Tensioners, Pulleys and Idler Wheels

Tensioners, Pulleys & Idler Wheels
Tensioners, Pulleys & Idler Wheels

Masterparts offers an incredibly wide range of air conditioner and crankshaft pulleys, idler pulleys and timing belt and micro-v belt tensioners (including hydraulic tensioners).

About tensioners, pulleys and idler wheels

Belt tensioners, pulleys and idler wheels are components in the drive belt system of a car.

They hold and guide the auxiliary drive belt, also known as a serpentine belt or Micro-V belt, as it transfers power from the crankshaft pulley to the auxiliary pulleys.

Together, the system is responsible for the smooth operation of a vehicle’s alternator, water pump, air conditioner and power steering.

About tensioners, pulleys and idler wheels Serpentine Belt

Diagram source: ACM

What do tensioners do in a car?

Belt tensioners maintain the correct tension of the Micro-V belt as it snakes around the pulleys. It’s a cylindrical component, similar in shape to a pulley, consisting of a tensioner arm, spring and base.

The tensioner’s role is to ensure the optimal drive of the pulleys in the system. It allows the belt to move seamlessly through the drive configuration to power all the auxiliary components at the same time.

What do pulleys do in a car?

The pulleys drive the auxiliary components in the car – the generator, power steering pump, air conditioner compressor and water pump.

As the drive belt or Micro-V belt winds around the system of pulleys, it causes each pulley to rotate and activate the corresponding engine accessory.

What do idler wheels do in a car?

Idler wheels are small grooved gears that direct the route of the belt from one pulley to another. Its only role is to keep the belt aligned with the belt tensioner and auxiliary pulleys.

How do tensioners, pulleys and idler wheels work together?

All three components work together to synchronise the rotation of the Micro-V belt around the auxiliary drive system.

The tensioner transmits pressure to the belt by way of a tensioner arm. It ensures the belt exerts adequate friction to rotate the pulleys and activate the accessories.

Idler wheels direct the moving belt to specific locations in the engine’s configuration. In the diagram above, idler wheels route the belt from the alternator to the air conditioner compressor to the crankshaft pulley.

Signs of worn or faulty tensioners, pulleys and idler wheels

When the engine is running, a whining, screeching, squealing or rattling noise can be a sign of a malfunctioning belt tensioner, one or more misaligned pulleys or worn idler wheel bearings.

If one component fails, it’s advisable to replace all the other parts, including the Micro-V drive belt.

Where to get tensioners, pulleys and idler wheels in South Africa

We offer door-to-door delivery. Alternatively, visit any of our branches.

Tensioners, pulleys and idler wheels in and around Cape Town:

Tensioners, pulleys and idler wheels in KwaZulu-Natal:

Tensioners, pulleys and idler wheels in Namibia:

Masterparts offers a full range of engine parts and accessories, along with suspension, steering, braking and electronic parts. Contact us if there’s a part you need and we’ll do our best to help.


Call us on 021 657 5757 or complete the form below to get a quote.

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