US Patent 10107435 Coupling

A coupling includes an engagement face included in an engagement hook which is set at an angle in a range where the engagement face is still inclined at a positive angle, which is maintained when the coupling and a counterpart coupling are in a coupling state, even if a fluid leaks as a result of opening a sealing portion of the couplings, at a state where the coupling state is maintained, or even if a hose or the like fitted to the coupling bursts when high pressure is applied to the coupling, the hose, etc., while in use.