The screw coupling is mounted on a hinge on the opposite side of the knuckle coupler.
Exceptions are the new LHB coaches imported from Europe, and a few other makes of carriages converted to use knuckle couplers.
British locomotive-hauled passenger carriages adopted a dual coupling system in the 1950s.
They have retractable buffers and a central Buckeye automatic knuckle coupler that lowers to reveal a hook for a screw-type chain coupling.
Today this dual coupling system has been adopted for all loco-hauled passenger trains in Great Britain to allow faster shunting operations.