Rear Steering Pump - TM-10-3930-634-340197

TM 10-3930-634-34

any defective part.

ton forscored areas or damage. Replace all defective

e. Reassembly. Refer to figure 5-16 and reassemble

parts.

the rear steering pump.

d. Reassembly. Refer to figure 5-15 andreassemble

f. Installation. Install the rear steering pump (TM

the three-position cylinder.

10-3930-634-12).

e. Test.

(1) Packing drag test.

5 - 1 8 . Steering Mode Selector Valve

(a) With the cylinder horizontal, fill the rod end

the cylinder with oil.

a. Removal.

(b) Open the head end part of the piston to the

(1) Access to the valve is through the steering

atmosphere by loosening nuts (6, fig. 5-15) and sepa-

compartment door beneath the cockpit.

rating head (14) from cylinder block (21).

(2) Refer to figure 5-17 and remove the steering

(c) With rod end under no load except normal

mode selector valve.

seal and wiper drag, pressurize the rod end of the cyl-

NOTE

inder and record the maximum pressure reached be-

Tag all hydraulic lines before removal.

fore the piston moves.

b. Disassembly. Refer to figure 5-18 and disassem-

(d) Repeat the above procedure for the head end

ble the steering mode selector valve.

of the cylinder.

c. Cleaning and Inspection.

(e) The piston may be operated as necessary for

(1) Clean all parts thoroughly, using solvent

wear in.

P-D-680 or equal.

(f) Piston rod will extend With maximum of 15

(2) Inspect parts for scored or worn areas, burs,

psi on the head side of the piston. Piston rod will re-

scratches, or other defects.

tract with maximum of 25 psi on the rod side of the

(3) Replace all defective parts.

piston.

d. Reassembly. Refer to figure 5-18 and reassemble

(2) Piston leakage test.

the steering mode selector valve.

(a) Fill the cylinder with oil. Seal the rod end

e. Installation. Refer to figure 5-17 and install the

and load the head end to not less than 2000 psi and

steering mode selector valve.

hold this pressure for 15 minutes. The packing gland

should be tightened enough that leakage stops.

5-19. Steering Gear Assembly

(b) Measure and record the travel of the piston

a. General.

during the 15 minutes.

(1) The action of the steering gear is both manual

(c) Repeat the procedure for the rod end of the

and hydraulic in effect. When the cam is turned to the

cylinder.

right or left by the driver's effort on the steering

(d) Maximum piston rod drift should not exceed

wheel, the stud of the inner lever is moved through the

one inch per hour.

groove of the cam (worm), thus rotating the lever shaft

f. Installation.

and providing angular movement of the steering gear

(1) Mount the three-position cylinder on the pit-

pitman arm. Whenever the driver's effort at the steer-

man arm and secure the base end in the pitman arm

ing wheel exceeds the preload of the centering springs,

clevis with a retaining pin.

the control valve is actuated and hydraulic power is ap-

(2) Install the piston rod end by securing the rod

plied to aid in steering. The pitman arm is splined to

end ball joint to the steering actuator arm.

the steering gear lever shaft and provides required

(3) Remove caps and connect hydraulic lines.

feedback to the operator giving some "road feel" and a

steering reference point. Mechanical disadvantage is

5-17. Rear Steering Pump

such that manual steering is not feasible. The engine

a. General. The rear steering pump is mounted on

must be running to provide hydraulic pressure for the

steering system. To force the steering system (with the

the torque converter and supplies hydraulic pressure

to the rear steering cylinders only.

engine not running) may result in damage to the sys-

b. Removal. Remove the rear steering pump (TM

tem.

10-3930-634-12).

(2) When the control valve spool is in the center

c. Disassembly. Refer to figure 5-16 and disassem-

position, the oil pressure at its two cylinder ports is

the rear steering pump.

low and equal and produces ineffective forces in the

d. Cleaning and Inspection.

cylinder. This results in no movement of the piston

(1) Clean the pump with solvent P-D-680 or

and no circulation of oil in the lines to the cylinder;

equal.

however, oil is circulating from the pump through the

(2) Inspect body and cover for cracks and damage.

control valve to the reservoir with sufficient pressure

(3) Inspect bearing for wear.

to overcome friction of lines and fittings.

(4) Inspect all parts for wear or damage. Replace

(3) Because hydraulic pressure is low in straight

5-25