Camshaft Timing Chain

Function

The timing chain, especially when new, guarantees the exact compliance with the valve timing. There is barely any play, because it is precisely led (see picture on top) from both sides. Even if it lenghtens minimally in the course of its operation, the chain tension adjuster, operated by the oil pressure, will compensate, and thereby avoid vibrations.

How it works

In earlier times it was common to use two-rowed (double role) chains. Nowadays, one row suffices. Sometimes both over head camshafts are driven by one single chain. More often, (see picture 2) two chains are used. These two, or more, may be put one after the other. Two hydraulic chain tension adjusters are necessary (see picture 3). This displays one of the advantages of the chain drive in comparison to the cambelt, with which this is not possible due to its sometimes special width.
The last example, too is not possible with a cambelt. A two-rowed chain is combined in such a way with two double driving wheels for the camshafts that their diameter is clearly larger than the distance between the driving wheels. The diameter of the wheel at the crankshaft might be larger, and thus more favorable. The chain may pass a larger arc, and there are more teeth involved.