Steering System

Power Steering System General Information

When there is no load on the vehicle, and the front tires are pointed straight ahead, the steering wheel spokes should be centered, ±10 degrees, as shown in Fig. 17.1 . See Group 46 of the Cascadia™ Workshop Manual for steering adjustment procedures.
  • 1. 9 o'Clock
  • 2. 3 o'Clock
Fig. 17.1, Proper Steering Wheel Position (with tires pointed straight ahead)
CAUTION
Never steam clean or high-pressure wash the steering gear. Internal damage to gear seals, and ultimately the steering gear, can result.
WARNING
Driving the vehicle without the power-assist feature of the steering system requires much greater effort, especially in sharp turns or at low speeds, which could result in an accident and possible injury.
Drivers should carefully use the power available with a power steering system. If the front tires become lodged in a deep chuckhole or rut, drive the vehicle out, instead of using the steering system to lift the tires from the hole. Also, avoid turning the tires when they are against a curb, as this places a heavy load on steering components and could damage them.

Power Steering Systems

Steering Gear System

The steering gear system includes the power steering gear, hydraulic hoses, power steering pump, reservoir, and other components. Some models are also equipped with a separate hydraulic power cylinder on the right side of the front axle, or a right-hand slave gear (such as the TRW RCH-45). The power steering pump, driven by the engine, provides the power assist for the steering system. If the engine is not running, there is no power assist. If the power-assist feature does not work due to hydraulic fluid loss, steering pump damage, or some other cause, bring the vehicle to a safe stop. Do not drive the vehicle until the cause of the problem has been corrected.

Rack and Pinion Steering System

The rack and pinion steering gear is mounted to the front axle with two brackets, and connected by tie-rod ends to the axle steering arms. When the steering wheel is turned, the intermediate steering shaft turns the input shaft, rotating the torsion bar and the valve. When the valve turns, power steering fluid is redirected and provides power assist to turn the pinion gear meshed with the rack teeth, moving the rack left or right. The rack, with a tie-rod at each end, then moves the steering arms on the axle, and pivots the wheels.
This design provides drivers with more responsive steering, with increased performance and “road feel.” It virtually eliminates steering issues when the driver hits a bump (bumpsteer), and significantly reduces roll steer when a vehicle goes into a curve. Wandering is significantly reduced as well, so the vehicle tends to drive straight on the highway. It has a lower steering ratio, which means drivers don't have to turn the steering wheel as much to get the wheels to turn a given distance. Overall, rack and pinion steering greatly improves steering response, and reduces driver effort and fatigue.