All MER power cars are equipped with Hughes patent couplers, invented by Mr Albert Hughes of G.F.Milnes and Co., Birkenhead. It was originally designed and used for steam tramway practice. The primitive but highly effective and reliable coupler gear features a pendulum lock which engages the coupler bar when it is pushed into the mouth of the coupler. Because coupler heights vary between the various batches of power and trailer cars (even on brand new wheels with their full diameter) it is common to marry only certain cars to certain trailers. Even then, the use of specially cranked coupler bars is needed. All Trailer Cars are fitted with an unusual emergency brake, operated by a chain attached to a fixed point on the Power Car. In the event of a breakaway, the chain is designed to apply the brake rigging on the trailer (and which is held on by a ratchet lock) and then part at a specially annealed 'weak link' which ensures the car's rigging incurs no damage.
1894 Tunnel Car 9 is paired to 1930 built English Electric Trailer 44. The chain which operates the trailer brakes in the event of a breakaway can be clearly seen. (Photo: MERS Collection)
