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What is an Accessory Belt Drive System?

12 Mar 2018

Category: Articles, Company News

Also known as the engine accessory drive, accessory belt drive systems (ABDS) have to support the increasingly sophisticated and diverse auxiliary features found in vehicles today. These amenities range from safety critical systems such as the power steering, through to comfort functions like the infotainment system, air conditioning and electric seating systems. As a result, it is imperative that the ABDS is correctly maintained for the wellbeing of all the features that are reliant on its prime operational condition.

Components in the Accessory Belt Drive System

The ABDS is comprised of a variety of individual components that work together in unison. The primary component is the system belt also known as, the multi-v belt (Gates’ Micro-V® belt) or traditionally, fan belt. This transfers power from the crankshaft pulley to all belt-driven accessories.

However, the other components in the ABDS play an equally important role in ensuring trouble-free system operation. These components are:


Maintains the correct tension on the belt at all times throughout its duty cycle. Inadequate belt tension causes noise, extremely high temperatures and premature belt-wear. If the tension is too tight, it can also cause excessive wear to the belt-driven accessories. Both scenarios can lead to poor functioning of belt-driven accessories.


Free-spinning wheel around which the belt travels to optimise belt routing and suppress belt flutter.

Torsional Vibration Damper

As VMs make engines smaller, lighter, and more powerful, the components are exposed to more strain, causing increased vibrations. This has led to the replacement of the crankshaft pulleys with torsional vibration dampers that have a rubber-damping element to absorb increased vibrations from the crankshaft. This works to extend the service lifespan of the crankshaft, Micro-V® belt and all belt-driven components.

Overrunning Alternator Pulley

Comfort and other accessory functions require extra electrical power that is derived from heavier alternators that compromise the belt performance when the engine decelerates. The overrunning alternator pulley allows the alternator to “free-wheel” or “overrun” every time the engine decelerates and, at the same time, dampens vibrations at the alternator. This pulley serves to extend the lifespan of the alternator, Micro-V® belt and all belt-driven components.

ABDS Maintenance & Repair Advice

As all components were installed at the same time at OE, they would have done the same amount of work, and experienced the same level of wear. If one part is beginning to struggle, there is a knock-on effect throughout the system. As a result, installers are advised to replace all ABDS components at once when carrying out any maintenance or repair work on any one component/aspect of the ABDS.

Keep it Simple with a Comprehensive ABDS Kit

To address the need for complete ABDS replacement, Gates has a complete range of Micro-V® kits that include all the necessary components to facilitate total system replacement.

For more information, please speak with your local Gates or FPS representative today.

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