Pressure-actuated fluid-flow coupling between relatively rotating members

A rotary coupling for feeding a gaseous or liquid pressurized medium from a first to a second machine part, said first and second machine parts being rotatable with respect to each other comprising:

• at least one feed piston for said pressurized medium which is essentailly a spring supported hollow piston in said first machine part;
• a sliding shoe mounted between said feed piston and said second machine part;
• a mechanically driven check valve which opens in the feed direction in said feed piston;
• and
• at least one piston spring braced between said feed piston and said first machine part whose compression force is directed opposite to that force which is exerted by said pressurized medium on said feed piston.

A rotary coupling for the transfer of a fluid under pressure between two relatively moving parts, comprising:

• means on one of said parts forming a cylinder;
• a piston slidable in said cylinder and having one end receiving said fluid under pressure and another end turned toward the other of said parts, said piston being shiftable by the pressure of said fluid in the direction of said other of said parts;
• a piston spring braced against said piston and biasing same in a direction opposite that in which said piston is displaceable by said pressure of said fluid;
• a checkvalve in said piston opening to permit fluid flow in said direction in which the piston is displaceable by said fluid only upon the pressure of said fluid exceeding the pressure required to displace said piston against the force of said spring;
• and
• a pair of annular sealing surfaces provided between said other of said parts and said piston and urged one toward the other upon displacement of said piston against the force of said spring, the force of said spring being sufficient to effect separation of said sealing surfaces upon the pressure of said fluid falling below said required pressure.