GB2063991A - A Releasable Coupling - Google Patents

Abstract

A releasable coupling comprising first and second members 10, 23 to be arranged coaxially, the first member carrying detent balls 14 and the second member having a surface portion engageable with the balls. The surface portion preferably includes a groove 24 and a number of dimples 25 corresponding to the number of balls. The detent balls are releasable by means of a sleeve 15 which is slidable on the first member and which has an internal shoulder 16 thereon for cooperation with the balls. In the embodiments described the member 10 is a housing for a drive output shaft 30 and member 23 a stationary cover for a driven shaft. Fastening the members together fastens the shafts together and drive is transmitted via the engagement of drive pin 30a in slots 33a. <IMAGE>

Description

SPECIFICATION A Releasable Coupling The invention relates to a releasable coupling and is particularly, but not exclusively, concerned with a coupling which will enable a driving member to be held in driving engagement with a driven member.

According to the invention there is provided a coupling comprising first and second members to be arranged generally coaxially, the first member having detent means thereon and the second member having a surface portion engageable with the detent means, said detent means being releasable by means of a releasing member and being co-operable with said surface portion so as to locate the first and second members in predetermined relative axial and rotational positions.

The first member is preferably tubular and the detent means is housed in the wall of the tube.

The detent means is preferably located in a radial aperture in the tube.

Preferably, the first and second members are of circular cross section and the said surface portion includes a groove in the second member which locates the members in the said relative axial positions. In such a case, the groove may be formed with a dimple or other formation which receives the detent means so as to locate the members in the said relative rotational positions.

The second member may be tubular and positioned within the first member. Preferably, the first member defines a housing for a first rotary shaft and the second member defines a housing for a second rotary shaft, the first and second rotary shafts having coupling means thereon which are brought into operative engagement to enable drive to be transmitted from one shaft to the other when the first and second members are located by said detent means. In such a case, the shafts preferably extend with working clearance through the tubular first and second members.

We find that such an arrangement is particularly useful in connecting an attachment such as a pump, a sheep shear hand set or a sheep shear blade grinder to a power unit.

The detent releasing member is preferably an axially slidable sleeve on the first member which in one axial position urges the detent means into engagement with said surface portion of the second member, and in another axial position allows the detent means to disengage the surface portion to enable the first and second members to be separated. The sleeve preferably includes an internal frusto conical shoulder which acts as a cam to urge the detent means towards the surface portion of the second member. Preferably, the sleeve is urged normally towards the nonrelease position by resilient means.

A releasable coupling in accordance with the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a longitudinal cross-section through a preferred form of coupling showing the first and second members interconnected, Figure 2 is a view similar to Figure 1 but showing the detent means released and the first and second members partially separated, Figures 3 and 4 are cross-sections of the coupling shown in Figures 1 and 2 on the lines Ill-Ill and tV-IV respectively, Figure 5 is a view of the coupling of Figure 1 drawn to a smaller scale and connecting part of a sheep shear hand set attachment to a power unit, Figure 6 is a view similar to Figure 5 but showing the coupling connecting a grinding attachment to the power unit and Figure 7 is a view similar to Figures 5 and 6 but showing the coupling connecting a pump to the power unit.

Referring firstly to Figures 1 to 4, a first tubular member 10 has three radial through bores 12 each of which has a shoulder 13 at its radially inner end. Each bore 12 houses a ball bearing 14 (constituting the aforesaid detent means) which is held captive therein by the shoulder 13 and by an axially slidable sleeve 1 5 on the member 10.

Instead of balls it is envisaged that a plunger arrangement could be used. The sleeve 1 5 has a frusto conical shoulder 1 6 around its inner periphery and a releasing recess 17 is defined between the left hand side of shoulder 16 as viewed in Figure 1 and a further shoulder 18 on the sleeve. A spring 19 extends between the right hand side of shoulder 1 6 and an annular surface 20 on the member 10. The spring 19 urges the sleeve normally to the left so that the shoulder 1 8 abuts a stop 22 on the member 10. In that position, the frusto conical surface of shoulder 1 6 engages the balls 14.

A second tubular member 23 fits coaxially within the member 10 with working clearance and is formed with a circumferential groove 24.

With the sleeve 1 5 moved to the right, the member 23 can initially be located in the member 10 so that the balls occupy the Figure 2 position.

The sleeve is then released and the member 23 moved further into the member 10 until the balls 14 move into the groove 24 under the influence of the sleeve 1 5. Axial separation of the members 10, 23 is thereby prevented. Alternatively the sleeve 1 5 can be held back until one or more balls locate in the groove 24 and the sleeve can then be released. The bottom surface of the groove is formed with three dimples 25 (see Figure 3).

Once the balls 14 are located in the groove 24, the members 10, 23 can be rotated relative to each other until the balls move into the dimples thus preventing further relative rotation. The balls 14 are urged radially inwardly by the frusto conical surface of shoulder 16 which acts as a cam under the influence of spring 1 9. The frusto conical surface normally prevents the balls 14 leaving the dimples 25 so the assembled members 10, 23 are unable to separate or twist relative to each other.

To separate the members 10, 23 the sleeve 1 5 is urged to the right against the spring 1 9 into the position shown in Figure 2. In that position, the balls 14 are able to move out of the groove 24 and partly into the releasing recess 17 so that the member 23 can be withdrawn.

The coupling has been found particularly useful for connecting a sheep shearing hand set or a grinder to a power unit.

As shown in Figure 5 the first member 10 forms part of a housing for a drive output shaft 30 of a power unit P. In Figure 5, the first member 23 forms part of a stationary cover 32 for a driven shaft 33 connected to universal joint 34. The universal joint transmits drive to one end of a flexible shaft (not shown) connected at its opposite end to a sheep shear hand set (also not shown). The shaft carries a driving pin 30a which locates in diametrically opposed slots 33a in a tubular extension of shaft 33. The shafts are rotatable with working clearance within the tubular member 23. To connect shaft 30 to shaft 33, the member 23 is inserted in the member 10 with the sleeve 1 5 in the Figure 2 position so that the driving pin 30a enters the slots 33a to enable drive to be transmitted to shaft 33.The sleeve 1 5 is then released so as to fix the members 10, 23 in position as described above. It will be evident that the coupling prevents axial separation of the shafts 30, 33.

The arrangement shown in Figure 6 is somewhat similar except that the member 23 forms part of a housing 31 for a driven shaft 35 connected to a circular grinding plate 36. The shaft 35 has a tubular portion formed with slots 35a which receive the driving pin 30a. The plate 36 is used for grinding sheep shear blades or combs in known manner. With the Figure 6 arrangement, the free end of tubular member 10 abuts a shoulder 37 on the member 23 before the groove 24 becomes exactly aligned with the balls 14. Therefore, the radially inward force applied to the balls 14 by the frusto conical surface of shoulder 1 6 tends to urge the balls against the right hand side of the groove which in turn applies an axial force on the member 23. The latter force tends to urge the member 23 towards the right.

With such an arrangement, the grinder housing and power unit are secured firmly together. The grinder has a column 38 for supporting an arm 39 on which the blade to be ground is mounted. The positioning of the dimples 25 is arranged so that the column can easily be positioned vertically for use. After inserting the member inside the member 10 with the column 38 substantially vertical, the sleeve 1 5 is released so that the balls 14 seat in the groove 24. The grinder housing is then rotated slightly towards the vertical until the balls snap into the dimples 25 to fix the grinder with the column 38 vertical.

Hitherto, sheep shearing sets and grinders have either been made separately, each with its own individual power unit, or have been combined in a single unit. In the former case, individual powered units are expensive and with the latter arrangement a complex gearing arrangement is necessary for providing drive.

However, the coupling of the invention enables a single power unit to be used for driving attachments and is highly advantageous in that respect.

Instead of connecting sheep shearing or grinding apparatus to the power unit P, the coupling can be used to connect a pump to the power unit. In Figure 7, a pump 40 has a connecting flange 41 secured to a flange 42 on one end of a sleeve 23. The pump has a drive spindle 43 connected to a slotted driven member 44 which is driven by the driving pin 30a on a driving shaft 30 as in Figures 6 and 7. The sleeve 1 5 cooperates with the balls 14 as before to hqld the sleeve 23 in position within member 10.

Claims (14)

Claims

1. A coupling comprising first and second members to be arranged generally coaxially, the first member having detent means thereon and the second member having a surface portion engageable with the detent means, said detent means being releasable by means of a releasing member and being co-operable with said surface portion so as to locate the first and second members in predetermined relative axial and rotational positions.

2. A coupling according to Claim 1, in which the first member is tubular and the detent means is housed in the wall of the tube.

3. A coupling according to Claim 2, in which the detent means is located in a radial aperture in the tube.

4. A coupling according to Claim 2 or 3, in which the first and second members are of circular cross section and the said surface portion includes a groove in the second member which locates the members in the said relative axial positions.

5. A coupling according to Claim 4, in which the groove is formed with a dimple or other formation which receives the detent means so as to locate the members in the said relative rotational positions.

6. A coupling according to any of Claims 2 to 5, in which the second member is tubular and is arranged within the first member.

7. A coupling according to Claim 6, in which the first member defines a housing for a first rotary shaft and the second member defines a housing for a second rotary shaft, the first and second rotary shafts having coupling.means thereon which are brought into operative engagement to enable drive to be transmitted from one shaft to the other when the first and second members are located by said detent means.

8. A coupling according to Claim 7, in which the shafts extend with working clearance through the tubular first and second members.

9. A coupling according to any preceding claim, in which the detent releasing member is an axially slidable sleeve on the first member which in one axial position urges the detent means into engagement with said surface portion of the second member, and in another axial position enables the detent means to disengage the surface portion to enable the first and second members to be separated.

10. A coupling according to Claim 9 in which the sleeve includes an internal frusto conical shoulder which acts as a cam to urge the detent means towards the surface portion of the second member.

11. A coupling according to Claim 9 or 10, in which the sleeve is urged normally towards the non-release position by resilient means.

12. A coupling according to any preceding claim in which a plurality of detent means is provided.

13. A coupling according to any preceding claim, in which the or each detent means comprises a ball.

14. A coupling according to Claim 13 when appendant to Claim 3, in which one end of the aperture is provided with retaining means for the ball.

1 5. A coupling constructed and arranged substantially as described herein with reference to the accompanying drawings.