What Are the Different Types of Alternator Parts?

Lori Kilchermann

Some of the more commonly-known alternator parts are the brushes, stators, bearings and pulleys. Many of the alternator parts such as the housing, cooling fan and the wiring harness are overlooked when any discussion about the alternator takes place. These are, however, very critical alternator parts that are directly responsible for proper operation of the component. While replacement of the entire assembly is often practiced to cure alternator problems, the alternator parts are often easily exchanged, making rebuilding the alternator a viable option in most instances.

The cooling fan is one of the most crucial components of an alternator.
The cooling fan is one of the most crucial components of an alternator.

The main component in an alternator is wire. Of all of the alternator parts, the wire is the key to producing electrical power. One of the most crucial components of all the alternator parts, however, is the cooling fan. Heat is the enemy of any alternator, and the inclusion of a quality cooling system is crucial to the long life and proper operation of the charging system. Many times, the importance of the cooling fan is overlooked when discussing critical alternator parts.

Wire is a key component of an alternator, because it is needed to produce electrical power.
Wire is a key component of an alternator, because it is needed to produce electrical power.

Most manufacturers use one of two types of fan designs. The simple stamped metal fan is the most common, with the other being similar in design to the impeller found inside many water pumps. The drive pulley is also a major factor in the operational success of an alternator. The speed at which an alternator is driven is directly related to the size of the drive pulley on the component. Changing the speed at which the alternator is turned directly affects the rate of charge the unit produces as well as the rate of cooling the fan allows.

A primary cause of most alternator failures is the brushes. The brushes are the point of contact between the spinning stator assembly and the stationary rectifier. This is also the gateway for the electricity produced by the alternator parts and the charging system. In many instances, replacing the brushes alone will rectify most alternator troubles. Advancements in bearing design have eliminated the bearing problems that would often be the cause of many alternator noise issues and failures.

Most alternators used since 1973 have included an internal voltage regulator. Prior to this, the regulator was mounted on the vehicle's firewall or radiator support and was the source of many charging difficulties. The inclusion of this component with the alternator parts has reduced the troubles commonly associated with the older charging systems. Fortunately, this newer-style alternator is easily retrofitted into older charging systems.

An automobile engine's alternator essentially serves as an electric generator.
An automobile engine's alternator essentially serves as an electric generator.

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Discussion Comments


I build and install home wind generators (windmills), and a lot of our systems use car or truck alternators to generate the voltage. I'm sure that the built-in regulator is great for a car, but they seem a lot more sensitive for the windmills. If anything breaks on the system, it is almost always the regulator, which means when they have to swap the whole alternator.

I can't really complain, because the things weren't designed for this application anyway. We are somewhat of an experimental group, and there are commercial windmills out there which use something purpose-built with less problems.

Still, it's s cheap fix, so no big deal. I would like it, though, if I could just change a regulator like before.


@emtbasic - I think you're right, and I could say the same thing about pretty much all of the changes that have been made to modernize cars, trucks, and other vehicles.

I hear older guys, who have been mechanics for a long time, complaining that "you can't work on these new cars". Really, I think that they are just not used to the new things that are part of an engine these days, and that in most ways it is now easier to work on and maintain a car because you don't have to worry about a bunch of small things that used to cause problems.

I do miss being able to pick up some alternator repair parts for a few bucks and not have to pay for a new one. Overall, though, it pays off because the new stuff doesn't break nearly as often.


I like most things about the newer alternators with the built-in voltage regulator. They definitely are more reliable and a lot less likely to leave you stranded than the old type.

The problem with them is that there isn't much you can do if the regulator fails, other than have it rebuilt if it's something expensive (like for large equipment, or maybe a ship or aircraft), or just buy a new one if it's a common automotive alternator.

With the old kind, you could often just swap the regulator and leave the alternator in place. Took less time, and was cheaper. I think overall the new way is better, but it was nice to just be able to swap one small part and not have to take everything apart.

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