GB2371255A - Spanner - Google Patents

Abstract

A socket-type spanner has an elongate body and a socket formed at one end of the body. The socket has a castellated side wall which forms a hexagonal, internal recess for engaging a bush nut or the like. Each opening of the castellated side wall is provided for receiving a respective corner of the nut. The diameter of the body is less than the outer diameter of the side wall and the outer diameter of the side wall is less than or equal to the pitch circle diameter of the hexagonal recess. This enables the socket to engage without play over the nut even when the nut is located in a conventional loop-in box.

Description

Spanner

The present invention relates to a spanner and particularly, but not exclusively, to a socket type spanner for use with, for example a power drill or rachet device. The invention has particular application with so-called"loop-in boxes"used in industrial electrical systems.

Figures 1 and 2 show, respectively, an end-on view and a longitudinal section through a conventional loop-in box 10 which has a main body 12 which is open at one end and closed by an end wall 16 at its other end. As can be seen in Figure 2 the body 12 has a cylindrical side wall portion extending from the end wall 16 and a further tapering side wall portion extending to the open end. A plurality of apertures 14 are located in the end wall 16 of the main body 12. Each of the apertures 14 is aligned with a respective tubular conduit 18 which has an internal screw thread. Each conduit 18 abuts the end wall 16 and is clamped thereto by means of a metal bush 20 (known as a"bush nut"). Each metal bush 20 has a cylindrical portion 22 having an external screw thread engaging the conduit 18. A nut portion 24 is provided at one end of the bush 20.

Each of the bushes 20 is inserted in a respective aperture 14 such that the nut portion 24 of each bush 20 abuts against the inner surface of the end wall 16 and the cylindrical portion 22 with the external thread extends through the aperture 14 and projects from the end of the main body 12 of the box 10. Each conduit 18 is then threaded on to a respective bush 20 by turning the bush clockwise in the manner of a conventional nut and thread.

In use, the cables of the electrical system are run through the conduits and into the loop-in box where they can be terminated, split or joined in any desired manner.

A problem with the above-described loop-in box is that the area of the end wall 16 is relatively small such that there is very little spacing between the bush 20 and the side wall of the body 12. Because of the cylindrical and tapering shape of the main body 12, conventional flat or ring spanners cannot be used to tighten or loosen the bushes 20 on the conduits. Moreover, the close spacing of the nut portions 24 of the bushes 20 and the side wall of the box 10 does not permit the use of conventional socket spanners. At present the usual method for tightening or loosening the bushes within the loop-in box is by means of pliers or adjustable grips. This is extremely awkward for the electrician and the process may result in damage to the bushes leaving sharp edges which can strip the insulation from the cables when the latter are pulled through the conduits.

The present invention aims to provide an improved tool for tightening or loosening the bushes within conventional loop-in boxes.

Accordingly, the present invention provides a socket-type spanner comprising: an elongate body and socket means at one end of said body; wherein said socket means has a castellated side wall forming an internal recess for engaging a nut or the like; each opening of the castellated side wall being provided for receiving a respective comer of the nut; the diameter of said body is less than the outer diameter of said side wall; and the outer diameter of said side wall is not greater than the pitch circle diameter of said recess.

In a preferred form of the invention said side wall is hexagonal for engaging a hexagonal nut and the outer diameter of said side wall is less than the pitch circle diameter of said recess. Alternatively, the outer diameter of said side wall is equal to the pitch circle diameter of said recess.

The above described spanner provides a number of advantages over existing spanners. In particular, the castellated side wall of the socket means allows the spanner to receive or grip nuts or the like located in extremely small places or positioned very closely together, without play or significant play. More particularly, the socket means needs have a maximum diameter no greater than that of the nut itself. In addition, the elongate intermediate portion of the spanner allows access to nuts which are in locations inaccessible to conventional spanners or sockets and additionally enable the torque applied to the nut to be increased.

The present invention will now be described, by way of example only, with reference to the

accompanying drawings in which : Figure 1 is an end view of a conventional loop-in box ; Figure 2 is a section through the loop-in box of Figure 1 along the line IT-IT ; Figure 3 is a side view of a preferred form of spanner according to the invention; and Figure 4 is an end view of the socket of the spanner of Figure 3 in the direction of arrow 4.

Referring to Figure 3, a preferred form of spanner according to the invention is shown generally at 100. The spanner has a generally cylindrical, elongate body 110 and is conveniently made from a single piece of hardened steel. The body 110 narrows at a rear end thereof to form a driving end portion 112 for attachment to a suitable driving apparatus such as a power drill, electric screwdriver or rachet device. In the embodiment of Figure 3 the driving end portion 112 has an hexagonal cross-section and is therefore suitable to be held in the chuck of a power drill or the bit-socket of an electric screwdriver. It will be appreciated, however, that the driving end portion 112 could be appropriately shaped for attachment to a rachet device or other suitable driving apparatus.

The body 110 is relatively small diameter along most of its length and at the forward end of the spanner, the cylindrical body 110 is flared outwardly to provide an increased-diameter driven end portion 114 to form a socket. This comprises an axially extending wall 116 which is preferably generally cylindrical, although any suitable shape may be used. The wall 116 proj ects forwardly from the driven end portion 114 to form a recess for engaging a bush nut.

The wall 116 has a generally cylindrical radially outer surface 122 and an inner surface 124.

The diameter of the body is typically less than half that of the outer surface 122. Although any suitable cross-sectional shape could be used for the inner surface 124, it is ideally shaped to conform to the shape of the associated nut and may be of any desired cross-section to suit the nut it is intended to engage. Hexagonal is the normal or preferred cross-sectional shape.

In the preferred embodiment the inner surface 112 is formed by a plurality of flat wall portions 118. Each of these wall portions is intended to engage a flat of the nut when the latter is engaged in the recess so that the nut is engaged without play. The wall 116 is castellated such that a respective opening 126 is formed between each wall portion 118.

The openings 126 are equidistantly spaced and are positioned to receive the apexes or comers of the nut and the socket dimensions are such that the diameter of the outer surface 122 is no greater than the Pitch Circle Diameter (PCD) of the internal surface 124 or the nut that the socket is intended to engage without play. The phrase"Pitch Circle Diameter"refers to the diameter of the circle which passes through the comers of the polygon formed by the sides of the recess or the nut to be engaged without play in the recess.

The narrow body 110 allows the socket to engage the nut without the tapered side wall portion of the body 12 of the box obstructing or preventing proper engagement. In addition, since the diameter of the outer surface 122 is no greater than the PCD of the internal surface 124 or the nut that the socket is intended to engage, the spanner can engage the nut fully and torque can be properly applied to the nut to turn the nut even though the nut is located in an extremely confined space.

By turning the spanner 100 by means of the driving apparatus, the nut may be tightened or loosened as required. It will be appreciated by those skilled in the art that the invention has particular application to the insertion and removal of the bushes used in the loop-in boxes described above. The castellated side walls of the socket are suitable to access the nut portions 24 of the metal bushes 20 even when the bushes are spaced very close together and close to the box wall. In fact, as shown in Figure 4, the diameter of the socket need be no greater than the maximum diameter of the nut itself. This is in contrast with conventional socket spanners where the external diameter of the socket is greater than the maximum diameter of the nut by an amount equal to twice the thickness of the socket walls. The reduction in size of the spanner according to the present invention compared with conventional sockets is particularly advantageous for accessing nuts or the like in extremely small spaces.

Claims (8)

1. Claims : 1 A socket-type spanner comprising : an elongate body; and socket means at one end of said body; wherein said socket means has a castellated side wall forming an internal recess for engaging a nut or the like, each opening of the castellated side wall being provided for receiving a respective comer of the nut; the diameter of said body is less than the outer diameter of said side wall; and the outer diameter of said side wall is not greater than the pitch circle diameter of said recess.
2. 2 A socket-type spanner as claimed in claim 1 wherein said side wall is hexagonal for engaging a hexagonal nut.
3. 3 A spanner as claimed in any preceding claim wherein the outer diameter of said side wall is less than the pitch circle diameter of said recess.
4. 4 A spanner as claimed in any preceding claim wherein the outer diameter of said side wall is equal to the pitch circle diameter of said recess.
5. 5 A spanner as claimed in any preceding claim wherein said body has a driving end opposite said one end for attachment to a driving apparatus.
6. 6 A spanner as claimed in claim 5 wherein said driving end has a hexagonal cross section for engagement with said driving apparatus.
7. 7 A spanner as claimed in claim 5 or 6 wherein the driving end is shaped for engagement with a screwdriver or the like.
8. 8 A spanner constructed and arranged substantially as herein described with reference to Figures 3 and 4 of the accompanying drawings.