GB2307658A - Open-ended spanner - Google Patents

Abstract

An open-ended spanner comprises two jaws 11,12 connected by a throat 14, the jaws being mounted on a handle 13, each jaw incorporating an inward facing flat, the flats being substantially parallel to each other such that the jaws will engage the flats of a nut, this arrangement being as found in a conventional open-ended spanner. However, a first jaw 11 is of conventional length whilst a second jaw 12 is substantially shorter in length than the first jaw such that, in use, with a nut engaged between the jaws the first and longer jaw can exert a turning force on the nut when the spanner is rotated in one direction, whereas the second jaw is too short to exert a similar turning force when the spanner is rotated in the opposite direction, thus creating in effect a ratchet-like action with no moving parts.

Description

OPEN-ENDED SPANNER Field of the Invention The present invention relates to open-ended spanners, and in particular to ratchet-effect open-ended spanners.

Background to the Invention Ratchet type spanners in a variety of forms have been known for many years.

For example, socket sets routinely contain a ratchet handle and ratchetoperating ring spanners are also widely available. However, both these known versions suffer from disadvantages. Firstly, the spanner or socket must be placed over the nut or bolt by aligning it above the portion to be undone and in line with the bolt axis. This presupposes that there is space between the nut/bolt and its surroundings for the complete depth of the spanner. This is very often a problem with sockets, which have considerable depth themselves, even before fitting them onto the handle.

Ratchet ring spanners suffer from additional problems. The ratchet mechanism is usually concealed within the circumference of the spanner and within the handle and as such must be kept compact. There is therefore a trade-off between tool strength and the external dimensions of the tool. This generally limits the force that may be applied with this type of spanner. The need to accommodate the ratchet mechanism also means that this type of spanner is generally flat in shape, rather than angled as with a conventional ring spanner.

Although useful if their place, none of these prior art spanners have the advantages of an open-ended spanner. An open ender can be slid around a nut/bolt head from the side, without the need for any space above the nut for the spanner to pass by. They can also operate in confined spaces by repeated rotation through a small arc, by repeatedremoval and repositioning back on the nut at the start of that arc. Although inconvenient and time consuming, this is sometimes the only way of undoing awkwardly positioned nuts/bolts.

The application of this type of ratchet technology to an open-ended spanner in the same way is clearly not possible. Attempts have been made to use serrated jaws as in EP 425,883 (Snap On Tools) or a movable anvil as in US4 255 990 (Doan). But these none of these ideas have proved a commercial success.

It is the object of the present invention to provide a ratchet-effect openended spanner with no moving parts which overcomes these disadvantages.

Summary of the Invention According to a first embodiment of the present invention there is provided an open-ended spanner comprising two jaws connected by a throat, the jaws being mounted on a handle, each jaw incorporating an inward facing flat, the flats being substantially parallel to each other such that the jaws will engage the flats of a nut, this arrangement being as found in a conventional openended spanner, characterised in that a first jaw is of conventional length while a second jaw is substantially shorter in length than the first jaw such that, in use with a nut engaged between the jaws, the first and longer jaw can exert a turning force on the nut when the spanner is rotate in one direction, whereas the second jaw is too short to exert a sirnilar turning force when the spanner is rotated in the opposite direction, thus creating what is, in effect, a ratchet-like action with no moving parts.

Preferably the throat is cut away by comparison with a conventional spanner at least in the region where the first jaw meets the throat such that the spanner can rotate freely when turning in the ratchet-mode direction.

According to a second embodiment of the present invention there is provided a spanner as described above wherein the first and second jaws are adjustably movable with respect to each other, the adjustment being adapted to vary the gap between the flats and thus provide an adjustable ratchet-effect openended spanner.

Brief Description of the Drawings Preferred embodiments of the present invention will now be more particularly described by way of example, with reference to the accompanying drawings, wherein: Figure 1 shows an open-ended spanner with asymmetric jaws; Figure 2 shows an adjustable spanner with asymmetric jaws.

Description of the Preferred Embodiments Figure 1 illustrates a plan view of an open-ended spanner with asymmetric shaped jaws. The spanner 10 comprises a first jaw 11 which approximates in size and shape to one of the jaws of a conventional open-ended spanner. It is this conventionally sized and shaped jaw which exerts a turning force as described below.

A second, shorter jaw 12 is also provided; the first and second jaws in combination being adapted to accommodate a typical nut or bolt head between them.

The jaws 11, 12 are connected by a throat 14, which in this example is arcuate in shape. The throat 14 forms part of the spanner handle 13 to which the jaws are attached.

As is typical with this type of spanner, the internal face of each jaw is substantially flat. These flats together engage the flat portions of a nut. The spanner illustrated is double-ended with the two ends having different across flats dimensions.

For the purpose of this example the term nut when used in the description is taken to include bolt, bolt head or any other shaped fixing which can conventionally be tightened or loosened with a spanner. It is the clear and stated object of this invention to provide a spanner which will perform all of the functions of a conventional spanner in terms of the fixings that it will operate.

The length of the second jaw is such that it will act to stabilise the spanner on a nut when it is rotated in anticlockwise direction as shown in Figure 1.

However, when rotated in the opposite direction the shorter jaw 12 is not sufficiently long to exert any appreciable turning force on the nut. When the spanner is rotated clockwise as shown in Figure 1 the lack of purchase by jaw 12 means that the spanner simply slips around the nut. Reversing the direction of rotation causes the spanner to grip the nut and exert a turning force once again. This is basically a direct consequence of the tip of the jaw 12 being missing. Thus it has been discovered that by making the two jaws asymmetric in size and shape it is possible to arrive at a situation where the smaller jaw can provide a stabilising effect against rotation in one direction whilst permitting the spanner to rotate freely around the nut in the other.

Thus a ratchet effect or ratchet action is achieved with no moving parts.

In this example, the spanner has been formed from a conventional spanner by filing or grinding off the tip of one of the jaws. The angle of this bevelled off region 15 is not as important as the length of the remaining portion of the flat 16. This measurement can be arrived at by trial and error for any particular size of nut i.e for a particular across-flats dimension.

To undo a nut it is simply inserted between the flats of an appropriately-sized spanner as shown in Figure 1. The spanner is then turned anticlockwise to start to undo the nut. Rotation of the spanner clockwise causes the flats to slip around the vertices of the nut without turning it. Further clockwise rotation undoes the nut some more. In effect, the flat internal face of the longer jaw 11, the flat face 17 and the shorter jaw 12 can, in combination, exert a turning force on a nut when turned in one direction but not in the other. Thus a ratchet effect or ratchet-action is created in an open-ended spanner.

As with any ratchet spanner once the nut is only hand tight the ratchet will cease to function, there being insufficient friction to operate it.

A further modification has also been made to ensure that the spanner will turn freely about the nut when ratcheting. By enlarging the throat at the bottom of one or both jaws it has been discovered that the nut will rotate more freely when ratcheting. One version of this is illustrated as depression 20 in Figure 1. This widened throat design ensures that the vertices of the nut do not contact the jaw/throat corner(s), reducing any friction that might occur.

In summary, these features alone or in combination provide a spanner which, whilst biting on and turning a nut in one direction, will slide around the nut when turned in the opposite direction. There is no necessity to remove the spanner from the nut to re-align it into a configuration in which it can bite again. Thus a ratchet effect is created with no moving parts.

To turn the nut in the opposite direction in this example, the spanner is simply rotated through 1800 about its longitudinal axis.

In a further embodiment this same technology can be applied to an adjustable spanner as shown in Figure 2. Open-ended adjustable spanners are well known. But it is possible to similarly shorten either one or other of the jaws of such a spanner with the same effect. If the movable jaw is kept to the full length then the throat at the bottom of this movable jaw can be enlarged. This simplifies the design and the amount of modification needed.

These examples have been based on spanners with flat-faced jaws. However, a variety of other shaped jaws are already known and this invention is intended to cover these shapes. For example, the jaws can be serrated with either symmetric or asymmetric grooves. Alternatively, the flat face may be interrupted by a V-shaped notch which can engage with a nut vertex.

Claims (4)

1. An open-ended spanner comprising two jaws connected by a throat, the jaws being mounted on a handle, each jaw incorporating an inward facing flat, the flats being substantially parallel to each other such that the jaws will engage the flats of a nut, this arrangement being as found in a conventional open-ended spanner, characterised in that a first jaw is of conventional length whilst a second jaw is substantially shorter in length than the first jaw such that, in use, with a nut engaged between the jaws the first and longer jaw can exert a turning force on the nut when the spanner is rotated in one direction, whereas the second jaw is too short to exert a similar turning force when the spanner is rotated in the opposite direction, thus creating what is, in effect, a ratchet-like action with no moving parts.

2. A spanner as claimed in Claim 1 wherein the throat is cut away by comparison with a conventional spanner at least in the region where the first jaw meets the throat such that the spanner can freely rotate when turning in the ratchet-mode direction.

3. A spanner as claimed in Claim 1 or Claim 2 wherein the first and second jaws are adjustably movable with respect to each other, the adjustment being adapted to vary the gap between the flats and thus provide an adjustable ratchet-effect open-ended spanner.

4. A spanner substantially as herein described with reference to and as illustrated in any combination of the accompanying drawings.