GB2219946A - Shaft coupling for a snooker cue - Google Patents

Abstract

A shaft coupling for joining together two shaft portions in substantially rigid manner e.g. two shaft portions of a snooker cue comprises a male fitting (10) securable to a facing end (11) of shaft portion (12) and a female fitting (13) securable to a facing end (14) of the other shaft portion (15). The male fitting comprises a locator pin 16 and an eccentric 17 rotatable with the pin, and the female fitting comprises a socket for receiving the locator pin 16 and the eccentric 17 in a first relative angular arrangement of the male and female fittings. Upon relative rotation of the fittings to a second position, the fittings become rigidly coupled together by virtue of interengagement between an inner face 21 of a mouth 20 defining the entrance to recess 19 with a corresponding face 22 provided upon the eccentric 17. <IMAGE>

Description

SHAFT COUPLING This invention relates to a shaft coupling for joining together two shaft portions in substantially rigid manner.

The invention has been developed primarily, though not exclusively, in connection with a coupling for joining together two portions of a snooker, billiards or pool "cue", so that the two portions are held together in a rigid assembly in which the two portions are held against rotation one relative to the other.

The use of couplings to join together the two halves of a snooker cue is well known, so that the cue halves can be transported and/or stored more readily in dis-assembled form. One conventional design of coupling comprises a screw thread projecting from the facing end of one of the halves, and a threaded socket in the facing end of the other half, and the halves are then joined together by relative rotation of the two halves. However, in order to obtain a substantially rigid joint between the two halves, it is necessary for a substantial length of screw thread to be provided, with consequent requirement for a considerable number of turns to be made in order to assemble or disassemble the two halves.

Also, most players like to have continuity in the line of the "grain" on the surface of the two halves, but with the conventional coupling there is no clearly defined end position which signifies complete assembly, and over a period of time wear may occur on the mating faces of the two halves, so that additional rotation becomes necessary to complete the rigid assembly, and this will inevitably bring the grain lines out of axial alignment.

It is also known from US patent 4231574 to provide a quick connector for attaching a handle portion to the shaft portion of a billiard cue, in which the connector includes fittings carried by the ends of the handle and shaft portions. the fitting on the end of the handle portion comprising a cylindrical body .waving an eccentric shoulder and an elongated central stud on the outer end thereof.

The fitting on the end of the shaft portion comprises a cylindrical body having an elongated central bore and an eccentric counter bore on the outer end thereof. The end of the handle portion is initially loosely joined with the end of the shaft portion by inserting the elongated central stud into the elongated central bore and the eccentric shoulder into the eccentric counter bore. Then, by twisting the portions relative to each other for a fraction of a turn, the eccentric shoulder cams against the eccentric counter bore, thereby causing the central stud to frictionally engage the wall of the central bore.

In this known connector, the engagement between the eccentric shoulder cams and the wall of the eccentric counter bore is a frictional engagement acting in a direction counter to the direction of attempted separation of the handle and shaft portions, and therefore the rigidity of the joint is determined by the degree of frictional contact, acting along the axis of the cue, and which is the sole means for preventing axial separation of the handle and shaft portions of the cue.

The invention is concerned also with an eccentric-type coupling, but which operates more positively in order to resist separation of the two portions, while still providing a quick and yet rigid assembly.

According to the invention there is provided a shaft coupling for joining together two shaft portions in substantially rigid manner and comprising a male fitting securable to a facing end of one of the portions and a female fitting securable to a facing end of the other of the portions, the male fitting comprising a locator pin and an eccentric rotatable with the pin and the female fitting comprising a socket for receiving the locator pin and the eccentric in a first relative angular arrangement of the male and female fittings. and in which:: the socket comprises a passage fo receiving the locator pin in order to align the two shaft portions and a recess in which the eccentric can be received upon initial presentation of the male fitting to the female fitting in the first relative angular arrangement of the male and female fittings, the fittings being relatively rotatable to a second position in which the fittings are rigidly coupled together; and, a mouth defining the entrance to the recess as an inner face engagable with a corresponding face provided on the eccentric, upon relative rotation of the fittings to the second position, so as to draw the male and female fittings axially towards each other thereby to clamp the shaft portions rigidly to each other.

Thus, a shaft coupling according to the invention provides a simple and yet rigid assembly, and which has positive resistance to relative axial separation of the two shaft portions.

A shaft coupling according to the invention is particularly applicable for use in forming a joint between two portions of a snooker, billiard or pool cue, such as between a handle or butt portion and the main shaft portion.

The eccentric which is rotatable with the locator pin is preferably generally oval in shape, and the face provided on the eccentric is preferably an inclined surface provided on the face of the eccentric remote from the front face which first enters the recess upon presentation of the male and female fittings.

Conveniently, the inner face on the mouth of the recess is inclined at approximately 300 to a radial line extending outwardly from the general axis of the fittings, and the eccentric is able to enter through the mouth of the recess when the fittings are in the first relative angular arrangement, and as the fittings relatively rotate towards the second position, the engaging faces of the eccentric and the mouth of the recess cone into progress.vely increasing engagement and with a progressively increasing relative axial movement towards each other, in order to bring the two shaft portions into rigid face-to-face contact. The coupling therefore provides a very rigid assembly which is both axially and rotationally secure upon relative rotation of the fittings to the second position.

The eccentric and the mouth of the recess at least are preferably made of metal, so that there will be very little wear occuring in use, thereby giving prolonged working life for the coupling.

One embodiment of shaft coupling according to the invention will now be described in detail, by way of example only, with reference to the accompany drawing, in which: Figure 1 is an exploded view of two shaft portions, prior to coupling together; Figure 2 is a perspective and schematic illustration of the two shaft portions after coupling together; Figure 3 is an exploded sectional view of male and female fittings of the shaft coupling; and, Figure 4 is a sectional view of the male and female fittings in the fully coupled position.

Referring now to the drawing, there is shown an embodiment of shaft coupling for joining together two shaft portions in substantially rigid manner, and in the illustrated arrangement comprises a coupling for joining together two shaft portions of a snooker, billiard or pool cue.

The shaft coupling comprises a male fitting 10 securable to a facing end 11 of shaft portion 12 and a female fitting 13 securable to a facing end 14 of the other shaft portion 15. The male fitting 10 comprises a locator pin 16 and an eccentric 17 rotatable with the pin and the female fitting 13 comprises a socket for receiving the locator pin 16 and the eccentric 17 in a first relative angular arrangement of the male and female fittings.

The socket in the female fitting is formed with a passage 18 for receiving the locator pin 16 in order to align the shaft portions 12 and 15 and a recess 19 (see Figure 3) in which the eccentric 17 can be received upon initial presentation of the male fitting 10 to the female fitting 13 in the first relative angular arrangement of the fittings. Thereafter, the fitting are relatively rotatable to a second position in which the fittings become rigidly coupled together, both against axial separation, and also against relative rotation.

The entrance to the recess 19 is defined by a mouth 20 having a bevelled inner face 21 (see Figure 3) which is engagable with a corresponding face 22 provided on the remote face of the eccentric 17 whereby, upon relative rotation of the fitting to the second position, the faces 21 and 22 gradually come into cooperation with each other and thereby draw the male and female fittings axially towards each other in order to clamp the shaft portions rigidly to each other.

Thus, the engagement of the locator pin 16 in passage 18 accurately aligns the shaft portions 15 and 12 axially, and as the eccentric 17 is relatively rotated, effectively it creates an increasing wedging action, as the faces 20 and 22 come into progressively greater contact, and this then draws the male and female fittings towards each other, and therefore also the facing ends 11 and 14 of the shaft portions into firm abuttment.

The male and female fittings are formed of suitable metal material, and particularly in relation to the faces 20 and 22, they are able to withstand repeated action without undue ware.

The preferred angle of the faces 21 and 22 is preferably of the order of 300 to a radial plane.

For certain applications, it will be possible for the male and/or female fittings to be made of suitable rigid plastics material, such as nylon.

Claims (6)

1. A shaft coupling for joining together two shaft portions in substantially rigid manner and comprising a male fitting securable to a facing end of one of the portions and a female fitting securable to a facing end of the other of the portions, the male fitting comprising a locator pin and an eccentric rotatable with the pin and the female fitting comprising a socket for receiving the locator pin and the eccentric in a first relative angular arrangement of the male and female fittings, and in which:: the socket comprises a passage for receiving the locator pin in order to align the two shaft portions and a recess in which the eccentric can be received upon initial presentation of the male fitting to the female fitting in the first relative angular arrangement of the male and female fittings, the fittings being relatively rotatable to a second position in which the fittings are rigidly coupled together; and, a mouth defining-the entrance to the recess has an inner face engagable with a corresponding face provided on the eccentric. upon relative rotation of the fittings to the second position, so as to draw the male and female fittings axially towards each other thereby to clamp the shaft portions rigidly to each other.

2. A shaft coupling according to Claim 1. in which the eccentric is generally oval in shape, and the face provided on the eccentric is an inclined surface provided on the face of the eccentric remote from the front face which first enters the recess upon presentation of the male and female fittings.

3. A shaft coupling according to Claim 1 or 2. in which the inner face on the mouth of the recess is inclined at approximately 300 to a radial line extending outwardly from the general axis of the fittings, whereby the eccentric is able to enter through the mouth of the recess when the fittings are in the first relative angular arrangement. and as the fittings relatively rotate towards the second position, the engaging faces of the eccentric and the mouth of the recess come into progressively increasing engagement and with a progressively increasing relative axial movement towards each other, in order to bring the two shaft portions into rigid face-to-face contact.

4. A shaft coupling according to any one of Claims 1 to 3, in which the eccentric and the mouth of the recess are made of metal.

5. A shaft coupling according to any one of Claims 1 to 4, and incorporated between two portions of a snooker, billiard or pool cue.

6. A shaft coupling according to Claim 1 and substantially as hereinbefore described with reference to, and as shown in the accompanying drawing.