Chapter 69 Steering System Fundamentals
Collapsible steering column
A column that is designed to crumble or slide together when forced forward during a collision
Tilt steering column
A column with a flex joint or U-joint that allows the top half of the column and the steering wheel to be positioned at different angles
Relay rod
Also called a center link, a steel bar that connects the right and left sides of the steering linkage
Center link
Also called a relay rod, a steel bar that connects the right and left sides of the steering linkage
Steering ratio
Also called gearbox ratio or steering gear reduction, is basically a comparison between steering wheel rotation and sector shaft rotation
Gearbox ratio
Also called steering ratio or steering gear reduction, is basically a comparison between steering wheel rotation and sector shaft rotation
Steering damper
An oil filled shock absorber found in some parallelogram linkage arrangements, it is attached between the vehicles frame and the center link
Variable-ratio gearbox
Changes the internal gear ratio as the front wheels are turned from the center position.
Steering gearbox
Changes turning motion into a straight-line motion to the left or right
Tie-rods
Connect the rack with the steering knuckles
Steering linkage
Connects the steering gearbox to the steering knuckles and the wheels
Steering column assembly
Consist of the steering wheel, steering shaft, column, ignition key mechanism, and sometimes a flexible coupling and a universal joint
Rack-and-pinion steering gear
Consists of a pinion shaft, a rack, a thrust spring, bearings, seals, and a gear housing
Integral power steering gearbox
Contains a conventional worm-and-sector gear, a hydraulic piston, and a flow-direction valve
Worm-and-roller steering gearbox
Contains a roller that is mounted on the sector shaft and meshes with the worm gear
Power steering pump
Engine driven and produces the hydraulic pressure for the steering system operation
Tie-rod assemblies
Fastens the center link to the steering knuckles
Rubber dust boots
Fit over the inner ball sockets to keep out dirt and water, as well as to hold in lubricating grease
Constant-ratio gearbox
Has the same gear reduction from full left to full right
Flexible coupling
Helps keep road shock from being transmitted to the steering wheel, also allows for slight misalignment of the steering shaft and steering gear input shaft.
Power steering hoses
High and low pressure, hydraulic, rubber hoses that connect the power steering pump and the integral gearbox or the power cylinder
Power steering fluid reservoir
Holds an extra supply of hydraulic fluid
Spool and rotary valves
Hydraulic control valves used to direct high pressure fluid to either side of the power assist piston and dump low pressure fluid back to the reservoir; used with both worm and rack-and-pinion gearboxes
Steering rack
Long steel bar with teeth along one section; it is the output of a rack and pinion gearbox
Manual tilt column
Makes use of a lever on the steering column to unlock the flex joint so the wheel can be moved up or down
Power tilt column
Makes use of a small electric motor, a control switch, and a gear mechanism to change the steering wheel angle or height
Memory tilt wheels
Makes use of a tilt control module (computer) to "remember" more than one steering wheel position
Recirculating-ball gearbox
Normally used with a linkage steering system, it has small steel balls that circulate between the gear members.
Pinion thrust spring
Preloads the rack-and-pinion gear teeth to prevent excessive gear backlash
Ball sockets
Provide for motion in all directions, allow linkage arms to swivel up and down (for suspension action) and from left to right (for turning)
Toe adjustment sleeve
Provided for changing the length of the tie-rod assembly during wheel alignment
Preload adjusting nut
Provided to set worm shaft bearing preload
Gearbox housing
Provides an enclosure for the other components of the steering gearbox, whether recirculating ball or rack and pinion gearbox
Ball nut
Rides on the ball bearings and the worm gear, it slides up and down as the worm gear rotates
Pinion gear
Rotated by the steering wheel and steering shaft; it is the input of a rack and pinion gearbox
Ball guides
Route extra ball bearings in and out from between the worm and ball nut
Road feel
Slight steering wheel pull caused by road surface
Idler arm
Supports the end of the center link on the passenger side of the vehicle
Steering column
Supports the steering wheel and the steering shaft
Worm shaft
The input gear connected to the steering column shaft, the balls fit and ride in the grooves in the worm gear
Sector shaft
The output gear from the steering gearbox, it transfers motion to the steering linkage
External cylinder power steering system
The power cylinder is not in the gearbox, and commonly bolted to the frame and the center link; the hydraulic control valve may be located in the gearbox or on the steering linkage
Pitman arm
Transfers gearbox motion to the steering linkage
Steering shaft
Transfers turning motion from the steering wheel to the steering gearbox
Parallelogram steering linkage
Type of steering linkage that includes a pitman arm, a center link, an idler arm, ball sockets, and two tie-rod assemblies, it may also include a steering damper.
Steering wheel
Used by the driver to rotate a steering shaft that passes through the steering column
Pressure-relief valve
Used in a power steering system to control maximum oil pressure, it prevents system damage by limiting pressure when needed
Gear lash adjusting screw
Used to set the sector shaft clearance