Steering and Suspension Systems Flashcards

A technician is performing a front-end inspection on a truck with I-beam front axle. Checking for king pin wear, the CORRECT method is to:

Answer: Support the axle to unload the wheel, then grip the tire at 12 and 6 o'clock and rock it to check for vertical play

With the axle unloaded, rocking the tire at 12 and 6 o'clock reveals king pin vertical play; 9 and 3 o'clock rocking checks wheel bearing play.

A motorcoach with air suspension repeatedly triggers the low-ride-height warning on one rear corner. The air spring, height control valve, and supply air check out fine. What should be inspected next?

Answer: Air lines and fittings for slow leaks between the height control valve and the air spring

Slow leaks in the air lines between the height control valve and spring allow the spring to bleed down when stationary, triggering the low-height warning.

Thrust angle alignment refers to:

Answer: The direction the rear axle(s) push the vehicle compared to the vehicle centerline

Thrust angle is the direction the rear axle(s) propel the vehicle; if not aligned with the vehicle centerline, the vehicle will dog-track or the steering will be off-center.

When replacing a pitman arm on a truck steering system, the technician should:

Answer: Align the master spline and torque the retaining nut to specification with a thread-locking compound

The master spline ensures the pitman arm is installed in the correct position relative to gear center; torquing to spec prevents loosening under load.

A leaf spring on a heavy truck is found to have a broken center bolt. What is the PRIMARY concern with continued operation?

Answer: The axle can shift fore or aft under the spring, causing misalignment and potential loss of control

The center bolt locates the axle on the spring pack; if broken, the axle can shift longitudinally, altering brake geometry and potentially causing severe handling instability.

What condition is indicated when a truck's steering requires significantly more effort to turn left than to turn right?

Answer: Internal leak in the power steering gear causing unequal assist in each direction

Internal seal or valve wear in the power steering gear can cause unequal hydraulic assist depending on steering direction, resulting in effort differences left versus right.

Scrub radius is defined as the distance between:

Answer: The point where the steering axis intersects the ground and the center of the tire contact patch

Scrub radius (also called steering offset) is measured at ground level between the steering axis projection point and the tire center — it affects steering returnability and torque steer.