GB2409494A

GB2409494A - Clamp securing two items in a single action

Info

Publication number: GB2409494A
Application number: GB0329843A
Authority: GB
Inventors: Julian Baycock
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-12-23
Filing date: 2003-12-23
Publication date: 2005-06-29
Anticipated expiration: 2023-12-23
Also published as: GB0329843D0; GB2409494B

Abstract

A clamp for attaching an item to a support element 42. The clamp comprises a first element 30 defining a receiving region 40 for the support element 42 and also defining an engagement region (70, fig. 5) such as a threaded bolt for engaging with a fixing region (72) of the item e.g. spotlight bracket. The clamp also comprises a locking element (74, fig 5) which is displaceable so as to engage the fixing region of the item to hold the item in a fixed position with respect to the support element, and also to cause the support element to be retained in the receiving region. Preferably the clamp also includes a bifurcate second member 50 pivoted at 60 which acts as a catch to retain the support element 42. Particularly for use in suspending spot lights.

Description

P105110GB/SAB

CLAMP

The present invention relates to a clamp and also to a stage lighting instrument hanger incorporating such a clamp.

Stage lighting instruments, and similar components used in the theatre, film and television industries, are often suspended from horizontal or vertically mounted round tubular bars of one form or another. These bars are generally of a standard size, which is typically between 48 and 50 millimetres in diameter, and are generally manufactured from aluminium or steel. To secure the stage lighting instruments, also known as "lanterns", or other equipment to these bars, specially designed clamps are used which, in general, are in the form of a hook which hangs over the bar and is then clamped to the bar by a wing bolt. Lanterns or other equipment are then attached to these clamping devices by way of a conventional nut, bolt and washer assembly which is tightened by hand or by a tool, such as a spanner.

In use, it is generally necessary to direct the beam from the lantern towards a specific part of the stage or acting area that is to be selectively illuminated. Adjustment of the lantern in the horizontal plane is generally achieved by rotating the lantern about the centrally located nut and bolt assembly which attaches the lantern to the clamping device. Adjustment in the vertical plane is achieved by tilting the lantern within its own yoke assembly.

Once the desired position of the lantern has been achieved it is then locked in position in order to hold it securely and to prevent further movement or accidental adjustment.

Locking of the horizontal adjustment is achieved by tightening the nut and bolt assembly by hand or via a tool. Locking of the vertical adjustment is achieved by way of a locking device incorporated as part of the yoke assembly.

From the above description, it is clear that conventional clamping devices for stage equipment have two locking mechanisms, one to lock the clamp to the tube, and another to hold the item of stage equipment secure with respect to the clamp. The conventional devices have various shortcomings, namely that the locking mechanisms are difficult to adjust without the use of tools, especially when working at great height.

Additionally the wing bolts used to clamp the device to a bar are often broken by using inappropriate tools and both locking mechanisms are subject to frequent inadvertent over lighting.

According to a first aspect of the present invention there is provided a clamp for attaching an item to a support element, the clamp comprising: a first element defining a receiving region having an entrance such that the support element can be introduced into the receiving region, and also defining an engagement region for engaging with a fixing region of an item that is to be secured using the clamp; and locking means displaceable so as to engage the fixing the region of the item, thereby holding the item in a fixed position with respect to the first element, and also to cause the support element to be retained in the receiving region.

Preferably, a second element is moveable to clamp the support element between itself and the first element.

In a preferred embodiment of the invention there is provided a clamp for attaching an item to a support element, the clamp comprising: a first element defining a receiving region having an entrance such that the support element can be introduced into the receiving region: a second element movable with respect to the first element; an attachment element for engaging with an item to be held by the clamp; and locking means displaceable so as to trap a fixing region of the item between the locking means and the second element, thereby holding the item in a fixed position with respect to the first element, and to move the second element into the receiving region so as to clamp the support element between the first and second elements.

It is thus possible to provide a clamp for hanging items of stage equipment in which a single tightening operation causes the item of stage equipment to be held secure with respect to the clamp, and simultaneously tightens the clamp on to the support element, which is typically a bar.

Preferably the first element forms a cavity having a depending lip such that, if the clamp is placed over a generally horizontal element, the clamp can hang from the element irrespective of the position of the second element. Thus, in use, a stage technician can simply hook the clamp over the support bar safe in the knowledge that the clamp will hang from the support bar irrespective of the position of the second element.

Preferably the first element is generally "C", "U" or "V" shaped, and the open mouth thereof faces generally downwardly.

Advantageously the receiving region may have a curved interior wall. In an embodiment of the present invention the receiving region is profiled to the substantially match, with a slight clearance, the profile of a scaffolding pipe.

Preferably the second element is secured to the first element, for example by a pivot which may also allow a predetermined amount of translational movement.

Preferably the second element is movable between a first position where the entrance to the receiving region is open to permit the support element to pass through the entrance, and a second position where the entrance is at least partially obstructed so as to prevent passage of the support element there through.

Advantageously the second element has a first surface which is bounded on either side thereof by a first protrusion and a second protrusion. Advantageously when the second element is at its first position the first protrusion is positioned inside or adjacent the receiving region such that relative movement of the support element into the receiving region causes the first protrusion to abut the support element such that further movement of the support element into the receiving region causes the second element to be moved from its first position to its second position. Advantageously, when the second element is at its second position, the second protrusion is positioned within or adjacent the entrance to the receiving region so as to close or partially close the entrance thereby preventing escape of the support element from the receiving region whilst the second element is at its second position.

Advantageously the first surface of the second element, and the first and second protrusions share a common surface which define a generally part circular wall.

Advantageously the attachment element comprises a rod or bar extending from the first element. The rod is preferably helically threaded such that it can cooperate with a nut or similar element. However, other fixing arrangements may be provided, and for example the attachment element may comprise a bar upon which a ratcheting or incremental unidirectional drive mechanism is disposed, for example of the type found in sealant dispensers and some wood working clamps.

Advantageously, in use, the attachment element is passed through an aperture in the yoke assembly of the lantern prior to use. The nut or other fixing arrangement is then attached to the attachment element thereby holding the yoke assembly moveably in place on the attachment element. Therefore, when the nut or other fixing arrangement is tightened up, it simultaneously causes the yoke assembly to be clamped between itself and a second surface of the second element whilst also urging the second element to move into position where it abuts the support element and causes the support element to be clamped between the first and second elements.

Advantageously one of the first and second elements extends along a direction perpendicular to the plane of the receiving region, i.e. in the longitudinal direction of the support element, so as to provide a contact region with the support element which inhibits twisting of the clamp with respect to the support element. This can be achieved by making one or both of the first and second elements extend along the direction of the support element, or by making one of the first and second elements relatively wide and the other of the first and second elements as a two part item extending either side of the other one of the first and second elements with the two parts being connected together.

Advantageously the first element has a handle portion formed thereon in order to facilitate manipulation of the clamp into and from engagement with the support element. The handle is preferably formed as a closed loop defining a further aperture, as this enables the handle to also be used as an attachment loop for a security chain or security restraint which is typically used as a secondary tether to prevent the clamp and the item attached thereto from inadvertently falling from the support element.

According to a second aspect of the present invention there is provided a lighting instrument hanger utilising a clamp according to the first or second aspect of the present invention.

The present invention will further be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective illustration of a prior art clamp unit used for fixing stage lanterns to support bars; Figure 2 is a schematic illustration of a stage lantern; Figure 3 is a cross-sectional view of a clamp constituting an embodiment of the present invention in the "open" position; Figure 4 is a cross-sectional view of the clamp shown in figure 3 at an intermediate position; Figure 5 shows the clamp at its closed position; and Figure 6 is a view of the clamp show in figure 5 when viewed in the direction of the Arrow "A".

Figure 1 shows a clamp arrangement of a variety that is commonly used in the theatre industry. The clamp, generally indicated 1 comprises an elongated member 2 folded over at a first end 4 thereof in order to form a substantially U shaped region 6. The member 2 is also folded over at a second end thereof to form a flange 8 having an aperture there through such that the yoke 10 of a stage lantern can be bolted to the flange 8.

In order to hang the stage lantern, attached to the clamp 2, from a support bar 12 the U shaped region 6 is simply hung over the support bar 12. However, in order to prevent movement of the clamp 2, a threaded bolt 14 extending in screw threaded engagement through a cooperating aperture 16 can be tightened to bear against the support bar 12 thereby trapping it between the end of the threaded element 14 and the opposing limb of the U shaped element 6. After the stage technician has secured the clamp 2 with respect to the support bar 12, the technician can then swivel the yoke 10 around in order to point the stage lantern in the desired direction. Once this directional alignment is achieved, the stage technician then tightens the nut and bolt arrangement 18 in order to bring the flange 8 and the yoke 10 into frictional engagement with one another thereby holding the stage lantern in the desired position. It can be seen that this operation requires an initial tightening operation to secure the clamp to the support element, followed by a second tightening operation to secure the stage lantern to the clamp and to secure the desired position.

Once the direction of the stage lantern has been set in the nominally "horizontal" plane, the vertical orientation of the stage lantern can be controlled by tilting it with respect to the yoke 10 since the stage lantern 20 is pivotally attached to the yoke 10. Once the desired vertical position is achieved the lantern is locked in place by the use of locking device 22 (not shown).

Figure 3 schematically illustrates a clamp constituting an embodiment of the present invention. A first element, generally indicated 30, has a substantially " U." shaped configuration formed by an end wall region 32 from which projections 34 and 36 extend. The mouth of the "U." shaped member faces in a generally downwardly direction thereby ensuring that the end 38 of the projection 34 is, in use, below the uppermost region 40 of the interior surface when the clamp is hung from a horizontal support, thereby ensuring that once the first element has been placed over a support element 42 the user can let go of the clamp without it falling off the support element 42.

A second clamp element 50 is pivotally attached to the first element 30. The second clamp element 50 has a first end portion 52 having first and second projections 54 and 56, respectively, extending therefrom. The second clamp element 50 is pivotable between a first position as shown in figure 3, and a second position as shown in figure 5. As can be seen from the figures, the introduction of the support element 42 into the reception region 40 brings the element 42 into abutment with the first projection 54.

This is shown more clearly in figure 4. Further relative movement of the support element 42 and clamp 30 such that the support element 42 bears against the inner surface 40 causes the second element 50 to rotate about its pivot and to assume the position shown in figure 5 in which the second projection 56 is positioned opposite the extension 38 and acts to restrict the size of the entrance to the receiving region thereby ensuring that the support element 42 is held captive therein.

A detent mechanism, such as a spring loaded ball bearing may be provided to act between the first and second elements 30 and 50 so as to releasably hold the second clamp element 50 in the second configuration, as illustrated in figure 5. A pivot pin 60 extending between the first and second clamp elements engages in a slot 62 formed in the second clamp element so as to allow for a limited amount of translational motion between the first and second clamp elements 30 and 50.

An attachment arrangement, in the form of a bolt and cooperating nut extends from an end portion of the first clamp element. In use, the bolt 70 passes through a cooperating aperture in a support bracket 72 of the lighting fixture as shown in Figure 5. The nut 74 is then engaged with the bolt such that the bracket 72 is held captive on the bolt between the nut 74 and an end portion 76 of the second clamp element 50. It should be noted that, in this configuration, the axis of the bolt 70 is substantially aligned with the axis of the slot 62. As the nut 74 is tightened by user, it initially closes the gap between the bracket 72 and the end portion 76 of the second clamp element, whilst more tightening of the nut eventually brings the bracket 72 into abutment with the second clamp element. Further tightening of the nut then causes the second clamp element to move upwardly thereby bringing the surface 52 of the second clamp element 50 into engagement with the support element 42. It can therefore be seen that force is acting between the nut 74, the bracket 72 and the lower surface 76 of the second clamp element, and also between the upper surface of the second clamp element 50, the support element 42 and the surface 40 within the reception region. Therefore the simple action of tightening the nut 74, which may for simplicity be formed with a large external diameter to facilitate manual operation, causes the clamp to engage with the support element 42 and to clamp the bracket 72 of the lighting fixture. This provides a simple one-handed operation performing both the tasks of locking the clamping device to the support element and locking the lighting fixture in the desired position. This is important given that the stage technician may be working at considerable height and possibly off a ladder or scaffolding tower.

It is of course important that the clamp is stable and does not bend or twist under load.

In order to achieve this, the first clamp element 30 may be made relatively wide, and the second clamp element 50 may be made of two identical components connected together either side of the first element 30, as shown in figure 6. If this configuration is utilised, then a slot 70 is provided in a base plate 72 connecting the elements 50 together in order to allow the composite second element to achieve the position illustrated in figure 5.

Other fixing elements may the provided in place of the nut and bolt combination. A clamp utilising a linear incremental drive mechanism is suitable for use in place of the nut and bolt.

It is thus possible to provide an easy to use clamp and lighting instrument hanger.

Claims

Claims 1. A clamp for attaching an item to a support element, the clamp

comprising: a first element defining a receiving region having an entrance such that the support element can be introduced into the receiving region, and also defining an engagement region for engaging with a fixing region of an item that is to be attached using the clamp; and locking means displaceable so as to engage the fixing region of the item, thereby holding the item in a fixed position with respect to the first element, and also to cause the support element to be retained in the receiving I O region.
2. A clamp as claimed in claim 1, wherein the first element has a depending lip such that the clamp can hang from the support element.
3. A clamp as claimed in claim I or 2, further comprising a second element moveable between a first position where an entrance to the receiving region is open to permit the support element to pass through the entrance, and a second position where the entrance is at least partially obscured so as to prevent passage of the support element therethrough.
4. A clamp as claimed in claim 3, wherein the second element is movable from the first position to the second position to clamp the support element between the first and second elements.
5. A clamp as claimed in claim 3 or 4, wherein introduction of the support element into the receiving region causes the second element to be moved from the first position to the second position.
6. A clamp as claimed in any of claims 3 to 5, wherein the locking means is displaceable so as to cause the fixing region of the item to urge the second element towards the second position.
7. A clamp as claimed in any of claims 3 to 6, wherein the locking means is displaceable to clamp the fixing region of the item between the locking means and the second element.
8. A clamp as claimed in any of claims 3 to 7, wherein the second element is pivotally attached to the first element.
9. A clamp as claimed in claim 8, wherein a predetermined amount of translational movement by the second element is permitted.
10. A clamp as claimed in any preceding claim, wherein the engagement region comprises a rod or bar extending from the first element.
11. A clamp as claimed in claim 10, wherein the rod or bar is helically threaded and the locking means is a threaded nut which cooperates with the rod or bar.
12. A clamp as claimed in any preceding claim, wherein the first element includes a handle portion formed thereon.
13. A clamp as claimed in claim 12, wherein the handle portion comprises a closed loop defining an aperture through the first element.
14. A clamp as claimed in any preceding claim, wherein the receiving region is profiled to substantially match the profile of the support element.
15. A clamp substantially as described herein with reference to, and as illustrated in, accompanying Figures 3 to 6.

15. A clamp for attaching an item to a support element, the clamp comprising: a first element defining a receiving region having an entrance such that the support element can be introduced into the receiving region; a second element moveable with respect to the first element; an attachment element for engaging with an item to be held by the clamp; and locking means displaceable so as to trap a fixing region of the item between the locking means and the second element, and to move the second element into the receiving region so as to clamp the support element between the first and second elements.

16. A lighting instrument hanger utilising a clamp as claimed in any preceding claim.

17. A clamp substantially as described herein with reference to, and as illustrated in, accompanying Figures 3 to 6.

ce;ee Amendments to the claims have been filed as follows 1. A clamp for attaching an item to a support element, the clamp comprising: a first element defining a receiving region having an entrance such that the support element can be introduced into the receiving region; an engagement element extending from the first element for engaging with a fixing region of an item that is to be attached using the clamp; locking means displaceable so as to engage the fixing region of the item, thereby holding the item in a fixed position with respect to the first element, and also to cause the support element to be retained in the receiving region; and a second element moveable between a first position where the entrance to the receiving region is open to permit the support element to pass through the entrance, and a second position where the entrance is at least partially obscured so as to prevent passage of the support element therethrough; wherein introduction of the support element into the receiving region causes the movement of the second element to the second position and the seond element to be releasably held in the second position.

2. A clamp as claimed in claim 1, wherein the first element has a depending lip such that the clamp can hang from the support element.

3. A clamp as claimed in claim 1 or 2, wherein the second element is movable from the first position to the second position to clamp the support element between the first and second elements.

4. A clamp as claimed in any preceding claim, wherein the locking means is displaceable so as to move the second element into the receiving region so as to clamp the support element between the first and second elements.

5. A clamp as claimed in any preceding claim, wherein the locking means is displaceable so as to cause the fixing region of the item to urge the second element se:e ce.: A; ce.; towards the second position and to clamp the support element between the first and second elements.

6. A clamp as claimed in any preceding claim, wherein the locking means is displaceable to clamp the fixing region of the item between the locking means and the second element.

7. A clamp as claimed in any preceding claim, wherein the second element is pivotally attached to the first element.

8. A clamp as claimed in claim 7, wherein a predetermined amount of translational movement by the second element is permitted.

9. A clamp as claimed in any preceding claim, wherein the engagement element comprises a rod or bar extending from the first element.

10. A clamp as claimed in claim 9, wherein the rod or bar is helically threaded and the locking means is a threaded nut which cooperates with the rod or bar.

11. A clamp as claimed in any preceding claim, wherein the first element includes a handle portion formed thereon.

12. A clamp as claimed in claim 1 1, wherein the handle portion comprises a closed loop defining an aperture through the first element.

13. A clamp as claimed in any preceding claim, wherein the receiving region is profiled to substantially match the profile of the support element.

14. A lighting instrument hanger utilising a clamp as claimed in any preceding claim.