GB2296211A - Spanner - Google Patents

Abstract

A spanner for a screwthreaded fitting having an internal bore and external flats, has two projections 12, 14 which define between them a gap to receive, as a close fit, a portion of the fitting between one of the flats and an adjacent region of the bore of the fitting. The projection 12 is circular in cross-section for location within the bore of the fitting and the projection 14 has a flat for engaging one of the flats of the fitting. <IMAGE>

Description

SPanner The present invention relates to a spanner, and more particularly to a spanner for male bushes.

Males bushes are commonly used in electrical installations, where they are used to connect a conduit which is for carrying electrical wires to an enclosure such as a wiring box, or trunking. The electrical conduit is fitted to the bush and the bush has an external thread which engages a threaded portion of the enclosure, or a nut may be used to secure the bush to the enclosure.

Conventionally, open ended spanners are used to tighten these bushes, but such spanners suffer from the drawback that if the access to the bush is such that the spanner head cannot be laid flat, then it becomes difficult to turn the spanner.

Also, the bush often needs to be installed close to a wall of the enclosure, with the result that the wall obstructs the spanner.

Ring spanners suffer from the same drawback in that the spanner must be laid substantially flat in order to engage the bush and this may not be possible. Furthermore, there must be clearance around all of the flats of the bush in order for a ring spanner to be placed over the bush.

A socket set may be used if there is sufficient clearance directly above the bush to enable the socket to be placed over the bush. However, the socket also requires clearance around all flats of the bush in order to be placed over the bush. Also, the head of a socket only engages the corners of the bush and does not cooperate with the flats.

Consequently, if the bush or the socket head is worn, the socket may be prone to slip around the bush.

According to the present invention, there is provided a spanner for a screwthreaded or other fitting having an internal bore and external flats, the spanner having two projections which define between them a gap which is adapted to receive, as a close fit, a portion of the fitting between one of the flats and an adjacent region of the bore of the fitting, whereby turning of the spanner results in turning of the fitting around the axis of the bore, one of said projections being of circular cross-section for location within the bore of the fitting and the other projection having a flat for engaging one of the flats of the fitting.

Since this spanner grips the fitting between its bore and a flat, it cannot slip easily around the fitting. Also, because of the two projections, one projection for the central bore and the other for a flat of the fitting, the spanner does not surround the fitting and may therefore be used when the fitting is located in an awkward position.

Preferably the one projection is longer than the other projection. Thus, the spanner may easily be located over the fitting by inserting the one, longer projection into the bore before engaging the other projection with the flat. In tightening the fitting, the spanner is successively turned, then lifted to disengage the second projection whilst leaving the first (circular-section) projection located in the bush, then turned to its original angle, re-engaged and turned again in the tightening direction: in this process, the circularsection first projection acts as an effective pivot point.

The spanner preferably comprises a solid round-section bar or shaft at one end of which is provided a head. The bar or shaft may form the one projection, the other projection being attached to the shaft. The bar or shaft may extend obliquely, and preferably perpendicular to the projections, or alternatively the bar or shaft may extend along the axis of the one projection. Alternatively the one projection may comprise a piece of solid, round-section bar fixed to a handle of the spanner.

The head of the spanner may comprise one of a set which may releasably be attached to a shaft, which may itself form part of a conventional socket set.

Embodiments of the present invention will now be described by way of examples only and with reference to the accompanying drawings, in which: FIGURE 1 shows a first embodiment of spanner according to the invention engaging a male bush; FIGURE 2 shows the spanner of Figure 1 in greater detail: FIGURE 3 shows a second embodiment of spanner fitted over a male bush; FIGURE 4 shows the spanner of Figure 3 in greater detail; FIGURE 5 shows a spanner head of a third embodiment of spanner; and FIGURE 6 shows a fourth embodiment of spanner according to the present invention.

Referring to Figure 1, there is shown a spanner 2 engaging a male bush 4 which is located in an enclosure 6. The male bush 4 comprises a screwthreaded fitting having flats 8 and a central bore 10. The spanner 2 has a head which comprises two projections. The first projection 12 extends along an axis which is, in use, parallel with the axis of the bore 10 of the bush 4, and the projection 12 extends into the bore 10. The head has a second, parallel projection 14 which, in use, extends outside the bush 4 and engages a flat 8 of the bush. The first and second projections 12,14 have a minimum separation 16 which corresponds with the minimum distance 18 between the bore 10 of the bush 4 and an adjacent flat 8. The spanner 2 has a handle 20 which extends perpendicular to the first and second projections 12,14.In Figure 1, the enclosure 6 comprises trunking of an electrical installation, and the trunking has flanges 30 which partly block access to the bush 4 within the enclosure 6.

The spanner 2 of Figure 1 is shown in greater detail in Figure 2. The handle 20 comprises a bar, for example of 12mm diameter, which may be formed of steel or any other suitable material. The bar is formed with a right angled bend 22 towards one end, to define the first projection 12. The second projection 14 comprises a plate which is attached to the bar, preferably by welding. The first and second projections 12,14 extend perpendicular to the handle 20, and the first projection 12 extends a greater distance from the axis of the handle 20 than the second projection 14. For example, the second projection 14 may be 12mm in length (distance dl) and the first projection 12 may be 20mm in length (distance d2). The separation 16 between the first and second projections 12,14 determines the bush for which the spanner is suitable.The spanner shown in Figures 1 and 2 has a separation of 3.5mm, which corresponds with one particular standard size of male bush used in the electrical industry.

The spanner 2 shown in Figure 3 has a functionally identical head to that shown in Figures 1 and 2. However, a shaft 24 extends from the head of the spanner along the axis of the first projection 12 such that the handle 20, which extends perpendicular to the projections 12,14, is spaced from the head by the shaft 24. This has applications when access can only be gained to the bush 4 from a distance above the bush, such as when the casing 6 has the form shown in Figure 3.

The spanner of Figure 3 is shown in greater detail in Figure 4. The handle 20 and the shaft 24 are formed from a bar, for example having a 12mm diameter. The first projection 12 is defined by the bar, and the second projection 14 comprises a plate which is welded to the bar. The first projection 12 extends beyond the second projection 14 as in the spanner of Figures 1 and 2.

A spanner head according to the invention is shown in Figure 5, which is adapted for use with a standard square socket set. Thus, the head 26 is provided with the first and second flanges 12,14 at one end, and the other end is provided with a square socket 28, for receiving the drive member of a standard socket set. The socket may, for example, define a square of half inch sides (12.7mm).

The spanner shown in Figure 6 comprises a handle formed from a piece of sheet metal folded into a square or rectangular section and pressed to provide finger grips. The projections 12,14 comprise a piece of round-section rod and a piece or rectangular-section strip fixed to the handle by rivetting.

In use, and for example as shown in Figure 1, the spanner is fitted over the bush 4 by inserting the first projection 12 into the bore 10. The first projection 12 is slightly longer than the second projection 14 to enable the spanner to be located easily on to the bush 4. Because the head of the spanner 2 shown in Figure 1 extends perpendicular to the axis of the handle 20, the head of the spanner may engage the bush 4 despite the position of the flanges 30 of the enclosure 6. The flanges 30 make the use of a conventional open ended spanner, or a conventional ring spanner, difficult because it is not possible to maintain the spanner flat.

Furthermore, the use of a standard socket set to tighten the bush 4 from within the enclosure 6 may not be possible because there may not be sufficient clearance directly above the bush 4 to enable the various components of a socket set to be fitted over the bush.

When the first projection 12 has been inserted into the bore 10, the spanner 2 is manipulated such that the second projection 14 extends outside one of the flats 8 and lies parallel with that flat. Thus, the first projection 12 engages part of the wall of the bore 10, and the second projection 14 engages an adjacent flat 8. The bush 4 can then be turned by turning the spanner 2.

In the field of electrical installations, a small number of standard male bushes are used for connecting conduits for electrical leads. Thus, a small set of spanners will be required for compatibility with the various sizes of male bush.

In particular, tithe separation 16 determines the size of male bush for which each spanner is suitable.

Since the second projection 14 engages a flat 8, there is a very low chance that the spanner can slip around the bush.

This is because the distance 18 between the bore and the flat is much greater at the corners of the bush than in the centre of the flats. In a conventional socket set, the socket is provided with twelve corner contact points, six of which contact the corners of a nut or bush over which the socket is placed. As only a small portion of the nut/bush, in the vicinity of each corner, is engaged, a worn nut/bush or socket may result in the socket slipping around the nut or bush.

The length of the projections 12,14 may be used if access to the bush 4 cannot be achieved from the side, but must be achieved from above. The opening in the top of the enclosure 6 may not be sufficient to enable standard sockets to be located near an edge of the enclosure such that a socket may not be placed over the bush. The spanner shown in Figures 3 and 4 may be used in this situation because the head of the spanner is provided at the end of a shaft 24.

The design of spanner head shown in Figure 5 will enable a number of heads to be used with a standard socket driver, and such heads may again be useful where it is not possible to fit a standard socket over the bush, or to pass standard sockets through the opening in the enclosure 6.

Reference has been made to a screwthreaded fitting although it is to be appreciated that the spanner may be used to turn any fitting having a bore and external flats. Also, there does not necessarily need to be a handle extending perpendicular to the projections 12,14 as, for example, a spanner could be formed having a handle resembling that of a conventional screw driver, for the situations explained with reference to Figure 3.

Claims (6)

Claims

1) A spanner for a screwthreaded or other fitting having an internal bore and external flats, the spanner having two projections which define between them a gap which is adapted to receive, as a close fit, a portion of the fitting between one of the flats and an adjacent region of the bore of the fitting, whereby turning of the spanner results in turning of the fitting around the axis of the bore, one of said projections being of circular cross-section for location within the bore of the fitting and the other projection having a flat for engaging one of the flats of the fitting.

2) A spanner as claimed in claim 1, in which said projections extend perpendicular to a handle of the spanner.

3) A spanner as claimed in claim 1 or 2, comprising a round-section bar having an end portion which forms said one projection.

4) A spanner as claimed in claim 3, in which said other projection comprises a separate member welded to said bar.

5) A spanner as claimed in claim 2, in which the handle is formed from a piece of sheet metal and said projections comprise separate members fixed to said handle.

6) A spanner substantially as herein described with reference to Figures 1 and 2, Figures 3 and 4, Figure 5 or Figure 6 of the accompanying drawings.