Valve cotters have the task of attaching the valve spring retainer to the valve, so that the valve spring always holds the valve in the required position.

While turned cotters were used earlier, cold formed cotters are state of the art today for valve stem diameters up to 12,7 mm (1/2 in.).

TRW has standardised valve cotters, to limit the number of types. The precise forming method guarantees uniform quality and ensures interchangeability.

Valve cotters are sub-divided into two groups, according to their function:

• Clamping types, where the frictio nal connection between valve, cotter and spring retainer
  is obtained in any operating situation.
   
• The non-clamping types, which allow free rotation of valve.

When replacing the valves, it is essential to use new cotters as well!