310T Steering and Suspension Systems 4 — Questions and Answers
Question 1: What does Ackermann steering geometry ensure during a turn?
- Both front wheels turn the same angle
- The inside front wheel turns at a greater angle than the outside wheel (Correct answer)
- The outside front wheel turns at a greater angle than the inside wheel
- Both front wheels remain parallel throughout the turn
Correct answer: The inside front wheel turns at a greater angle than the outside wheel
Ackermann geometry angles the inside wheel more sharply so both front wheels can follow their own turning radius without tire scrub.
Question 2: A technician notices the air pressure in one air spring on a rear tag axle is significantly lower than the other side. What is the MOST likely result?
- Increased caster on the tag axle
- Uneven load distribution causing axle thrust angle change (Correct answer)
- Higher than normal toe-out on turns
- Reduced Ackermann effect
Correct answer: Uneven load distribution causing axle thrust angle change
Unequal air spring pressure causes one side of the axle to ride lower, shifting the axle and altering its thrust angle relative to the vehicle centerline.
Question 3: When a hydraulic power steering pump is pressure-tested and output pressure is low at idle but reaches spec when the engine speed is increased, what is indicated?
- A worn or faulty flow control valve (Correct answer)
- A leaking power steering gear
- A collapsed high-pressure hose
- A faulty pressure relief valve
Correct answer: A worn or faulty flow control valve
A worn flow control valve allows flow to bypass at low pump speeds, reducing pressure at idle while higher RPM compensates through increased volume.
Question 4: What is the function of the king pin inclination (KPI) angle?
- Sets the amount of steering wheel return after a turn
- Provides directional stability by creating a self-centering effect and reducing steering effort (Correct answer)
- Controls the maximum steering lock angle
- Determines the amount of toe change during suspension travel
Correct answer: Provides directional stability by creating a self-centering effect and reducing steering effort
KPI creates a geometric pivot that causes the front of the vehicle to lift slightly in a turn, providing a self-centering force and reducing steering effort.
Question 5: A coach steering system uses an electric power steering (EPS) assist. The driver reports steering assist is present at low speeds but disappears at highway speeds. This is:
- A fault — EPS should provide full assist at all speeds
- Normal operation — EPS reduces assist as speed increases for better road feel (Correct answer)
- A sign of a failing EPS motor
- Caused by a faulty vehicle speed sensor sending no signal
Correct answer: Normal operation — EPS reduces assist as speed increases for better road feel
EPS systems are speed-sensitive by design, providing maximum assist at low speeds and progressively reducing assist at higher speeds to improve stability and road feel.
Question 6: Feathered (saw-tooth) wear across the face of a tire tread is a diagnostic indicator of:
- Excessive camber
- Incorrect toe adjustment (Correct answer)
- Overinflation
- Worn shock absorbers
Correct answer: Incorrect toe adjustment
Feathered wear, where tread blocks are worn sharp on one edge and rounded on the other, is caused by incorrect toe setting (toe-in or toe-out).
Question 7: What is the purpose of the drag link in a conventional truck steering system?
- Connects the two front steering knuckles to maintain parallel steering
- Transmits steering motion from the pitman arm to the steering knuckle or tie rod (Correct answer)
- Provides the primary pivot point for front wheel steering
- Controls the rate of steering gear response
Correct answer: Transmits steering motion from the pitman arm to the steering knuckle or tie rod
The drag link connects the pitman arm (output of the steering gear) to the steering knuckle arm or cross-tube, transmitting the steering input to the front wheels.
310T Steering and Suspension Systems 4
What does Ackermann steering geometry ensure during a turn?