Golf clubs having telescopic shafts are known An adjustable shaft for a golf club is disclosed in UK application number 0103671. 4. This application discloses a golf club shaft which can be extended from an undamped to a clamped position. The clamping force is applied by rotation of a screw which is in turn rotated by means of a locking key. The locking key can be removed before the clamping force is fully applied This can make the golf club unsafe during use.

The present invention seeks to overcome the above disadvantage of the prior art.

According to the present invention there is provided a key locking mechanism for the shaft of a golf club, the key locking mechanism comprising an inner body extending along a long axis between proximate and distal ends, the distal end being engaged with a loading device, the proximate end being adapted to receive a key, the inner body being free to rotate about the long axis in response to the turning of the key; an outer body slideably engaged within a recess of the golf club shaft, the outer body being free to be displaced in the direction of the long axis; the inner and outer bodies being interengaged by means of a camming surface and cam follower so as to convert rotational motion of the inner body about the long axis to linear displacement of the outer body along the long axis; the locking mechanism further comprising a locking member arranged to be urged into engagement with the key by the outer body on sliding of the outer body along the long axis in response to turning of the key.

The key can only be removed from such a key locking mechanism after a predetermined number of turns. This has the advantage that the key can only be removed once the golf club shaft is fully clamped.

Preferably, the inner body is cylindrical. The outer body can be tubular, the inner and outer bodies being co- axial.

The outer body can comprise a groove for receiving a protrusion extending from the recess. This provides a simple method of ensuring the outer body is free to be slideably displaced along the length of the inner body but cannot rotate with it.

The camming surface can be helical. This ensures the displacement of the outer body is smooth when the inner body is rotated.

The camming surface and cam follower can be interengaged helical threads. Such threaded surfaces are simple to manufacture and provide a reliable method of converting rotational motion into linear motion. The inner body can comprise an axial bore for receiving the key.

The inner body can comprise at least one radial bore extending from the axial bore to an outer surface of the inner body, the locking member being receiving within the radial bore, the locking member being longer than the length of the bore such that the locking member will protrude from one end of the radial bore.

The locking member can be spherical having a diameter larger than the length of the radial bore.

The radial bore can taper inwardly toward the axial bore so urging the locking member outwardly to a position extending beyond the outer surface of the inner body.

Preferably the inner surface of the outer body comprises a locking surface in close cooperation with the outer surface of the inner body and an unlocking surface separated from the outer surface of the inner body.

The key locking member can further comprise the key, the key having a recess for receiving the locking member.

The present invention will now be described by way of example only, and not in any limitative sense with reference to the accompanying drawings in which Figure 1A shows a cross section of the key locking mechanism according to the invention with the key free to be removed; Figure 1B shows a cross section of the same locking mechanism with the key captive.

Shown in Figure 1A is the grip end of a collapsible shaft of a golf club A recess 1 extends from the end of the golf club along its length. Positioned within the recess 1 is a locking mechanism according to the invention. The locking mechanism comprises an inner body 2 having proximate and distal ends 3,4. Attached to the distal end 4 is a loading device 5 which is responsible for converting the rotation of the inner body 2 into a clamping force, clamping the shaft to the extended position.

The proximate end 3 of the inner body 2 is adapted to receive a key 6. In this embodiment the inner body 2 is cylindrical and a circular axial bore 7 extends from the proximate end 3 towards the distal end 4 along the length of the inner body 2 for receiving the key 6. The inner body 2 is free to rotate about the long axis in response to the turning of the key 6.

A portion of the outer surface 8 of the inner body 2 comprises a helical thread 9 located between the proximate and distal ends 3,4 of the inner body 2. There are a plurality of radial bores 10 extending from the axial bore 7 to the outer surface 8 of the inner body 2.

Each radial bore 10 is slightly tapered, the diameter of the radial bore 10 decreasing towards the axial bore 7.

Positioned within each radial bore 10 is a spherical locking member 11. The diameter of the locking member 11 is slightly larger than the length of the radial bore 10, so ensuring that the locking member 11 always protrudes from one end of the radial bore 10. The slight taper of the radial bore 10 ensures that in the unperturbed position the locking member 11 rests extending from the outer surface 8 of the inner body 2.

Engaged with the inner body 2 is an outer body 12. The outer body 12 has a threaded portion 13 on its inner surface 14 which is inter-engaged with the threaded portion 9 of the inner body 2. A groove 15 extends along the length of the outer surface 16 of the outer body 12.

This groove 15 receives a protrusion 17 extending from the recess 1 so ensuring the outer body 12 is not free to rotate about the long axis with the inner body 2. The outer body 12 can however slide along the length of the long axis.

The inner surface 14 of the outer body 12 comprises locking and unlocking portions 18,19. The locking portion 18 closely cooperates with the outer surface 8 of the inner body 2. In contrast, there is a slight gap between the unlocking portion 19 of the outer body 12 and the inner body 2.

In Figure 1A the locking mechanism is shown in an unlocked configuration with the key 6 being free to be inserted or removed from the axial bore 7. In use the key 6 is inserted into the axial bore 7 until a recess 20 in the key 6 is adjacent to the radial bore 10. The key 6 is turned so turning the inner body 2. The threads on the inner and outer bodies 2, 12 act as a cam surface and cam follower converting the rotational motion of the inner body 2 into linear motion of the outer body 12 toward the distal end 4 of the inner body 2 In the unlocking position the spherical locking member 11 is positioned such that it extends beyond the outer end of the radial bore 10. It does not extend into the axial bore 7 as shown. Since the unlocking portion of the outer body 12 overlies the radial bore 10, the locking member 11 is free to extend in this way.

As rotation of the inner body 2 continues the outer body 12 will be displaced until the locking portion 18 of the inner surface overlies the radial bore 10. This urges the locking member 11 inwardly so that a portion of it extends beyond the radial bore 10 and into the axial bore 7 as shown in Figure 1B. The key 6 can now not be removed. In order to remove the key 6 the inner body 2 must be rotated in the opposite direction until the unlocking portion 19 of the outer body 12 again overlies the radial bore 10.

In this embodiment the outer body 12 is cylindrical lying co-axially with the inner body 2. In an alternative embodiment the outer body 12 can be semi-circular.

In an alternative embodiment of the invention the inner body 2 comprises only one radial bore 10.

In a further alternative embodiment of the invention the locking member is frustoconical or cylindrical.

In a further alternative embodiment, the radial bore can be stepped in diameter