WHEEL NUT LOCKS

The present invention relates to apparatus for use in inhibiting the unintentional loosening of nuts, and is especially, but not exclusively, related to apparatus for locking a pair of vehicle wheel nuts to prevent them from loosening during motion.

Many accidents have resulted from commercial vehicle wheels becoming detached from a vehicle. There are several reasons why a wheel may become detached while a vehicle is in motion, these include: a nut and stud/bolt becoming loose and/or breaking, incorrect torque setting of a nut (wheel loss can result from over tightening as well as insufficient tightening) and the use of incorrect and/or poor quality components.

In order to reduce the probability of accidents occurring there are a number of devices already known in the art which can be fitted to a vehicle wheel nut in order to prevent the nut from loosening and hence a wheel detaching from a vehicle.

GB 2330637, in particular, discloses a road wheel nut locking clip for a vehicle which prevents road wheel nuts from becoming loose as a result of vibration. The clip is comprised of a single component which fits onto a pair of adjacent wheel nuts. In order to fit a nut locking clip of this kind the nuts first have to be tightened to their correct specific torque setting, which may, of course, vary for a given vehicle. A consequence of tightening a nut to its optimum torque setting is the nut will have a fixed configuration which may not complement the configuration of the clip.

Therefore, in order to force the clip to fit a pair of adjacent wheel nuts it is necessary to either over-tighten or loosen one or more nuts which may result in a wheel becoming detached from the vehicle.

Other nut securing devices have been proposed - for example, Nylon ^® Insert Locknuts. Such a Locknut may have a Nylon insert on its thread engaging surface. In use, the nut is free spinning until the bolt enters the locking insert, at which time the bolt threads then become impressed into the Nylon. The Nylon insert exerts constant pressure against the threads of the bolt, thereby preventing the nut from rotating. However, it has been found that Nylon Insert Locknuts do not withstand severe vibration.

It is an object of this present invention to provide apparatus which overcomes, or at least substantially reduces, the disadvantages associated with known types of nut securing devices, for example those discussed above.

Accordingly, a first aspect of the invention provides apparatus for securing wheel nuts of a vehicle, the apparatus comprising a first part for engaging a first nut, a second part for engaging a second nut and a flexible elongate member to inter engage said first and second parts, wherein, in use and coupling the parts, the member is arranged to adopt a configuration having a greater degree of curvature than when not coupling the first and second parts.

A second aspect of the invention provides apparatus for preventing wheel loss due to vibration, the apparatus comprising a first part for engaging a first nut, a second part for engaging a second nut and a flexible elongate member, wherein said member causes said first and second parts, in use, to grip said respective first and second nuts.

A third aspect of the invention provides a two-part apparatus for securing wheel nuts of a vehicle, the apparatus comprising a first part for engaging a first nut, a second part for engaging a second nut and a flexible elongate member to inter engage the first and second parts, wherein the member is integrally formed with one of the first or second parts.

A fourth aspect of the invention provides apparatus for visually indicating that one or more of a pair of adjacent vehicle wheel nuts has become at least partially loose, the apparatus comprising a flexible elongate member for bridging the distance between said first and second nuts, wherein, in use, at least a portion of the flexible elongate member is adapted to adopt a first conformation when the nuts are both sufficiently tightened and a second conformation when at least one nut has at least partially loosened.

A fifth aspect of the invention provides a method of fitting apparatus for securing wheel nuts of a vehicle, the apparatus comprising a first part for engaging a first nut, a second part for engaging a second nut and a flexible member to inter engage said first and second parts, which method comprises:

■ preferably, inter engaging said first and second parts with the flexible member;

■ fitting said second part to said second nut or said first part to said first nut;

■ tensioning the member; and

■ fitting the other of said first or second part to the other of said first or second nut.

A sixth aspect of the invention provides a method for visually indicating that one or more of a pair of vehicle wheel nuts are secure, which method comprises:

■ preferably, tightening a pair of adjacent wheel nuts to their correct specific torque setting;

■ fitting apparatus comprising a flexible elongate member such that the member bridges the distance between said first and second nut and is adapted to adopt a first conformation when the nuts are both sufficiently tightened and a second conformation when at least one nut has come at least partially loose,

wherein said first and second conformations are visually distinguishable from each other thereby providing an indication that at least one of the nuts requires tightening. Preferably, the elongate member is formed integrally with the first or second part.

Preferably, the other of the first or second part is adapted to receive a portion of the member, in use.

Preferably, the elongate member is curved, in use.

Preferably, the elongate member is less curved, e.g. straight, when the first and second parts are uncoupled.

A locking means may be provided within said first part and/or said second part.

Preferably, a first locking means may be curved or, alternatively, it may be any other suitable shape.

Preferably, the first locking means comprises a pair of facing edges.

Preferably, at least one facing edge comprises serrations or other formations such as castellations or notches.

More preferably, at least one facing edge is straight or smooth-sided. Having at least one straight or smooth-sided edge allows parts of the apparatus to slide during assembly. The first or second part may comprise a body portion and said member extending therefrom. Preferably, the body portion has a neck. Preferably, the member extends from the neck. Alternatively, the member may be separate from the parts.

Preferably,, the member extends substantially tangentially from the body portion of the first or second part.

Preferably, the member extends from and is comprised of the same material as the body portion of the parts. Alternatively, the member may be made from any other suitable material, for example, spring wire.

Preferably, the member is twisted at a position adjacent the body portion of the first part. Alternatively, the member upstands from the body portion, for example, at right angles at the juncture between the member and the body portion.

Preferably, the member comprises a second locking means.

Preferably, the second locking means comprises a portion upstanding from the member.

Preferably, the portion extends orthogonally from a distal end of the member.

The portion may extend from a first or second major face of the member. The member may comprise more than one portion. Where the member comprises more than one portion, the portions may extend from the same or different faces of the member.

The portion may comprise at least one bearing face to engage the first locking means. Preferably, the at least one bearing face engages, in use, a serration, notch or castellation of the first locking means. Alternatively, the bearing face may abut a straight edged face of the first locking means.

The member may have a width of greater than 5mm and less than 20mm, say, between 6mm and 10mm, for example, 8 to 10mm.

Preferably, the member is flattened to approximately lmm thick.

The member may be formed to have variable stiffness along its length, for example, by having increased resilience in a centre portion.

Preferably, in use, the member causes said first and second parts to grip, e.g. bite into, said respective first and second nuts.

This may prevent wheel loss, for example, due to vibration.

The inner peripheral edge which defines the second aperture may be smooth sided and the first locking means may be provided by an alternative end form, for example a pin or a peg extending through a major face of the first or second part to provide a hook for a bearing face of the second locking means to engage. Preferably, the inner edge which defines the aperture of the first part and/or the second part is formed with gripping means, for example, castellations or serrations, preferably serrations.

More preferably, the gripping means bite into and grip the nut such that, in use, relative movement of said nut about its corresponding stud/bolt is inhibited.

The gripping means may have an internal angle of greater than 100° and less than 180°, say, between 120° and 160°, for example, 140°.

It is to be appreciated that the gripping means may be formed into any other suitable geometry or shape for effective gripping about the circumference of said nut. For example, the aperture of the first part and/or the aperture of the second part may be configured to match the shape of the circumference of the respective first and/or second nut.

The first part and/or the second part may comprise raised portions extending therefrom to facilitate fitting.

Alternatively, holes may be provided within the parts to accommodate a tool (not shown) for fitting and/or removal.

The raised portions may upstand from a major face of the first and/or second part. Preferably, the raised portions are made from the same material as the first part and/or the second part. Alternatively, they may be made from any other suitable material, for example a plastics material.

The raised portions may be located opposite each other around the periphery of the body of the first part and/or the second part. Alternatively, they may be fixed in any other suitable position.

The apparatus may be over-moulded with, for example, a sheath. The sheath may comprise one or more parts.

Preferably, the sheath provides an indication that the wheel nuts are locked and secure.

Preferably, the sheath is moulded over the member portion of the apparatus.

Alternatively, the sheath may be clipped onto the apparatus.

The sheath may be a plastics material, or it may be formed from any other suitable material, for example, a polymeric material or any other suitable deformable elastics material.

Preferably, the sheath is highly visible, for example, it may be fluorescent.

Alternatively, the apparatus may be used in conjunction with other known indicator devices. The apparatus may be fitted for use on a right handed screw thread nut and bolt assembly. Alternatively, the apparatus may be fitted for use on a left handed screw thread nut and bolt assembly.

Preferably, the apparatus allows for any configuration of nut torque to be accommodated.

More preferably, it is not necessary to deviate from the optimum torque setting of a vehicle wheel nut in order to accommodate the apparatus.

Preferably, the first part and/or the second part are stamped from thin gauge spring steel or other suitable material.

Preferably, the steel has a gauge of greater than 0.5mm and less than 5mm, say, between 1 and 3mm, for example, 2mm.

Preferably, the first part and/or the second part are substantially planar.

Preferably, the first part and/or the second part are freely detachable from each other when not in use.

The parts may be substantially circular in shape.

Preferably, one of the parts is substantially D-shaped. Preferably, tension provided within the member causes the first part and/or the second part to resist loosening of said first and second nuts, in use.

The apparatus may be reused.

Preferably _. , reuse is effected by disengaging the first and second locking means and releasing the tension within the member.

It is considered good practice to re-torque vehicle wheel nuts after, say, the first 20 miles of use and then periodically thereafter.

Therefore, advantageous features of the apparatus include the ability to accommodate different nut orientations when fully torqued and for enabling re-torquing after installation without having to remove completely the apparatus from the wheel nuts. These features can be achieved by adjusting the location of a bearing face of the member to an alternative serration or notch of the first locking means. A smooth-sided facing edge enables the parts to slide efficiently during such an adjustment.

It is to be appreciated that two or more apparatus as described herein can be employed for use on a vehicle wheel to effectively lock and prevent relative movement of the wheel nut and bolt assemblies in order to prevent a vehicle wheel detaching from a vehicle.

It is to be appreciated that the apparatus described herein is not limited to use on vehicle wheels. The apparatus may be used to prevent nut loss in situations where nut and bolt/stud assemblies are vulnerable to mechanical movement, for example, washing machines or other machinery susceptible to vibration.

Furthermore, the apparatus may be suitable for use in securing any nut subject to vibration, for example, on rail, track or trackside machinery. Examples of use may include securing nuts for fixing railway lines to one another or for fixing railway sleepers to railway lines. Other uses may include pressure vessels, generators and so on.

In order that the invention may be more fully understood, a preferred embodiment of apparatus according to the present invention will now be described by way of example only and with reference to the accompanying drawings in which:

Figure 1 is a side view of the apparatus, in use, according to the present invention;

Figure 2 is a side view showing details of the elongate member of the first part engaging the first locking means of the second part before tensioning;

Figure 3 shows a view along line YY of the apparatus of Figure 2; Figure 4 shows a view along the line ZZ of the apparatus of Figure 2;

Figure 5 shows an alternative embodiment of the apparatus of Figure 1;

Figure 6 and Figure 7 show blanks of the alternative embodiment of Figure

5;

Figure 8 is a side view of apparatus of a further embodiment according to the present invention; Figure 9 is a side view of apparatus of a yet further embodiment according to the present invention;

Figure 10 shows an alternative member which can be used with any embodiment of the present invention; Figure 11 is a side view of apparatus of another embodiment according to the present invention;

Figure 12 is a schematic showing the forces acting on first and second parts; and Figure 13 is a graph showing measured vibration test data.

Referring now to Figure 1, there is shown apparatus 1 suitable for securing wheel nuts of a vehicle.

The apparatus 1 is comprised of two parts: a first part 2 and a second part 3, both parts 2, 3 being freely detachable from each other when not in use.

The first 2 and second 3 parts are stamped from a piece of sheet material, for example, sheet metal or any other suitable material.

The first part 2 comprises a body portion 22 and an elongate member 23 extending therefrom. The body portion 22 is substantially circular in shape and comprises an aperture 21 suitably sized and dimensioned to receive a first nut 100 of a nut and stud/bolt 101 assembly 100, 101, for example a nut and stud/bolt assembly 100, 101 for securing a vehicle wheel to a vehicle. The inner edge of the body portion 22 defines the aperture 21 of the first part 2 and is formed with gripping means 24, for example serrations.

Extending from the body portion 22 is an elongate member 23. The member 23 extends, preferably substantially tangentially, from the body portion 22.

The member 23 has a twist 27 at a location adjacent the body 22 of the first part 2 by an angle of approximately 90° to form a leaf spring.

It is to be appreciated that Figure 1 is a view from the side of the apparatus 1. Accordingly, the elongate member 23 has a top facing first major surface 23a and a bottom facing second major surface 23b.

The distal end of the elongate member 23 has second locking means in the form of a portion 28 extending therefrom. The portion 28 will be discussed in further detail in relation to Figures 2 to 4.

The body portion 22 of the first part 2 has two raised portions 26 extending therefrom. The raised portions 26 extend orthogonally from a major face of the first part 2 and are located opposite each other.

The second part 3 of the apparatus 1 is substantially D-shaped and comprises an aperture 31 suitably sized and dimensioned to receive a second nut 102 of a nut and stud/bolt assembly 102, 103. The inner edge which defines the aperture 31 of the second part 3 is formed with gripping means 34, for example serrations.

The second part 3 comprises a second aperture 37. The second aperture 37 is substantially linear and has a length defined by a pair of facing edges: a first edge 37a and a second edge 37b. The second aperture 37 provides a first locking means 33, for example serrations or other formations such as notches, formed along the first and second edges 37a, 37b.

The second part 3 has two raised portions 36 extending therefrom. The raised portions 36 extend orthogonally from a major face of the second part 3 and are located opposite each other.

Figures 2, 3 and 4 show the securing mechanism between the elongate member 23 of the first part 2 and the first locking means 33 of the second part 3 in further detail.

It is to be appreciated that Figures 2, 3 and 4 each show the apparatus 1 in loose configuration prior to tensioning the elongate member 23.

As can be seen from Figure 2 the portion 28, which is shown passing through the second aperture 37 of the second part 3 (indicated by the dotted lines), has a first bearing face 28a and a second bearing face 28b. Figures 3 and 4 each show the portion 28 extending from a second major surface 23b of the elongate member 23. The portion 28 has a length 28c which is comparatively shorter than the length of the elongate member 23. In order to assemble the apparatus 1, two adjacent wheel nuts 100, 102 are first tightened to their correct specific torque setting.

The two parts 2, 3 are loosely assembled by engaging the elongate member 23 of the first part 2 with the first locking means 33 of the second part 3. Figures 2, 3 and 4 show the loose assembly of the apparatus 1 in detail. It can be seen that the portion 28 extends through the second aperture 37 of the second part 3. The first bearing face 28a engages a notch of the lower facing edge 37a of the first locking means 33. The second bearing face 28b engages a notch of the upper facing edge 37b of the first locking means 33.

The second part 3 is then mounted onto the second nut 102 such that the nut 102 fits snugly within the aperture 31.

The first part 2 is rotated by a few degrees about the bolt 101 to introduce tension within the elongate member 23 before being mounted onto the first nut 100 such that the nut 100 fits snugly within the aperture 21. The first part 2 is rotated clockwise when the apparatus 1 is installed on a right-handed screw thread and anticlockwise when installed on a left-handed screw thread.

The parts 2, 3 are urged clockwise when applied on right-handed screw threads in order to resist the nuts 100, 102 from unwinding. Alternatively, when applied on left-handed screw-threads, the parts 2, 3 are to be urged anticlockwise in order to prevent the nuts 100, 102 from unwinding. For simplicity, the remainder of the specification will assume a right-handed screw thread nut and bolt assembly. This does not in any way limit the invention to right-handed screw threads.

In order to assemble (or disassemble) the apparatus 1 with relevant ease the raised portions 26, 36 can be handled by the user (not shown). However, the apparatus 1 is designed to allow for re-torquing after installation without having to completely remove the apparatus 1 from the wheel nuts 100, 102. It is to be appreciated that tension within the member 23 will vary during re-torque, Therefore, in order to maintain an effective amount of tension within the member 23 a bearing face 28a, 28b of the member 23 can be adjusted to an alternative serration or notch of the first locking means.

In use, (i.e. after introducing tension), the member 23 adopts a curved configuration. The resultant force acting to straighten the member 23 is shown by the arrow A ₌ As a consequence of the resultant force A, the peripheries of the member tend to move in the direction indicated by the arrows B.

Assuming that the nut and bolt configuration is of a standard right-handed screw thread, the overall effect of the apparatus 1 is to impart a torque in the clockwise direction which, in effect, inhibits the nuts 100, 102 from unwinding.

In use, the act of loosening the first and/or second nut 100, 102 is to increase tension in the elongate member 23 which, in turn, resists further loosening by causing a tightening torque on the nut 100, 102. As shown in Figure 1, the apparatus 1 comprises a sheath 10 which substantially covers the elongate member 23. The sheath 10 is used as a visual aid in order to examine the position of the apparatus 1 when installed onto a nut and bolt assembly 100, 101; 102, 103 and can provide an early indication that a nut has loosened.

Referring now to Figure 5, there is shown a second embodiment of apparatus according to the present invention, wherein parts of the apparatus similar to those of the first embodiment are given the same number but are denoted with a prime ( ^' ).

The apparatus 1' is comprised of two parts: a first part 2' and a second part 3', both parts 2', 3' being freely detachable from each other when not in use.

The first 2' and second 3' parts are stamped from a piece of sheet material, for example, sheet metal or any other suitable material A blank to be formed into each part of the apparatus is shown respectively in Figure 6 and Figure 7.

The first part 2' comprises a body portion 22' and an elongate member 23' extending therefrom. The body portion 22' is substantially circular in shape and comprises an aperture 21' suitably sized and dimensioned to receive a nut of a nut and bolt assembly, for example a nut and bolt assembly for securing a vehicle wheel to a vehicle.

The inner edge of the body portion 22' defines the aperture 21' of the first part 2' and is formed with gripping means 24', for example serrations. Extending from the body portion 22' is an elongate member 23'. The member 23' extends, preferably substantially tangentially, from the body portion 22'. At the juncture of the member 23' and the body portion 22', the member 23' upstands from the body portion 22' at right angles thereto. Therefore, the elongate member 23' has a first major surface 23a' and a second major surface 23b'.

The distal end of the elongate member 23' has second locking means in the form of a portion 28' extending therefrom. The portion 28' upstands from the second major surface 23b' of the elongate member 23'.

The body portion 22' of the first part 2' has two raised portions 26' extending therefrom. The raised portions 26' extend orthogonally from a major face of the first part 2' and are located opposite each other.

The second part 3' of the apparatus 1' is substantially D-shaped and comprises an aperture 31' suitably sized and dimensioned to receive a nut of a nut and bolt assembly.

The inner edge which defines the aperture 31' of the second part 3' is formed with gripping means 34', for example serrations.

The second part 3' comprises a second aperture 37'. The second aperture 37' is substantially linear and is defined by a pair of facing edges: a first edge 37a' and a second edge 37b'. The second aperture 37' provides the first locking means 33', for example serrations or other formations such as notches, formed along the first edge 37a'. The second edge 37b' is a smooth-sided straight edge.

The second part 3' has two raised portions 36' extending therefrom. The raised portions 36' extend orthogonally from a major face of the second part 3' and are located opposite each other.

The apparatus 1' is assembled in a similar way to the apparatus 1 of the earlier embodiment of the invention.

In this embodiment, however, the first major surface 23a' of the elongate member 23' engages the upper facing straight edge 37b' of the first locking means 33' where it provides an abutment. A bearing face 28a' of the portion 28' engages a notch of the lower facing edge 37a' of the first locking means 33'.

In use, (i.e. after introducing tension), the member adopts a substantially curved configuration. The resultant force acting to straighten the member is shown by the arrow A'. As a consequence of the resultant force A', the peripheries of the member tend to move in the direction indicated by the arrows B'.

Assuming that the nut and bolt configuration is of a standard right-handed screw thread, the overall effect of the apparatus 1' is to impart a torque in a clockwise direction which, in effect, inhibits the nuts 100, 102 from unwinding. In effect, tension within the elongate member imparts a rotating moment on the first and second parts T ₁ 3' of the apparatus which, in turn, causes the parts 2', 3' to "bite" into their respective nuts (not shown).

In use, the act of loosening the first and/or second nut (not shown) is to increase tension in the elongate member 23' which, in turn, resists further loosening by causing a tightening torque on the nut.

Referring now to Figure 8 there is shown apparatus 1000 of an alternative embodiment according to the present invention.

The apparatus 1000 is shown in use.

The apparatus 1000 is comprised of a first part 1001, a second part 1002 and a flexible elongate member 1003.

The parts 1001, 1002 are substantially D-shaped and comprise an aperture 1004 suitably sized and dimensioned to receive a nut 100, 102 of a nut and stud/bolt assembly 100, 101; 102, 103.

The inner edge which defines the aperture 1004 of the part 1001, 1002 is formed with gripping means 1005, for example serrations.

The parts 1001, 1002 comprise a second aperture 1006. The second aperture 1006 is substantially linear and is defined by a pair of facing edges: a first facing edge 1006a and a second facing edge 1006b. The second aperture 1006 provides the first locking means 1007. The first facing edge 1006a is serrated and the second facing edge 1006b is straight.

The parts 1001, 1002 have two raised portions 1008 extending therefrom. The raised portions 1008 project orthogonally from a major face of the parts 1001, 1002 and are located opposite each other.

The apparatus 1000 comprises a flexible elongate member 1003 which is freely detachable from both parts 1001, 1002. The member 1003 is preferably formed from thin gauge spring steel in order to function as a leaf spring.

Each end of the member 1003 comprises second locking means in the form of a portion 1009 which extends orthogonally from the member 1003. The portions 1009 extend orthogonally from opposite faces of the member 1003.

As can be seen from Figure 8 _? the portions 1009, which are shown passing through the second apertures 1006 of the respective parts 1001, 1002 (represented by the dotted lines), each have a bearing face 1009a suitable for engaging the serrations or notches of the first facing edge 1006a of the first locking means 1007.

In order to assemble the apparatus 1000, two adjacent wheel nuts 100, 102 are first tightened to their correct specific torque setting.

The two parts 1001, 1002 are loosely assembled by engaging a first portion 1009 of the elongate member 1003 with the first locking means 1007 of a first part (1001 or 1002) and a second portion 1009 with the first locking means 1007 of the other part (1001 or 1002). The bearing face 1009a of the portion 1009 engages a notch of the first facing edge 1006a of the first locking means 1007.

The two parts 1001, 1002 are positioned adjacent one another and urged together to introduce tension within the flexible elongate member 1003 (as shown in Figure 8). Each part 1001, 1002 is then mounted onto its respective nut 100, 102 such that the nut 100, 102 fits snugly within the aperture 1004.

When assembled, the second facing edge 1006b provides an abutment which prevents the elongate member 1003 from straightening. The elongate member 1003 adopts a substantially S-shaped configuration. The resultant forces acting to straighten the member are shown by the arrows F. As a consequence of the resultant forces F, the peripheries of the member tend to move in the direction indicated by the arrows G.

Assuming that the nut and bolt configuration is of a standard right-handed screw thread, the overall effect of the apparatus 1000 is to impart a torque in the clockwise direction which, in effect, inhibits the nuts 100, 102 from unwinding.

In effect, tension within the elongate member 1003 imparts a rotating moment on the parts 1001, 1002 which in turn cause the parts 1001, 1002 to "bite" into their respective nuts 100, 102. In order to improve the ease of assembling such apparatus 1000, the elongate member 1003 may be formed with increased resilience in its centre portion. In this case each end portion of the member 1003 retains its spring-like features.

Figure 8 shows an embodiment of the apparatus wherein each portion 1009 extends orthogonally from opposite faces of the elongate member 1003. In an alternative embodiment of the invention, the portions 1009 may extend orthogonally from the same face of the elongate member 1003.

As in the embodiment shown in Figure 1, the apparatus 1000 of Figure 8 may comprise a sheath (not shown) which substantially covers the elongate member 1003. The sheath is used as a visual aid in order to examine the apparatus 1000 when installed onto a nut and bolt assembly 100, 101; 102, 103 and can provide an early indication that a nut has become loose.

Referring now to Figure 9,- there is shown a further embodiment of apparatus according to the present invention, wherein parts of the apparatus similar to those of the first embodiment are given the same number but are denoted with a double prime ( ^" ).

The apparatus 1" is comprised of two parts: a first part 2" and a second part 3", both parts 2", 3" being freely detachable from each other when not in use.

The first 2" and second 3" parts are stamped from a piece of sheet material, for example, sheet metal or any other suitable material. The first part 2" comprises a body portion 22" and an elongate member 23" extending therefrom. The body portion 22" is substantially circular in shape and comprises an aperture 21" suitably sized and dimensioned to receive a nut of a nut and bolt assembly, for example a nut and bolt assembly for securing a vehicle wheel to a vehicle.

The inner edge of the body portion 22" defines the aperture 21" of the first part 2" and is formed with gripping means 24", for example serrations.

Extending from the body portion 22" is an elongate member 23". The member 23" extends, preferably substantially tangentially, from the body portion 22". At the juncture of the member 23" and the body portion 22", the member 23" upstands from the body portion 22" at right angles thereto. Therefore, the elongate member 23" has a first major surface 23a" and a second major surface 23b".

The distal end of the elongate member 23" has second locking means in the form of a portion 28" extending therefrom. The portion 28" extends orthogonally from the first major surface 23a" of the elongate member 23".

The body portion 22" of the first part 2" has two raised portions 26" extending therefrom. The raised portions 26" extend orthogonally from a major face of the first part 2" and are located opposite each other. The second part 3" of the apparatus 1" is substantially D-shaped and comprises an aperture 31" suitably sized and dimensioned to receive a nut of a nut and bolt assembly.

The inner edge which defines the aperture 31" of the second part 3" is formed with gripping means 34", for example serrations.

The second part 3" comprises a second aperture 37". The second aperture 37" is substantially linear and is defined by a pair of facing edges: a first edge 37a" and a second edge 37b". The second aperture 37" provides the first locking means 33", for example serrations or other formations such as notches, formed along the second edge 37b". The first edge 37a" is a smooth-sided straight edge.

The second part 3" has two raised portions 36" extending therefrom. The raised portions 36" extend orthogonally from a major face of the second part 3" and are located opposite each other in an offset fashion.

The apparatus 1" is assembled in a similar way to the apparatus 1 of the earlier embodiment of the invention.

However, in this embodiment the portion 28" extends from the first major surface 23a" of the elongate member 23". A bearing face 28a" of the portion 28" engages a notch of the second facing edge 37b" of the first locking means 33".

In use, (i.e. after introducing tension), the member adopts a substantially S-shaped configuration. The resultant forces acting to straighten the member are shown by the arrows A". As a consequence of the resultant forces A", the peripheries of the member tend to move in the direction indicated by the arrows B".

Assuming that the nut and bolt configuration is of a standard right-handed screw thread, the overall effect of the apparatus 1" is to impart a torque in a clockwise direction which, in effect, inhibits the nuts 100, 102 from unwinding.

It is to be appreciated, as with all embodiments of this invention, that the apparatus will have the same advantageous effect when applied to left-handed screw threads. This is achieved by reversing the apparatus.

Referring now to Figure 10, there is shown an alternative elongate member 200 which may be used with any embodiment of the present invention.

The member 200 possesses the same flexible properties as previously discussed.

The distal end of the member 200 is formed into a key 201 with a guide edge 203 and notches 202 formed therein. The notches 202 provide a means for engaging the facing edges of the first locking means, for example a notch or serration (see Figures 1 to 6, 8 and 9).

In use, the guide edge 203 is passed through the second aperture of the adjacent part (see Figures 1 to 6, 8 and 9) so that the notches 202 can engage the upper and lower facing edges of the first locking means. It is to be appreciated that the alternative member shown in Figure 10 has the same effect as the elongate member described throughout this specification.

Referring now to Figure 11, there is shown a further embodiment of apparatus according to the present invention, wherein parts of the apparatus similar to those of the first embodiment are given the same number but are denoted with a triple prime ('").

Only features of the apparatus 1"' that differ substantially from the features of previous embodiments will be discussed herein.

The body portion 22'" of the first part 2'" has a neck 50'" which has formed at a distal end thereof an elongate member 23'". At the juncture between the member 23'" and the neck 50'", the member 23'" upstands from the neck 50'", for example at right angles thereto. The elongate member 23'" has a first major surface 23a'" and a second major surface 23b'" which enables the member 23'" to function as a leaf spring.

The second part 3'" comprises a second aperture 37"'. The second aperture 37'" is substantially linear and is defined by a pair of facing edges: a first facing edge 37a'" and a second facing edge 37b'". The second aperture 37'" provides first locking means 33'", for example serrations or other formations such as notches, formed along the first edge 37a'". The second edge 37b'" is a smooth-sided edge. As will be appreciated, the elongate member 23'" is substantially shorter than the elongate members 23, 23', 23", and 1003 of previous embodiments.

In use therefore the aperture 37'" of the second part 3"' is rotated so that it is closer to the first part 2"' than in any previous embodiment. In effect, this brings the first 33'" and second 28'" locking means (i.e. the aperture 37'" and the upstanding portion 28'") closer to one another for inter engagement.

Without wishing or intending to be bound by any theory, by having the parts 2'",

3'" in this orientation with respect to one another it is considered that the forces acting on the nuts 100'", 102'" by the parts 2'", 3'" are more direct and may be increased.

The forces are shown diagrammatically in Figure 12.

Assuming a standard right-handed nut and bolt assembly, the arrows A'" indicate the direction in which a nut 100"', 102'" is tightened onto a bolt (not shown). Similarly, the arrows B'" indicate the direction in which a nut 100'", 102'" is loosened from a bolt, e.g. as a consequence of mechanical vibration. Again, without wishing or intending to bound by any theory, the Applicant considers that the loosening of either nut 100'", 102'" is maximally resisted if a bridge is provided between the two points C" of parts 2'", 3'".

In other words, a loosening torque B'" on nut 102'" will transmute via points C" to a tightening torque A'" on nut 100'". However, because bolt 100'" is maximally tightened to its optimal torque setting, bolt 100'" will resist loosening of bolt 102'" by imparting a tightening torque A'" on bolt 102'". This applies vice versa.

Referring now to Figure 13 there is shown a graph which shows measured vibration test data of a M8 x 1 mm pitch bolt configuration when subjected to the Junkers test. The Junkers test is a transverse vibration test well known to those skilled in the art of engineering, therefore the test and its apparatus will not be discussed in any great detail.

Referring now the graph, the x-axis indicates the number of transverse cycles and the y-axis indicates the retained clamp load between the nut and the bolt. Decay X is a plot of load vs number of cycles where apparatus 1'" of the present invention is used; Decay Y is a plot of load vs. number of cycles where a Nylon Insert Locknut is used; and decay Z is a plot of load vs. number of cycles where a nut and bolt with no securing means is used.

Before each experiment the clamping force of the nut and bolt was set by tightening until loaded with 15 kN. Each nut and bolt configuration was then subjected to 2000 transverse cycles of the Junkers Test.

As can be seen, the apparatus 1'" (decay X) outperformed both the Nylon Insert Locknut (decay Y) and nut and bolt with no securing means (decay Z).

In particular, after 2000 cycles the nut and bolt secured with the apparatus 1'" had a retained clamping force of 8 kN (i.e. the nut and bolt were still tight).

Conversely, the Nylon Insert Nut configuration had plateaued at approximately 0.5 kN after 400 cycles, indicating that the nut and bolt had become loose. Finally, the nut and bolt having no securing means had detached from one another after approximately 400 cycles.

Visual inspection of the nuts during each test showed that the Nylon Insert Nut and the nut having no securing means were rotating (loosening) about the bolt. Conversely, the nut secured with the apparatus of the present invention did not rotate about the bolt.