Heavy Duty Steering Systems

The primary function of a heavy duty truck steering system is to:

Control suspension height Provide controlled directional change of the vehicle with acceptable effort and feedback Apply service brakes Increase engine power

Most heavy trucks use which type of steering gear?

Rack and pinion Recirculating ball worm-and-sector or integral power steering gear Cable-operated steering Chain drive steering

The steering knuckle is the component that:

Connects the steering wheel to the column Supports the wheel ends and pivots on kingpins or knuckle pins for steering Controls brake timing Supports the transmission

Kingpins in heavy duty steering axles:

Support the frame Serve as pivot pins between the axle beam and steering knuckles Control engine timing Adjust brake stroke

The drag link connects:

Steering wheel to seat Pitman arm to steering arm on the knuckle Axle to frame Brake chamber to slack adjuster

The tie rod connects:

Steering gear to steering column Left and right steering arms to keep wheels toed correctly Front axle to frame Brake pedal to master cylinder

Toe setting on a steering axle refers to:

Camber angle of the wheels Inward or outward angle of the wheels when viewed from above Caster angle of the kingpin Steering wheel diameter

Power steering pumps on heavy trucks are typically driven by:

Electric motors only Engine belt or gear drive supplying flow to the steering gear The transmission output shaft directly Hand pumps

Integral power steering gears combine:

Only manual gear components Mechanical steering gear and hydraulic power assist in one unit Brake valves and steering valves Engine and transmission controls

Steering gear lash (free play) that is excessive can cause:

Improved steering response Loose steering feel and poor vehicle control Reduced tire wear Better directional stability

Caster angle in steering geometry affects:

Vertical load on the axle only Self-centering tendency and straight-line stability Engine timing Brake fade

Camber angle is defined as:

Tilt of the steering wheel Tilt of the wheel from vertical when viewed from the front Toe measurement Distance between axles

Power steering fluid leaks are often found at:

Tire beads only Hoses, fittings, pump shaft seals and steering gear input/output seals Brake shoes Frame rails

Steering stops on heavy trucks are used to:

Limit maximum steering angle to prevent tire and component interference Increase turning radius Adjust ride height Control brake balance

Power steering return lines should be routed:

To the suction side of the pump without filtration To the reservoir through appropriate filtration and cooling if equipped Directly onto the ground To the engine crankcase

A 'steering axle' on a heavy truck is usually:

A driven axle A non-driven front axle designed for steering and load support A tag axle behind the drive axles A trailer axle

Wheel alignment settings that are incorrect can cause:

Uniform tire wear and stable handling Irregular tire wear, pulling and poor handling Improved fuel economy Elimination of steering wander

The steering column assembly includes:

Only the steering gear Steering shaft(s), column housing, bearings and sometimes tilt/telescoping mechanisms Axle beam Brake drums

The ILM Heavy Duty Steering Systems module expects parts technicians to:

Set up wheel alignments Recognize components such as steering gears, pumps, knuckles, kingpins, drag links and tie rods for parts supply Adjust steering stops directly Design new axle beams

Power steering reservoirs normally include:

Only air Fluid level marks, return and suction ports, and often a filter or screen Exhaust valves Brake components

A truck that pulls to one side could have:

Perfect steering alignment Unequal tire pressure, brake drag, misalignment or steering gear issues Only engine problems Correct camber on both sides

Returnability (self-return to centre) of the steering wheel after a turn is influenced mainly by:

Toe only Caster angle and steering geometry Cab height Differential ratio

Power steering pump flow and pressure specifications are important so that:

Correct radiator size is chosen Steering assist matches gear requirements without overloading components Fuel consumption is maximized Brake systems can be pressurized

Steering linkage joints such as tie rod ends typically use:

Solid welded joints Ball and socket designs with tapered studs Only straight pins Rubber hoses

If a steering gear is replaced, the parts technician must supply a unit with:

Any number of turns lock-to-lock Correct mounting pattern, input/output shaft configuration, ratio, rotation and port locations as specified Only approximate similarity Any available unit that fits the frame

Steering dampers (stabilizers) are sometimes used to:

Increase steering effort Reduce shimmy and sudden steering shocks Increase turning radius Eliminate need for alignment

Excessive free play at the steering wheel may be caused by:

New steering components Worn steering gear, loose linkages, worn kingpins or wheel bearings Correct alignment Properly adjusted gear

Hydraulic power steering systems generally include:

Pump, reservoir, steering gear, hoses and sometimes an oil cooler Only an electric motor Only mechanical linkages Air compressor and air tanks

On some vehicles, auxiliary hydraulic steering cylinders are used to:

Operate brakes Assist in turning multiple axles or very heavy steering axles Support cab suspension Control exhaust brakes

When ordering steering knuckle or kingpin kits, necessary information includes:

Only wheel size Axle manufacturer, model, axle capacity and vehicle application Cab colour Seat fabric type

Steering stop adjustment is important to:

Prevent tire-to-frame or suspension interference at full lock Increase turning circle unnecessarily Control brake application Change ride height

Steering gear mounting bolts and frame brackets must:

Be of any grade available Be correct grade and torque to prevent movement and cracking Be only hand tight Be replaced with smaller bolts to allow flex

Power steering fluid type is important because:

Any oil can be used The manufacturer specifies compatible fluids to protect seals, pumps and gears Gear oil is always acceptable Water can be substituted in an emergency

The steering wheel position relative to wheel angle is maintained by:

Proper installation of steering shaft splines and centering of steering gear Brake adjustment Shock absorber selection Spring arch

In the ILM Heavy Duty Steering Systems module, exploded views help parts technicians to:

Calculate wheel alignment Visualize component relationships and identify individual service parts Set steering wheel height Select cab colours

Steering boxes often have a 'high point' or centre position which:

Is the loosest point Is designed to have minimum lash and must align with straight-ahead vehicle position Is only used in reverse Has maximum free play

If power steering assist is lost but manual steering remains, likely causes include:

Broken axle beam Pump failure, loss of fluid or drive belt failure Steering gear mechanical failure only Flat tires on drive axles

Road feel in a steering system refers to:

Engine vibration Feedback through the steering wheel that helps the driver sense surface conditions and vehicle response Noise from the exhaust Operation of the HVAC system