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How Do Alternator Clutch Pulley Works?

Do you know how do alternator clutch pulley works? This auto-electrical part is not so simple working as it is important to a vehicle. Before purchasing a new clutched alternator pulley for your vehicle you must be aware of its function and usage.

Today, most of the vehicles are occupied with advanced pulleys that are built to reduce noise, harshness, as well as vibration. This extends the life of the alternator.

The modern vehicles have one-way or so called decoupler pulleys.

Pulleys present in the alternators are required with proper performance, so the alternator has long life and better health.

In this post, we will discuss alternator clutch pulleys and its functions. Read this guide to understand the functioning, working, and other components of this auto electrical part.

What is an Alternator and Alternator Clutch Pulley?

Read about Alternator

Alternators are a very important auto-electrical part in an automobile. Generally, it is a generator whose function is to generate electricity and distribute in the car and all the electric accessories of the car.

Excluding some of the hybrid models, most of the cars with standard combustion engines have alternators. Most probably, your vehicle also has a coconut sized alternator mounted in front of the engine and runs all around. The common components of an alternator are:

  • Rotor and stator
  • Voltage regulator
  • Diode rectifier
  • Cooling fan

Read about Alternator Clutch Pulley

On the other hand Pulley is something more interesting in itself!

Well, pulleys are simply built to transfer power. In pulley system or automotive belt, engine generates power and it is directly transferred to crankshaft from the pulley belt.

From the front belt to pulley there are numbers of accessories attached together. Like, power steering pump, alternator, water pump, air conditioning compressor, etc.

Earlier, automobiles had a narrow V-shaped belt that was used to drive the accessory pulleys as three separate belts. But now the V-shaped belt has become small with ribs on the other sides.

So flat and ripped side of belt both can be used effectively in driver pulleys. This belt comes in the market with various names like Multi-V belt, Polly-V belt, Serpentine belt, Micro-V belt, and Poly-Ribbed belt.

The number of ribs on the belt depends upon the type of vehicle and also the width of the belt. The width varies from 5 to 8 where 6 is the most used width in automobiles.

Alternator pulleys also come in different diameters.

Read about Clutch Pulleys and Decoupler Pulleys

The clutch pulleys used for decades were trouble free and fail proof. However, they were not completely secured, for which some alternatives came in the market.

First, OWC (One Way Clutch type pulley) also known as Overrunning Alternator Pulley (OAP) came. Within a few years Overrunning Alternator Decoupler pulleys (OAD)  werelaunched.These complex pulleys were launched due to some critical reasons.

How does the Clutch Alternator Pulley work? 

The best way to understand the working of clutch alternator pulley working is to compare it with a running bike. When you peddle a bicycle it starts running but after having some speed even after you stop pedalling…the bicycle keeps running.

A bicycle uses momentum and speed and keeps running because of the free wheel.

You can even peddle back but it does not affect the forward motion. But if you peddle faster than it will again start travelling forward.

An alternator pulley works similarly like this!

When you change the gears, the engine constantly changes speed. It drops hundreds of RPMs within a second when you shift from a lower gear to upper gear. However, the alternator keeps spinning at higher speeds. The engine will slow down as the alternator shifts gears and lower the RPMs.

Here, the role of a clutch pulley comes in.

Similar to the bicycle, the alternator also goes down free until it matches the speed of the engine. Pulley will again get engaged in this time. Alternator pulleys are vital to absorb crankshaft pulsation from hitting the alternator. In between the combustion time, the crankshaft rotates rapidly and changes speeds within milliseconds.

How to test Alternator Pulley?

The testing for alternator pulley can be done very easily.

To test the clutch alternator pulley, start by making the serpentine belt off that allows the pulley to rotate independently. Now, hold the alternator internals…you can use culling fins in the opposite side. Counter hold the alternator, you can use opposite sides of cooling fins. Insert a screwdriver so cooling fins do not spin and then rotate the pulley clockwise. It will not move!

Next, rotate the pulley clockwise. This will go on as cooling fins are held on. Now, even if it does not rotate clockwise then it needs to be replaced as it got locked by the alternator shaft.

Is my Alternator Pulley failing?

There are some basic signs through which you can see if your alternator clutch pulley is failed or not. The most basic one is to see if the serpentine belt tensioner has failed or not, if it is…then the chances of a failed alternator pulley are there.

Another way is to see if the serpentine belt tensioner is jumping or not. If it is not rotating smoothly then you should replace the alternator clutch pulley.


This was my review on a most frequently asked question, how do alternator clutch pulley works? I hope you have found the required details and understand the working of this auto-electrical tool

Alternator and its components like a clutch pulley are very important for a vehicle. So, after testing their condition if you have found any damage or irregular functioning by these components then you need to replace them. It assures safe and smooth driving.

Well, I will recommend checking branded alternators and its components on FARGO. This website provides a wide range of auto-electric parts in India. Their products are from OEMs as well as listed from branded manufacturers. You can check and purchase automobile parts at a very affordable price. So, make sure to visit on FARGO

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