Loose wheel nut indicator

Apparatus for visually indicating a loose wheel nut on a motor vehicle has a first ring for engaging a first wheel nut so as to be rotatable therewith and a second ring for engaging a second wheel nut adjacent to the first wheel nut so as to be rotatable therewith. The first ring has a first pointer for indicating a start position of the first ring, and the second ring has a second pointer for indicating a start position of the second ring. A resiliently flexible elongate member interconnects the first and second rings. The elongate member is configured to curve in at least two directions and has a first end portion connected to the first ring and an opposed second end portion connected to the second ring. In use, any loosening rotation of the first wheel nut will cause the first ring and is pointer to rotate therewith, thereby providing a visual indication of a loosening of the first wheel nut.

TECHNICAL FIELD

The present invention relates to a loose wheel nut indicator and, in particular, to an apparatus for visually indicating a loose wheel nut of a road motor vehicle. More particularly, the present invention relates to such an apparatus which may also be used to prevent any loosening of a wheel nut which is adjacent to the loose wheel nut, such that any further loosening of the loose wheel nut is restrained.

BACKGROUND ART

Road motor vehicles commonly have disc wheels which are held onto a hub of an axle by a plurality of wheel nuts, usually six, eight or ten in number, that are adapted to be threadably engaged to a corresponding number of studs equally spaced in a circle around the hub flange. The studs pass through holes in the wheel, and the wheel is secured to the hub by screwing the nuts tightly onto the studs to the correct torque.

However, the wheel nuts may loosen over time due to continuous or prolonged vibration of the vehicle and its front and rear axles. This problem may be particularly pronounced in heavy road motor vehicles and many other commercial road vehicles, which may have a larger number of axles, more than one wheel held onto each hub thereof, and very large and heavy wheels which make tightening of the nuts relatively difficult.

The tendency for wheel nuts to loosen over time in all road motor vehicles may be accelerated by a number of factors. These include a failure to initially tighten the nuts to the correct torque, the fitting of an incorrect wheel nut, the regular overtightening of the nuts with automated tools that cause stretching and fatigue of the studs, and the “settling” of the wheel on the hub that may occur after a wheel change which causes the force of the nut on the hub to be reduced.

Loosening of the wheel nuts can have serious adverse consequences. If a wheel nut becomes loose while the vehicle is in motion, the wheel may experience an increased radial load which, if unchecked, can cause severe damage to the wheel itself and/or to the stud, hub and possibly even the nut. In extreme cases, the wheel nut may unscrew from its stud or the wheel may sever the stud due to excessive bending loads, causing the wheel to detach from the hub with potentially disastrous results.

There have been many and varied attempts to address these problems, most of which have met with little or no success.

One approach has involved finding ways of preventing wheel nuts from becoming loose.

Apart from maintaining regular inspection and, if required, correction of wheel nut tighteners, well known self locking nut systems have been developed which rely on an interference fit between the thread on the stud and the thread on the nut to create a lock which stiffens the rotation of the nut, either by a portion of the nut thread being deformed and providing a resistance during the threaded engagement, or by locating a nylon or other deformable insert within the threaded bore of the nut and through which the stud cuts the thread against a stiffening resistance.

A problem with self locking nut systems is that they are designed to operate at maximum locking effectiveness for one tightening cycle only and, if used more than once, will have markedly reduced locking capability. Furthermore, the self locking nut cannot be tightened quickly by hand in the initial stage of its threaded engagement with the stud because the lock stiffens the rotation of the nut, with the result being that a spanner or other tool is required also at the initial stage, thereby considerably lengthening the time it takes to tighten the wheel nut and hence attach the wheel to the hub. These problems and shortcomings may be unacceptable to many users given that a wheel nut may have to be removed many times during the life of a vehicle. Replacement of worn out or damaged nuts would also become very expensive.

Another approach has involved finding ways to visually indicate in a timely manner when a wheel nut becomes loose so that appropriate intervention can occur to retighten or replace the nut before serious damage results.

It is known to provide loose wheel nut indicators in the form of one piece polymeric rings or caps which are firmly clipped around or over an individual wheel nut and which include a pointed or arrowhead portion to visually indicate any loosening of the wheel nut by its unwanted rotation.

A problem with loose wheel nut indicators of the type described above is that the arrowhead portion needs to be pointing in a predetermined start direction and any indication of wheel nut loosening must require the identification of deviation from that initial direction. In many cases, loosening of a wheel nut that may lead to problems could result from a rotation of greater than about 5°, but for rotations from about 5° to up to about 20°, identification of such deviation may be very difficult to visually detect or may be missed altogether with the use of such one piece, clip on, pointed indicators.

Furthermore, these indicators operate on individual wheel nuts, and so any loosening of one nut is independent of the behaviour of any of the other nuts. Therefore, each indicator does not have any means of preventing any other nut from loosening or of restraining any further loosening of the already loosened nut.

Australian Innovation Patent No. 2010 101 053, now ceased, discloses a loose wheel nut indicator in the form of a cap or cover having a body that can closely fit over a tightened nut so as to be rotatable with the nut, and which includes a dial or other means that is rotatable relative to the nut for visibly indicating any loosening of the nut. This indicator is complex in its construction, requiring both a body and a dial which are separately manufactured, together with a complex structure for their cooperation with the nut, and furthermore operates only on individual nuts.

DISCLOSURE OF INVENTION

It is an object of the present invention to provide a loose wheel nut indicator that overcomes, or at least substantially ameliorates, the problems and shortcomings of the aforementioned prior art, or at least provides a useful alternative.

According to the present invention, there is provided an apparatus for visually indicating a loose wheel nut on a motor vehicle, comprising:(a) a first means for engaging a first wheel nut so as to be rotatable therewith and having a first pointer for indicating a start position of the first engaging means,(b) a second means for engaging a second wheel nut adjacent to the first wheel nut so as to be rotatable therewith, and having a second pointer for indicating a start position of the second engaging means, and(c) an elongate member which is resiliently flexible and which interconnects the first and second engaging means, the elongate member being configured to curve in at least two directions and having a first end portion and an opposed second end portion, wherein the first end portion is connected to the first engaging means and the second end portion is connected to the second engaging means, such that, in use, any loosening rotation of the first wheel nut will cause the first engaging means and its pointer to rotate therewith, thereby providing a visual indication of a loosening of the first wheel nut.

Preferably, the elongate member is configured such that any straightening of the elongate member caused by loosening of the first wheel nut will cause the elongate member to apply a compressive tension on the second engaging means, thereby countering any loosening rotation of the second wheel nut to prevent any loosening thereof.

Preferably, the elongate member is configured such that the compressive tension applied on the second engaging means will cause the elongate member to apply a compressive tension on the first engaging means, thereby countering any further loosening rotation of the first wheel nut to restrain any further loosening thereof.

It is preferred that each of the first and second engaging means is selected from the group consisting of rings, caps, loops and covers.

Each of the first and second engaging means may, in some preferred embodiments, be a ring having spaced apart transverse grooves formed on the inwardly facing surface of the ring so as to grip the wheel nut around its angled corners.

Alternatively, each of the first and second engaging means may be a cap having spaced apart transverse grooves formed on the inwardly facing surface of the cap so as to grip the wheel nut around its angled corners.

In a preferred form, the elongate member is configured to include the general shape of an inverted S.

Preferably, each of the first and second pointers comprises an arrowhead formed integrally with the respective engaging means.

According to another aspect of the present invention, there is provided a method for visually indicating a loose wheel nut on a motor vehicle, including the steps of:(a) providing a first apparatus and a second apparatus according to the present invention,(b) engaging the first apparatus and the second apparatus with respective adjacent first and second pairs of first and second wheel nuts, wherein the start position of each of the first and second engaging means indicated by the respective pointer is such that a first pointer of a first engaging means of the first apparatus points in a direction that is aligned with a direction of pointing of a second pointer of a second engaging means of the second apparatus, and(c) visually monitoring any rotation of the pointer of the first engaging means and/or the pointer of the second engaging means of each of the first and second apparatus to indicate a loosening of the respective wheel nut.

MODES FOR CARRYING OUT THE INVENTION

The apparatus10shown inFIGS. 1 and 2is to be used primarily for visually indicating a loose wheel nut on a road motor vehicle, but may also be used to prevent any loosening of an adjacent wheel nut which, in turn, may restrain any further loosening of the loose wheel nut.

The apparatus10has a pair of rings12,14for engaging around respective first and second wheel nuts which are adjacent to each other and arranged as a part of a conventional, equally spaced, circular arrangement of wheel nuts around the hub flange of a disc wheel. Alternatively, the apparatus10may have a pair of caps, loops, covers or other suitable means for engaging a pair of adjacent wheel nuts.

The rings12,14are rotatable with their respective wheel nut by having spaced apart transverse grooves16formed on their inwardly facing surface so as to grip the wheel nut around its angled corners. Such common rotation may alternatively be due to some other form of profile or shape on one or more inwardly facing surface of the wheel nut engaging means which creates the necessary grip, or due to the tightness with which the wheel nut engaging means grips the nut.

The rings12,14have a respective pointer18,20which indicates a start position of each ring. Each pointer18,20is, in this embodiment, in the shape of an arrowhead and is formed integrally with its ring. Alternatively, the pointer may be in the form of a barb or be otherwise wedge shaped, or may comprise some other form of visual indicator of a start position, such as a printed, grooved or embossed line.

The apparatus10also has an elongate member22which is made of a resiliently flexible material, such as polypropylene or a low density polyethylene (LDPE) or other suitable polymer material, and which interconnects the rings12,14.

In this embodiment, the elongate member22is formed integrally with the rings12,14, which are thus made of the same polymer material as the elongate member, such as by a plastic injection moulding process. Alternatively, the rings12,14may be made of a different material to the elongate member22and the separate components connected together under suitable heat and pressure conditions or by other suitable connecting means.

The elongate member22is configured to curve in at least two directions. In this embodiment, where the nut tightening direction is clockwise, this curved configuration of the elongate member22includes the general shape of an inverted S (similar to a reflected S) when the apparatus10is viewed in use (which view is from the positions used to show the apparatus inFIGS. 1 and 2). As best shown inFIG. 1, a central portion24of the elongate member22defines the general shape of an inverted S which is the predominant shape in the configuration of the elongate member22. As such, the central portion24curves in two directions with a single point or region of inflection26therebetween. There are shorter first and second curved end portions28,30of the elongate member22extending from respective opposite ends of the central portion24at which there are points or regions of inflection32,34. The curved end portions28,30are connected to the respective rings12,14. Each change in the direction of curvature in the configuration of the elongate member22is identified by the points or regions of inflection26,32,34.

In this embodiment, each of the first and second curved end portions28,30is connected to its respective ring12,14at a point and in a direction that is generally perpendicular to a line that is tangential to the point, although other suitable points and directions at which the curved end portions28,30are connected to the rings12,14are within the ambit of the invention, such as tangential directions.

In use, an apparatus10is engaged to each adjacent pair of wheel nuts on a disc wheel of a road motor vehicle.

The start position, in this instance of use, of each of the rings12,14indicated by the respective pointer18,20is such that the pointer18of the ring12of one apparatus points in a direction that is aligned with a direction of pointing of the pointer20of the ring14of an adjacent apparatus10.

Any loosening rotation of the first wheel nut will cause the ring12and its pointer18to rotate therewith, thereby providing a visual indication of a loosening of the first wheel nut. This will also cause the elongate member22to become straighter, and so provide a possible further visual indication of the loose first wheel nut.

This result will also arise in the course of use of the apparatus of the invention having any of the above described configurations of the elongate member interconnecting the first and second wheel nut engaging means.

Furthermore, the configuration of the elongate member22is such that any straightening of the elongate member22caused by loosening of the first wheel nut will cause the elongate member22to apply a compressive tension on the ring14, thereby countering any loosening rotation of the second wheel nut to prevent any loosening thereof.

Moreover, the configuration of the elongate member22is such that the compressive tension applied on the ring14will cause the elongate member22to apply a compressive tension on the ring12, thereby countering any further loosening rotation of the first wheel nut to restrain any further loosening thereof.

The apparatus40shown inFIGS. 3 and 4has the same use or purpose as the apparatus10, and is similar in structure and function to the apparatus10, and so like features are identified, and are to be understood, by reference to like numerals.

The apparatus40only differs structurally from the apparatus10by having a pair of cut-outs42,44formed on opposite sides of each pointer18,20, and by having a plurality of raised lines46or ribs formed on the upper surface of an upwardly projecting annulus portion48immediately surrounding the grooves16of each ring12,14. In this embodiment, there are twelve raised lines46which are equidistant and radially spaced apart from each other, but the number of such lines may vary.

The apparatus50and60, shown inFIGS. 5 to 8andFIGS. 9 to 12, respectively, have the same use or purpose as the apparatus10and40, and have some features which are like, or similar in structure and function to, features of the apparatus10and40. Like features are identified, and are to be understood, by reference to like numerals.

The apparatus50, shown inFIGS. 5 to 8in isolation and shown inFIGS. 13 to 16when engaged with a first pair of first and second wheel nuts, differs structurally from the apparatus10and40by having a pair of caps52,54for engaging around, and over the top of, respective first and second wheel nuts which are adjacent to each other. The top56of each cap52,54is slightly dome shaped.

The caps52,54of apparatus50, like the rings12,14of apparatus10and40, are rotatable with their respective wheel nut by having spaced apart transverse grooves16formed on their inwardly facing surface so as to grip the wheel nut around its angled corners.

The caps52,54have a respective pointer18,20at the upper ends thereof which indicates a start position of each cap. Each pointer18,20is formed integrally with its cap56.

The apparatus50also has an elongate member22which is made of a resiliently flexible material and which integrally interconnects the caps52,54at the upper ends thereof. The elongate member22of apparatus50is configured to curve in a similar way to that of apparatus10and40, and is connected at its opposed ends to the respective caps52,54in a similar way to that of apparatus10and40.

FIGS. 13 to 16show the apparatus50engaged in the manner described above with a first pair of first and second wheel nuts57,58which may be threadably engaged to corresponding studs arranged through a disc wheel of a road motor vehicle or the like.

The apparatus60shown inFIGS. 9 to 12differs structurally from the apparatus10and40, and is similar to the apparatus50, by having a pair of caps62,64. However, unlike the pair of caps52,54of apparatus50, the caps62,64of apparatus60have a respective top66which is shaped to resemble the top of a nut.

The caps62,64of apparatus60, like the rings12,14of apparatus10and40and like the caps52,54of apparatus50, are rotatable with their respective wheel nut by having spaced apart transverse grooves16formed on their inwardly facing surface so as to grip the wheel nut around its angled corners.

The caps62,64have a respective pointer18,20at the lower ends thereof which indicates a start position of each cap. Each pointer18,20is formed integrally with its cap.

The apparatus60also has an elongate member22which is made of a resiliently flexible material and which integrally interconnects the caps62,64at the lower ends thereof. The elongate member22of apparatus60is configured to curve in a similar way to that of apparatus10,40and50, and is connected at its opposed ends to the respective caps62,64in a similar way to that of apparatus10,40and50.

The use of each apparatus40,50and60can be readily understood by reference to the earlier description of the use of the apparatus10above and by substituting reference in that description to the rings12,14of apparatus10with reference instead to the rings or caps of each apparatus40,50and60.

By way of specific example,FIGS. 17 and 18show the use of apparatus40shown inFIGS. 3 and 4engaged to each adjacent pair of wheel nuts57,58on a disc wheel70of a road motor vehicle. For ease of reference, each of the above apparatus40shown inFIGS. 17 and 18is identified separately as apparatus40ato40e.

FIG. 17shows the start position of each apparatus40ato40e. In this instance of use, the pair of rings12,14of each apparatus40ato40ehas a start position indicated by the respective pointers18,20. The pointer18of the ring12of any one of the apparatus40ato40epoints in a direction that is aligned with a direction of pointing of the pointer20of the ring14of an adjacent one of the apparatus40ato40e.

FIG. 18shows that, with use, there has been a loosening rotation of the wheel nuts57,58to which apparatus40a,40band40eare each engaged. For example, the loosening rotation of the wheel nuts57,58to which apparatus40ais engaged has caused the rings12,14and their respective pointers18,20of that apparatus40ato rotate therewith, thereby providing a visual indication of a loosening of those nuts57,58. This has also caused the elongate member22of apparatus40ato become straighter, and so provide a further visual indication of the loose wheel nuts57,58.

The straightening of the elongate member22has also applied a compressive tension on the ring14, thereby countering any loosening rotation of the wheel nut58to prevent any further loosening thereof.

The compressive tension applied on the ring14has also caused the elongate member22to apply a compressive tension on the ring12, thereby countering any further loosening rotation of the wheel nut57to restrain any further loosening thereof.

It will also be readily apparent to persons skilled in the art that various modifications may be made in details of design and construction of the loose wheel nut indicators described above without departing from the scope or ambit of the invention.