This invention relates to screw-coupled connectors. It relates particularly to the kind of connector that might be used for applications such as tube connectors, electrical or fibre-optical connectors and where the two halves of a connector fitting are joined by a screw-threaded member.

When the two parts of a screw-coupled connector are to be joined together, it is necessary that* they should be fully engaged together and correctly mated. Under conditions of restricted space or where there are high ambient noise levels, it may be difficult in practice to check that a full engagement has in fact taken place. It would be convenient if the connector could include an indicator that would be able to show when the full engagement state had been reached.

The present invention was devised to provide a solution to this problem.

According to the invention, there is provided a screw-coupled connector comprising two coupling parts which are capable of being secured together by the rotation of an internally screw-threaded nut carried on one of the parts, in which the said one part includes a sleeve which is

^~ ~ rotatable independently of the nut, the sieve carrying a plunger which is capable of being moved axially under

spring pressure in order to enter a hole on the nut when the sleeve and nut are suitably aligned, the said plunger when in the hole serving to hold a ball against axial movement along an inclined plane located on a friction ring, the friction ring also serving as a surface against which the said, other: part of the coupling is to be located when the two: parts; are mated.

The rrrcrXinced plane of the friction ring may have an upper ball support position where the ball has been moved axially to push the said plunger out of the hole on the nut, such that the sleeve is disengaged from driving the nut. The inclined plane may have a drive face adjacent a lower ball support position whereby movement of the sleeve in a suitable direction will hold the ball against said face and prevent any- axial movement of the ball.

Preferably, the hole in the nut carries a chamfer on one side thereof, such that the plunger will tend to leave the hole- more easily when the sleeve is rotated in one direction than otherwise. The sleeve may carry a spring cap arranged to permit adjustment when necessary of the spring force applied to the plunger.

By. way of example, a particular embodiment of the invention will now be described with reference to the accompanying drawing, in which:

Figure 1 shows in part an axial cross-sectional view of the screw-coupled connector.

Figure 2 is a detail of the nut showing the hole with chamfer on the nut, and.

Figure 3 shows part of the friction ring and the profile of the inclined plane.

As shown in the drawing, the screw-coupled connector comprises a first connector part 1 which is capable of being coupled to a second connector part 2 by means of an internally screw-threaded nut 3 carried on the second part 2.

The first, connector part 1 may in fact be a suitable connector body part or alternatively a flanged shaft or tube which is required to be mated with the second part 2.

-The second connector part 2 is provided with a body 4 which supports the nut 3 and also a sleeve 6. A rear circlip 5 on the body secures the nut 3 and sleeve 6 in place but permits separate rotation of these parts about the body.

The nut 3 includes an internal screw thread portion 7 which is capable of engaging external threads on the first part 1 when the coupling action is being effected.

Mounted for axial movement on the sleeve 6, is a plunger 8 which is movable by a spring 9 that is supported against a spring cap 11. Since the sleeve 6 can be rotated about the nut 3 when these parts are suitably aligned, the plunger 8 can be caused to enter a hole 12 in the nut. In this position, the plunger 8 can displace a spacer 13 which

bears against a ball 14.

The ball 14 is thus spring loaded up against a friction ring 16 which is located between the nut 3 and the first connector part 1. The friction ring 16 is provided with an inclined plane 17 (Figure 3) and this plane has a drive face 18 at one end and an upper ball support position 19 at the other end. The ball is thus capable of resting in either of two a ially-displaced positions on the plane according to whether the ball is located at the drive face 18 or the support position 19.

In operation of the connector, when it is required to couple the second connector part 2 to the first part 1, the sleeve 6 is rotated clockwise so that the internal thread portion 7 on the nut 3 will engage the thread's on the first part 1. Further rotation of the sleeve 6 tightens the connection and the flange on the first part 1 eventually presses the friction ring 16 against the surface of the nut 3. When enough pressure has been applied to the friction ring 16 this is eventually stopped from further rotation whilst the nut 3 is still able to be moved a short radial distance with respect to the ring 16.

This further movement of the nut 3 causes the ball 14 to be carried up the inclined plane 17 and the ball comes to rest in the upper ball support position 19. The axial movement which the ball 14 experiences in being moved up the

plane causes the ball to push the spacer 13 and the plunger 8 to the right as shown in Figure 1. Eventually the plunger 8, is pushed out of the hole 12 (via a chamfer 21 located at one side of the hole) on the nut and there is then no remaining connection permitting a drive to take place between the sleeve 6 and the nut 3. Consequently, the sleeve 6 becomes freely rotatable and any further movement of the sleeve 6 in a clockwise direction will have no driving action on the nut 3.

The sudden change to a freely rotatable action of the sleeve which becomes apparent upon fastening the connector is a clear indication that the parts of the connector have been fully engaged and correctly mated.

Further rotation of the sleeve 6 in a clockwise direction has no additional effect on the connector.

In order to separate the two parts of the connector, the sleeve 6 is rotated in an anticlockwise direction. This causes the plunger 8 to pass across the end of the hole 12 and strike against the wall of the hole at a side opposite to that which carries the chamfer 21. This action permits a small amount of torque to be applied to the nut 3 and the ball 14 is moved from the upper ball support position 19 down the inclined plane 17 to the drive face 18. The resulting axial movement permitted to the ball allows the plunger 8 to enter the hole 12 and the full torque

can then be applied to the nut 3. Rotation of the nut 3 by the sleeve 6 allows the screw-thread portion 7 to release the threads on the first part 1 so the two parts can be separated.

The foregoing description of an embodiment of the invention has been given by way of example only and a number of modifications may be made without departing from the scope of the invention as defined in the appended claims. For instance, it is not essential that the sleeve 6 should use only a single plunger to apply the driving force to the nut 3, in a different embodiment an alternative number of plungers such as two or three could be used.