There are 3 major types of alternators pulley available in the market .
Let us understand which are all the types & its purpose. It is principally important to know the differences and why these newer pulleys are required in today's vehicles.
First, there is a known fact that larger alternators are used in automobiles, ten to fifteen years ago it was common to have 60A to 70A alternators on vehicles, now with the more usage of all the electronic gadgets, it is common to have 160A to 200A alternators. These larger alternators with more mass & coupled with more fuel efficient engines caused problems for the serpentine drive system. Some of these issues include belt slip which leads to chirping noises, increased belt tensioner motion & broken tensioners.
These belt drive issues are addressed by car manufacturers by utilizing newer technologies like OAPs & OADs on the alternators.
Learn More:- BASIC UNDERSTANDING OF A AUTOMOBILE ALTERNATOR
Let us learn more about types of alternators pulley & its functions.
1. Solid pulley
This is a standard and old type serpentine belt alternator pulley. The only function of this pulley is to drive the alternators. If the alternator has a solid pulley, only replace it if damaged, rusted, or worn.
2. OAP (Overrunning Alternator Pulley)
This kind of pulley works in a manner where a one way clutch mechanism has been incorporated into the alternator's pulley. If we turn the OAP , we are able to notice that it rotates freely in the overrun direction and immediately locks the drive direction. This is an internal one way clutch that allows the insides of the alternators to course to stop when the engine is shut off. This overrunning feature is what eliminates the belt chirp noises during the engine shutdown as well as during the transmission shifting.
3. OAD (Overrunning Alternator Decoupler) -Alternators Pulley
The OAD, not only has the one way clutch inside the pulley to address the belt chirp noises just like OAP but it also incorporates special steel torsion spring that absorbs engine vibration that are caused by the firing of each cylinder and the lower idle speeds of engines, just like the OAP , the OAD rotates freely in the overrun direction , however it will engage softly with a spring in the drive direction, it is the patented internal steel spring that absorbs the rotational engine vibrations of the alternators and absorbing this vibration will allow the belt tensioner to remain calm on the newer more fuel efficient engines.
It is important to know which pulley, the vehicle has been designed with, as these three Alternators pulley technologies are not interchangeable.
