The use of chains to drive camshafts in internal combustion engines has a long history. Nevertheless, timing chains are used increasingly in modern engines. The reason is that timing chain drives are very well suited to current and future requirements.
Timing chain drives are characterised by:
Depending on the application, chains with different pitches and types are used. Chain tensioning elements, which generally have hydraulic damping, ensure that the chain runs in a smooth and controlled manner despite irregular crankshaft rotation and varying drive moments of the camshaft(s). The tolerances in the engine and thermally induced geometrical changes are compensated by the tensioners, as are wear of the chain and elastic elongation due to high dynamic loads. The chains run on the slack side over tensioning and guide rails that must be matched to the requirements during the development phase by appropriate selection of material and geometry. Sprockets of different sizes and designs ensure the correct ratio and, if necessary, a change in the direction of rotation.