HYDRAULIC CUB PUMP UNIT - HYDRAULIC PUMP

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REPLACEMENT (Cont)

TM-55-1905-219-14-7 Landing Craft Utility (LCU) 1667 Class Boston Hull Numbers 1667-1670 NSN 1905-00-168-5764 Manual

HYDRAULIC CUB PUMP UNIT - HYDRAULIC PUMP - MAINTENANCE INSTRUCTIONS (Continued).

TM 55-1905-219-14-7

3-206. HYDRAULIC CUB PUMP UNIT - HYDRAULIC PUMP - MAINTENANCE

INSTRUCTIONS.

LOCATION

ITEM

ACTION

REMARKS

GENERAL.

1. This pump is used to develop hydraulic fluid flow for the operation of the steering system equipment. The

positive displacement pumping cartridges are the rotary vane type with shaft side loads hydraulically balanced.

2. All units are designed so that the direction of rotation, pumping capacity and port positions can be readily

changed to suit particular applications.

ASSEMBLY AND CONSTRUCTION.

1. The unit consists principally of a ported body, a ported cover and a pumping cartridge. Components of the

pumping cartridge are an elliptical cam ring, a slotted rotor splined to fit the drive shaft and twelve vanes fitted to the-

rotor slots.

2. The pumping cartridge cam ring is sandwiched between the body and cover. A ball bearing and bushing

located in the body and pressure plate respectively support each end of the drive shaft and center the rotor within the

cam ring. As the drive shaft is driven by the prime mover, the rotor and vanes generate flow by carrying fluid around the

elliptical cam ring contour. Fluid enters the cartridge through the inlet port in the body and is discharged through the

pressure plate into the outlet port of the cover.

3. Fluid flow is developed by the pumping cartridge. The action of the cartridge is illustrated below. The rotor

is driven within the cam ring by the driveshaft, which is coupled to a power source. As the rotor turns, centrifugal force

causes the vanes to follow the elliptical inner surface of the cam ring.

4. Radial movement of the vanes and-turning of the rotor cause the chamber volume between the vanes to

increase as the vanes pass the in- let sections of the cam ring. This results in a low pressure condition which allows

atmospheric pressure to force fluid into the chambers. (Fluid outside the inlet is at atmospheric pressure or higher).

5. This fluid is trapped between the vanes and carried past the large diameter or dwell section of the cam ring.

As the outlet section is approached, the cam ring diameter-decreases and the fluid is forced out into the system. System

pressure is fed under the vanes, assuring their sealing contact against the cam ring during normal operation.

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