Coupling for a hydraulic or pneumatic assembly

1. A coupling for a hydraulic or pneumatic assembly comprising:

a housing having a bore;

a female coupler movable within the bore between an operating position whereat, when a male coupler is coupled thereto, the male coupler is retained in the female coupler, a release position whereat the male coupler can be released from the female coupler, and a coupling position whereat the male coupler can be coupled to the female coupler;

a pressure relief valve that includes a plunger movable from a closed position to an open position respectively blocking and permitting release of pressurized fluid from a flow passage inside the female coupler;

a cam member movable to initially move the valve plunger from its closed position to its open position and then to move the female coupler from its operating position to its release position, thereby allowing the pressure relief valve to release pressurized fluid from the flow passage of the female coupler prior to removal of the male coupler; and

a stop member for moving the plunger from its closed position to its open position when the female coupler is moved to its coupling position, thereby allowing the pressure relief valve to release pressurized fluid from the flow passage of the female coupler prior to coupling of the male coupler;

wherein the cam member can move away from the plunger when the female coupler is in its coupling position and the plunger is held in its open position by the stop member.

2. A coupler as set forth in claim 1 , wherein the stop member is movable relative to the housing.

3. A coupler as set forth in claim 1 , wherein the stop member is movable with the cam member.

4. A coupler as set forth in claim 1 , wherein locking members lock the female coupler to the housing when the female coupler is in the operating position.

5. A coupler as set forth in claim 1 , wherein the housing includes a sump chamber and wherein the flow passage in the female coupler communicates with the sump chamber when the plunger is in the open position.

6. A coupler as set forth in claim 1 , wherein the stop member includes a surface which pushes the plunger to the open position and wherein this surface includes an opening for the fluid released from the flow passage in the female coupler to pass therethrough.

7. A coupler as set forth in claim 1 , further comprising another bore in the housing, another female coupler, another pressure relief valve, another cam member, and another stop member.

8. A coupler as set forth in claim 7 , wherein the cam members are movable by a lever.

9. A coupler as set forth in claim 7 , wherein the lever can only move one female coupler from the operating position to the release position at a time.

10. A coupler as set forth in claim 7 , wherein the lever comprises a rod pivotal about a pivot point and wherein the cam members are carried by the rod on opposite sides of the pivot point.

11. A female coupler assembly wherein a cam member can move away from a pressure relief valve plunger when a female coupler is in a coupling position and the plunger is held in an open position by a stop member, wherein the stop member is positioned relative to the plunger so that, regardless of the position of the cam member, the stop member will engage the plunger when the female coupler is in the coupling position.

12. A female coupler assembly as set forth in claim 11 , wherein the stop member is movable relative to the housing.

13. A female coupler assembly as set forth in claim 11 , wherein the stop member is movable with the cam member.

14. A female coupler assembly as set forth in claim 11 , wherein locking members lock the female coupler to a housing when the female coupler is in the operating position.

15. A female coupler assembly as set forth in claim 11 , wherein the stop member includes a surface which pushes the plunger to the open position and wherein this surface includes an opening for the fluid released from the flow passage in the female coupler to pass therethrough.