Gladhand connector
A gladhand connector on a trailer
A pair of gladhand connectors between railroad cars
A Gladhand coupler is an interlocking hose coupling fitted to hoses supplying pressurized air from a tractor unit to an air brakes on a semi-trailer, and a locomotive to railway air brakes on railroad cars. Mating rubber grommets provide a positive seal. Joined halves separate automatically when depressurized.
Gladhand connectors resemble a pair of "hands shaking" when interlocked, hence the name.