Tube couplings

A tube coupling comprising a coupling body having a throughway open at one end to receive a tube, an end cap in screw-threaded engagement with the coupling body to move between initial and advanced positions along the coupling body and having an opening for the tube and an internal cam surface tapering towards the tube opening, a collet in the end cap engaging the cam surface to lock a tube in the cap with movement of the collet outwardly of the cap and to release the tube when depressed inwardly of the cap, and stop means in the coupling body to limit movement of the collet inwardly of the end cap, the initial position of the end cap on the coupling body allowing a tube to be inserted and locked in the end cap by the collet and to be released by depressing the collet inwardly of the cap and the advanced position of the end cap holding the collet adjacent the stop means in the coupling body to prevent release of the tube;

• characterised in that detent means are provided acting between the cap and coupling body to provide resistance to movement of the cap along the coupling body until the cap reaches said initial position on the coupling body and to allow said further movement of the cap to the advanced position.