Steering: Description and Operation

GENERAL DESCRIPTION
The hydraulic power steering system consists of a pump, an oil reservoir, a steering unit, a pressure hose and a return hose.

THE STEERING UNIT (GEAR)
The power steering unit is a rack and pinion type. The toe-in angle can be adjusted by turning the rod on each side. The steering housing cannot be disassembled.

THE STEERING PUMP
The Hydraulic pump is a vane-type design. The submerged pump has housing and internal parts that are inside the reservoir and operate submerged in oil. There are two bore openings at the rear of the pump housing. The larger opening contains the cam ring, pressure plate, thrust plate, rotor, and vane assembly. The smaller opening contains the pressure line union, flow control valve, and spring.
The flow control orifice is part of the pressure line union.
The pressure relief valve inside the flow control valve limits pump pressure.

THE STEERING COLUMN
The steering column has three important features in addition to the steering function:
1. The column is energy absorbing, designed to compress in a front-end collision to minimize the possibility of injury to the driver of the vehicle.
2. The ignition switch and lock are mounted conveniently on the column.
3. With the column mounted lock, the ignition and steering operation can be locked to prevent theft of the vehicle.

The column can be disassembled and reassembled. However, to insure the energy absorbing action, use only the specified screws, bolts and nuts as designated, and tighten them to the specified torque.

Handle the column with care when it is removed from the vehicle. A sharp blow on the end of steering shaft or shift lever, or dropping the assembly could shear or loosen the fasteners that maintain column rigidity.

THE PRESSURE SWITCH
When hydraulic pressure reaches 3430 kPa (500 psi), the pressure switch closes causing the Engine Control Module (ECM) to actuate the idle air control valve, which increases the engine rpm to prevent the overload-induced engine speed slow down. The switch opens when hydraulic pressure drops to 2940 kPa (430 psi).