Steering and Suspension Systems Flashcards

A driver reports a condition known as 'memory steer,' where the truck continues to pull to one side after a turn and must be manually corrected. Which of the following is the MOST likely cause of this symptom?

Answer: Binding kingpins

Memory steer occurs when steering components bind, preventing the natural self-centering action of the steering geometry. Binding or overly tight kingpins are a primary cause, as they introduce excessive friction into the steering knuckle's pivot points, overcoming the caster angle's ability to return the wheels to a straight-ahead position.

Which of the following wheel alignment angles has the primary responsibility for creating directional stability and promoting steering wheel returnability after a turn?

Answer: Caster

Caster is the forward or rearward tilt of the steering axis when viewed from the side. A positive caster angle positions the tire's contact patch behind the steering axis pivot, creating a self-aligning torque that helps the vehicle maintain a straight path and causes the steering wheel to return to center.

What is the primary function of a height control valve in a heavy-duty truck's air suspension system?

Answer: To automatically maintain a predetermined ride height regardless of the load.

The height control valve is mechanically linked to the axle and frame. It senses changes in the distance between them due to loading or unloading and automatically adds or removes air from the air springs (bellows) to maintain a constant, preset ride height.

During a 'dry park check,' an assistant rocks the steering wheel back and forth while the truck's full weight is on the ground. The technician observes vertical (up-and-down) movement in the drag link where it connects to the steering arm. This observation indicates:

Answer: A worn drag link socket

A dry park check is designed to identify looseness in steering components under normal load. Rotational or horizontal movement in the drag link is normal, but any vertical play within the ball-and-socket joint indicates excessive wear. The component with vertical play must be replaced.

A technician observes severe cupping, or scalloped wear, on both steer axle tires. Which of the following conditions is the MOST likely cause?

Answer: Worn or failing shock absorbers

Tire cupping is a wear pattern of high and low spots caused by the tire bouncing and not maintaining consistent contact with the road. The most common cause is worn shock absorbers that can no longer dampen suspension oscillations, allowing the tire to hop on the road surface.

On a tandem-axle suspension, what is the main purpose of longitudinal and transverse torque rods?

Answer: To control axle positioning and absorb braking and acceleration forces.

Torque rods are critical links that connect the axle housing to the frame. They prevent the axle from rotating during acceleration and braking (axle wrap) and also maintain the axle's lateral and longitudinal alignment, which is essential for proper handling and driveline angles.