Abstract: A snap-closure coupling for flowing medium ducts has two halves one of which can be plugged into the other. The arrangement is such that the flow paths through both the plug half (which is connected to a medium source) and through the socket or sleeve half (which is connected to a reservoir, such as the applied brakes of a trailer) will be blocked when the plug half is pressureless and the sleeve half is pressurized. However, when the plug half is inserted into the sleeve half, the flow paths through both halves are automatically opened.

Abstract: A socket valve of a quick-coupling for fluid lines under pressure has a sliding sleeve into an end recess of which a portion of a plug valve of the coupling is insertable, to be held by locking means. The sleeve is movable between a securing position in which it holds the locking means in locking position, and two axially displaced release positions in which it permits the locking means to release the plug valve. The sleeve is spring-biased to the securing position. As an additional safety factor, the sleeve is surrounded by an annular chamber at least one open end of which receives an annular piston. The chamber is communicated with the pressure fluid in the valve so that, when the sleeve is in the securing position, the fluid pressure biases the piston to a position in which it prevents accidental uncoupling of the plug valve, even in the event the biasing spring for the sleeve should break.

Abstract: A quick-closure coupling for hydraulic lines in which two insertable coupling halves are lockable in a coupling position, and are constructed in the form of a plug valve and a sleeve valve, each having a closure piece. The closure piece is spring loaded in the closure direction, and held in a closed position when the coupling halves are separated. One of the coupling halves is provided with a stop which restricts a valve stroke of the closure piece in the opening position. The other coupling half has the closure piece loaded with a stronger spring and has a valve stroke equal to twice the opening stroke of the other closure piece. One of the coupling halves has a closure piece which can execute the opening stroke, and has a locking device which is ready to lock due to axial displacement of the closure piece beyond a single opening stroke.