Abstract: An automatically locking bayonet coupling mechanism includes, a linear guide structure for preventing relative rotation between the coupler halves, a sleeve rotatably mounted on one of the coupler halves, a spring captured between the sleeve and the coupler half on which it is mounted to generate a torsional force between the sleeve and the coupler half, an L-shaped groove in the other of the coupler halves, and a bayonet pin extending from the sleeve and arranged to engage cam surfaces defined by edges of the groove. As the coupler halves are pushed together linearly, engagement between the bayonet pin and a first of the cam surfaces causes the sleeve to rotate against the force of the spring. Subsequently, the bayonet pin is caused to engage a second of the cam surfaces that forms a locking ramp.