GB2186221A - Improvements relating to adjustable spanners - Google Patents

Abstract

The spanner has a main body portion from which projects a first jaw 2. A second jaw 3 is located within the body 1 about a pivot. A lever arm 5 is mounted about a further pivot 6 within the body 1. The engaging ends of the jaw 3 and the lever arm 5 incorporate gearing teeth which interact so as to cause the jaw 3 to be moved towards or away from the jaw 2 as the lever 5 is rotated about the pivot 6. A light pressure is provided by a leaf spring 8 to bias the jaw 3 towards the jaw 2. In use the tip of the spanner is moved against the side of a nut and the reaction of the tip 9 of the jaw 3 against the nut causes the jaws to open so that the nut will be surrounded by the jaws and gripped by teeth 10. Movement of the lever 5 in the direction of the arrow 12 causes the nut to be gripped tightly by the jaws 2 and 3 and further movement of the lever will cause the nut to be rotated. In a further embodiment, the first jaw 2 may be pivotally connected (21, Fig. 8) to the body 1. <IMAGE>

Description

SPECIFICATION Improvements relating to adjustable Spanners This invention relates to spanners which are adjustable so that they can be used to tighten nuts or bolts having varying head sizes or where it is desired to be able to tighten the spanner onto a nut or bolt head after the initial location of the spanner.

There are generally two types of adjustable spanner. In one type the gripping jaws are connected to a respective one of a pair of lever arms which have to be gripped together by the user. This causes fatigue and it may be impossible to apply an adequate pressure so that the spanner slips on a nut before full tightening is achieved. Another form of spanner has an adjustment member whereby the jaws can be moved towards one another into engagement with a nut. However when used with a worn or small nut it is difficult to achieve really tight engagement of the jaws with the nut. Furthermore there may be limited accessibility to the area where the nut is to be found so that it may not be possible to operate the tightening mechanism once the spanner is located over the nut.

It is an object of this invention to provide an adjustable form of spanner which is automatic in operation and which can be brought into tight engagement with a nut or bolt head automatically.

Accordingly this invention provides an adjustable spanner comprising a support body on which is pivotally mounted a lever arm having a bearing portion to one side of the pivot and a hand gripping portion to the other side of the pivot, a first gripping jaw mounted on or integral with the body, and a second gripping jaw pivotally mounted on the body to face the first jaw, and engaging with the bearing portion of the lever arm by means of mutually engaging gear teeth, whereby movement of the lever in one direction will cause the two jaws to move together.

When using a spanner constructed in this way, as the pressure is applied to the lever a progressively greater force is applied to the second jaw in a direction towards the first jaw so that the grip on a nut or bolt head increases with the pressure applied to the lever arm. However, when the pressure is released on the lever arm the gripping force on the nut or bolt head becomes substantially less enabling the spanner to be rotated in a non-tightening direction prior to applying a further tightening action.

It is preferred that a light spring should bias the second jaw towards the first jaw so that the jaws will be lightly in contact with the nut or bolt head prior to application of force to the lever arm. The ends of the jaws of the spanner can be pushed against the nut or bolt head to separate the jaws until they can become correctly positioned about the nut or bolt head for subsequent tightening. In other circumstances it may be desirable to provide a light spring which biases the second jaw away from the first jaw so that the spanner can be more readily introduced about a nut or bolt head. The spring may be a leaf spring attached to the body or the first jaw and bearing against the second jaw.

In one arrangement the gearing will comprise multiple teeth engaging on facing ends of the lever arm and the second jaw. In a preferred embodiment, however, the gearing will comprise major bearing teeth (ideally one on each of the lever arm bearing portion and the interengaging portion of the second jaw) which bear against one another as the lever is moved in said one direction. Generally it will be of advantage to provide that the gearing also includes minor teeth which react against the major teeth when the lever moves in the other direction. These act mainly to ensure that the major bearing teeth do not come out of engagement with one another.

As a modification to the basic design a portion of the support body could extend beyond the pivot point with the lever arm, to lie alongside the hand gripping portion of the lever arm, for engagement by a finger of the user. This enables the spanner, when used, to be gripped in such a way that there is a positive force on the two jaws towards one another.

It is possible to provide that the first gripping jaw is also pivotally mounted on the support body and incorporates a finger extending from the pivot point to bear against the side of the hand gripping portion of the lever arm.

It is greatly preferred that the facing portions of the two jaws should incorporate gripping teeth. Ideally the array of teeth on one of the jaws will be arranged to define an angled gripping area to receive a corner of a nut. The teeth could be provided on replaceable blocks removably received within the jaws.

The invention may be performed in various ways and preferred embodiments thereof will now be described with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a preferred form of spanner of this invention; Figures 2 and 3 illustrate the principles of operation of the spanner of Figure 1; Figure 4 is an illustration of a modified form of spanner of this invention; Figures 5 and 6 show the principles of operation of the spanner of Figure 4; and Figures 7 to 9 show further preferred embodiments of spanners of this invention.

The spanner shown in Figures 1 to 3 has a main body portion 1 from which projects a first jaw 2. A second jaw 3 is located within the body 1 about a pivot 4. A lever arm 5 is mounted about a further pivot 6 within the body 1. As can be seen from Figures 2 and 3 the engaging ends of the jaw 3 and the lever arm 5 incorporate gearing teeth 7 which interact so as to cause the jaw 3 to be moved towards or away from the jaw 2 as the lever 5 is rotated about the pivot 6. A light pressure is provided by a leaf spring 8 to bias the jaw 3 towards the jaw 2.

In use the tip of the spanner is moved against the side of a nut and the reaction of the tip 9 of the jaw 3 against the nut causes the jaws to open so that the nut will be surrounded by the jaws and gripped by teeth 10.

The set of teeth on the jaw 2 are formed, as illustrated, to define an angled gripping area 11 to receive a corner of the nut. The lever 5 is now moved in the direction of the arrow 12 to cause the nut to be gripped tightly by the jaws 2 and 3 due to movement of the jaw 3 by the lever 5 and further movement of the lever will cause the nut to be rotated.

Further incremental rotations of the nut can be achieved by moving the lever backwards and forwards. When the lever 5 moves in the rearward direction the pressure on the jaw 3 will be released and the jaws 2 and 3 will slide around the nut. When it is desired to rotate the nut in the opposite direction the spanner is turned over so that the gripping force of the lever 5 now acts in the opposite direction.

The form of spanner illustrated in Figure 4 is very similar in construction and operation to that shown in Figures 1 to 3 except that the gearing teeth are differently formed. Here there is provided a major bearing tooth 13 or 14 on the lever arm 5 and the jaw 3 which enables a substantial operating force to be ap piied without fear of damaging the gearing parts. Minor bearing teeth 15, 16 operate to ensure that the gearing between the lever 5 and the jaw 3 does not become disengaged.

The two limiting stages of opening and closing of the jaws 2 and 3 by the lever 5 are illustrated in full and dashed outlines respectively in Figure 4 which shows also how the spanner may be used to tighten nuts of any size between the smallest 17 and the largest 18 for that spanner. Of course the spanner itself (of any of the forms described herein) may be made to any size for a required purpose.

In the modified construction shown in Figure 7 the lever arm 5 is formed with a trigger grip recess 19 within which is positioned an extension 20 of the body 1. This extension 20 can be held by a finger of the user so as to apply a gentle initial force on the jaw 2 (integrally with the body 1) as the jaw 3 is moved in the opposite direction by the lever 5. In a further modification shown in Figure 8 the jaw is also mounted about a pivot 21 to the body 1 but a finger 22 extends beyond the pivot 6 to engage against the side of the lever arm 5.

Rotation of the lever arm 5 will apply a gentle biassing force, through the finger 22, to the jaw 2 as well as applying the major gripping force on the jaw 3. Modified, alternative, spring biassing arrangements are also illustrated in Figure 8. The leaf spring 23 acts in a direction to keep the jaws 2 and 3 closed.

The positioning of a bent leaf spring 24 or 25 at the positions indicated will act to bias the jaws 2 and 3 into an open position. Figure 9 illustrates a spanner more of the form shown in Figure 4 with the possible alternative position for a leaf spring 26 which can be provided instead of the leaf spring 8 to bias the jaws 2 and 3 into the open position.

In all the embodiments illustrated it would be possible to provide the gripping teeth 10 on blocks received, for example, slidably within slots in the jaws 2 and 3. A worn set of teeth can then be removed and replaced by blocks incorporating new teeth.

Claims (12)

1. An adjustable spanner comprising a support body on which is pivotally mounted a lever arm having a bearing portion to one side of the pivot and a hand gripping portion to the other side of the pivot, a first gripping jaw mounted on or integral with the body, and a second gripping jaw pivotally mounted on the body to face the first jaw, and engaging with the bearing portion of the lever arm by means of mutually engaging gear teeth, whereby movement of the lever in one direction will cause the two jaws to move together.

2. A spanner according to claim 1, wherein a light spring biases the second jaw either towards or away from the first jaw.

3. A spanner according to claim 2, wherein the spring is a leaf spring attached to the body or the first jaw and bearing against the second jaw.

4. A spanner according to any one of claims 1 to 3, wherein the gearing comprises multiple teeth engaging on facing ends of the lever arm and the second jaw.

5. A spanner according to any one of claims 1 to 3, wherein the gearing comprises major bearing teeth which bear against one another as the lever is moved in said one direction.

6. A spanner according to claim 5, wherein the gearing also includes minor teeth which react against the major teeth when the lever moves in the other direction.

7. A spanner according to any one of claims 1 to 6, wherein a portion of the support body extends beyond the pivot point with the lever arm, to lie alongside the hand gripping portion of the lever arm, for engagement by a finger of the user.

8. A spanner according to any one of claims 1 to 7, wherein the first gripping jaw is also pivotally mounted on the support body and incorporates a finger extending from the pivot point to bear against the side of the hand gripping portion of the lever arm.

9. A spanner according to any one of claims 1 to 8, wherein the facing portions of the two jaws incorporate gripping teeth.

10. A spanner according to claim 9, wherein the array of teeth on one of the jaws is arranged to define an angled gripping area to receive a corner of a nut.

11. A spanner according to claim 9 or claim 10, wherein the teeth are provided on replaceable blocks removably received within the jaws.

12. An adjustable spanner of any of the forms substantially as herein described with reference to the accompanying drawings.