[0001] This invention relates to a rotation indicator device for mounting on a nut or bolt head, which has a periphery of polygonal shape and which is rotatable relative to a second member, which is fixed in position, to indicate rotation of the first member relative to the second member. BACKGROUND

[0002] Rotation indicator devices are known for mounting on threaded fastening members, such as nuts and bolts, to indicate whether these have rotated and, in effect, worked loose since a previous fastening operation. Such devices are, accordingly, mounted onto the fastening member in a substantially non-rotatable manner so that they will rotate with the fastening member and by means of an indicium, typically a pointer, which is moved from an initial predetermined position, it will be evident whether the nut or bolt has itself rotated. These devices are particularly widely used nowadays for fitting onto vehicle wheel nuts to indicate during periodic checks or servicing, whether any loosening of a wheel nut has occurred and therefore that re- torqueing is necessary. The safety reason for this is self-evident since during normal operating conditions with vibration and impacts during vehicle travel, there is a risk of certain wheel nuts working loose. If this should occur load is transferred to other nuts of the same wheel, leading to a greater chance of failure of several nuts and ultimate risk of a serious accident in the absence of routine checking and re-torqueing.

[0003] The applicant has for many years supplied rotation indicator devices, as first disclosed in GB 2242720, under the registered trademark "Checkpoint". These are provided in a range of sizes to fit each specific size of nut, as there are a number of different sizes employed for different types of vehicle and/or by different manufacturers of vehicle and/or in different countries, for example 30, 32, 36, 38 mm diameter. The indicator devices are simple in structure being a ring of plastics material provided around the interior surface with a plurality of equally- spaced alternating grooves and teeth so as to fit reliably and non-rotatably onto the hexagonal periphery of the respective wheel nut, and also provided with a radially outwardly directed pointer. Once all the nuts on a wheel have been tightened to correct specification, these devices are fitted onto each nut typically so that the pointers are directed around the circular array of wheel studs. The number and spacing of the grooves and teeth on the interior are chosen to allow fitting of each device onto the respective wheel nut with the pointer in a suitable selected position. Any subsequent misalignment of the pointers which is noted upon visual inspection is indicative of loosening of the nut to which the misaligned device is mounted. The devices are highly visible, typically being fluorescent yellow. They are produced by moulding from polypropylene or a copolymer of polypropylene which is chosen for its accuracy of shape, ability to grip, durability, cost effectiveness, and temperature indication of a "hot wheel" condition.

[0004] Aforesaid rotation indicator devices have been in use on vehicles in various climates and travel conditions for over 20 years and have proved highly satisfactory. As an alternative, however, it is desirable to offer owners of mixed fleets of vehicles the possibility to source and stock either a single rotation indicator device which can be adapted in size to fit the entire range of different sized nuts used on vehicles of that owner, or at least a smaller number of sizes of rotation indicator device, each being adapted to fit part of the range of different sizes of nuts (or different spacing between nuts) which are currently employed on the vehicles of that owner. It is also advantageous for a wholesaler to stock such a product that fits a multiple of wheel nut sizes.

[0005] A rotation indicator device having this objective is disclosed in WO 2014/169345. The present invention seeks to provide an alternative design of multi-size rotation indicator device which is particularly easy to use and is less expensive to produce. SUMMARY OF THE INVENTION

[0006] The present invention provides a rotation indicator device, for mounting on a nut or a bolt head, which has a periphery of polygonal shape and which is rotatable relative to a fixed position member, to indicate rotation of the nut or bolt head relative to the fixed position member. The device comprises a flexible strip attached to a laterally projecting indicator. The flexible strip has first and second portions extending in a common plane, the first portion extending from the indicator to a first end of the strip and the second portion extending from the indicator to a second end of the strip. The first and second portions of the flexible strip are adapted to define an annular body to be mounted onto and encircle the periphery of the nut or bolt head. The first and second portions have first and second ratchet- toothed sections of opposite pitch angles, which ratchet- toothed sections are arranged to be moved across each other in a circumferential direction of the annular body to reduce the size of the annular body but engage to prevent relative movement in an opposite circumferential direction. The flexible strip has an inner surface and an outer surface and the inner surface is provided with equally spaced alternating teeth and grooves so that the annular body can be non-rotatably secured around the periphery of the nut or bolt head, in any one of a plurality of selected rotational positions, by engagement of one or more of the grooves with respective corners or apices of the periphery of the nut or bolt head.

[0007] The first ratchet- toothed section is provided along the outer surface of the first portion of the strip in an end region of said first portion which serves as a tongue, and the second ratchet-toothed section is provided in a channel defined by a flange which is connected to the outer surface of the second portion of the strip, the channel having an open side in an upward, axial direction from the common plane of the flexible strip portions which define the annular body so that the tongue is insertable through the channel to form the annular body to the size of the nut or bolt head by engagement of the opposed ratchet- toothed sections, but the tongue is releasable from the channel by lifting in an upward direction from said common plane and out of the open side of the channel.

[0008] Accordingly it is a relatively quick and simple exercise for a user to insert the tongue into and through the channel as far as is necessary to create an annular body approximately to the size required for the maximum dimension across the nut onto which the device is to be fitted. The first ratchet- toothed section is moved across the second ratchet- toothed section in the insertion direction, but is prevented from moving in the opposite direction. It would be typical to create an annular body of slightly larger size than the nut, then position it onto the nut and then push the first and second portions circumferentially further together to complete tightening around the periphery of the nut so that the apices of the nut are non-rotatably held by the grooves in the interior of the annular body. In other words, the first and second portions are overlapped with mutually engaged ratchets until the device grips the periphery of the nut and does not rotate relative to the nut.

[0009] In preferred embodiments of the rotation indicator device of the invention the ratchet- toothed sections of opposite pitch angle have mutually opposed abutment surfaces which extend across the depth of the strip and of the channel, respectively, at an inclination relative to said common plane. An inclination of between 75° and 89° is suitable. The abutment surfaces incline in the direction in which the tongue is insertable into the channel towards the open side of the channel. [0010] As noted, the tongue is released from the channel by the simple action of lifting upwards, out of the side of the channel, which is completely open throughout its length. This disengages the ratchet- teeth on the tongue from the ratchet- teeth on the inside of the channel.

[0011] The purpose of the inclination of the respective ratchet- teeth abutment surfaces is to prevent inadvertent release of the tongue upwardly out of the channel. The preferred angle of inclination has been found effective and reliable, yet still permits production of the device by moulding and satisfactory release from the moulding tool.

[0012] Typically, the flexible strip will have substantially parallel upper and lower surfaces and the inclination of the teeth of opposite pitch angle of the ratchet- toothed sections will be relative to these substantially parallel upper and lower surfaces. [0013] In preferred embodiments of the rotation indicator device of the invention the equally spaced alternating teeth and grooves provided on the inner surface of the flexible strip are provided continuously throughout the length of each of the first and second portions. In this way the device can be non-rotatably secured around the periphery of the nut or bolt head in a particularly reliable manner because by appropriate size and spacing of these teeth a plurality of the grooves will always mechanically inter-fit with respective corners or apices of the periphery of the nut or bolt head.

[0014] Typically in embodiments of the rotation indicator device of the invention the indicator will comprise a pointer extending outwardly from the outer surface of the strip so as to point radially outwards when the strip is formed into the annular body. It is advantageous, in this regard, that the pointer is connected to the flexible strip only by a neck formation, which may also be referred to as a bridge. This means a connection which is significantly narrower in extent than a base of the pointer.

[0015] The advantage in providing such a narrow connection is that an even flexibility is then maintained throughout the entire flexible strip, without any significant non- flexible or less flexible region between the first and second portions of the strip. This in turn avoids specific flex points which are more vulnerable to wear and to failure. This is important for the durability of the rotation indicator which may be used on vehicles in harsh environments such as hot or cold climates, where the vehicles and wheel nuts are subject to extremes of vibration, airborne grit, dust and like debris with corrosive properties. Uneven flexure around the annular body may result in shape defects allowing the device to loosen and rotate relative to the wheel nut so that it no longer performs its function. In the course of its use the device may be required to be released from time to time to allow re-torqueing and then re-attached with size adjustment. In the longer term variability in flexure around the annulus may reduce the overall life of the device and possibilities for reliable re-attachment and re-use.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The invention will be described further, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a perspective view from above of a preferred practical embodiment of the rotation indicator device of the invention;

Figure 2 is a perspective view from below of the same embodiment;

Figure 3 is a top plan view of the same embodiment; Figure 4 is an enlarged cross section along line IV-IV in Figure 3;

Figure 5 is a top plan view showing the device in a condition where it has been forcibly uncurled and its respective ends are about to be connected to form an annular body for fitting onto a wheel nut; Figure 6 is a similar top plan view showing the device at a subsequent stage where it has been adjusted in size and fitted onto the wheel nut; and

Figure 7 shows a vehicle wheel with rotation indicators, as in Figure 6, mounted onto each of its wheel nuts, with respective pointers directed towards the adjacent nut in a clockwise direction. DETAILED DESCRIPTION

[0017] Referring to figures 1 to 3, a preferred practical embodiment of the rotation indicator device in accordance with this invention comprises a flexible strip 10 to which a pointer 12 is connected by a narrow bridge 14. The device is moulded in one piece of plastics material. A suitable material is a copolymer of polypropylene and polyethylene similar to that used for known one size wheel nut rotation indicator devices supplied by the applicant under the trade mark "Checkpoint". This material is best suited to the purpose, being durable, flexible, with good friction grip properties and cost-effective. It also has suitable melting point, which can be chosen in a range of about 125° C to about 165° C, depending on the temperatures likely to be encountered in use. Excessive heating, indicative of possible braking problems for a wheel, will tend to cause melting of the device and indicate to the user that there is a potential underlying problem to be investigated. Materials with higher melting points, such as nylon, would not have this added advantage and would be more expensive.

[0018] The device is moulded with the flexible strip 10 in a curled configuration in the manner of a spiral in a single plane, as evident in these figures 1 to 3. [0019] The flexible strip 10, for purposes of description, can be said to consist of a first portion 20 extending from the connection 14 (to the pointer 12) to a first end 21 and a second portion 30 extending from the connection 14 to a second end 31. In the initial condition a substantial part of the second portion 30 is curled inside the first portion 20.

[0020] The flexible strip 10 has an inner surface 1 1 and an outer surface 13, between which the thickness of the strip is defined. The entire inner surface 1 1 , continuously along its length is provided with equally spaced alternating teeth 15 and grooves 16. The flexible strip 10 also has an upper surface 17 and a lower surface 18, between which the depth of the strip is defined. The depth of the strip is typically in the region of 8 mm.

[0021] The bridge 14, i.e. the neck of the pointer 12, is, in this embodiment, formed by a pair of side by side wedge shaped portions 19, as best seen in figure 2. These portions, rather in the manner of buttresses, taper from being equal to the depth of the strip 10 where they connect to the strip, to part way across the underside of the pointer 12.

[0022] The first and second portions 20, 30 of the flexible strip carry respective ratchet- toothed sections 22, 32 which are to be capable of moving across each other in one direction, but prevented from moving in the opposite direction by abutment of respective oppositely facing abutment surfaces 24, 34 on the ratchet teeth. The first ratchet toothed section 22 is formed on the outer surface 13 of the first portion 20 in an end region of said first portion 20 which, in use of the device, provides a tongue. The second portion 30 of the flexible strip 10 is formed with a flange 33 projecting outwards from an end region of the outer surface 13 to define a U-shaped channel 35 having a base 36 and an outer wall 37. The second ratchet toothed section 32 is formed on the inner surface of that wall 37. The channel 35 is open to the other side 17 of the device, as apparent in figures 1 and 3 of the drawings. In use of the device, as shown in figures 5 and 6 of the drawings, the channel 35 receives the tongue section 22 of the first portion 20.

[0023] The first portion 20 is formed with an outwardly, i.e. radially, projecting tab 28 at the junction between the ratchet-toothed section 22 and the remainder of the portion. This tab 28 is L-shaped in cross-section, having an axially extending portion and a circumferentially extending portion, the latter standing slightly proud above the upper surface 17 of the strip 10, as viewed in figure 1. The outer wall 37 of the flange 35 on the second portion 30 is similarly formed with an outwardly, i.e. radially, projecting tab 38 of similar L-shaped configuration. These tabs 28, 38, serve as gripping tabs for pressing together by a thumb and finger of a user, as will be explained. The tab 28 also serves as a lifting tab to enable release of the first portion 20 from the in use condition of the device, as will be explained.

[0024] The end region of the second portion 30 of the flexible strip 10 in the vicinity of the flange 33, namely the region leading immediately up to the end 31 , is tapered in its thickness towards said end 31. [0025] As shown in figure 4, the abutment surfaces 34 of the ratchet toothed section 32 in the channel 35 extend across the depth of the channel, i.e. of the inner surface of the channel wall 37, at a slight inclination from being perpendicular relative to the base 36 of the channel. An angle of inclination of between 75° and 89° is suitable. However an angle of inclination of between 85° and 89° may be used. The inclination is from the base 36 to the top of the channel (i.e. to the upper surface 17 of the strip portions 30) in the direction indicated by arrow A. This is the direction, from the end 31 of the strip portions 30, in which the end 21 of the tongue 22 will be inserted and move through the channel 35 in use of the device. The abutment surfaces 24 of the other ratchet toothed section 22 of the first portion 20 of the strip (namely of the tongue) are necessarily of matching inclination so that respective teeth of the portions 22, 32 will accurately inter engage. Accordingly, these abutment surfaces 24, 34 incline at a corresponding angle across the depth of the strip portion 20 between the lower and upper surfaces 18, 17 of the strip in the direction of the end 21.

[0026] The manner of use of the device is apparent from figure is 5 and 6. By application of modest manual force the flexible strip 10 is uncurled and opened out against its inherent bias until an annular shape is formed by the strip 10 with the ends 21 and 31 circumferentially spaced, as shown in figure 5. The end 21 of the first portion 20, i.e. the end of the tongue 22, is then inserted through the channel 35 from the end 31 , namely in the direction of arrow A. The channel 35 is dimensioned so that the tongue 22 is a close sliding fit in the channel as the ratchet toothed section 22 moves circumferentially across the corresponding ratchet toothed section 32 inside the channel 35. As is customary with opposing ratchet teeth, the teeth 24 move over the teeth 34 in the insertion direction A but are prevented by abutment from moving in the reverse direction. Additionally, however, because the respective teeth 24, 34, of the ratchet sections 22, 32 are sloping slightly backwards at their lower end, towards the base of the channel (as described above with reference to figure 4) the ratchet teeth 22 are impeded from sliding upwards. This counters any tendency for the tongue 22 inadvertently to lift out of the open side of the channel 35.

[0027] In this manner, an annular body is formed by the strip portions 20, 30, which body is close to but slightly larger than a wheel nut 40 onto which the rotation indicator is to be fitted. The wheel nut 40 should already be tightened to appropriate degree on a stud 41 of the wheel hub. The final stage of fitting may suitably be carried out in situ with the annular body placed around a nut 40. The ratchet toothed sections 22, 32 are then pushed further across each other inside the channel 35 by manual drawing together of the grip tabs 28, 38. The taper of the end region of the portion 30 avoids the interior of the annular body having any significant step change in diameter where the portions 20, 30 overlap.

[0028] The number and spacing of the teeth and grooves 15, 16 and their continuity around the entire interior surface 1 1 is such that several grooves 16 will directly fit onto the apices of the nut 40, which is hexagonal, irrespective of the size of the nut. In this respect, typical nut sizes are any one of 30, 32, 33, 36 and 38 mm across the nut. Therefore, a reliable, non- rotatable fitting is achieved such that if the nut 40 rotates, the device rotates as well and movement of the pointer 12 provides visual indication of the rotation of the nut 40.

[0029] If the device needs to be removed from the wheel nut 40, for example in

circumstances where the nut requires re-torqueing, the ratchet toothed section (tongue) 22 can be released from the channel 35, i.e. from engagement with the corresponding ratchet toothed section 32, by appropriate manual manipulation and force. Thus, a combination of the grip tabs 28, 38 being slightly drawn together and at the same time the tab 28 being lifted outwards of the plane of the annular body, i.e. in the direction of the upper surface 17 of the strip, should lift the end 21 out of the open side of the channel 35. In this way, the engagement afforded by the slight inclination of the ratchet teeth 24, 34 is released.

[0030] The invention is not restricted to the details of any forgoing embodiments. Variations in detail of configuration, size, spacing, material are possible in other embodiments within the scope of the claimed invention. In particular, in modified embodiments of rotation indicator device of the invention a plurality of marker tabs may be provided extending outwardly from the upper or outer surface of the strip at locations along the end region 22 of the first portion 20 of the strip serving as the tongue. The purpose of these would be to indicate the required position of the tongue relative to the channel to achieve an annular body of precise size to fit particular wheel nut sizes. In this respect, a formation providing a reference point for such markers is shown adjacent the channel 35 in figures 1 and 3 of the illustrated embodiment. Another variant would be addition of a further lifting tab in the form of a terminal tab at the free end 21 of the tongue.