Overrunning alternator pulleys from Triscan for a large part of the car parc

The increased demand for even more comfort in cars, e.g. air conditioning, seat heating and other comfort facilities, puts pressure on the capacity of the car’s alternator. Therefore, the car manufacturers have started using even more powerful alternators, which especially in situations of deceleration put strain on the micro-v belt. In order to reduce the strain on the micro-v belt system, the car manufacturers have developed an overrunning alternator pulley, which as opposed to the conventional alternator pulley allows the alternator to ”overrun” when the engine decelerates and thus absorbs the vibrations in the alternator and the other belt drive components. 

The program of V-belts includes micro-v-belt kits, V-belts, belt tensioners, pulleys, alternator pulleys and installation tools ​

Benefits of the overrunning alternator pulley:

  • Allows the use of alternators with increased effect
  • Reduces wear and tear on all belt drive components
  • Eliminates belt slip and removes noise
  • Absorbs vibrations
  • Increases the life span of all belt drive components

There are two types of overrunning alternator pulleys:

  • OWC - rotates freely in one direction and locks immediately in the other direction
  • OAD - rotates freely in one direction and allows a small angular rotation in the other direction.

As none of the pulley types are interchangeable, it is very important only to use the pulley type that the vehicle was originally equipped with. So if a vehicle calls for a solid pulley, OWC or OAD, the same category of pulley must be installed. Like any other part overrunning alternator pulleys do not last forever, (and technicians will be replacing more and more of them). A worn pulley can cause vibrations in the belt drive system, and it will often lead to a broken tensioner. 

How to test if an overrunning alternator pulley needs replacement

Overrunning alternator pulleys do wear out, but this is not always visible to the naked eye. In collaboration with Gates, Triscan has put together a troubleshooter, in which you will be guided how to test if an overrunning alternator pulley is near failure. You will find the troubleshooter here.