B61G3/00—Couplings comprising mating parts of similar shape or form which can be coupled without the use of any additional element or elements
B61G3/04—Couplings comprising mating parts of similar shape or form which can be coupled without the use of any additional element or elements with coupling head having a guard arm on one side and a knuckle with angularly-disposed nose and tail portions pivoted to the other side thereof, the nose of the knuckle being the coupling part, and means to lock the knuckle in coupling position, e.g. "A.A.R." or "Janney" type