Q: How Do Belt Pulleys Work?

asked by on

How do belt pulleys work?

Your car has two main types of pulleys, crank pulleys and accessory pulleys. The crank pulley delivers motion to the other pulleys by means of either a serpentine belt or a v-belt, and they in turn activate the accessories in your vehicle. Idler pulleys may take the place of an accessory. Tensioner pulleys simply work to keep the proper tension on the belts.

Every engine-driven accessory has a drive pulley attached to it. Drive pulleys are responsible for operating each of the engine accessories. These accessories include the crankshaft, water pump, generator, power steering pump, A/C compressor, oil pump, supercharger (if equipped), and secondary air pump (if equipped).

The crankshaft is the main driver. The accessory drive belt is routed so that it rides on every pulley. When the crankshaft turns, the crank pulley moves the drive belt which, in turn, moves all of the other pulleys on the engine. This causes the pulleys to turn the accessories that they are attached to. The faster the crank turns, the faster the pulleys turn.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1,000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  1. Home
  2. Questions
  3. How Do Belt Pulleys Work?

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: A/C V-belt keeps going bad within six months.

Hi there. Check the angle of the V-belt as its mounted on the air conditioner pump. For the belt to burn off or decay that fast, either the belt is too tight, too loose, or the pulley is offset from...

Q: Car belts making noise.

There are several bearings in the pulley system that is driven by your serpentine belt. It is not uncommon for them to go bad occasionally and make noise. However it is also possible that your belt may be worn, or...

Q: Fixed Timing Chain Guide Bolt Threads Stripped

If the bolt threads are stripped and the hole is enlarged for the timing chain guide bolts then you will need to install a thread repair insert. You will have to follow the thread repair kits instructions by drilling out...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.