the pinion shaft (spool valve) slightly. This action moves the control valve and aligns the specific oil passages. Pump pressure is then allowed to flow through the control valve, the hydraulic line, and into the power cylinder. Hydraulic pressure then acts on the power piston and the piston action assists in pushing the rack and front wheels for turning.

STEERING SYSTEM MAINTENANCE

Maintenance of the steering system consists of regular inspection, lubrication, and adjusting components to compensate for wear. When inspecting the steering system, you will need someone to assist you by turning the steering wheel back and forth through the free play while you check the steering linkage and connections. You will also be able to determine if the steering mechanism is securely fastened to the frame. A slight amount of free play may seem insignificant, but if allowed to remain, the free play will quickly increase, resulting in poor steering control.

After prolonged use, steering components can fail. It is important that the steering system be kept in good working condition for obvious safety reasons. It is your job to find and correct any system malfunctions quickly and properly

Steering Linkage Service

Any area containing a ball-and-socket joint is subjected to extreme movements and dirt. The combination of these two will cause the ball- and-socket joint to wear. When your inspection finds worn steering linkage components, they must be replaced with new components. Two areas of concern are the idler arm and the tie-rod ends.

IDLER ARM SERVICE. - A worn idler arm causes play in the steering wheel. The front wheels, mostly the right wheel, can turn without causing movement of the steering wheel. This is a very common wear point in the steering linkage and should be checked carefully.

To check an idler arm for wear, grab the outer end of the arm (end opposite the frame) and force it up and down by hand. Note the amount of movement at the end of the arm and compare it to the manufacturer's specifications. Typically, an idler arm should NOT move up and down more than 1/4 inch.

The replacement of a worn idler arm is as follows:

Separate the outer end of the arm from the center link. A ball joint fork or puller can be used to force the idler arms joint from the center link.

With the outer end removed from the center link, unbolt and remove the idler arm from the frame.

Install the new idler arm in reverse order of removal. Make sure that all fasteners are torqued to manufacturer's specifications. Install a new cotter pin and bend it properly.

TIE-ROD END SERVICE. - A worn tie-rod end will also cause steering play. When movement is detected between the ball stud and the socket, replacement is necessary.

The replacement of a worn tie-rod end is as follows:

Separate the tie rod from the steering knuckle or center link. As with the idler arm, a ball joint fork or puller can be used.

With the tie rod removed from the steering knuckle or center link, measure tie-rod length. This will allow you to set the new tie rod at about the same length as the old one.

NOTE

The alignment of the front wheel is altered when the length of the tie rod is changed.

Loosen and unscrew the tie-rod adjustment sleeve from the tie-rod end. Turn the new tie-rod end into the adjustment sleeve until it is the exact length of the old tie rod.

Install the tie-rod ball stud into the center link or steering knuckle. Tighten the fasteners to manufacturer's specifications. Install new cotter pins and bend correctly. Tighten the adjustment sleeve and check steering action.

Manual Steering System Service

Steering system service normally involves the adjusting or replacement of worn parts. Service is required when the worm shaft rotates back and forth without normal pitman arm shaft movement. This would indicate that there is play inside the gearbox. If excess clearance is NOT corrected after the adjustments, the steering gearbox must be replaced or rebuilt.

MANUAL GEARBOX ADJUSTMENT. - Since there are numerous steering gearbox configurations, we will discuss the most common type, recirculating ball and nut. There are two basic adjustments - worm bearing preload and over center clearance.