A coupling comprises a pair of clutch end members, a clutch centre member disposed between the clutch end members, and an actuator coupled to one of the end members. Each end member includes concentric V-grooves disposed on a respective face thereof. The centre member is axially movable between the end members, and includes a pair of opposing surfaces. One of the opposing surfaces includes concentric V-grooves configured to mesh with the V-grooves of one of the end members. Another of the opposing surfaces includes concentric V-grooves configured to mesh with the V-grooves of another of the end members. The actuator is configured to couple the end members and the centre member together by urging the V-grooves of the end members into engagement with the V-grooves of the centre member.