Power Steering Gear Description Rack and Pinion
The movement of the steering wheel has the following results:
| • | The movement of the steering wheel transfers to the pinion. |
| • | The movement of the pinion transfers through the pinion teeth. |
| • | The pinion teeth mesh with the teeth on the rack. |
| • | This action causes the rack to move. |
The power rack and pinion steering system has a rotary control valve. The rotary control valve directs the hydraulic fluid that flows from the hydraulic pump to either side of the rack piston. The integral rack piston attaches to the rack. The integral rack piston has the following effects:
| • | The rack piston converts hydraulic pressure to linear force. |
| • | The linear force moves the rack left or right. |
| • | The linear force transmits to the inner and the outer tie rods to the steering knuckles. |
| • | The steering knuckles turn the wheels. |
The system will require more steering effort if hydraulic assist is not available. If hydraulic assist is not available, the system will maintain manual control.
Power Steering Gear Description Non-Rack and Pinion
The power steering gear contains a recirculating ball system that acts as a rolling thread between the worm shaft and the rack piston. The worm shaft is supported by a pre-loaded thrust bearing and 2 conical thrust races at the lower end. A bearing assembly in the adjuster plug supports the shaft's upper end. When the worm shaft turns right, the rack piston moves up in gear. Turning the worm shaft left moves the rack piston down in gear. The rack piston teeth mesh with the sector, which is part of the pitman shaft. Turning the worm shaft turns the pitman shaft. The pitman shaft turns the wheels through the pitman arm and the steering linkage.
The control valve in the steering gear directs the power steering fluid to either side of the rack piston. The rack piston converts the hydraulic pressure into a mechanical force. If the steering system loses hydraulic pressure, you can control the vehicle.
