaft. The function of this shaft is to drive the revolving group of which it is a part. The revolving group consists of the following units: shaft (1), universal joint (8), cylinder barrel (4), pistons (6), connecting rods (7), barrel spring (19), socket ring (2), and barrel keys (12).

The main shaft rotates in two roller bearings, one of which is contained in the smaller

  end of the case itself, and the other in the valve plate.

At the point where the shaft intersects the socket ring, it forms a closed yoke to which the universal joint (8, Figure 2-13) is held by the shaft pin (9). The shaft is flattened and perforated on two sides to provide for the barrel keys (12) which drive the barrel. A grooved section on the shaft receives the barrel lock spring (18, Figure 2-13) which serves only to prevent the barrel from slipping off the shaft.

The correct amount of end-play for the main shaft, amounting to 0.015 of an inch, is insured by inserting a spacer in the bearing recess of the valve plate beyond the shaft bearing. The thickness of this disk is determined after the rest of the parts have been fitted to each other, so that it can compensate for end-play error caused by tolerances in the manufacture of the other parts.

c. The socket ring. The socket ring, (2, Figure 2-13) contains the sockets into which the large ball-ends of the connecting rods are secured.

Four arms extend inward from the socket ring body to form slots or pockets which receive the bearing blocks. Allen-head screws secure the bronze bearing blocks which support the main shaft trunnions. The universal joint consists of a shaft-trunnioned block oscillating with the pin (9) in the yokes of the main shaft. The trunnions of the trunnion block operate on the bearing surfaces cut into the main shaft yoke. The working torque of the shaft is transmitted through the socket ring, the universal joint trunnions, and the main shaft pin. The back of the socket ring is equipped with a roller track with two roller faces. These become the outer races of the axial thrust bearing (10) and radial thrust bearing (17).

An examination of the socket ring will disclose that the sockets are spaced unequally around the main shaft. The reason for this irregularity in the location of the sockets is that when two parts connected by a universal joint rotate in different planes-that is, on different axes-their angular velocities

 
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(number of degrees through which they turn in a given length of time) are not equal throughout all phases of a cycle.

In other words, if one of these parts is driven at a constant speed of rotation, the part which it drives through the universal joint will alternately lag behind, and then catch up with, the part which is driving it.

The mathematical or geometrical proof of this fact is too complex to be given here. The fact remains that this is exactly what happens in the relationship between the rotational speed of the main shaft of the Waterbury speed gear and that of the socket ring which it drives, whenever the tilt-box is tilted away from vertical; the main shaft is driven by an electric motor at constant speed, while the socket ring, when tilted away from vertical, alternately lags behind it and catches up, during each full revolution of the shaft.

The greater the angle of tilt away from vertical, the greater the inequality of motion between the two parts during a given revolution. If this irregularity were not corrected, the delivery of fluid would rise and fall in volume throughout each complete revolution, resulting in uneven surges instead of smooth, uninterrupted flow.

Therefore, in order to reduce this irregularity in the pumping action of the pistons to a minimum, they are spaced in such a way that the inequalities in the distances between them will just compensate for the inequalities of motion between the shaft and the socket ring. The cylinders, of course, are also unequally spaced in the cylinder barrel to correspond with the spacing of the sockets.

A little study will show that this compensation can be only approximate, for two reasons, which result in two separate factors of error:

1. The first factor of error results from the fact that the amount of inequality of motion between the two rotating parts varies with the angle of tilt. At zero degrees' tilt, the inequality is zero, as the two parts are then rotating in the same plane. At maximum tilt in either direction, the inequality is at its maximum. And at any intermediate angle

  between zero and maximum, the amount of inequality is proportional to the degree of tilt. Obviously the spacing or calibration, of the socket, can be correct only for one particular angle, and becomes less and less accurate as the socket ring is tilted either way from this angle. For the A-end speed gear used in the submarine, the calibration angle is 10 degrees (in either direction from neutral).

Figure 2-14. Diagram of B-end.
Figure 2-14. Diagram of B-end.

2. The second factor of error results from the fact that the inequality of motion between the two rotating parts is continuous throughout any given cycle, or revolution, while the location of the sockets, and of the cylinders in the barrel, is discontinuous. Therefore it would be impossible to make the calibration exact-even neglecting the first factor of error-unless the number of sockets and cylinders was infinite, so that they formed a continuous, irregular line around the circumference of the socket ring and cylinder barrel.

In this connection, there is a further structural difference between the A-end and B-end speed gears besides those already noted in Section 2C3c. The sockets in the A-end are located at unequal distances from each other, but at the same distance from the centerline of the shaft. The sockets in the B-end, however, are located at unequal distances not only from each other but also from the center. In other words, the spacing of the A-end sockets is unequal but concentric, while that of the B-end sockets is not only unequal but eccentric as well. The reason for the double calibration is that the calibration of the B-end must compensate not only for its own internal mechanical inequality of motion, caused by

 
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the action of the universal joint, but also for the surges, or slightly unequal pumping, of the A-end pump when this is its source of hydraulic power. Therefore, in the

Figure 2-15. Separating shaft from barrel.
Figure 2-15. Separating shaft from barrel.

calibration of the B-end socket ring and cylinder barrel, an attempt is made to correct two errors at once:

1. The unequal spacing of the cylinders from each other compensates for the internal mechanical inequality motion arising from the action of the universal joint in the B-end motor itself.

2. The eccentricity or unequal spacing, of the cylinders from the center, compensates for the surge delivery of the A-end pump so that the B-end shaft will turn at exactly the same speed as does the A-end shaft when the A-end tilt-box is at maximum tilt. The A-end is calibrated for an angle of tilt 10 degrees either side of neutral; the B-end is calibrated for the full tilt of 20 degrees from vertical, corresponding to the permanent tilt of its angle-box.

d. The cylinder barrel. The cylinder barrel is in reality a cylinder block into which seven or nine separate cylinders are bored. The length of the cylinders is such that the pistons riding within each separate cylinder will, as a group, always be within the cylinder

  barrel (see Figure 2-15). As noted in the description of the socket ring, the cylinders are spaced unequally from each other to compensate for the inequality of motion between the socket ring and the main shaft arising from the action of the universal joint. (For a fuller description of this feature, see Section 2C4b).

The cylinder barrel has keyways cut into it and is loosely attached to the main shaft by two keys (12, Figure 2-13), so that end play of the shaft will not be transmitted to the barrel. The looseness of this attachment of the cylinder barrel is intentional; its purpose is to allow a slight play, permitting. the pressure of the oil being pumped, or of the spring, when the pump is not pumping, to hold the barrel squarely against the valve plate.

The spring, which is backed by the main shaft yoke, maintains the barrel continuously against the valve plate when the pump is not running, or when the socket ring is in neutral. When the unit is pumping, the oil under pressure automatically maintains the barrel against the valve plate, since the cylinder ports are smaller than the cylinders of the barrel, so that the pistons, forcing oil out of the cylinder during the discharge stroke, will also cause the oil to exert a force against the walls formed by the ports, holding the barrel tight against the valve plate.

e. Piston assembly. Each cylinder in the cylinder barrel contains a piston which has been ground and fitted in the cylinder, and therefore requires no rings or packing. Figure 2-16 shows a cutaway view of a single piston. The shallow grooves cut around

Figure 2-16. Cutaway of piston assembly.
1) Piston; 2) connecting rod; 3) cap nut; 4) socket
cap.
Figure 2-16. Cutaway of piston assembly. 1) Piston; 2) connecting rod; 3) cap nut; 4) socket cap.

 
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the piston interrupt the streams of oil leakage, thereby tending to trap small particles of dirt or grit which otherwise might score the piston and cylinder surfaces.

Each piston (6, Figure 2-13) is connected to the socket ring (2) by a connecting rod (7). The rods have ball-ends, one larger than the other. The large end is secured into the socket ring, the small end into the piston.

1. Assembly of connecting rods to socket ring. The connecting rods are secured in the socket ring in the following manner. Into the face of the socket ring are bored and tapped seven or nine holes, one for each piston rod. Each hole is then provided with two hollow bronze half-bushings which, when fitted to each other, form a spherical, cuplike socket in which the large ball-end is held. The inner half, called the ring socket, is press-fitted into the bottom of the hole. The outer half, called the socket cap, fits against it, sliding into the hole with a rather free fit.

The socket cap is ring-shaped; its inside diameter is sufficient to allow it to be slipped over the small end of the connecting rod, before that end has been secured into the piston.

To lock the two halves solidly together in the bottom of the hole, a threaded piece shaped like a short section of pipe, called the socket-cap nut, is then also slipped over the small end of the rod and screwed down on top of the socket cap.

In assembling the socket, the two halves are not actually fitted directly to each other. Instead, a thin metal ring, called a shim, or spacer, whose function is to maintain proper clearance for the contained ball-end, is inserted between them, thus correcting any misfit resulting from tolerances in manufacture of the different parts. Spacers for each assembly are individually selected to suit that particular assembly.

The fit between ball and socket, when assembled and locked in by the cap nut, should be free enough to allow the connecting rod, when standing upright, to fall over sideways by its own weight. It must never be loose enough to permit any axial motion, or

  end-play, in the rod. If end-play exists, the socket must be disassembled and the shim replaced by a thinner one. If, on the other hand, the fit is too tight, a thicker shim is needed.

2. Assembly of connecting rods to pistons. The manner in which the small ball-end of the connecting rod is secured into the piston is somewhat different from the manner of securing the large end into the socket ring (see Figure 2-16).

The piston itself (1) is of bronze, and the inner half of the socket is hollowed out of the metal of the piston.

Since the outer half, or socket cap (4), must serve to hold the small ball-end in place in the piston socket, it must necessarily have a smaller inside diameter than the diameter of the small ball. Therefore if it were formed as a single piece, it could not be slipped on or off the rod at all. Accordingly, it is made up as a split bushing, that is, split into two equal semicircular segments which are dropped into the piston after the ball of the connecting rod is placed in the inner hollow, or socket proper. Then the piston is carefully tapped or shaken until the two segments of the split bushing fall into place around the rod. The piston socket-cap nut (3) is flanged and slotted to provide a wrench grip. Like the ring socket-cap nut, it is threaded. After the split bushing is in place, the nut is screwed down through the tapped part of the piston interior to secure the socket assembly firmly into the bottom.

The fit between socket and ball should be the same in the piston socket as in the ring socket, that is, a free fit with no end-play. As in the socket ring assembly, spacers or shims of the required thickness are used between the inner edge of the split bushing and the shoulder cut in the piston against which they fit to form the socket cup.

As can be seen in Figure 2-16, a small hole is drilled through the crown of the piston. This furnishes passage to the oil for lubrication of the surfaces of the ball and socket. Another hole (not visible in the figure) is drilled lengthwise through the connecting rod, ending at the tip of each ball.

 
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Thus both sockets are provided with continuous high pressure lubrication whenever the pump is running. The oil, thus pumped from the external, or high pressure, side of the piston, leaks into the case, or inactive system, and is a part of the oil loss which must be constantly fed back into the active system through the replenishing valves.

f. The valve plate. The valve plate (16, Figure 2-13) serves as an end-plate, or cover plate, for one end of the speed gear. Into it are cast the oil passages which empty into the suction and discharge ports (14, Figure 2-13). It also holds the outer race of the roller bearing (11, Figure 2-13) in which the end of the main shaft revolves.

Figure 2-17 shows the inner face of the valve plate against which the cylinder barrel rotates. Oil is drawn into or discharged from the cylinder through crescent-shaped

Figure 2-17. Cutaway of valve plate.
1) Main shaft bearing; 2) collector channel; 3) air
vent; 4) replenishing valve; 5) replenishing valve retainer plug; 6) port.
Figure 2-17. Cutaway of valve plate. 1) Main shaft bearing; 2) collector channel; 3) air vent; 4) replenishing valve; 5) replenishing valve retainer plug; 6) port.

  channels (6) cast in the inner face of the valve plate. These communicate directly with the passage leading to the external ports on the valve plate's outer side. The two channels are divided at the top and bottom by flat faces called lands.

As the cylinder barrel rotates, the cylinders pass in succession across these lands. For a brief moment, fluid is locked in each cylinder as it crosses the land.

The valve plate also contains two replenishing valves and four vent valves, which are described in Section 2C4h.

g. The tilt-box and the control shaft. The tilt-box provides the roller tracks against which the socket ring rotates, or, to put it another way, it provides the opposite races for the radial and axial thrust bearings described in Section 2C4c.

The socket ring may be tilted to any desired angle of tilt from 0 degrees to 20 degrees in either direction. This is accomplished by a tilt-box (3, Figure 2-18), which is suspended on two trunnions (10) formed on the box itself and which ride in bronze bearings (11) located in the sides of the case. An elongated hole is cut through the center of the tilt-box to give free passage to the main shaft at any degree of tilt of the tilt-box.

The tilt-box is retained in its bearings by two retaining trunnions (4, Figure 2-18) which are screwed through from the outer sides of the case and enter bushed holes in the tilt-box.

The angle of the tilt-box is determined by the control shaft (1, Figure 2-18) which tilts the tilt-box on its trunnions to obtain the desired amount of pumped fluid and to control the direction of pumping.

The end of the control shaft which protrudes from the case is threaded. This end is connected to a control device either to the linkage of a control cylinder assembly (if it is functioning as a motor-driven pump), or to a pump-stroke setting lever (if it is functioning as a telemotor pump).

The control shaft fits into the case of the speed gear through the control shaft bearing

 
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(2). External oil leakage is prevented by the packing (8), held in place by the packing gland cap (9).

The control trunnion pin (5) is secured to the control shaft, inside the pump case, by a dowel pin (12) which is peened over at both ends. The control trunnion pin is fitted with a pair of small square blocks, the outer guide block (6) and the inner guide block (7); one of these pairs can be seen in the illustration.

The vertical chamber in which the control shaft moves is drilled cylindrically, and then fitted with guides, or tracks, whose inner surfaces are cut into rectangular channels, thus giving the chamber a rectangular shape. The outer guide blocks are held within these rectangular vertical tracks, with which they make a smooth, sliding fit. The inner and outer guide blocks are free to move

  independently, having no connection with each other, except that they are both carried on the trunnion pin, riding with it as it moves up and down with the control shaft.

The fingers of the tilt-box (3) form a pair of square recesses within which the inner guide blocks (7) are held with a fit just tight enough to allow the block to be tapped into the recess by hand. This inner block is also free to turn smoothly on the trunnion pin. Therefore, as the control shaft is moved by the external linkage, the inner guide blocks, carrying with them the fingers of the tilt-box, will cause the tilt-box to rotate on its trunnions. Thus, the control shaft is fitted to the tilt-box through the inner blocks, and, as the shaft is moved by the external linkage to any given position, the tilt-box will assume a corresponding angle of tilt to follow it,

Figure 2-18. Cutaway of control shaft.
1) Control shaft; 2) control shaft bearing; 3) tilt-box; 4) tilt-box retaining trunnion; 5) control trunnion pin;
6) control guide block (outer); 7) control guide block (inner); 8) packing; 9) packing-gland cup; 10) trunnion; 11) trunnion bearing; 12) dowel pin for control trunnion pin.
Figure 2-18. Cutaway of control shaft. 1) Control shaft; 2) control shaft bearing; 3) tilt-box; 4) tilt-box retaining trunnion; 5) control trunnion pin; 6) control guide block (outer); 7) control guide block (inner); 8) packing; 9) packing-gland cup; 10) trunnion; 11) trunnion bearing; 12) dowel pin for control trunnion pin.
 
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within the limits of its angular rotation (20 degrees from vertical in each direction).

h. Minor parts. Any oil which has been lost from the active, or pressure, side of the system by leakage, is replenished in the active, or pressure, side from the case through two check valves, called replenishing valves (4, Figure 2-17) which are located in the valve plate. There is one for each port. The replenishing valves allow replenishment of oil from the case to the active, or pressure, side of the system on the suction side of the pump. When this side of the pump is the discharge side, the check valve will be seated by the oil pressure, thereby preventing oil from escaping from the active, or pressure, side of the system back to the case.

The hole in the valve plate through which the valve is inserted is kept closed by a plug known as the replenishing valve retainer plug (5). Above each port is a needle valve (3, Figure 2-17) which provides the means for venting air out of the valve plate. Two additional needle valves are placed in corresponding positions at the underside of the ports, to be used as vents when the pump is mounted upside down.

At the point where the shaft passes through the case, oil leakage is prevented by an oil seal (13, Figure 2-13). The seal is made of a synthetic rubber ring protected by metal guards. (A steel ring, with a ground surface, is fitted into the metal guards which rotate directly against a ground surface on the pump end-plate.) The entire assembly of the oil seal rotates with the shaft.

2C5. Operation of the Waterbury A-end speed gear. a. As a motor-driven pump. Three motor-driven A-end speed gears are used in the submarine to furnish normal hydraulic power, one for the steering system, one for the stern plane tilting system, and one for the bow plane tilting system. Each speed gear is driven by an electric motor at 440 revolutions per minute. The motor used to drive the speed gear on the steering system is rated at 15 horsepower; the motors used for driving the speed gears in the bow and stern plane systems are rated at 7.1 horsepower each.

  The shaft of the motor is direct-coupled to the main shaft of the A-end pump, driving it clockwise as viewed from the motor end of the pump. Since the direction and speed of rotation are fixed, the only variable factor in determining how much oil is pumped by the pistons, and in which direction it will be pumped, is determined by the positions of the tilt-box.

As this is one of the motor-driven pump installations, the control shaft, which determines the position of the tilt-box, is itself controlled, through bell-crank linkage, by the action of a control cylinder plunger.

Figures 2-19, 2-20, 2-21, and 2-22 illustrate the relationship between angle of tilt and pumping action. In Figure 2-19, the control shaft is centered, the tilt-box is at neutral, the socket ring is parallel to the cylinder barrel, and no pumping action will occur since each piston occupies the same amount of space in its cylinder throughout each cycle, or revolution. There is no suction and no

Figure 2-19. Tilt-box at neutral.
Figure 2-19. Tilt-box at neutral.

Figure 2-20. Tilt-box at slight tilt.
Figure 2-20. Tilt-box at slight tilt.

 
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displacement. Note the position of the control shaft and inner guide block.

In Figure 2-20, the control shaft has been pushed down a short distance, tilting the tilt-box slightly away from vertical, inclining the upper part away from the cylinder barrel.

Figure 2-21. Tilt-box at maximum tilt.
Figure 2-21. Tilt-box at maximum tilt.

Figure 2-22. Tilt-box at reverse tilt.
Figure 2-22. Tilt-box at reverse tilt.

Since the socket ring is now rotating in a different plane from that of the cylinder barrel, each piston will acquire a reciprocating motion, moving back and forth within its cylinder during each full revolution, as it alternately approaches and withdraws from the cylinder barrel. Therefore, as they rotate, each piston will alternately draw oil into its cylinder during that half of the revolution in which it is approaching the topmost position, and drive it out of the cylinder again during the other half of the revolution during which it is approaching the lowest position. Each of the seven or nine pistons, in turn, repeats this process during each revolution. The volume of oil pumped will be relatively small, as the socket ring is tilted only

  slightly from the vertical, and, consequently, the displacement within the cylinders is small.

In Figure 2-21, the control shaft has been pushed down to its maximum travel, tilting the tilt-box to its maximum angle of tilt, still in the same direction away from vertical as in Figure 2-20. The plane of rotation of the socket ring now makes an angle of 20 degrees with the plane of rotation of the cylinder barrel. The piston displacement inside the cylinders is at maximum, resulting in an increased amount of oil being pumped, in the same direction as in the preceding figure.

In Figure 2-22, the control shaft has been raised to its maximum travel, again tilting the tilt-box and socket ring to a maximum angle of 20 degrees' tilt away from the vertical, but in the opposite direction. Again there is maximum piston displacement, but since the direction of rotation is unchanged, the flow of oil through the pump is reversed.

Since the control shaft can tilt the tilt-box to any desired angle of tilt within the 20-degree range on either side of neutral, it is evident that the number of gradations in the quantity of oil pumped from zero to maximum is infinite. This factor makes possible the fineness of control which is an outstanding advantage of these pumps.

It should be made clear that, when the A-end pump is pumping the maximum quantity of oil, it is not necessarily delivering it at maximum pressure. The reason for this is that the farther the socket ring is tilted away from the vertical and the greater the consequent piston displacement, the greater the quantity of oil pumped in a given length of time; on the other hand, the smaller the angle of tilt, and consequent piston displacement, the greater will be the mechanical advantage of leverage exerted against the oil being pumped. Therefore, if the angle of tilt is small, and the resistance encountered by the oil is sufficient to act as an effective obstacle to its flow, enormous pressure will be developed.

b. As a hand-driven telemotor pump. The output of the motor-driven Waterbury A-end pump is controlled by a hand-driven telemotor A-end pump. Three basic differences should

 
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be noted between the operation of the motor-driven A-end pump and of the hand-driven telemotor A-end pump:

1. In the motor-driven A-end pump, the direction of rotation of the main shaft is fixed, while in the telemotor pump, the shaft may be rotated in either direction by the attached handwheel.

2. In the motor-driven A-end pump, the direction of tilt, as well as the angle of tilt of the tilt-box, are variable; in other words, it may be tilted up to 20 degrees in either direction away from the vertical.

3. In the motor-driven A-end pump, therefore, the direction in which fluid is pumped will be determined only by the direction in which the tilt-box is tilted. In the telemotor pump, the direction in which fluid is pumped will be determined only by the direction in which the main shaft is rotated.

Though the tilt-box in the telemotor pump can be tilted in only one direction, the angle of this tilt is variable, and may be set at anything from minimum to maximum. In the case of the telemotor pump, this angle is controlled by a pump-stroke setting lever, or pump control lever, which is placed by hand at any desired setting.

2C6. The Waterbury. B-end motor. a. Summary of structural differences. The basic differences in structure between the A-end pump and B-end motor have already been discussed (see Section 2C3c). They may be summarized as follows:

1. The A-end speed gear has a variable displacement feature consisting of a tilt-box whose position is determined by the vertical control shaft. In the B-end speed gear, this tilt-box is replaced by the angle-box, a casting secured to the inside of the case, which gives to the socket ring a fixed tilt of 20 degrees in one direction from the perpendicular (see Figure 2-14). The B-end motor has no control shaft.

2. Both the A-end and B-end speed gears have the sockets spaced at unequal distances from each other in the socket ring. In the B-end, however, the sockets are also placed at unequal distances from the center of the

  socket ring; in other words, in the A-end the sockets are unequally spaced but are concentric, while in the B-end, they are unequally spaced and eccentric.

2C7. Operation of the Waterbury B-end speed gear. a. Use of the Waterbury B-end speed gear in submarine hydraulic systems. The A-end speed gear is used primarily as a pump, converting mechanical torque into hydraulic fluid displacement, while the B-end speed gear is usually used as a hydraulic motor, converting hydraulic fluid displacement into mechanical torque. In practice, only two B-end motor installations are used on the submarine:

1. A No. 10-B motor is used on all late classes of submarines, both of Portsmouth design and Electric Boat Company design, for operating the rigging gear of the bow diving planes, forward capstan, and anchor windlass. The hydraulic power to operate this installation comes from the main hydraulic system. The shaft of the No. 10-B motor, through a clutch and a series of gear trains, operates the bow plane rigging gear, forward capstan, and anchor windlass. This No. 10-B motor will be replaced by a No. 10-A unit to decrease the rigging-out time for the bow planes, since the A-end, by maintaining a small angle of tilt on the tilt-box, can rotate faster with a given amount of oil from the main system, assuming that the external loading is not excessive.

2. In some earlier classes of boats, a No. 5-B motor was used for the tilting of the bow diving planes. In this type of installation, the source of hydraulic power was a No. 5 A-end pump driven by an electric motor; fluid under pressure was delivered to the No. 5-B motor, whose shaft, through a gear train, rotated a large herringbone sector gear fixed to the tiller of the plane stocks.

b. Principles of operation of the B-end motor. When the Waterbury B-end speed gear is used as a hydraulic motor, the principles of its operation are the reverse of those of the Waterbury A-end pump. Instead of torque being applied to the main shaft from some external source to force the piston to displace oil, and thereby develop fluid

 
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pressure, here the fluid pressure is admitted to the cylinders in order to force them to reciprocate and rotate the shaft, developing in the shaft a torque which is then used to actuate some mechanism.

This will be made clearer by referring again to the diagram, Figure 2-14. The oil under pressure enters the channel in the valve plate. From the channel it flows into all the cylinders on that side whose ports are open to that channel. This oil will tend to push the pistons on this side of the cylinder barrel out of their cylinders, exerting a force against the socket ring. The socket ring, fitting squarely against the axial roller bearing of the angle-box, which is at an angle and is free to turn, will thereby receive the force exerted on it by the pistons and their connecting rods and convert it into rotary motion. The socket ring will therefore rotate against the inclined plane of the angle-box, transmitting its motion through the universal joint to the shaft. Thus, the impulses received by the pistons through the channel on the pressure side of the valve plate tend to apply a torque to the entire revolving group, consisting of the cylinder barrel, socket ring, and shaft.

As each cylinder in the cylinder barrel is carried around toward its topmost position (see Figure 2-14), the space in that cylinder continues to increase as the oil under pressure forces the piston farther out of the cylinder, to its maximum intake stroke. At this moment, the port of this cylinder is passing across the land on the valve plate, between the two crescent-shaped channels, and the oil in the cylinder remains trapped in it as long as the cylinder port remains in contact with the land.

As this cylinder begins its descent on the other side of the motor, its piston, whose socket in the socket ring is now riding down the other side of the inclined plane on the angle-box, is once again pushed down into the cylinder, expelling the trapped oil through the cylinder port into the opposite crescent-shaped channel. Consequently, the space within the cylinder continues to decrease during this half of the cycle until it once again reaches its lowest position, where again the

  port of this cylinder is passing across the opposite land of the valve plate, at which time its piston has reached its maximum discharge stroke.

If the oil under pressure, called pressure oil, is continuously delivered to the side of the motor, each piston in turn, as it receives the impact of the oil against it, will go through this cycle, receiving oil from one channel on the ascending half of its cycle and discharging it through the other on the descending half of its cycle, transmitting to the socket ring, and thus to the shaft, a smooth, virtually nonpulsating torque which, as long as the shaft is free to turn, will be translated into continuous rotation in one direction.

The port on that side of the motor which receives pressure oil from the outside line is termed the supply port; the other port, through which the oil is expelled when the pistons have completed their discharge stroke, becomes the return port.

Since the direction of tilt of the angle-box is fixed, the direction in which torque is applied to the shaft will be determined by which port the motor receives the pressure oil. In other words, if oil were delivered under pressure to the opposite port, in the example we have just considered, all the movement described would be reversed. The pistons would push the socket ring in the opposite direction, and as a result, the shaft would turn in the opposite direction.

In other words, since the direction of tilt of the angle-box is fixed, it is clear that the direction in which the shaft of a B-end motor rotates is determined exclusively by the direction in which fluid is pumped to it. And since the angle of tilt is fixed, it is clear that the speed with which the pistons are pushed out of their cylinders by the pressure oil, and the consequent speed of shaft rotation, will depend exclusively on the quantity of oil delivered to the motor in a given length of time.

If the shaft were free to turn, and carrying no load, it is clear that to keep it turning just enough force would be needed at the supply port to overcome the inertia and internal friction of the moving parts. However, when a load is applied to the shaft, an

 
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additional force proportional to the load must be exerted against the pistons on the pressure side of the motor. Since the piston area remains constant, this increase of force can be made available only by an increase in the pressure of the oil delivered to the motor. Therefore, it is obvious that the amount of torque available at the shaft will depend exclusively on the amount of pressure, in pounds per square inch, of the oil being delivered to the motor.

The operational principles of a B-end motor may now be summarized as follows:

1. The function of the B-end motor is to receive hydraulic power from an outside source in the form of continuous fluid displacement and convert it into a rotary motion of its shaft.

2. The direction in which its shaft rotates is determined by which of its two ports receives the supply of pressure oil.

3. The speed of rotation of its shaft depends on the quantity of pressure oil delivered to it per unit of time.

4. The amount of working torque available at its shaft is determined by the amount of hydraulic pressure available at its supply port. In practice, the normal working pressure of the oil from the main hydraulic system received at the supply port of the No. 10 B-end motor to operate the bow plane rigging gear, windlass, and capstan runs between 600 and 700 pounds per square inch.

2C8. Service instructions. a. Air in the system. Air in the hydraulic system hinders its efficient operation, and great care must be taken to prevent the entrance of air into the lines, and to get rid of any air which may have accumulated there. This applies also to the Waterbury speed gear, whose case must be kept filled with oil and free of air bubbles. To vent off any accumulated air in the valve plate, open the two air vent valves (3, Figure 2-17) on top of the valve plate. Turn the shaft over a few times while the vent valves are still open, to relieve any air which may be trapped in the oil. Despite these precautions, there may still be air in the system. The Waterbury speed gear should be run for a

  few minutes without load and with the vent valves closed, then stopped and the vents again opened as before until all air is removed. The hydraulic system should be vented periodically until all air has been removed.

NOTE. The presence of air in the hydraulic system may be detected by noisy operation and by speed variations in the B-end, especially slowing down under load.

b. Handling controls. The life of the Waterbury speed gear can be materially prolonged by observing proper precautions. Avoid unnecessary sustained overloads. Even though the gear is protected by relief valves, it is well to slow down when excessive pressure is indicated or when obvious shocks are expected. For example, when securing an anchor, the windlass should be operated slowly during the last few feet of chain travel. Do not keep the A-end operating unnecessarily.

c. Opening for inspection. As long as the equipment operates satisfactorily, it should not be opened. The units give the best service when they are not disturbed.

2C9. Overhaul. Waterbury speed gears are carefully assembled machines. Therefore, when repairs are necessary, it is always best to return them to a tender or base where trained personnel and special tools are available. Unexpected circumstances, however, sometimes make it necessary to restore the units to immediate service, regardless of whether the repairs may endure.

The following overhaul procedure is intended for such an emergency. It describes primarily the B-end with variations for the A-end procedure.

a. Disassembly. 1. Removing the oil. Close all cut-out valves on the piping connected to the pump. Remove the drain plug on the bottom of the case and drain the oil. Disconnect the piping from the unit. Remove pump from mounting.

2. Removing valve plate. Remove the nuts and the bolts which attach the valve plate to the ease. Tap the end of the shaft to free the valve plate from the case. Take off the valve plate, being careful not to bring the

 
35

Figure 2-23. Removing replenishing valve block cover.
Figure 2-23. Removing replenishing valve block cover.

machined surfaces in contact with hard objects.

3. Removing valves from valve plate. The block containing the valves is mounted on the side of the valve plate. Remove the four bolts as in Figure 2-23. In some installations there is only a plug to be removed. Take off the cover, and the replenishing valve parts can then be removed as in Figure 2-24.

4. Removing oil seal. To do this, remove the six bolts around the circular cover plate. Remove the cover plate, and the oil seal elements can then be pulled out (see Figure 2-25).

5. Separating case from rotating group. Rest the open end of the case, through which the cylinder barrel is visible on a pair of wooden blocks. Remove the angle-box screws from the end of the case. Lift the case straight

Figure 2-24. Taking out replenishing valve.
Figure 2-24. Taking out replenishing valve.

  Figure 2-25. Taking off end cover.
Figure 2-25. Taking off end cover.

up as in Figure 2-26. The angle-box should remain with the revolving group. If it does not, reinsert two of the angle-box screws part way and loosen by tapping lightly. On the A-end, the revolving group is removed without its tilt-box. The tilt-box may be freed by removing the trunnion retainers on the side of the case. With the control in its neutral position, lift the tilt-box straight out from its bearings.

6. Removing shaft from barrel. The end of the shaft beyond the barrel contains the inner race for the valve plate roller bearing (11, Figure 2-13). This must be taken off with a bearing puller which is furnished as a special repair tool. Pry off the barrel lock ring with a screwdriver. Rest the barrel on

Figure 2-26. Lifting case.
Figure 2-26. Lifting case.

 
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the two wood blocks mentioned earlier. Lift up the shaft, socket ring assembly, and pistons as in Figure 2-15, being careful not to mar the surfaces of the pistons.

7. Separating socket ring from shaft. Remove the screws which hold the bronze trunnion shaft bearing blocks in the socket ring as in Figure 2-27. With the socket ring carefully held, drive the bearing blocks out by tapping gently with a wooden drift. Figure 2-28 shows this operation. Push the shaft through the socket ring as in Figure 2-29.

8. Separating piston assembly from socket ring. It is seldom necessary to dismantle the entire socket ring assembly. Disassemble only the pistons which require obvious repairs. Since the parts of each group, such as pistons, rods, caps, and trunnion blocks are hand-fitted at original assembly, care should be taken to reassemble them so that individual parts are returned to their original location. Corresponding fitted parts are usually numbered or punched as a relocation guide. For example, ring socket caps and nuts are numbered to correspond with hole numbers in the socket ring. If the parts are not marked, they should be marked by numbers or punch marks as they are removed. The slot on the cap nuts and the corresponding locking hole on the socket ring are

Figure 2-27. Removing trunnion bearing block screws.
Figure 2-27. Removing trunnion bearing block screws.

  Figure 2-28. Driving-out trunnion bearing blocks.
Figure 2-28. Driving-out trunnion bearing blocks.

prickpunched for identification. Connecting rods are not marked and should be tagged with the numbers corresponding to their pistons.

Remove lock springs or split pins. Loosen the cap nuts which secure the ball-ends of the connecting rods (2, Figure 2-16) in the socket ring. Pull the caps and rods out of the socket ring, being careful not to wedge the edges of the caps into the threads of the socket ring.

Figure 2-29. Separating shaft from socket ring.
Figure 2-29. Separating shaft from socket ring.

 
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Use a wooden clamp to prevent injury to a piston when separating it from a rod. Make the clamp by boring a hole of the same diameter as the piston. Split the wood at the center of the hole. Place the piston between the two jaws just formed, in a vise. The piston should be clamped at its solid end only, to avoid crushing the hollow part. Unscrew the piston cap nut (3). Pull the connecting rod (2) out with the two halves of the split bushing (4). Keep the two together for reinstallation in the same piston (1).

9. Removing shaft trunnion block. Drive the main shaft pin retainer out of the trunnioned block. Drive the main shaft pin out of the block and shaft. If it should be necessary to replace the main shaft pin bushings, it can be done by driving the main shaft pin bushing out of the shaft.

10. Overhauling radial and thrust roller bearings. The thrust and radial bearings fit loosely into the angle-box or tilt-box, which ever the case may be, and may be lifted out as illustrated in Figure 2-30. If any of the rollers shows a defect, it should be removed. This can be accomplished by removing the rivets that hold the parts of the cage together. A cage may be assembled with three or four rollers missing, provided no two adjacent

Figure 2-30. Removing bearings.
Figure 2-30. Removing bearings.

  boxes are left empty. This is suggested only as an emergency repair. If spare bearings are available, they should be used.

The socket thrust race is secured to the socket ring by a shrink fit. It may be removed by driving it off with a pin inserted into the driving holes in the socket ring. This race is reversible. When its bearing surfaces become worn, it can be turned over.

The box thrust race fits snugly in either the tilt-box or angle-box and can be lifted out. This race is also reversible and can be turned over if one side is worn.

The radial race is attached by a tap fit and should be removed from the box by gently jacking it out with a hook-shaped bar.

Reassembly of the thrust race to the socket ring requires a shrink fit. It will therefore be necessary to heat the race in an oil bath to a temperature of about 270 degrees Fahrenheit.

b. Reassembly. 1. Fitting connecting rods to socket ring. If replacement parts are used in the socket ring assembly, it will first be necessary to fit the connecting rods into the sockets. Assemble and tighten the cap nut until the rod is held firmly in the socket, just tight enough to allow it to be moved backward and forward and from side to side without difficulty. Repeat this motion several times until a bearing surface is established. This surface should be a band about 1/32-inch in width around the ring socket and socket cap.

When a satisfactory bearing surface has been obtained, the fitting for proper freedom of movement without end-play should be made in the following way. Assemble connecting rods in the ring sockets with the ring socket caps and cap nuts. The rod should fit freely but without perceptible end-play. If the fit is so loose that the connecting rod shakes endwise after the nut has been tightened, it is necessary to dress down the end of the socket cap slightly to obtain a tighter fit. When dressing down the cap, draw it carefully over a fine file or emery cloth, and be sure to check the end for squareness.

If, however, the rod fits too tightly, place a shim between the socket cap and the socket.

 
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To complete the installation of the replacement rod, mark the lock hole location in the lock groove of the socket ring with a prick-punch. Carefully align the marks so that the resulting hole will line up with a notch in the cap nut. Drill a hole which will come through the center of the notch. The nut must be kept from turning during the drilling operation. Remove burrs.

After all the replacement rods have been fitted into the sockets, disconnect them for further reassembly later. Each rod must be tagged for proper relocation.

2. Fitting connecting rods to pistons. The method of fitting the connecting rods in the pistons differs somewhat from that of fitting them in the socket because of the split bushing. The following procedure is recommended for the rod and piston adjustments where there is a split socket cap (4, Figure 2-16) which must be seated firmly against the socket of the piston in addition to bearing properly on the ball-end of the connecting rod. If possible, secure a set of circular laminated shims. If this is not possible, prepare a set of circular shims in thicknesses ranging from 0.001-inch to 0.020-inch which will fit between the piston socket cap (3, Figure 2-16) and its seat in the piston. Laminated or prepared shims should be of smooth, flat brass and without burrs. Place shims 0.015-inch thick in the piston and reassemble the rod, cap, and nut, screwing the nut down tight. Check the rod for end-play. If it is too tight, select a thicker shim. When the end-play has become imperceptible, lock the piston cap nuts in place. Reassemble the pistons and connecting rods in the socket ring and insert the pistons in their respective cylinders in the cylinder barrel.

3. Reassembling shaft and socket ring. Press the main shaft bushings, into the holes in the shaft yoke and secure them with the bushing pins. With the shaft trunnion block in the yoke, press the main shaft pin (9, Figure 2-13) through the block, passing it through the bushings in the yoke, and secure it in the block with the shaft pin retainer. Place the trunnion bearing blocks on the trunnions of the shaft pin and pass the shaft

  through the socket ring, observing that the socket which is radially in line with the trunnion bearing block is in line with the shaft keyway. Secure the blocks with screws.

4. Reassembling shaft, barrel, and socket ring. Place the barrel spring (19, Figure 2-13) and keys (12, Figure 2-13) on the shaft. The barrel key marked "V" is to be in line with the keyway at the end of the shaft. Stand the shaft on end with the socket ring down. Keep it in that position in a properly padded vise. Lower the cylinder barrel (4, Figure 2-13) with its pistons over the shaft and keys so as to bring the corresponding connecting rods and their sockets in the socket ring together. In this operation, the pistons must be retained in their cylinders to prevent their sliding out of the barrel.

NOTE. The barrel must slide freely over the keys. The barrel lock ring is then slipped over the end of the shaft and snapped into the shaft groove. Assemble the connecting rod ends into the sockets of the socket ring with the ring socket caps and cap nuts. Screw the nuts down to the locking position as determined by the earlier fitting process. Insert cotter pins into the nuts. Press the inner race of the valve plate roller bearing (11, Figure 2-13) on the end of the shaft. The revolving group is now ready for assembly with the case.

5. Assembling B-end shaft group and angle-box to case. Carefully place the revolving group on a flat surface with the barrel down. Place the rollers in position on the rotating group. Place the angle-box and races on top of the rollers. Work the box back and forth until it is properly seated.

Press the angle-box dowels into place in the case. Lower the case over the revolving group so that the dowels slip into the holes in the angle-box and the box seats in the recess of the case.

6. Assembling A-end control shaft and tilt-box. If the parts of the control have been disassembled, restore them in the control housing. Replace the washer and screw the control shaft bearing (2, Figure 2-18) down tight. Insert the packing (8, Figure 2-18) and the gland and secure it with the gland cap

 
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(9, Figure 2-18). Prepare the tilt-box for installation by pressing down the radial race. Insert the thrust race and put the rollers in place. Press the retaining trunnion bushings into their sockets in the tilt-box. For the installation, set the case open-end up. Place the case trunnion bushings which are half segments, in the openings in the sides of the case so that the tilt-box forks engage the outer control guide blocks. Replace the washers and screws in the tilt-box retaining trunnion.

7. Assembling A-end revolving group to case. Support the case with the open end up, leaving enough space underneath for the full projecting length of the shaft and for inserting the case bolts from the bottom. Suspend the revolving group by an eyebolt screwed into the end of the shaft and lower the group into the case so that the lower end of the shaft goes through its bearing and the socket ring rests properly on the rollers in the tilt-box. The group will rotate freely if it is properly seated. This seating should be checked carefully to make sure the socket ring is not riding the shoulders of the roller bearings.

8. Assembling valve plate. Press the outer races of the valve plate roller bearing into place. Set the rollers on the race as shown in Figure 2-31. Make a gasket out of the same thickness of fibrous paper that was previously installed to act as a seal between the valve plate and case. Clean the valve plate surfaces thoroughly. Stick the gasket to the inner face with a thin layer of grease. Then oil the side of the gasket which comes into contact with the case. Place the intershaft disk into the recess of the valve plate. If this was removed, it should be restored with heavy grease so that it will not fall out when the valve plate is inverted. Cover the surfaces of the cylinder barrel and the valve plate with a film of oil. Lower the valve plate onto the case and secure with the case bolt nuts. Replace the oil seal elements as in Figure 2-3 and bolt the end cover in place.

  9. Overhaul tools. A few special tools are provided for the overhaul of Waterbury speed gears. They consist of:

1 piston cap nut wrench, size 5
1 ring socket cap nut, size 5
1 socket cap nut wrench, size 10
2 angle-box guide rods, size 10
1 spanner wrench
1 race puller

Figure 2-31. Inserting valve plate bearing.
Figure 2-31. Inserting valve plate bearing.

Figure 2-32. Installing oil seal.
Figure 2-32. Installing oil seal.

 
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