Timing Belt: Description and Operation

Camshaft and Balance Shaft Drives


Camshaft drive











The camshaft drive consists of a conventional single-toothed belt driving both camshafts and the oil pump.

The belt tension is controlled by a spring-loaded jockey pulley, while alignment is maintained by two idlers.


Balance shaft drive











Rotating in opposite directions, the two balance shafts are driven from the crankshaft by a double-toothed belt, the left-hand shaft by the inner and the right-hand shaft by the outer teeth.

A jockey pulley mounted eccentrically on the housing below the right-hand balance shaft is used to control the belt tension, the alignment of which is maintained by an idler. Since tensioning of the balance shaft belt is critical, the instructions contained in the workshop manuals should be followed exactly.

Overtensioning of the belt may damage the shaft housings, while insufficient tension may cause misalignment, leading to severe engine damage.