Belt Drive, Basic Function - GF13.21-P-1001A
Engine all (4xWD)
Engine all (CAR)
Sample diagram of belt drive
Overview
This document contains information on:
- General
- Function
- Belt drive
- Belt tension
General
To drive the auxiliary assemblies important for vehicle operation via a belt, the belt drive uses the rotary movement of the crankshaft.
Function
Belt drive
A belt pulley is flange-mounted on the free crankshaft end. The belt pulley is designed in this connection as a torsional damper (5) and dampens the speed fluctuations of the successive combustions in the cylinders. This dampening ensures low-wear and low-noise use of the poly-V-belt.
The belt pulley drives the ancillaries via a poly-V belt by means of friction. To enable the ancillaries to have different rotational speeds, the different diameters of the driving and driven belt pulleys create a gear ratio.
Possible ancillaries which the belt drive drives include:
- Alternator (3)
- Coolant pump (1)
- Refrigerant compressor (4)
- Belt-driven starter alternator
Belt tension
The crankshaft rotates due to the sequence of the individual combustions in a non-uniform movement. These speed fluctuations are compensated for in the belt drive by a belt tensioner (2) and ensure that the tension in the poly-V-belt is constant. The belt tensioner (2) is flange-mounted directly on the alternator (3).
The compensating element generates the belt tension via a tensioner pulley mounted so that it can rotate and a spiral spring integrated in the belt tensioner (2).
Over the runtime of the engine, the poly-V-belts elongate due to their construction from composite fiber. In order to prevent the poly-V-belt from slipping, the belt tensioner (2) compensates for this elongation.