Many rapid transit lines in this country use a coupler with similar operation. Key System, for example, used Tomlinson couplers with button contact electrical circuits underneath. Air brake lines also were incorporated in the coupler. Cars could be coupled and uncoupled without having to deal with control system electrical jumpers or air brake hoses. Cars could be uncoupled by pushing a botton in the cab without having a man on the ground. After cars were coupled, a botton in the cab would turn on control system circuits and open valves in air brake pipes.

Tomlinson couplers are tight-lock preventing any problems with slack action in trains.