Overrunning Alternator Pulleys

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Overrunning Alternator Pulleys

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Overrunning Alternator Pulleys

Design and function

An overrunning alternator pulley consists essentially of:

A) Belt pulley 
B) Needle bearing 
C) Pinch rollers with coupling function 
D) Spring (only in case of overrunning alternator decoupler)

Overrunning Alternator Pulleys

As a result of the coupling function of the overrunning alternator pulley torque is transmitted only in one direction.

Thanks to its integrated spring/damper system, the overrunning alternator decoupler also decouples the multi V-belt from the alternator, thereby enabling it to damp resonance more effectively.


Replacement interval:

Overrunning alternator pulleys are subject to aging and wear and therefore have to be regularly checked and replaced. Continental recommends inspecting the operation of the overrunning alternator pulley every 60,000 km and, if in doubt, changing it every 120,000 km.


  • Store in a dry, dust-free and cool place (ideally 15-25°C)
  • Avoid contact with all liquids (oil, water etc.)


  • Faulty overrunning alternator pulleys are often the cause of noise or damage in the belt drive (e.g. tensioner)
  • Continental offers the Conti TOOL BOX OAP for fitting
  • Overrunning alternator pulleys can always be identified by their cover cap