GB2362442A

GB2362442A - Locking device for a bolt head or nut

Info

Publication number: GB2362442A
Application number: GB0011611A
Authority: GB
Inventors: Howard Nigel Patrick Hollowell
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-05-16
Filing date: 2000-05-16
Publication date: 2001-11-21
Also published as: GB0011611D0

Abstract

A locking device (1) for preventing rotation of a bolt (2) or nut relative to a workpiece (3) has a hexagonal hole (11) into which a head of the bolt (2) or nut fits and a clearance hole (10) through which a bolt shaft can pass. The device (1) engages an edge of the workpiece (3) so that the bolt (2) or nut cannot rotate relative to the workpiece (3).

Description

2362442 1 EASY-FIT BOLT READ LOCKING DEVICE This invention relates to the

way that the trunnion arm of a lantern is attached to its support or clamp.

Most lanterns used in the British Theatre are suspended from a bar by means of a 'G' clamp which is in turn bolted to its trunnion arm or yoke. The pan element of the focusing operation is locked by tightening the nut and bolt combination that passes through both the trunnion arm and the 'G' clamp. In the past the hole in the ion arm was often threaded so that a machine screw of the correct thread could be locked in place and then passed through a clearance hole in the 'G' clamp, a washer, spring washer and finally a nut so that only one tool was needed to lock the pan. The drawback being the amount of time that it took to change the bolt if a different type of support was required, or worse still if this support had to use a bolt with a different thread. As most lantern manufacturers hope to sell to as Wide a range of users as possible, each with their own preferred means of suspending their lanterns, most manufacturers now provide a large clearance hole in their trunnion arms for versatility. This is where the problem lies for the 'G' clamp user; two tools are now required to lock off the pan whilst holding the lantern in the right direction.

The object of this invention is to prevent the head of the pan locking bolt rotating more than a few degrees relative to the trunnion arm so that only one tool is needed to lock it.

Accordingly, this invention provides a device that prevents a bolt or its nut rotating independently to one of two or more objects bolted together, having a spanner like feature into which the bolt's head or nut fits, utilising the shaft of the bolt to secure the device in place and contact with a feature on the object preventing the device's independent rotation.

Preferably, for its initially intended application on a lantern's trunnion arm, this device is made of a piece of sheet steel about 2-3 mm thick, with two holes in it, folded into a 'U' section to fit around the on arm, so that the holes are aligned at each end of the suspension bolt hole. At one end there is an hexagonal hole into which the bolt head fits thus preventing the bolt rotating independently to the device, at the other end there is a circular clearance hole through which the thread or shank of the suspension bolt passes holding the device in place, which can only rotate until it comes into contact with the edge of the trunnion arm.

A preferred embodiment of the invention will now be described with reference to the accompanying drawings in which:

FIGURE 1 shows the device from above; FIGURE 2 shows the device from the side; FIGURE 3 is a section through the device, ion arm, bolt assemble and 'G' clamp along the line A-B as show in FIGURE I; FIGURE 4 shows in perspective, a lantern suspended from a bar with the device in place.

2 Referring to the drawing, the device 1 comprises of a piece of sheet steel folded into a U section as shown in Figure 2, with an hexagonal hole 11 and a circular hole 10 in its two flanges as shown in Figures 1, 2 and 3.

The device 1 is fitted by sliding it over the trunnion arm 3 so that its hexagonal hole 11 and circular hole 10 line up with the suspension bolt hole 12. The suspension bolt 2 is passed up through these holes so that its head fits snugly into the hexagonal hole 11 and rests under the trunnion arm 3. The 'G' clamp 5 can be attached to the protruding suspension bolt 2 by means of a washer 8, spring washer 9, and nut 4. The pan element of the focusing operation can now be locked tight by holding the trunnion arm 3 and tightening nut 4 with a spanner as the bolt 2 cannot rotate far independently to the trunnion arm 3.

Figure 4 shows how the lantern 7 is supported by the trunnion arm 3, which is attached to the 'G' clamp 5 by the nut 4 and bolt 2 utilising the device 1, this in turn hooks over the suspension bar 6.

3

Claims

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2.

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6.

An easy-fit bolt head locking device includes a device that prevents a bolt or its nut rotating independently to at least one of two or more objects bolted together, utilising the shaft of the bolt to secure the device in place, having a spanner like feature into which the bolt's head or nut fits and contact with a feature on the object preventing the device's independent rotation.

An easy-fit bolt head locking device as claimed in Claim 1 where the device has a clearance hole through which the thread or shank of the bolt in question passes, thus holding the device in place.

An easy-fit bolt head locking device as claimed in Claim 1 or Claim 2 where the spanner like feature is in the form of an hexagonal hole of an appropriate size to fit snugly around the head or nut of the bolt in question.

An easy-fit bolt head locking device as claimed in Claim 1, Claim 2 or Claim 3 where the feature on the object preventing the device's independent rotation is an edge of that object.

An easy-fit bolt head locking device as claimed in any proceeding claim where the device is made from a piece of sheet steel folded into a U section, to fit around the object, with the hexagonal hole and the circular clearance hole aligned at each end of the bolt hole in the object, so that once the bolt is in place the device can only rotate around it until it comes into contact with the edge of the object.

An easy-fit bolt head locking device substantially as herein described and illustrated in Figures 1, 2, 3 or 4 of the accompanying drawings.