Drive Train Systems Flashcards

A heavy-duty truck experiences a vibration that increases with vehicle speed but is NOT affected by engine RPM. The MOST likely cause is:

Answer: Driveshaft imbalance or worn U-joints

A speed-related vibration independent of engine RPM points to the driveshaft or U-joints rather than engine components.

Which type of differential is BEST suited for a drive axle that regularly operates on slippery surfaces?

Answer: Limited-slip differential

A limited-slip differential transfers more torque to the wheel with better traction, improving performance on slippery surfaces.

When checking driveshaft working angles, the front and rear U-joint angles should be:

Answer: Equal and in opposite phase

Equal but opposing working angles cancel out velocity fluctuations and prevent vibration in the driveline.

A manual transmission jumps out of a high gear under load. The MOST probable cause is:

Answer: Worn shift fork or detent springs

Worn shift forks or weak detent springs allow the synchronizer sleeve to slide back out of engagement under load.

In a tandem drive axle arrangement, the purpose of the inter-axle differential (power divider) is to:

Answer: Distribute torque equally between the front and rear drive axles

The inter-axle differential allows the two drive axles to rotate at different speeds while splitting torque between them.

What does a higher numerical axle ratio (e.g., 4.56:1 vs. 3.73:1) provide?

Answer: Lower top speed with higher torque multiplication

A higher numerical gear ratio provides greater torque multiplication at the wheels but limits top speed.

A technician notices the clutch pedal has very little free play. What is the MOST likely result if this condition is ignored?

Answer: Premature clutch disc wear and slipping

Insufficient free play keeps the release bearing partially loaded against the pressure plate, causing the clutch to slip and wear prematurely.