Alternator Pulleys

Alternator pulleys often function as unintended conduits for torsional vibrations originating from the crankshaft. These vibrations amplify under low RPM or idle conditions, introducing resonance frequencies into the belt drive. Advanced pulley systems with built-in one-way clutch mechanisms and damped overrunning decoupler (OAD) features isolate these torque spikes. The use of internal helical springs with defined preload constants and high-cycle fatigue-resistant damping polymers effectively reduces vibration propagation into the alternator shaft and accessory systems. 

During aggressive deceleration or start-stop engine operation, the alternator experiences torque reversal conditions that often result in belt slippage or tensioner overextension. Overrunning pulley designs with controlled angular backlash allow the rotor to decouple momentarily, minimizing instantaneous belt load variation. This is achieved through internal ramp-and-roller or strut-based clutch systems, which are tuned for engagement torque thresholds above 8–10 Nm and response times under 100 milliseconds, thereby avoiding torque shock transfer.