Valve cotters, also known as valve keepers, collets or locks, have the task of attaching the spring retainer (or, alternatively, the valve rotator) to the valve. This ensures that the valve spring always holds the valve in the required position.

Federal-Mogul Powertrain has standardized valve cotters and is taking a leading role in the design of cotters. Cotters are either precision cold stamped or turned to guarantee uniform quality and interchangeability. Cold stamping is the process used for cotters utilized for valve stems up to 12 mm in diameter. All other cotters (13 mm and larger) are turned.

Specifications: 

Federal-Mogul Powertrain cotters are used on all types of engines. They are divided into two categories depending on their function:

• Clamping types, i.e. frictional connection between valve, cotter and spring
  retainer (rotation device)
• Non-clamping types, i.e. allowing free rotation of the valve
• KK, LK, NK, RK and SK types are clamping single groove cotters presenting different cone angles and heights to influence the clamping characteristics
• MK is a freely rotating multi-groove version with 3 or 4 beads depending on size; the MK halve cones touch each other allowing free turning of the valve stem