<div class="application article clearfix" id="description">
<p class="printTableText" lang="en">243537 <br><br>
PATENTS FORM NO. 5 <br><br>
Fee No. 4: $260.00 <br><br>
PATENTS ACT 1953 COMPLETE SPECIFICATION <br><br>
After Provisional No: 243537 <br><br>
Dated: 13 January 1993 <br><br>
AN ADJUSTABLE WRENCH <br><br>
I Yang Xuming, a Chinese citizen and a New Zealand resident of 27C Sandringham Road, Mt Albert, Auckland, New Zealand hereby declare the invention for which I pray that a patent may be granted to me, and the method by which it is to be performed to be <br><br>
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particularly described in and by the following statement: & N f<:'~.. <br><br>
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AN ADJUSTABLE WRENCH <br><br>
Technical Field <br><br>
This invention relates to an adjustable wrench. For convenience only, the invention will predominantly be described as an adjustable wrench used for tightening/loosening nuts, or for gripping and/or turning rod like members, however it is to be understood that it is not to be limited as such. <br><br>
Background Art <br><br>
Spanners used for turning nuts generally comprise standard open ended spanners and ring spanners/box spanners. Open ended spanners operate by applying a load to opposite end corners of opposite faces of a nut to thereby exert a turning moment on the nut. Generally the arrangement is such that forces are applied equally to the opposite end corners of the opposite faces and normal thereto, and on either side of the axis of symmetry of the nut, so that the resultant turning moment is equal to the force applied times the distance between the forces. <br><br>
With ring spanners/box spanners, as well as gripping the nut at opposite end corners of opposite faces, as with the open ended spanner, the nut is also gripped at the other corners of the nut. The loading on the nut can thus be distributed among the six corners, enabling a higher loading (turning moment) to be applied to the nut without failure of the nut corner portions. Also since diagonally opposite corners of the nut can be gripped, turning forces can be applied perpendicular to the diagonal. In this case, the resultant spreading force due to an inclined loading on the <br><br>
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nut face is carried by the hoop forces in the ring. ^ <br><br>
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With adjustable wrenches applicable to the present invention which comprise two jaws having grip faces for gripping a nut or rod like member which are pivotally connected so that the distance between the jaws is adjustable, a similar principal applies when used for turning nuts. However, when used for gripping and/or turning rod like members, the turning moment is dependent on friction and hence a high compressive load normal to the surface is required. Design of the gripping surface and location of the pivot point is thus critical for satisfactory operation of the wrench. <br><br>
Designs of such adjustable wrenches such as that disclosed in New Zealand Patent No. 233283, are generally aimed at providing a tool suitable for both pipe and hexagonal nuts, and thus tend to have course serrations to bite into the surface of a round object. The design is directed to maintaining a good grip on the object by ensuring that the object is subjected to a high crushing force when being turned. <br><br>
The tool New Zealand Patent No. 233283, comprises a handle member having a handgrip portion at one end thereof and a fixed jaw portion at an opposite end thereof, and a movable jaw member which is pivotally mounted on the handle member. The pivotal mounting in this case can be optionally set enabling the jaws to be separated to accommodate a greater range of objects. The fixed jaw portion has a serrated convex grip surface facing away from the pivot point and is formed such that a distance from the pivot point to the second grip surface varies with angle of rotation about the pivot point. The movable member generally comprises a hook shaped member with a plurality of serrated planar gripping surfaces inclined to each other. In one design of the disclosure, <br><br>
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while another design shows two serrated grip surfaces at 60° to each other. These jaw designs are suitable for gripping both round objects and hexagonal objects such as nuts. Although the three grip surface design can accommodate a range of nuts, when the nut face is longer than the grip face, the nut is held by its corners. Since the serrations are not specifically designed to accommodate the corners, as with a ring spanner, high point loads result. The two face design overcomes this to some degree, since it enables the nut corner to always be seated at one location. However, again the loadings on the nut are similar to those with a ring spanner. Since a hoop force cannot be provided however, as with a ring spanner, a high diagonal compressive loading must be applied. This tends to crush the nut. Furthermore, the loadings on the faces of the nut in contact with the movable jaw grip faces Eire, as with a ring spanner, not normal to the faces of the nut, and thus tend to tear the surface. Moreover, since the resultant force from these loadings depends on the crushing force applied, its direction can vary so that it does not necessarily pass through the pivot point. Also there is no suggestion nor disclosure of the desirability of having such a relationship between the surfaces and the pivot point. ^ <br><br>
Although the provision of a plurality of grip surfaces may enable the loadings on the nut to be distributed over more contact surfaces as with a ring spanner, since the jaws are movable, there is a higher likelihood of slipping, so that any advantage may be overshadowed by the damage to a nut surface in the case of slipping. <br><br>
Another disadvantage of this tool when used for nuts is that the grip surface on the movable member comprises at least two serrated grip surfaces. As well as causing damage to the surface in V <br><br>
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slipping, as mentioned before, this tends to impair operation of the wrench during ratcheting movement wherein the movable surface is aligned with a new nut face. In this ratcheting operation, the corner of the nut catches on the serrations, detracting from the smoothness of 5 operation and causing unnecessary damage to the nut corner. <br><br>
Conventional tools such as that mentioned above thus suffer from various disadvantages and in particular are generally not suitable for use on precision components where a minimum crushing loading is desirable. <br><br>
It is an object of the present invention to address the foregoing problems 10 or at least to provide the public with a useful choice. <br><br>
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only. <br><br>
Disclosure of Invention <br><br>
15 According to one aspect of the present invention there is provided an adjustable wrench comprising: <br><br>
an elongate handle member having a handgrip portion at one end thereof, a first grip surface at an opposite end thereof, and a recess portion formed therein adjacent said first grip surface, <br><br>
20 a movable jaw member having a second grip surface, and a tongue member adapted to be accommodated in said recess portion, <br><br>
pivot means for pivotally connecting said movable jaw member and said handle member together about a pivot axis passing through said hajndle member and said tongue member, and , V* ;5 ;a coil spring accommodated within said recess portion and pivotally fixed at opposite ends thereof to said movable member and said handle member respectively so as to bias said movable member to pivot about said pivot point in a first sense which results in a reduction in distance between said first grip surface and said second grip surface, a coiled portion of said coil spring being accommodated within the recess portion throughout an allowable range of movement of said movable member. ;According to another aspect of the present invention there is provided an adjustable wrench substantially as described above wherein said movable jaw member further comprises a thumb grip portion on an outer surface thereof, said thumb grip portion being formed to a shape such that said movable jaw member may be pivoted about said pivot point in an opposite sense to said first sense by a pulling action of a thumb/finger of a hand when gripping said hand grip portion. ;According to another aspect of the present invention there is provided an adjustable wrench substantially as described above wherein said recess portion is formed with a flat surface which lies in a plane substantially parallel to a longitudinal axis of said handle member. * <br><br>
With an adjustable wrench as described above, an object to be gripped may be easily inserted between the first and second grip surfaces. The object may then be gripped therebetween by turning of the handle member in the appropriate direction so that the distance between the first and second grip surfaces tends to reduce. The grip on the object is thus increased so that the object is firmly gripped and turned as the wrench is turned. <br><br>
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Due to the location of the pivot point and the curvature of the first grip surface, when an axi-symmetric object is located on the planar second grip surface and gripped between the first and second grip surfaces, the forces applied to the surface of the object are directed to lie on opposite sides of the axis of symmetry of the object. Hence the forces always contribute towards turning the object as well as applying a pressure on the surface to ensure grip. Thus a more optimum application of forces is obtained compared to other adjustable wrenches. <br><br>
Specifying the curvature of the first grip surface to ensure that a plane of the second grip surface is substantially parallel to a tangent of the first grip surface passing through a point of the first grip surface closet to the second grip surface, ensures that a maximum moment is exerted on an object having flat parallel opposite faces (such as with a hexagonal nut), and held between the jaws. This is because the normal to the curved first grip surface at the point of contact will be normal to the flat face gripped thereby, and thus pass at a maximum distance from the axis of rotation, resulting in a maximum turning moment from the force applied thereto. <br><br>
The arrangement wherein the locating surface is positioned to ensure that a tangent to the second grip surface through an inner corner of a flat sided object (such as a hexagonal nut) located on the second grip surface by the location surface passes substantially through the pivot point, ensures that the loading on the inner corner is normal to the surface of the object and acts directly on the pivot point. A more desirable loading on the surface of a nut may thus be achieved. For example, the direction of the force is such as to minimise forces parallel to the surface of the nut which may tend to tear the surface. <br><br>
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The second grip surface on the movable jaw member may be serrated to provide a better grip on an object to be turned. The first grip surface may however be smooth for use in gripping objects such as nuts having flat faces. <br><br>
The first grip surface on the handle member may also be serrated, and may be formed as a curved surface. However it is also possible for his surface to be formed as a series of smooth flat surfaces angled to each other so as to better grip the faces of a nut without damaging the surfaces thereof. <br><br>
The pivotal connection between the movable jaw member and the handle member may comprise a pin passing through a hole in the handle member and another hole in the movable jaw member so that movable jaw member may pivot about the pin. The movable jaw member may have a forked portion at the pivotal connection of sufficient width for the handle member to be fitted between the forks at the pivotal connection. The pivot pin may be fitted through holes formed in the forks, and through a hole formed in the handle member. Alternatively, the handle member may have a slot formed in the region of the pivotal connection, and the movable jaw may be provided with a tongue portion which may be fitted into the slot, with the pivot pin passing through opposite walls of the slot and through a hole in the tongue portion. <br><br>
The pivot pin may be secured in position either by a thread which engages either with a portion of the handle member or with a portion of the movable jaw member. Alternatively, the pivot pin may comprise a rivet. However any other means of pivotally connecting the movable jaw member to the handle member may be possible. For example the movable jaw member may be provided with a pin or pins which are able to slide in <br><br>
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grooves in the handle member, and be located in said grooves at different positions. A similar arrangement may be possible where the movable jaw member is pivotally connected to the handle member by pivot sockets formed on an outer surface of the handle member. These arrangements 5 of the pivot may be suitable for a wrench wherein the pivot position may be varied, so that the wrench can be used for a wide range of objects. The only requirement for the pivotal connection means apart from its location as mentioned before, is that the movable jaw member may pivot relative to the handle member in a way such that the distance between the first and 10 second grip surfaces may be varied. <br><br>
The resilient member may be any suitable member which may provide an urging force to urge the movable jaw member relative to the handle member, so as to cause the distance between the first and second grip surfaces to reduce. The resilient member may comprise a spring having 15 one end connected to the handle member and another end connected to the movable jaw member. In the case of a spring, any type of spring may be possible. For example a leaf spring or coil spring may be used. <br><br>
The provision of the resilient member to urge the movable jaw member to a close condition where the first and second grip surfaces approach each 20 other may improve the operability of the wrench. For example, since the first and second grip surfaces are urged towards the closed condition, the movable jaw member of the wrench may be pressed against an object to be turned so that the jaws are opened under a resilient force until the distance between the jaws is sufficient to accommodate the object. At 25 this condition the wrench may be turned, thereby gripping and turning the object. The provision of a resilient member may not however be necessary on some embodiments since the first grip surface of the y.••'•••• <br><br>
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movable jaw member may be formed so as to enable an object to be caught against this surface when the wrench is in an open condition, and the object subsequently gripped as the handle member is turned relative to the movable jaw member. <br><br>
When a resilient member is fitted to urge the movable jaw member towards a closed condition, the movable jaw member may be easily opened by pressure on the thumb grip portion on the movable jaw member. The thumb grip portion may be any suitable shape which enables the thumb/ finger of the hand holding the handle member to grip and turn the movable jaw member against the resilient force of the resilient member. A simple angled corner shape may be sufficient for the thumb grip. This corner portion may be further provided with a serrated surface to improve grip, however a smooth surface may be sufficient and easier to form. <br><br>
Further aspects of the present invention will become apparent from the ensuing description which is given by way of example only and with reference to the accompanying drawings. <br><br>
Brief Description of Drawings <br><br>
Figure 1: is a schematic plan view of an adjustable wrench according to an embodiment of the present invention; and <br><br>
Figure 2: is a detailed view of a part of the wrench of Figure 1 for illustrating an arrangement of forces acting on a nut. <br><br>
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Best Modes for Carrying out the Invention <br><br>
With reference to Figure 1 there is shown a wrench according to an embodiment of the present invention generally indicated by arrow 1. The wrench 1 comprises an elongate handle member generally indicated by arrow 2 and a movable jaw member generally indicated by arrow 3. The handle member 2 comprises a hand grip portion 4 at one end thereof and a fixed jaw portion 5 at another end thereof. A slot 6 (shown in dotted outline) is formed in the end adjacent to the fixed jaw portion 5, for accommodating a tongue 7 formed on the movable jaw member 3. A pivot hole 8 is drilled through the side faces of the slot 6 of the handle member 2 and through the tongue 7 of the movable jaw member 3 so that a pivot pin 9 may be fitted therethrough. The movable jaw member 3 is thus able to pivot relative to the handle member 2 about the pivot pin 9. The pivot pin 9 comprises a threaded portion which may be screwed into a corresponding threaded portion formed in one face of the slot 6, thereby providing a means for securing the pivot pin 9 in position. <br><br>
The fixed jaw portion 5 of the handle member 2 comprises a generally convex first grip surface 10 facing away from the location of the pivot pin 9 and formed such that a distance from the pivot pin 9 to the first grip surface 10 varies with angle of rotation about the pivot pin 9. This curvature is also made so as to ensure a predetermined relation to a second grip surface on the movable member 3 as described below. In this embodiment the first grip surface 10 is formed with serrations to assist in gripping an object. ^\ ^ , <br><br>
11 <br><br>
The movable jaw member 3 is generally formed as a beak shape with a second grip surface 11 formed at an end portion opposite to the tongue portion 7, and a location surface 25 inclined thereto. The second grip surface 11 is formed as a generally planar surface having serrations to improve grip on objects. <br><br>
As shown more clearly in Figure 2, the inclination and location of the second grip surface 11 and curvature of the first grip surface 10 is such that a plane A-A through the second grip surface 11 lies substantially parallel to a plane B-B tangent to the first grip surface 10 at a closest point X to the second grip surface 11, throughout a range of pivotal movement of the movable jaw member 3 relative to the fixed jaw portion 5. Loads Fl, F1 applied to a nut 20 when being turned by the wrench 2, as well as lying on opposite sides of the axis of symmetry 21 of the nut 20, are also substantially perpendicular to the opposite parallel faces 22, 23 of the nut 20 so that a maximum turning movement (equal to the force Fl times the distance "d" between the parallel lines of force Fl) can be applied with minimum loadings along the surfaces 22, 23. Hence as well as providing optimum turning movement to the nut 20, tearing of the surfaces 22, 23 can be minimised due to the loads being substantially normal to the surfaces. <br><br>
Also as shown in Figure 2, the location of the pivot point 24 provided by the pivot pin 9 is such that when the nut 20 is located on the second surface 11 by the location face 25, a normal to the face 22 of the nut 20 (coincident with force Fl) and passing through an inner edge corner 26, passes substantially through the pivot point 24. <br><br>
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The loading Fl at the corner 26 is thus applied directly to the pivot pin 9, with minimal loading in a direction along the surface 22 of the nut 20, minimising any tendency for the surface 22 to slide on the second grip face 11 and damage the nut 20. <br><br>
As shown in Figure 1, a resilient member in the form of a coil spring 12 is provided between a hole 13 formed in the tongue portion 7 of the movable jaw member 3, and a hole 14 formed in a wall of the slot 6 of the handle member 2. The spring 12 is arranged so as to urge the movable jaw member 3 relative to the handle member 2 so as to cause the distance between the first grip surface 11 and second grip surface 10 to reduce. The arrangement of the resilient member ensures minimum wear to the ends of the spring and surface of the hole 13, compared to conventional tools wherein a leaf spring in generally used with one end fixed and the other end sliding. <br><br>
A thumb grip portion 15 is formed on an outer surface of the movable jaw member 3 in the form of a 90° corner. The shape of the thumb grip portion 15 is such that the movable jaw member 3 may be easily turned by the thumb when the wrench 1 is being hand held by the hand grip portion 4. <br><br>
In using the wrench 1 of this embodiment, a nut or rod like member may - -be inserted between the first grip surface 11 and second grip surface 10, the first and second grip surfaces 11, 10 being opened to accommodate the object, by thumb pressure pulling action on the thumb grip portion 15 against the resilient force of the spring 12. The object may then be securely gripped by turning the handle member 2 in a clockwise direction <br><br>
(in Figure 1) so that the distance between the first and <br><br>
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surfaces 11, 10 tends to reduce. Since the movable jaw member 3 is pivotally attached to the handle member 2, an object to be gripped may be easily caught in the beak shape portion of the movable jaw member 3 and then gripped as the handle member 2 moves relative to the movable jaw member 3, bringing the second grip surface 10 towards the first grip surface 11. Turning the handle member 2 in an anti-clockwise direction (in Figure 1) results in the fixed jaw 5 turning relative to the movable jaw member 3 so that the distance between the first and second grip surfaces 11, 10 tends to increase, thereby releasing a grip on an object being gripped. The wrench 1 may then be removed from the object, or may be again turned clockwise to turn the object being gripped. <br><br>
I believe the advantages of my invention to be as follows, however it should be appreciated that all such advantages may not be realised on all embodiments of the invention, and the following list is therefore given by way of example, as being indicative of potential advantages of the present invention. Furthermore, it is not intended that the advantages of the present invention be restricted to those of the list which follows: - <br><br>
1. The wrench may be easily used for tightening/loosening nuts or gripping rod like members. Since the wrench releases the grip with reverse rotation, an object may be easily turned with successive clockwise, anti-clockwise movements of the wrench, without the need to disengage the wrench from the object being turned. <br><br>
2. The grip surfaces may be easily formed as smooth angled surfaces for use as a spanner in tightening/loosening nuts so that the surface of the nut is not damaged but the grip capability is not :—J <br><br>
3. The provision of a thumb grip enables the wrench to be used easily with one hand. Furthermore, the design is particularly suitable for precision type wrenches for use on objects which may be damaged by conventional type wrenches. <br><br>
4. Since the movable jaw member is able to pivot about the handle member, the object to be gripped may be easily caught in the beak section of the movable jaw member and then gripped by turning the handle member. The wrench is thus ideal for one handed operation in situations where accessibility is limited. <br><br>
Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims. <br><br>
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