A truck with a high-torque, low-rpm engine exhibits a great deal of gear noise and spline wear on drivetrain parts. The truck uses a rigid disc clutch. The most likely cause is:

• A. Driver abuses the clutch by releasing it too rapidly
• B. Engine produces torsional vibration, which should be removed from the drivetrain by using a dampened disc clutch
• C. Engine mounts are worn
• D. Engine rating is such that the transmission requires the use of an oil cooler

Answer: (B)

The key idea is that torque pulses from a high-torque, low-rpm engine create torsional vibrations that travel through the drivetrain. A rigid disc clutch cannot absorb these vibrations, so the pulses are transmitted to gears and splines, producing gear noise and accelerated wear. A dampened disc clutch adds springs or a damper between the clutch parts to absorb or smooth out these torsional vibrations before they reach the transmission and axle gears, protecting spline surfaces and reducing noise. In this situation, damping is necessary because the engine’s torque pulses are large, whereas worn engine mounts or oil cooler needs don’t address the vibration issue, and driver technique wouldn’t eliminate the inherent torsional forces.