GB2101194A

GB2101194A - Fastening elongate members

Info

Publication number: GB2101194A
Application number: GB08120978A
Authority: GB
Inventors: Anthony Kenny
Original assignee: ACCESS PLANT
Current assignee: ACCESS PLANT
Priority date: 1981-07-07
Filing date: 1981-07-07
Publication date: 1983-01-12
Also published as: GB2101194B

Abstract

A first elongate member is attached e.g. by welding to the body 8 of a clamp 2. A second member is a loose tolerance fit in hole 10 until arm 14 is lifted to rotate eccentric 12 into a position in which it grips the second member firmly. A ring sliding on the second member may be used to hold the handle 14 in its raised position. To prevent the handle being rotated downwards to a position in which it can interfere with whatever the first member is attached to, the eccentric 12 is provided with a lug 36 which engages a rib 38 in the horizontal position. Eccentric 12 is provided with groove 24 complementing to curvature of hole 10. <IMAGE>

Description

SPECIFICATION Elongate member with a fast action locking device This invention relates to an elongate member with a fast action locking device.

There are various types of upstanding work structures that are assembled at a work site and that are disassembled after use at the work site.

These work structures may be, for example, in the form of work towers which are built up from separate frames or which are built up from discrete vertical and horizontal members.

The upstanding work structures are often assembled and disassembled in difficuit conditions by unskilled labour. It may sometimes be difficult with existing equipment to satisfactorily assemble and disassemble the upstanding work structures and it is an aim of the present invention to obviate or reduce this problem.

Accordingly, this invention provides a first elongate member having a fast action locking device for locking a second elongate member to the first elongate member, the first and second elongate members forming part of a work structure of the type that is assembled at a work site and that is disassembled after use at the work site, and the locking device comprising a body, a hole in the body for receiving the second elongate member, a cam member positioned in the body and adjacent the hole, and a handle, the locking device being such that the cam member is rotatable by the handle into and out of locking engagement with the second elongate member, and the locking device being such that in use the second elongate member is a loose tolerance fit in the hole for ease of assembly and disassembly when the cam member is in its non-locking position, and is a tight tolerance fit in the hole for giving a rigid work structure when the cam member is in its locking position.

Preferably, the locking device is positioned at one end of the first elongate member so that the first and second elongate members are lockable in end to end relation.

In one embodiment of the invention, the handle extends into the body and is secured directly to the cam member.

In this embodiment of the invention, the first elongate member may be one in which the cam member is supported on a shaft, and in which the handle is secured directly to the cam member and the shaft whereby the handle is effective to secure the cam member to the shaft.

In another embodiment of the invention, the elongate member is one in which the cam member is supported on a shaft, in which the shaft extends through one side of the body, and in which the handle is secured to the portion of the shaft that extends through the side of the body.

In either embodiment of the invention, the shaft may be supported by support bushes positioned in the body of the locking device. The support bushes are advantageously positioned in slots formed in the body of the locking device. The support bushes may be in the form of plates or washers that are square or round in plan.

Preferably, the handle has a gripping knob at its end remote from the cam member.

The cam member may have an aperture for receiving the shaft, the aperture being off centre to give the cam member a cam action as it is rotated about the shaft. Usually, the cam member will have a profile that is substantially the same as the profile of the second elongate member. The first and second elongate members will usually be tubes that are round in cross section. It is however to be appreciated that members of other cross sectional shapes may be employed.

Preferably, the locking device is permanently secured to the first elongate member. In this case, the locking device may, for example, be welded to the first elongate member. If desired, the locking device may be releasably secured to the first elongate member.

The present invention also extends to an upstanding work structure of the type that is assembled at a work site and that is disassembled after use at the work site, whenever including a first elongate member in accordance with the invention.

The upstanding work structure may he in the form of a work tower, the first elongate member being part of a frame section of the work tower.

Alternatively, the upstanding work structure may be in the form of a work tower, the first elongate member being part of a discrete vertical member of the work tower, the discrete vertical member having lugs, clamps or other fittings for receiving discrete horizontal members of the work tower and/or discrete vertical members of the work tower.

The first elongate member of the present invention may be made from metals that are currently employed in work structures such for example as aluminium alloys.

An embodiment of the invention will now be described solely by way of example and with reference to the accompanying drawings in which: Figure 1 is a perspective view of a fast action locking device; Figure 2 is a plan view of part of the locking device shown in Figure 1; Figure 3 shows the cam employed in the locking device of Figure 1; and Figure 4 shows part of an upstanding work structure having severai first elongate members employing the locking device illustrated in Figure 1.

Referring to the drawings, there is shown a fast action locking device 2 which, as shown in Figure 4, is positioned at one end of a first elongate member 4. Figure 4 shows that pairs of first elongate members 4 are employed to form the uprights of frame sections 6 and these frame sections 6 can be mounted on top of one another by utilising the locking device 2 to form an upstanding work structure 7 of the type that is assembled at a work site and disassembled after use at the work site.

The locking device 2 comprises a body 8, a hole 10 in the body 8 for receiving a second elongate member which, in the embodiment shown in Figure 4, is the lower end of another member 4 forming part of another frame section 6 which is to be mounted on top of a lower frame section 6 so that two members 4 are in end to end relation in the locking device 2. In Figure 1, the locking device 2 has been shown on its own and it has not been shown connected to one end of a member 4 as in Figure 4.

The locking device 2 further comprises a cam member 1 2 which is positioned as shown in the body 8 and adjacent the hole 10. A handle 14 extends through a slot 1 6 in the body 8 and engages the cam member 12. The cam member 12 is positioned on a shaft 18 and the handle 14 extends through the cam member 12 into the shaft 18 so that the handle 14 is effective to secure the cam member 12 to the shaft 1 8. The shaft 1 8 is itself mounted in square bushes (not shown) which slide into position down slots 20 formed in the body 8.

The cam member 12 is provided with a hole 22 for receiving the shaft 1 8. As shown most clearly in Figure 3, the hole 22 is slightly off centre so that as the cam member 12 is turned, the required cam action occurs.

It will be seen that the hole 10 is of circular cross section for receiving an elongate member 4 which is also of circular cross section. The cam member 12 is provided with a grooved surface 24 which is of substantially the same profile as the profile of the member 4 to be inserted into the hole 10.

It will be appreciated that when the locking device 2 is welded at its body 8 to one member 4, then part of the hole 10 will be for receiving another member 4. This other member 4 will be a loose tolerance fit in the hole 10 so that assembly and disassembly of a complete upstanding work structure can easily be effected. The member 4 which is a loose tolerance fit in the hole 10 is extremely easily secured in position merely by moving the handle 14 through a predetermined angle to cause the cam member 1 2 to bear tightly against the member 4. The tolerances will be taken up and the member 4 will be very securely locked in position.If weight is applied to the member 4, this can only succeed in forcing the member 4 further into the hole 10 which will further rotate the cam member 12, albeit to a small degree, and further tighten the cam member 12 against the member 4. Release of the member 4 from the hole 10 is easily effected by moving the handle 14 the opposite way.

The handle 14 will normally be effective to continue tightening against the elongate member 4 through a 1 800 angle of rotation. It is however presently preferred that the handle will only be moved through substantially a 900 angle of rotation.

The handle 14 is cranked as shown. A first cranked part 26 of the handle 14 provides a hand gripping portion which enables the handle 14 easily to be gripped even, for example, when it is in a cam-locking upright position against an elongate member 4.

When the handle 14 is in a cam-locking upright position, it is advantageous to ensure that the handle 1 4 is not accidentally knocked downwards to a release position. Therefore, in a preferred embodiment of the invention, the handle 14 is provided with a second cranked part 28. The end 30 of the handle 14 is made to be sloping as shown, for example to make an inclined angle of approximately 450. If a loose ring 32 (see Figure 4) is placed over the elongate member 4 above the body 8, then the ring 32 can slip over the sloping end 30 of the handle 14 and over the second cranked part 28 of the handle 14. The ring 30 will not be able to slip down over the first cranked part 26 of the handle 14 and it will be apparent that the ring 32 will be effective to maintain the handle 14 in its upright position.The handle 14 can then be moved to a cam-releasing position merely by raising the ring 32 up the elongate member 4 until the ring 32 is clear of the handle 14, and then pulling the handle 14 downwardly.

If the handle 14 is moved too far downwardly, it may tend to interfere with a lower frame section 6. For example, the handle 14 could engage the uppermost horizontal bar 34 of a lower frame section 6. In order to avoid this possibility, it is preferred that the handle 14 can only be moved downwardly to a substantially horizontal position.

Therefore, inside the body 8, the cam 12 is provided with a dowel pin 36. As the handle 14 is moved downwardly, this dowel pin 36 engages an ear 38 of the body 8 and prevents further downward movement of the handle 14 when the handle 14 is in a substantially horizontal position.

When the handle 14 is moved upwardly, the dowel pin 36 moves away from the ear 38.

The locking device 2 can be made of various materials such for example aluminium alloys. The cam member 12 is advantageously made of an aluminium alloy that is of the same type of material as the elongate members 4. This will avoid undue wear of either the cam members 12 or the elongate member 4 during use of the locking devices 2. The bushes that are inserted in the slots 20 may be, if desired, of carbon steel or other hard material.

In addition to the locking device 2 being simply and speedily operated, it will be apparent that the locking action is very positive. This gives an advantage over previous scaffold fittings where elongate members 4 have often been held in end to end relation relying on wedge devices which often give an insufficiently tight fit.

It is to be appreciated that the embodiment of the invention described above with reference to the drawings has been given by way of example only and that modifications may be effected. Thus, for example, the shaft 18 may extend through one side of the body 8 and the handle 14 may be secured to the portion of the shaft 18 that extends through the side of the body 8.

Claims

1. A first elongate member having a fast action locking device for locking a second elongate member to the first elongate member, the first and second elongate members forming part of a work structure of the type that is assembled at a work site and that is disassembled after use at the work site, and the locking device comprising a body, a hole in the body for receiving the second elongate member, a cam member positioned in the body and adjacent the hole, and a handle, the locking device being such that the cam member is rotatable by the handle into and out of locking engagement with the second elongate member, and the locking device being such that in use the second elongate member is a loose tolerance fit in the hole for ease of assembly and disassembly when the cam member is in its non-locking position, and is a tight tolerance fit in the hole for giving a rigid work structure when the cam member is in its locking position.

2. A first elongate member according to claim 1 in which the locking device is positioned at one end of the first elongate member so that the first and second elongate members are lockable in end to end relation.

3. A first elongate member according to claim 1 or claim 2 in which the handle extends into the body and is secured directly to the cam member.

4. A first elongate member according to claim 3 in which the first elongate member isone in which the cam member is supported on a shaft, and in which the handle is secured directly to the cam member and the shaft whereby the handle is effective to secure the cam member to the shaft.

5. A first elongate member according to claim 1 or claim 2 in which the first elongate member is one in which the cam member is supported on a shaft, in which the shaft extends through one side of the body, and in which the handle is secured to the portion of the shaft that extends through the side of the body.

6. A first elongate member according to claim 4 or claim 5 in which the shaft is supported by support bushes positioned in the body of the locking device.

7. A first elongate member according to claim 6 in which the support bushes are positioned in slots formed in the body of the locking device.

8. A first elongate member according to any one of the preceding claims in which the handle has a gripping knob at its end remote from the cam member.

9. A first elongate member according to any one of the preceding claims in which the cam member has an aperture for receiving the shaft, the aperture being off centre to give the cam member a cam action as it is rotated about the shaft.

1 0. A first elongate member according to any one of the preceding claims in which the cam member has a profile that is substantially the same as the profile of the second elongate member.

11. A first elongate member according to any one of the preceding claims in which the locking device is permanently secured to the first elongate member.

12. A first elongate member according to claim 1 and substantially as herein described with reference to the accompanying drawings.

13. An upstanding work structure of the type that is assembled at a work site and that is disassembled after use at the work site, whenever including a first elongate member as claimed in any one of the preceding claims.

14. An upstanding work structure according to claim 13 in the form of a work tower, the first elongate member being part of a frame section of the work tower.

1 5. An upstanding work structure according to claim 13 and in the form of a work tower, the first elongate member being part of a discrete vertical member of the work tower, the discrete vertical member having lugs, clamps or other fittings for receiving discrete horizontal members of the work tower and/or discrete vertical members of the work tower.

1 6. An upstanding work structure according to claim 13 and substantially as herein described with reference to Figure 4 of the accompanying drawings.