Power Steering: Notes

The power steering system consists of the:

• power steering pump.
• power steering fluid reservoir.
• power steering pressure and return lines.
• power steering fluid cooler.
• steering gear.

The power steering system uses a vane-type pump to move the fluid from the reservoir to the steering gear and through the rest of the steering hydraulic system. The power steering pump is mounted to the engine and driven by the engine accessory drive belt. Power steering fluid is pulled into the pump from the reservoir. The power steering fluid is trapped between the pump vanes and moved to the high-pressure side of the pump creating a flow of fluid. The restriction of this flow by the steering gear creates the pressure that provides the steering assist. A combined pressure relief/flow valve is built into the pump to control the maximum pressure and flow provided to the steering system. This action prevents damage to the system and provides the correct level of assist during all engine speeds. While under pressure, the power steering fluid flows through the high-pressure power steering line to the steering gear. The fluid exits the gear and flows through the return line, the cooler and finally to the reservoir. The reservoir slows the fluid, allowing air to escape and filters the fluid before returning it to the pump.

Some vehicles are equipped with a Hydro-Boost® brake booster. The Hydro-Boost® brake booster is a hydraulically operated brake booster powered by the power steering pump. The power steering pump provides the fluid pressure to operate both the power brake booster and the power steering gear.

A Hydro-Boost® reserve system (accumulator) stores sufficient fluid under pressure to provide at least 2 power-assisted brake applications in the event the power steering pump fluid flow is interrupted. The brakes can also be applied manually if the reserve system is depleted.