What does the alternator pulley do?

What does the alternator pulley do?
What does the alternator pulley do? Image source: Pixabay

This is the class 7 topic of physics if you can recall your childhood times. Remember we learned about the use of pulleys, a simple machine to fetch water from wells. It comes in the same category as inclined planes, screws, wheels, etc that use simple mechanical advantage to multiply force and torque.

In some cases, it multiplies torque, while in some places force while in some cases it multiplies both force and torque depending on the situation. Here we are discussing the alternator pulley and its working mechanism. But with innovations in almost every field around us, these pulleys got a modernized touch as well.

In automobiles what happens is that the engine with the use of fuel generates the required power which is then transferred for varied utility such as compressor, alternator, and water pump and what would be more efficient than pulley. For smooth functioning of the modern internal combustion engine, an overrunning alternator pulley is used.

Variations in the automobile with time

When automobiles came into the use for mass use, a V-shaped belt with three distinct belts was the most used to drive pulleys with vehicles. In the beginning, belts were a matter of concern whether these belts could drive pulleys with 3 belts, but they did. Nowadays the cars have one single belt capable of displacing all the necessary pulleys. The difference is that earlier the V-shaped belt was narrow and nowadays that is a wide one with flat one side and ribs of V-shaped on the other side.

Now the question arises as to how to differentiate which belt is to be used in which vehicle. This is dependent on the engine according to which the number of ribs is decided to be grooved on one side of the belt. And as the number of ribs increases or decreases as per the engine the width of the ribs also changes. The most used width ranges from 5 to 8, while most of the demand comes for 6. Not only the belts but also the alternator pulleys also come in various diameters due to the variety of belts that actually drives the pulleys.

Hence, many names have been assigned to belts such as Micro-V belt, Poly-Ribbed Belt, Poly-V belt, Multi-V belt, and others.

Why Overrunning alternator pulley?

In the whole of the vehicle, it is the alternator that has the maximum speed and moment of inertia. This denotes that any defect in the rotation directly influences the belts causing mechanical wear and tear. These rotational defects cause the accelerating and decelerating forces to act on the alternator, thus causing serious damage to it as well.

In such cases Overrunning alternator pulley makes sure that the accelerating portion of the first-hand power to the crankshaft is used to drive the alternator.

Making the engine work smooth

The use of Overrunning alternator pulley with a one-way clutch makes a significant positive change in the engine by lowering the force in the belt drive. This single change does a miracle by increasing the longevity of the engine and other components by the factor of 10. The noise of the engine is reduced and the velocity of the generator is increased thus making the engine a smooth fair.

This also results in the saving of quite an amount of energy leading to lower carbon dioxide (CO2) emissions. Another example where Overrunning alternator pulley reduces the workload of components is while staying in traffic jams. In such cases, due to alternator pulley, less load is subjected to belts.

Design and structure

If someone going by the name would go with the expectation that he or she would see the pulley as used in wells to fetch water, then you will be utterly disappointed. There is no such resemblance by looking from outside.

The diameter facing outwards is made according to the Poly-V belt, a one-sided clutch, two seals, and inner rings. To prevent the pulley from getting spoiled with salt-water deposits a cover is fitted on the front of the alternator. On customer’s demand overrunning alternator pulleys are made a little flexible, but to do so a modular system is designed. Many people still go for spring decouplers instead of overrunning alternator pulleys. In these pulleys, you do not need any adjustment for different alternator sizes. So, if you want to go with advanced technology, overrunning alternator pulleys are the pick.

The decoupling process

The main objective of the pulley is to decouple the generator from the rotational defects in an internal combustion engine. Most of the parts of the generator do not work in accordance with the mishappenings of the crankshaft when the engine starts. By opening in the overhauling direction, it decouples the inertial torque of the alternator during a considerable change in deceleration like the change of gears.