MCB, Buckeye, tightlock (in the UK), automatic couplers (in some Australian states) or centre buffer couplers.

Types

There are many variations of knuckle coupler in use today, and even more from the past. Some variants of knuckle couplers include:

Janney: the American original, a rather finicky coupler; reportedly annoying to make open and close. This design was obsolete by 1900.

MCB: In the latter 1880s the Master Car Builder's Association (MCB) were faced with