Poly-V / Serpentine Belts

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The Poly-V belts are produced for auxiliary transmissions of cars, commercial vehicles, heavy duty vehicles and buses. Service belts control almost all auxiliary systems. They have very important functions controlling the correct operation of

  • The climate control compressor
  • The power steering pump
  • In some cases even the water pump
  • The alternator

The Poly-V belt and the A/C compressor

The Poly-V belt, with a pulley system, powers the air temperature control system compressor. Its task is to compress the coolant gas circulating within the air temperature control system. It is recommended to always keep the service belt in perfect working order, especially in summer. The functioning of the air temperature control system also depends on this.

The Poly-V belt and the power steering pump

The Poly-V belt powers the power steering pump. The latter is present in almost all cars, ensuring smoother and safer driving. A malfunctioning service belt can make the steering system barely manoeuvrable, compromising the safety of all passengers on board.

The Poly-V belt and the water pump

On some types of cars, the service belt operates the water pump, ensuring the circulation of coolant within the cooling circuit. Thanks to the water pump, the engine and its components can remain at an optimal temperature. Without it, the engine would emit very high temperatures, causing malfunctions.

The Poly-V belt and the alternator operation

The main characteristic of the Poly-V belt is that it powers the alternator by recharging the battery that operates:

  • Starting of the engine
  • The dashboard control panel
  • The headlights
  • The electric windows
  • The air temperature control system.


Dayco Poly-V belts are all made of EPDM (Ethylene-Propylene-Diene-Monomer) and guarantee:

  • Excellent resistance
  • Reliability
  • Silent operation
  • Long service life.

Main features of the Poly-V belts:

  • Highly flexible for use on small diameter pulleys
  • Power transmission also with the back of the service belts, in the case of the “DPK” (Double Poly-V)
  • Resistance to high operating temperatures for longer service life
  • Managing high workloads while maintaining consistently high performance

Poly-V replacement

Replacing the Poly-V belt requires technical equipment and vehicle knowledge typical of technicians or those who know mechanics. Attention must be paid to the correct tension to be applied to the service belt and the correct positioning on the pulleys. In any case, the best is to turn to a trusted mechanical technician. For this type of operation, it remains the best choice.

Discover all the codes of the service belt range by accessing our Dayco Catalog.

Download the service belt brochure here.

Or contact us here.

Web Catalog

Europe market: Packaging environmental labelling


Poly-V Belts Brochure

Web Catalog


Web Catalog

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