WO2008122079A1

WO2008122079A1 - Nut rotation indicator

Info

Publication number: WO2008122079A1
Application number: PCT/AU2008/000487
Authority: WO
Inventors: Roy Neil Mchutchinson
Original assignee: Intellec Development Group Pty Ltd
Priority date: 2007-04-04
Filing date: 2008-04-04
Publication date: 2008-10-16
Also published as: AU2008235250A1

Abstract

A nut rotation indicator (11) comprising a body (12) having a pair of opposed arms (15,16) and an indicating element to provide a visual indication of the rotational position of the body (12), wherein the arms (15, 16) are adapted in use to be clamped into engagement with a nut.

Description

"NUT ROTATION INDICATOR"

Field of the Invention

This present invention relates to an indicator of rotational movement of a nut. The invention is particularly suited for use upon the wheel nuts of large transport and haulage vehicles. However, the invention is not limited to this application and is useful in many other situations where loosening of nuts is a problem.

Background to the Invention

There are many applications where nuts may tend to loosen during use. A particular example is retaining nuts of wheels of large transport/haulage vehicles, such as road trains and mining site haulage vehicles. This loosening is present on these vehicles in particular because of the loads placed upon the wheel studs which results in a substantial variation in strain in the stud as the wheel rotates over rough ground. In other applications loosening results from continual vibration imposed upon the nut.

In the case of transport and haulage vehicles, the loosening can lead to catastrophic failure. Although each wheel is secured by many studs and nuts, so that if one nut is loosened the wheel load will be distributed over the remaining studs/nuts, in fact the effect is more serious than is at first apparent. Under high loads, and particularly over rough ground, the dynamic load is not necessarily shared evenly over all studs/nut. If one nut loosens, the adjacent studs share a substantially greater portion of the additional load for a portion of the rotational cycle. This higher loading upon adjacent studs/nuts can increase the likelihood of loosening of nuts on adjacent studs. If one adjacent nut loosens under this increased loading to provide two adjoining loose nuts, then an even higher loading will be placed upon the next adjacent nut. It will be appreciated that with each additional nut coming loose, it increases the likelihood of further nuts loosening. In addition, if several nuts are loosened, then the stress upon the next stud is raised to a level that may lead to breakage of the stud. Rapidly after that the wheel will be torn from the vehicle as the remaining studs fail. Of course this is a major safety hazard as well as being an expensive breakdown.

This problem is sufficiently serious that many operators have introduced preventative maintenance procedures. Maintenance personnel are instructed to loosen and retighten all nuts on all wheels on a frequent basis - even daily. This in itself becomes an onerous task due to the number of nuts to be tightened and the effort required with the large sized "rattle guns" (pneumatic impact drives) that must be used. It has been found that operators will often merely apply the "rattle gun" to tighten the nuts only, rather than loosening them first. This can readily lead to certain of the nuts being over-tightened leading to a consequent failure of the nut and/or stud, and then to loss of the wheel.

Previous attempts have been made to identify visually whether a nut has rotated during use from its initial tightened position. However, these methods have not proved successful. Markings on the nut quickly become covered by mud and so are ignored. Moulded nut "caps" have been tried but have been found to loosen rapidly in use and then fall off.

References to prior art in this specification are provided for illustrative purposes only and are not to be taken as an admission that such prior art is part of the common general knowledge in Australia or elsewhere.

Summary of the Invention

According to the present invention, there is provided a nut rotation indicator comprising a body having a pair of opposed arms and an indicating element to provide a visual indication of the rotational position of the body, wherein the arms are adapted in use to be clamped into engagement with a nut. Preferably, the opposed arms comprise a first arm and second arm pivotally connected at first ends thereof. The first and second arms in a preferred embodiment are flexible such that pivotal movement of the first and second arms relative to each other is via the first and second arms flexing about the joined first ends.

In a preferred embodiment, the joined first ends of the first and second arms are tapered to a point and the point comprises the indicating element.

Preferably, the first arm comprises a first diverging portion extending away from the first end thereof and a first arcuate portion extending from the first diverging portion, the second arm comprises a second diverging portion extending away from the first end thereof and a second arcuate portion extending from the second diverging portion and the nut is clamped between the first and second arcuate portions by pivoting of the first arm towards the second arm.

The inner surfaces of the first and second arcuate portions preferably include teeth to engage with external surfaces of the nut.

In a preferred embodiment, the nut rotation indicator further comprises: a strap; a first aperture in the first arm; and a second aperture in the second arm; wherein when the strap is passed through the first aperture, through the second aperture and tensioned to pull the first and second arms towards each other to clamp the nut.

Preferably, the strap extends outwardly from the outer end of the second arm and an engagement means is provided on second arm to engage with the strap for tensioning of the strap after the strap has passed through the second aperture. Preferably, the engagement means comprises a tang in the second aperture which engages with serrations on the strap such that the strap can be pulled through the second aperture and the tang engages with the serrations on the strap to prevent the strap passing back through the second aperture.

Preferably, an outer surface of the arcuate portion of the first arm is provided with a channel which receives the strap. An outer surface of the second arcuate portion is also preferably provided with a channel such that the strap, after passing through the second aperture is received in the channel on the second arcuate portion. A retaining member may be provided adjacent an outer end of the second arm such that the strap is passed through the retaining member.

In one embodiment, the channels are defined by pairs of walls extending along the outer surfaces of the first and second arms. The walls on the second arm are preferably provided with aligned holes for receiving a key having a slotted end such that when the slotted end is inserted into the holes, the strap is engaged in the slot and rotation of the key pulls the strap through the second aperture, thereby tensioning the strap and pulling the first arm towards the second arm.

The tang is preferably provided with a release arm such that movement of the release arm disengages the tang from the strap.

In a further embodiment, the strap is provided as a separate member having a buckle at one end to receive the other end such that pulling the end through the buckle tensions the strap.

Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. Likewise the word "preferably" or variations such as "preferred", will be understood to imply that a stated integer or group of integers is desirable but not essential to the working of the invention. Brief Description of the Drawings

The nature of the invention will be better understood from the following detailed description of preferred embodiments of the nut rotation indicator, given by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is an isometric view of the first embodiment of a nut rotation indicator and associated key; Figure 2 is a sectional view of the embodiment of the nut rotation indicator as shown in Figure 1 ;

Figure 3 is a wireframe view of the embodiment shown in Figure 1 ; Figure 4 is a further wireframe view of the embodiment shown in Figure 1 ;

Figure 5 is an isometric view of the embodiment shown in Figure 1 , showing the serration strap threaded for use;

Figure 6 is an elevation of the associated key illustrated in Figure 1 ;

Figure 7 is an isometric view of the associated key in engagement with the embodiment shown in Figure 1 ;

Figure 8 is an elevation of an indicator of the embodiment as shown in Figure 1 as used in engagement with a nut on a wheel;

Figure 9 is an isometric view of the embodiment in use as shown in Figure 8;

Figure 10 is an isometric view of the key in engagement with the embodiment shown in Figure 1 used for disengagement of the strap with the pawl;

Figure 11 is an isometric view of a nut rotation indicator according to a second embodiment; and

Figure 12 an isometric view of the nut rotation indicator as shown in Figure 11 , retained by a separate serration strap. Detailed Description of Preferred Embodiments

A preferred embodiment of a nut rotation indicator 11 in accordance with the invention, as illustrated in Figures 1 to 10, comprises a body 12 and a strap 14.

The body 12 comprises, a pair of opposed arms 15, 16 connected together at first ends thereof such that the first and second arms may pivot relative to each other. The joined first ends of the first and second arms 15, 16 are tapered in width towards an end forming a point which acts as an indicating element 21. The indicating element 21 provides an indication of rotational movement as is discussed below.

Each of the first and second arms 15, 16 have a diverging portion 22, 23 extending away from the joined first ends thereof. In profile, the diverging portions 22, 23 and joined first ends therefore provide a generally "Y" shaped form.

The outer end of the first arm 15 comprises a first arcuate portion 31 extending from the first diverging portion 22. The outer end of the second arm 16 also is provided with a second arcuate portion 41 extending from the second diverging portion 23. The curvature of the first arcuate portion 31 is opposite to that of the second arcuate portion 41 such that an inner surface 32 of the first arcuate portion 31 faces an inner surface 42 of the second arcuate portion 41.

The inner surfaces 32, 42 of each of the arcuate portions 31 , 41 are profiled by a series of teeth 33, 43 respectively formed by a plurality of parallel ridges extending transversely across the inner surfaces 32, 42.

An outer surface 35 of the first arcuate portion 31 is bounded by two ridge-like walls 36 extending outwardly along the longitudinal edges of the first arcuate portion 31 to provide a channel. At the intersection between the diverging portion 22 of the first arm 15 and the first arcuate portion 31 is provided a first aperture 25 penetrating from the outer surface 35 to an inner surface.

The construction of the second arcuate portion 41 is somewhat similar to that of the first arcuate portion 31 having an outer surface 45 bounded by two ridge-like walls 46, 47 extending outwardly from longitudinal edges of the second arcuate portion 41 to provide a channel on the outer surface 45. A second aperture 26 penetrates from the outer surface 45 to an inner surface at the intersection between the diverging portion 23 of the second arm 16 and the second arcuate portion 41.

The walls 46, 47 protrude further from the outer surface 45 in the vicinity of the inner end 48 of the second arcuate portion 41. Through each of the walls 46, 47 are provided aligned holes 51 , 52.

Also provided is an engagement means for the strap 14 to engage with the second arm 41. The means to engage with the second arm comprises a pivotally supported tang 61 provided in the second aperture 26. The tang 61 is provided with serrations 63 to act as a pawl as is explained below. The tang 61 is also provided with a release arm 64. A gap 49 is provided in the wall 47 to enable external access to the release arm 64 when the indictor 11 is in use. Adjacent the outer end 44 of the second arcuate portion 41 is provided a retaining member 55 covering the channel for a short distance.

The strap 14 extends outwardly from the outer end 44 of the second arcuate portion 41 and is of width slightly less than the width between the walls 46 & 47 and thickness sufficient to be flexible yet of sufficient strength to sustain the tensile load that will be described. The strap 14 has a series of transverse serrations 18 on an inner surface 17, being on the same side as the inner surface 42 of the second arcuate portion 41. As shown in Figures 3, 4 and 5, the length of the strap 14 is sufficient for it to be wrapped around the length of the outer surface 35 of the first arcuate portion 31 , being retained within the channel formation between the walls 36, passed through the aperture 25 in the first arm 15 and through the aperture 26 in the second arm 16, around the length of the outer surface 45 of the second arcuate portion 41 between the walls 46 and 47, and through the aperture formed by the retaining member 55.

In use, when the strap 14 is passed through apertures 25 and 26 it is pulled with some tension, as is described further, below. The tang 61 is positioned and oriented so that the tang 61 engages the serrations 18 of the strap 14. The strap 14 is held relative to the tang 61 by the rear edge of the aperture 26 in the second arm 16 so that when it is resiliently stretched, it is locked in engagement with the serrations 63 of the tang 61.

The indicator 11 is typically formed by moulding from plastics material with relatively high tensile strength and resilience such as nylon. The strap 14 may therefore be pulled through the apertures with sufficient force to resiliently stretch it and thereby lock the strap 14 against the tang 61.

It will be appreciated that when the strap 14 is locked by the tang 61 in this way it results in a compressive force being applied around both arms 15, 16 of the indicator to thereby cause them to pivot about the apex 24. The strap 14 acts as an extension of the second arm 16 and the strap extends around the first arcuate portion 31. The tensile force applied to the strap thus provides an inwardly directed force against both arcuate portions 31 and 41.

In use, as shown in Figures 6, 7 and 8, the arcuate portions 31 , 41 of the indicator are placed around a nut, the ridges of the teeth 33 being oriented parallel with the central axis of the aperture of nut. The indicator 11 is rotated relative to that axis so that the indicating element 21 points towards an adjacent nut/stud of the wheel, or in any known predetermined position. As the strap 14 is tightened, the two arcuate portions 31 and 41 are clamped around the nut. The indicator 11 will then be rotated slightly so that a ridge 81 between two external faces of the nut is positioned between two teeth 33, 43 of the arcuate portions 31 , 41. When clamped by the tension of the strap 14, the engagement of the teeth 33, 43 with respective ridges 81 of the nut prevents the indicator 11 from rotating relative to the nut during use. Once in place, any loosening of the nut will be visible by the altered position of the indicator element 21.

Associated with indicator 11 is a key 71 as shown is Figures 1 , 6, 7 and 10. The key of the embodiment comprises an elongate shaft 72 having a handle 75 at one end and engagement fingers 73, 74 at the opposed end. The handle 75 may be of any convenient form to enable it to be firmly grasped by a user and a substantial rotation force applied. Optionally, the handle includes one or more apertures 79 to enable a cord to be passed through it or for hanging the key from a supporting nail when not in use.

The shaft is generally of thin, cylindrical, tubular form and optionally is provided with a slotted aperture 76 extending along a substantial portion of its length.

The fingers 72, 73 extend in the direction of the axis of the shaft 72 and each have a form of a truncated circular tubular section, opposed to each other, as if formed by forming an axially oriented slot 78 in a circular tubular piece. The external curved surfaces have a radius a smaller than the radius of curvature of the shaft 72 so that a step is provided between shaft 72 and the fingers 73, 74. A second finger 74 extends to a greater degree than the first finger 73 to provide a tab 77.

Conveniently, the handle is moulded from a rigid plastics having good strength material such as an acetyl resin.

In use the fingers 73, 74 of the key 71 are passed into holes 52 and 51 of the indicator 11 after the strap 14 is passed through apertures 25, 26 so that the strap 14 engages in the slot 78 between the fingers of the key 71. When the key is rotated it rotates a portion of the strap 14 and thereby applies a substantial tension to it. Because of the tension that may be applied in this way, it is possible to resiliently deflect the arcuate portions 31 , 41 somewhat to maintain a substantial clamping pressure to thereby secure the indicator 11 to the nut even in adverse conditions.

The tab 77 on finger 74 is used to release the tang 61 from engagement with the strap 14. As shown in Figure 10, the tab 77 is used to engage release arm 64 to apply a pressure to it to release engagement of the serrations 63 with the strap 14. Thus, the indicator can easily be removed when the nut must be removed or tightened.

In one embodiment, the plastics material from which the indicator 11 is formed includes a luminescent plastics additive. Such materials now exist which maintain the luminescence for periods in excess of 10 hours. This luminescence will enable the driver of a transport vehicle to identify at night any nut that may loosened after a very brief inspection.

A second embodiment of the nut rotation indicator is shown in Figures 11 and 12. As shown in the Figures, the indicator of the second embodiment is substantially identical to the first embodiment except that strap 14 is omitted. In this embodiment, a separate strap 91 is used with the indicator 11. Such straps, for example cable ties, are well known and widely used and include a buckle 92 at one end thereof with a pawl mechanism to engage the serrations of the strap 91.

In using the second embodiment, the indicator is placed around a nut as with the first embodiment, after which the strap 91 might be threaded through apertures 25 and 26, around the second arcuate portion 41 and then the first arcuate portion 31 with the end of the strap 91 being passed through the buckle 92. However, this arrangement of the threading of the does not provide the ability to tighten the tension on the strap properly using the key.

In a third embodiment, (not shown) the retaining member 55 is provided in a form having greater strength than that required for the first embodiment to act as a stop for the buckle 92 of the serration strap 91. The strap 91 is threaded first through the aperture of the retaining member 55 in the direction so that it extends forwardly in the same orientation as the strap 14 of the first embodiment. Strap 91 is then threaded around the first arcuate portion 31 and then through apertures 25 and 26 as for the first embodiment. The serration of strap 91 will engage the serrations 63 of tang 61. The strap 91 may then be tensioned using the key 71 in the same way as for the first embodiment.

It will be readily apparent to persons skilled in the relevant arts that various modifications and improvements may be made to the foregoing embodiments, in addition to those already described, without departing from the basic inventive concepts of the present invention. Therefore, it will be appreciated that the scope of the invention is not limited to the specific embodiments described and is to be determined from the appended claims.

Claims

1. A nut rotation indicator comprising a body having a pair of opposed arms and an indicating element to provide a visual indication of the rotational position of the body, wherein the arms are adapted in use to be clamped into engagement with a nut.

2. A nut rotation indicator in accordance with claim 1 , wherein the opposed arms comprise a first arm and second arm pivotally connected at first ends thereof.

3. A nut rotation indicator in accordance with claim 2, wherein the first and second arms are flexible such that pivotal movement of the first and second arms relative to each other is via the first and second arms flexing about the joined first ends.

4. A nut rotation indicator in accordance with claim 3, wherein the joined first ends of the first and second arms are tapered to a point and the point comprises the indicating element.

5. A nut rotation indicator in accordance with any one of claims 2 to 4, wherein the first arm comprises a first diverging portion extending away from the first end thereof and a first arcuate portion extending from the first diverging portion, the second arm comprises a second diverging portion extending away from the first end thereof and a second arcuate portion extending from the second diverging portion and the nut is clamped between the first and second arcuate portions by pivoting of the first arm towards the second arm.

6. A nut rotation indicator in accordance with claim 5, wherein inner surfaces of the first and second arcuate portions include teeth to engage with external surfaces of the nut.

7. A nut rotation indicator in accordance with any one of claims 2 to 6, further comprising: a strap; a first aperture in the first arm; and a second aperture in the second arm; wherein when the strap is passed through the first aperture, through the second aperture and tensioned to pull the first and second arms towards each other to clamp the nut.

8. A nut rotation indicator in accordance with claim 7, wherein the strap extends outwardly from the outer end of the second arm and an engagement means is provided on second arm to engage with the strap for tensioning of the strap after the strap has passed through the second aperture.

9. A nut rotation indicator in accordance with claim 8, wherein the engagement means comprises a tang in the second aperture which engages with serrations on the strap such that the strap can be pulled through the second aperture and the tang engages with the serrations on the strap to prevent the strap passing back through the second aperture.

10. A nut rotation indicator in accordance with claim 8 or 9, wherein an outer surface of the arcuate portion of the first arm is provided with a channel which receives the strap.

11. A nut rotation indicator in accordance with claim 10, wherein an outer surface of the second arcuate portion is provided with a channel such that the strap, after passing through the second aperture, is received in the channel on the second arcuate portion.

12. A nut rotation indicator in accordance with claim 11 , wherein a retaining member is provided adjacent an outer end of the second arm such that the strap is passed through the retaining member.

13. A nut rotation indicator in accordance with any one of claims 10 to 12, wherein the channels are defined by pairs of walls extending along the outer surfaces of the first and second arms.

14. A nut rotation indicator in accordance with claim 13, wherein the walls on the second arm are provided with aligned holes for receiving a key having a slotted end such that when the slotted end is inserted into the holes, the strap is engaged in the slot and rotation of the key pulls the strap through the second aperture, thereby tensioning the strap and pulling the first arm towards the second arm.

15. A nut rotation indicator in accordance with any one of claims 9 to 14, wherein the tang is provided with a release arm such that movement of the release arm disengages the tang from the strap.

16. A nut rotation indicator in accordance with claim 7, wherein the strap is provided as a separate member having a buckle at one end to receive the other end such that pulling the end through the buckle tensions the strap.

17. A nut rotation indicator in accordance with any one of the preceding claims, wherein the body is constructed of a luminescent material.