Patent ID: 7731240

Claim:
A pipe coupling for joining together the ends of two adjacent pipes, the coupling including a body portion having opposite open ends each adapted to receive a respective end cap, said body portion defining a generally central bore along a central axis of the coupling for receiving the ends of the two adjacent pipes in respective open ends of the bore, and a locking arrangement for locking each pipe to the coupling, wherein each pipe is to be inserted into a respective open end of the bore in an axial inward direction and removed from that open end of the bore in an axial outward direction, each locking arrangement including: an annular chamber; an inlet for allowing fluid into the chamber; an annular seal which is arranged to move within the annular chamber axially of the coupling; a plurality of grippers which are disposed adjacent respective open ends of the bore and radially moveable towards the central axis of the coupling from an inoperative condition to an operative condition, each gripper including a gripping formation arranged, in the operative condition of the gripper, for operatively gripping a pipe inserted into the bore of the body portion, and for releasing the pipe in the inoperative condition of the gripper, and a locking formation including a radially inwardly open recessed area in the gripper into which a radially outwardly projecting portion of the body portion extends, the recessed area including an axially outwardly facing surface facing toward the respective open end of the bore and arranged to move generally radially toward the central axis into axially facing locking relationship with an axially inwardly facing surface of the projecting portion of the body portion, in the operative condition of the gripper, to axially lock the gripper to the body portion wherein the body portion opposes forces tending to pull the gripper from the respective open end of the bore, and to move generally radially away from the central axis out of said axially facing locking relationship in the inoperative condition of the gripper; and at least one locking element between the annular seal and the grippers for locking the grippers to the body portion and to a pipe end within the body portion, the or each locking element including a sloping inner surface which is engageable with a corresponding sloping outer surface on at least one of the grippers so that axial displacement of the at least one locking element under fluid pressure within the annular chamber causes radial displacement of the grippers into the operative condition, axially locking the grippers to the body portion and clamping the pipe end within the body portion.