TOPIC 1. GENERAL DESCRIPTION - TM-10-3930-644-14-P0327

TM 10-3930-644-14&P

POWER STEERING SYSTEM

TOPIC 1. GENERAL DESCRIPTION

The power steering system converts hydraulic oil

When the steering wheel is turned to the right, oil is

movement into mechanical movement to turn the steer

directed by the steering unit to the forward port in the

wheels with ease. The steer axle assembly with the

steering cylinder. As the hydraulic oil pressure is applied

steer wheels is mounted to the frame and is located at

to the piston, the piston and plunger rod move outward.

the rear of the lift truck. The main components in the

The plunger rod by means of the drag link then pushes

power steering system are the steering valve unit, and

on the pivot arm which rotates on the pivot pin. As the

steering cylinder. The hydraulic oil that is supplied to the

pivot am rotates, the steer wheels move into position for

steering valve unit is directed to one of the steering

a right turn due to the movement of the tie rods.

cylinder ports. As the oil enters the steering cylinder, the

plunger rod begins to extend or retract, depending upon

The movement of the steering system is just the

which port in the cylinder the hydraulic oil is directed. A

opposite when the steering wheel is turned to the left.

short drag link or yoke is installed on the end of the

The hydraulic oil is then directed to the rear port in the

steering cylinder plunger rod and is connected to the

steering cylinder which causes the plunger rod to retract.

steer axle pivot arm. Also connected to the pivot arm

As the plunger rod retracts the drag link pulls on the

are right and left tie rods which in turn are attached to

pivot am and the steer wheels move into position for a

the respective steer wheel spindles.

left turn due to the opposite movement of the tie rods.

TOPIC 2. STEER AXLE

A. REMOVAL

8. Lower the jack with the axle on it, and withdraw

the axle from under the vehicle.

1. Remove the floor plate and toe plate.

B. DISASSEMBLY

2. Attach a suitable hoist to the rear of the truck

and raise the track until the drag link and steer

1. Remove the axle mounting housing from steer

axle are accessible. Block the front wheels, and

axle pivot pin.

place blocks under both sides of the frame to

support the rear of the vehicle. Blocks and

2. Remove cotter pins, adjusting plugs, ball seats,

chain must not interfere with removal of steer

and springs from the tie rods, and separate the

axle.

tie rods from the pivot arm.

3. Remove steer wheels and wheel bearings.

3. Remove cotter pin and nut from ball socket, and

remove the tie rods from the spindles. Loosen

4. Disconnect drag link from pivot arm by loosening

the nut on the ball socket, and remove the ball

the adjusting plug at the end of the drag link until

socket and nut from the tie roe tubes.

the link can be lifted from the ball stud on the

pivot arm.

4. Remove expansion plugs from king pin bores in

the axle assembly. Drive roll pins from king pins

5. Place a jack under the steer axle assembly and

and spindles, and remove the king pins, needle

raise jack enough to take the stress from the

bearings and spindles from the axle.

axle mounting capscrews and nuts.

5. Type I Steer Axle:

6. Type III Steer Axle Only:

Remove wedge bolt (Fig 3), and washer.

Loosen jam nut and back away adjusting screw

Remove pivot pin, and spacers, and lift pivot

in frame just ahead of the steer axle's front pivot

arm from axle assembly. Remove bushings

pin. (Adjusting screw is used to take up end

from axle.

play between steer axle's front pivot pin and the

frame).

Type II and III Steer Axles:

7. Remove

nuts

and/or

lockwashers,

and

Use a punch to straighten out stake indentation

capscrews that secure the axle to the frame.

in end of nut. Remove nut, washer, seal and

lower cone; lift pivot

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