Hydraulic Pump - TM-10-3930-627-340095

(3) Disconnect suction and return line hoses

d. Repair.

Since most working surfaces of the

nearest tank. Remove four attaching nuts, lock washers

cylinders are hard chrome plated, do not try to hone or

and flat washers, take tank from mounting studs on

stone away scratches. Replace all nonmetallic parts at

frame and remove tank from underside of truck.

assembly, and any parts showing wear or damage that

b. Installation.

in the judgment of the technician would cause trouble in

(1) Mount the tank on the four studs provided on

the expected period before next scheduled overhaul.

the frame, and install the four nuts, flat washers and

e. Assembly.

lock washers which hold it in place.

Note. Take special care to keep all

(2) Connect suction and return line hoses to tank

parts of the hoist cylinder clean

connection points.

during reassembly.

Wet interior

(3) Replace plug in bottom of tank, and refill tank

parts with clean lubricating oil OE10.

with specified quantity of hydraulic fluid.

MIL-L-2104, before installing them.

c. Repair. Repair is limited to steam or solvent

Reassemble as follows:

cleaning of the interior, removal of dents and welding or

(1) Install new bearings (25, fig. 12-2) over

brazing of leaks. Use standard shop techniques for

secondary plunger (29). Push plunger into secondary

these repairs.

cylinder (22) from bottom and install new packing (23)

and washer (24) in groove in base of secondary

12-3. Hydraulic Pump

cylinder. Screw cylinder end (3) into secondary cylinder.

(2) Install bearing (20) in base of secondary

a. Removal.

cylinder and install packing (19) against base of bearing.

(1) Disconnect the suction and pressure lines.

Insert packing retainer (18). Insert wiper ring (17) in

Cap or plug disconnected lines immediately.

packing nut (16) and install packing nut in bottom of

(2) Remove screws and lock washers which

secondary cylinder.

attach pump to engine and take off pump. If pump is

(3) Install bearing (10) in top end of plunger (28).

not to be serviced immediately, cover all openings with

Install bearing (15) in primary cylinder (21). Install guide

masking tape, or plug them to keep dirt out of pump.

(26) and retaining ring (27).

b. Installation.

(4) Install cylinder (22) with assembled items

(1) Position pump to mounting pad on engine,

through bottom of primary plunger (28) and install both

engaging pump drive gears.

in primary cylinder (21).

(2) Install mounting screws and washers, and

(5) Install new packing (14) and retainer (13). Put

connect pump suction and pressure lines, and the power

wiper ring (12) in packing nut (11) and install packing

steering pressure line.

nut on end of primary cylinder (21).

c. Disassembly.

(6) Place packing (9) over plunger (29) and install

(1) Remove cotter pin and nut holding pump gear

packing retainer (8). Put wiper ring (7) in packing nut

(not shown) to drive gear shaft (11, fig. 12-3). Remove

(6); install nut over plunger (29) and thread into plunger

retaining ring (1), and eight screws (3) securing

(28). Install two new washers (2) and replace screws

mounting flange cover (2) to housing (17). Press seal

(1). Do not tighten packing nut more than necessary to

(4) out of mounting flange cover.

stop leakage, since the packing will expand when fluid

(2) Remove driven gearshaft (10), drive gearshaft

pressure is applied, to form a seal. If the nut is

(I1), four bushings (9 and 12) and two pins (13).

overtightened the packing will wear out prematurely.

(3) Remove two packing retainers (7) and

packings (5, 6, and 8). Do not remove two pins (16)

12-2. Hydraulic Tank

from housing (17) unless necessary.

Discard all

nonmetallic items removed.

a. Removal. It will be necessary to raise the truck or

d. Repair.

park it over a service pit for certain steps of the

(1) Check mating surfaces of cover (2) to housing

following procedures. The truck must be spotted where

(17) for irregularity.

removal and installation of the tank can be done without

(2) True up any warpage of these surfaces if it

moving the truck.

can be done with removal of 0. 005 inch or less of

(1) Lower carriage fully and tilt and tie uprights

metal.

back.

(3) Replace any other worn parts.

(2) Remove hydraulic fluid from tank. Either

e. Assembly. Soak all parts in lubricating oil OE10

remove plug from bottom of tank and drain fluid into

and assemble by reversing the disassembly procedure

large container, or use a suction transfer pump, with

above.

pickup hose inserted to bottom of tank through fill

opening.

12-5