GB2597948A

GB2597948A - Vehicle repair and re-threading apparatus and method

Info

Publication number: GB2597948A
Application number: GB2012457.4A
Authority: GB
Inventors: Sibary Wheatcroft Ivor
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-08-11
Filing date: 2020-08-11
Publication date: 2022-02-16
Anticipated expiration: 2040-08-11
Also published as: GB2597948B; GB202012457D0

Abstract

A method and apparatus for repairing a stripped thread of a road vehicle axle, whilst the axle remains on the vehicle, comprises attaching to said axle a grinding tool 600 comprising a rotatable grinding surface (706 fig. 7); moving said grinding surface (706 fig. 7) along and around a perimeter of said axle to create a substantially circular cylindrical end of said axle; attaching to said axle a threading tool 601 comprising a cutting head (1202, 1208 fig. 12); and moving said cutting head (1202, 1208 fig. 12) around a perimeter of said substantially circular cylindrical end of said axle to put a thread in said end of said axle. An end portion of the axle may be built up with weld to provide a mass of metal for grinding and threading. The grinding tool 600 and threading tool 601 are each lightweight and manually portable and can be operated by a single person operator without the need for removing the axle from the vehicle, and without the need for a full workshop facility. The method and apparatus can form the basis of a mobile axle re - threading service for commercial road vehicles.

Description

VEHICLE AXLE REPAIR AND RE-THREADING APPARATUS AND METHOD

Field of the Invention

[0001] The present invention relates to a method and apparatus for re threading a vehicle axle. Particularly, although not exclusively, the invention relates to a method and apparatus for re-threading a vehicle axle of a commercial road vehicle without the need to remove the axle from the vehicle.

Background of the Invention

[0002] Large commercial vehicles for road use comprise two or more axles, each axle carrying two or more road wheels.

[0003] Referring to Figure 1 herein, a typical known articulated lorry comprises a tractor unit and a trailer, wherein the tractor unit has a front axle carrying a pair of front wheels, one or more rear axles, each rear axle carrying two or more wheels, and the trailer unit having typically between one and four axles, each axle carrying either two or four road wheels.

[0004] There are many types and variations of axle available for fitting to road going heavy goods vehicles, including axles having disc brakes or drum brakes; full width axles which extend across the width of a trailer and stub axles which are mounted on a moveable sub frame. In general an axle comprises a circular cylindrical bar or rod of metal which has a smooth surface, and on to which a rotatable hub is fitted. At an end of the axle, there is a relatively smaller diameter portion which has a thread. The between the hub and the axle is a set of roller bearings which enable the hub to spin around the axle. The hub is retained to the axle in the axial direction by an annular end retaining nut having an internally facing thread which engages with the externally facing thread on the end portion of the axle.

[0005] Referring to Figure 2 herein there is illustrated schematically in perspective view, a known axle assembly 200 for a commercial heavy goods vehicle. A circular cylindrical tubular axle housing 201 is mounted on a pair of trailing arms 202, 203, a forward end of each trailing arm being connected to a vehicle chassis by a corresponding respective mounting pillar 204, 205, and a rear end of each failing and being connected to the vehicle chassis by a corresponding respective air suspension unit 206, 207, each trailing arm being damped by a corresponding respective damper or shock absorber device 208, 209. Inside the circular cylindrical tubular axle housing 201, there is an elongate circular cylindrical solid metal axle. At each end of the axle, there is mounted a wheel hub 210, 211. The wheel hub is mounted to the central axle via a set of roller bearings, and is retained to the end of the axle by a retaining nut. The axle is static and non-rotating and the wheel hubs rotate about the ends of the axles, each on a set of bearings.

[0006] For a wheel on the left-hand side of the vehicle, as taken in the direction of forward movement of the vehicle the thread and retaining nut have a left hand thread, and on the right-hand side of the vehicle, the thread and retaining nut have a right-hand thread, so that if there is any friction between the retaining nut and the wheel, this acts to tighten the nut rather than loosen the retaining nut.

[0007] Figure 2 shows one example of a heavy goods vehicle axle assembly. In other versions, depending on the type of axle assembly, a known axle may comprise either a circular cylindrical elongate bar which extends the full width of the vehicle, or a short stub axle which is mounted to an axle carrier component, which itself is mounted to a vehicle suspension, with the road wheels being attached to the axle via a set of roller bearings.

[0008] Referring to Figure 3 herein, there is illustrated schematically in partial cutaway view an axle with hub assembly 300 on one end of the axle. The axle comprises a circular cylindrical metal shaft 301 having a toughened or hardened surface of a relatively larger diameter, having at one end a reduced diameter end portion 302 onto which is formed a screw thread 303. There is a step change in diameter between the larger diameter portion of the axle shaft and the smaller diameter end portion of the axle. Wheel hub 304 is attached over the relatively larger diameter portion of the axle shaft and rotates around the axle shaft on a roller bearing 305. The roller bearing 305 comprises an inner race 306 and an outer race 307, where the outer race rotates around the inner race. An end retaining nut 308 retains the bearing on to the axle shaft in the axial direction preventing the roller bearing moving axially along the axial direction of the shaft.

The end retaining nut bears against the inner race and is tightened on to the inner race using a torque wrench to a torque of around 700Nm.

[0009] Periodically, the bearings between the axle spindle and the wheel hub fail, due to high mileage or high loading, and this results in increased friction between the hub and the axle. Each bearing has an inner race which is mounted on the axle and an outer race which is mounted inside the hub. The inner race is retained to the end of the axle with a retaining nut which engages a threaded portion at the end of the axle. Normally, the friction between the inner and outer race is low, enabling the wheel hub to spin freely on the axle. However when the bearing fails, there is increased friction between the inner race and the outer race, and sometimes there is complete lock-up between the inner and outer races. As the vehicle moves forward, the outer race starts to rotate the inner race on the axle, and as the flat face of the retaining nut bears against the inner race, the inner race starts to tighten the retaining nut above its normal torque of around 700Nm, typically, up to two or three times that torque. This results in the end retaining nut which secures the hub to the spindle over tightening.

[0010] The end retaining nut becomes cold welded to the thread on the end of the axle, and when removing the nut to remove the wheel hub and change the bearing this results in stripping of the thread on the axle, so that both the axle and the nut can no longer be used. A new nut and axle are needed, or alternatively there needs to be a new nut, and a repaired re -threaded axle.

[0011] Referring to Figure3 herein, there is illustrated schematically in view from one side an annular hub retaining nut 400, where the internally facing thread of the nut has been stripped due to the nut tightening onto the end of an axle shaft. The retaining nut is damaged beyond repair and a new retaining nut is required. Shown facing upwardly is a flat annular surface of the retaining nut which bears against a side of an inner race of the bearing between the axle shaft and the wheel hub.

[0012] Repair or replacement of the axle requires removal of the axle from the vehicle, building up the stripped or damaged threaded end with weld, mounting the axle into a lathe to turn the axle end to a clean circular surface, and then re-threading the end of the axle on the lathe. This means that the vehicle has to visit a workshop having the correct machine tools. Removal and refitting of the axle from the vehicle takes two workers around four hours of labour each. If a new axle shaft is being fitted, there is the down time when the road vehicle cannot be used whilst waiting for delivery of the new axle shaft or spindle, plus the additional cost of the new axle shaft or spindle. If the axle or spindle is being repaired, then in addition to the strip down time and refitting time, there is the time needed to build up the damaged threaded end, turn off the excess weld on a workshop static machine tool / lathe and tore-thread the end of the axle.

[0013] Specific embodiments and methods according to the present invention aim to provide a human portable apparatus which can be used to repair an axle end in situ without removal of the axle from a road vehicle, and without the need to take the axle to a workshop for repair, thereby reducing off road time of the vehicle, and repair costs.

Summary of the Invention

[0014] According to a first aspect there is provided a method of repairing a stripped thread of a vehicle axle, whilst said axle remains in situ on the vehicle, said method comprising, whilst the axle remain on the vehicle: attaching a grinding tool to said axle, said grinding tool comprising a rotatable grinding surface; moving said grinding surface along and around a perimeter of said axle to create a substantially circular cylindrical end of said axle; attaching a threading tool to said axle, said threading tool comprising a cutting head; and moving said cutting head around a perimeter of said substantially circular cylindrical end of said axle to put a thread in said end of said axle.

[0015] Preferably said stage of attaching said grinding tool to said axle comprises clamping said grinding tool to said axle.

[0016] Preferably said stage of moving said grinding surface around said axle comprises manually rotating the whole of said grinding tool around said axle.

[0017] Preferably said stage of moving said cutting head around a perimeter of said axle comprises manually rotating said cutting head around said axle.

[0018] Preferably said step of attaching a threading tool to said axle comprises sliding an inner collar of said threading tool over an end of said axle, and securing said inner collar to said axle.

[0019] Preferably said grinding tool is removed from said axle prior to fitting said threading tool to said axle.

[0020] Said stage of rotating said grinding surface around a perimeter of said axle may comprise moving a centre of rotation of said rotatable grinding surface towards a geometric central axis of said axle.

[0021] Said stage of rotating said grinding surface around a perimeter of said axle may comprise moving a centre of rotation of said rotatable surface towards an outer surface of an end region of said axle.

[0022] Suitably said centre of rotation of said rotatable grinding surface is moved towards or away from said perimeter of said axle by a distance increment in the range 0.05mm to 0.2mm.

[0023] Suitably a distance of a tip of said thread cutting tool is moveable towards a geometric central axis of said axle or spindle by a distance increment in a direction radially outwards said geometric central axis in the range 0.05mm to 0.2mm.

[0024] Preferably the method includes building up an end portion of said axle or spindle with weld to provide a mass of metal for grinding and threading.

[0025] Preferably the grinding tool has an overall weight of less than 25 kg, and ideally of less than 15 kg.

[0026] The method as claimed in a one of the preceding claims, wherein said threading tool has an overall weight of less than 25 kg, and ideally less than 15 kg.

[0027] According to a second aspect there is provided a tool for grinding an axle shaft of a road vehicle, said tool comprising: a clamp for attaching to a circular cylindrical outer surface of said axle shaft; a rotatable grinding wheel; a movable mounting for mounting said rotatable grinding wheel; an electric motor for driving said rotatable grinding wheel.

[0028] Preferably said movable mounting comprises a mounting which is slidable in a directions towards and away from said clamp.

[0029] Preferably said movable mounting comprises a first plate having an elongate channel, and a second plate having a protruding carriage portion which slides along said elongate channel.

[0030] Preferably an axis of rotation of said rotatable grinding wheel is spaced apart from a main geometric central axis surrounded by an internal surface of said clamp.

[0031] Preferably said rotatable grinding wheel is pivotally mounted on said mounting about a pivotal axis which is perpendicular to and spaced apart from an axis of rotation of said grinding wheel.

[0032] Said rotatable grinding wheel maybe pivotally mounted on said mounting about a pivotal axis, such that a perimeter of said grinding wheel describes a substantially toroidal segment path as said grinding wheel is pivoted about said pivotal axis [0033] According to a third aspect there is provided a threading tool for cutting a thread onto a vehicle axle in situ on a vehicle, said tool comprising: a tubular inner sleeve for fitting over said axle; a tubular outer sleeve for fitting over said inner sleeve; an mounting plate mounted to said tubular outer sleeve; and a cutting tool holder mounted to said adjustable mounting plate.

[0034] Preferably the threading tool further comprises a slidably adjustable plate assembly which is removably attachable to said mounting plate.

[0035] Preferably said tubular inner sleeve comprises an outwardly facing thread on an outer surface of said sleeve.

[0036] Preferably said wherein said tubular outer sleeve comprises an inwardly facing thread.

[0037] Preferably said tubular inner sleeve comprises an outwardly facing thread; and said tubular outer sleeve comprises an inwardly facing thread; wherein said outwardly facing thread of said inner sleeve engages said inwardly facing thread of said outer sleeve so that when said outer sleeve is rotated relative to said inner sleeve, said outer sleeve moves both rotationally and axially with respect to said inner sleeve.

[0038] Said cutting tool holder maybe movable towards and away from a main geometrically central length axis of said inner sleeve.

[0039] Preferably said tubular inner sleeve comprises a plurality of threaded apertures extending in a direction radially towards a geometric central axis of said tubular inner sleeve; and a plurality of threaded bolts, located in said threaded apertures.

[0040] According to a fourth aspect a sleeve assembly for a threading tool for cutting a thread onto a vehicle axle in situ on a vehicle, said sleeve assembly 25 comprising: a tubular annular inner sleeve having a first externally presenting threaded portion; a tubular annular outer sleeve having an inwardly facing threaded portion of a same pitch as said externally presenting threaded portion; and a radially extending mounting plate rigidly secured to said outer sleeve.

[0041] Preferably said inner sleeve comprises a smooth circular cylindrical central bore.

[0042] Preferably said outer sleeve comprises an externally presenting mounting for mounting a lever to said outer sleeve.

[0043] Said inner sleeve may comprises at least one radially extending screw capable of extending and contracting in a radial direction towards and away from a main geometric central axis of said inner sleeve.

[0044] Within a kit there may be provided a set of sleeve assemblies, each as described above, wherein individual sleeve assemblies within the set have different internal bore diameters to other sleeve assembly in the set.

[0045] Within the set of sleeve assemblies there may be provided an individual sleeve assembly which has an externally presenting threaded portion and a said inwardly facing threaded portion of a pitch which is different to a pitch of the externally facing an inwardly facing threads of other sleeve assemblies in the same set [0046] Other aspects are as set out in the claims herein.

Brief Description of the Drawings

[0047] For a better understanding of the invention and to show how the same may be carried into effect, there will now be described by way of example only, specific embodiments, methods and processes according to the present invention with reference to the accompanying drawings in which: Figure 1 herein illustrates schematically a conventional multi-axle articulated heavy goods vehicle; Figure 2 herein illustrates schematically one example of a known axle assembly for a conventional heavy goods road vehicle; -1 0-Figure 3 herein illustrates schematically in partial cutaway view an end of an axle shaft, mounting a wheel hub, onto which is fitted a road wheel: Figure 4 herein illustrates schematically a first side of a known hub retaining nut for retaining a rotating hub to an end of an axle shaft the retaining nut having a damaged internal thread; Figure 5 herein illustrates schematically in perspective view, one end of an known axle shaft, having a reduced diameter end portion having a damaged screw thread; Figure 6 herein illustrates schematically a grinding tool and a threading tool according to specific embodiment of the present invention; Figure 7 herein illustrates schematically the grinding tool in view from a first Figure 8 herein illustrates schematically the grinding tool in view from a first end; Figure 9 herein illustrates schematically the grinding tool from a second, side, opposite to the first side; Figure 10 herein illustrates schematically the grinding tool from a second end, opposite to the first end; Figure 11 herein illustrates schematically the grinding tool in perspective view from the first side and the second end, having an additional leverage bar fitted; side; Figure 12 herein illustrates schematically the threading tool from a first side, Figure 13 herein illustrates schematically the threading tool from a second side, opposite to the first side; Figure 14 herein illustrates schematically the threading tool from a first end; Figure 15 herein illustrates schematically the threading tool from a second end opposite to the first end; Figure 16 herein illustrates schematically an alternative sleeve assembly for the threading tool for cutting an alternative pitch of thread on an axle; Figure 17 herein illustrates schematically use of the grinding tool attached to the end of a damaged axle, when grinding a groove or channel adjacent to a threaded portion on a reduced diameter end of the axle; Figure 18 herein illustrates schematically view of operation of the grinding tool attached to the end of a damaged axle continuing a grinding action of the thread region at the end of the axle; Figure 19 herein illustrates schematically a further view of operation of the grinding tool to grind down the damaged axle thread area; Figure 20 herein illustrates schematically an end of an axle after the threaded section has been ground down the grinding tool, and then built up with weld to create a new mass of metal, which can be subsequently ground down to a circular cylindrical surface and then threaded, Figure 21 herein illustrates schematically use of the threading tool to cut the thread in the welded end part of the axle, the threading tool being in a first rotational position; Figure 22 herein illustrates schematically a view of the threading tool from a second perspective, with the threading tool in the first rotational position; Figure 23 herein illustrates schematically a view of the threading tool during threading of the end of the axle, in a second rotational position; and Figure 24 herein illustrates schematically in view from one side the finished repaired and re-threaded axle end.

Details Description of the Embodiments

[0048] There will now be described by way of example a specific mode contemplated by the inventors. In the following description numerous specific details are set forth in order to provide a thorough understanding. It will be apparent however, to one skilled in the art, that the present invention may be practiced without limitation to these specific details. In other instances, well known methods and structures have not been described in detail so as not to unnecessarily obscure the description.

[0049] In the specification, in the figures like parts are denoted by like reference numerals.

[0050] In this specification the term axle means a circular cylindrical shaft the end of which is suitable for mounting a wheel hub via a set of bearings and a retaining nut.

[0051] In this specification, where the main axis of an axle is referred to, this is used to mean a geometric centre line of a circular cylindrical outer surface of the axle. The terms "main central axis" and "central axis" are to be construed accordingly.

[0052] Referring to Figure 6 herein, there is illustrated schematically grinding tool 600 and a threading tool 601. The grinding tool 600 is used for grinding away a portion of damaged screw thread on the end of an axle. The threading tool 601 is used for cutting a new screw thread into the relatively smaller diameter end of the axle. Each tool is small and light enough so as to be carried individually by a human of average build, and typically each tool weighs less than 25 kg and preferably less than 15 kg Grinding Tool [0053] Referring to Figures 7 to 11 herein there is shown schematically the grinding tool which fits around the end of axle on the shaft portion of the axle, for grinding away a portion of damaged thread on the end of the axle.

[0054] Referring to Figure 7 herein, the grinding tool 600 comprises a clamp assembly 700 for clamping around a main shaft of the axle at a position along the length of the axle such that the part of the axle which is to be ground and re-threaded is between the end of the axle and the mounting position of the clamp; a backplate 702 rigidly attached to one part of the clamp; a slidable grinder mounting plate 703 which is mounted to the back plate 702; a grinder mounting frame 704 mounted to the grinder mounting plate 703 and which is movable with respect to the slidable grinder mounting plate; and an electric motor driven grinder 705 having a body and a rotatable grinding wheel 706.

[0055] The mounting frame 704 comprises a plate 719 and first and second arms, 720, 721 which are rigidly attached to the plate 704 and which extend in a direction which lies across a main plane of the substantially flat plate 704. At a distal end of each arm there is provided an aperture for accepting a pivotable fixing device, for example a bolt and washer, which connects the grinder to the mounting arms, enabling pivotable movement of the grinder about the mounting frame.

[0056] The grinder comprises a main body, which is pivotally attached to the mounting arms 720, 721. Pivoting of the grinder about the ends of the mounting arms, in the embodiment shown is about two intersecting pivotal axes.

However in other embodiments, the two pivot points on the mounting frame may lie on a single pivotal axis.

[0057] Each axis of pivot between the respective arms of the mounting 5 frame and the grinder body lies across and spaced apart from the main geometric central axis through the centre of the clamp when the clamp is fitted to an axle shaft.

[0058] A main plane coincident with the main outer surfaces of the disc -shaped grinding wheel is intersected by a main central axis through the centre of the clamp.

[0059] An axis of rotation of the grinding wheel lies substantially across the pivotal axis of the grinder in the mounting frame.

[0060] The mounting plate 703 and the lower plate 719 of the mounting frame 704 are slidable with respect to each other, and in the prototype embodiment are constructed from two plates of a linear sliding machine tool mount which comprises a channel track in one plate and a protruding insert or carriage portion which fits into the track. The track and the carriage are connected by either a worm drive or a rack and pinion arrangement which is controlled by a rotary control wheel 710 to move the two plates relative to each other. Accuracy of linear movement of the mounting frame 704 relative to the mounting plate 703 is accurate to within 0.1mm in the prototype embodiment grinding tool, but in other embodiments, the accuracy may be in the range 0.05mm to 0.2 mm.

[0061] In a variation of the best mode embodiment, the slidable mounting plate 703 which carries the mounting frame 704 may also slide on an adjustable slide mount with respect to the fixed mounting plate 702, so that the whole mounting frame 704 can be moved side to side relative to the clamp, along a line parallel to the main geometric centre axis of the clamp when the clamp is attached to an axle, as well as towards and away from the clamp, having both X and Y direction movement.

[0062] In the best mode embodiment shown, movement of the outer perimeter of the grinding wheel 706 in a direction along a direction coincident with the length of the axle is effected by sliding the clamp along the length of the axle. Rotation of the grinder about the circumference of the axle is effected by rotating the whole grinding tool about the axle shaft. The grinding tool can be rigidly set at any axial position and at any angular position about the axle by tightening the clamp shells to each other using the tightening means, in this case the bolts 730 -733 connecting the clamp shells.

[0063] The rotatable grinding wheel or disc 706 rotates about axes of rotation which are fixed in relation to the body of the grinder. The grinder is attached to the arms of the mounting frame 704 by a pair of bolts 707, 708 such that the grinder is moveable and can be tilted about an axis of movement which moves the axis of rotation of the grinding wheel so that the perimeter of the rotating grinding wheel can sweep backwards and forwards in an arc which has a tangent parallel to the main central axis of the aperture surrounded by the clamp, which coincides with the main central axis of an axle shaft to which in use, the clamp is fitted. The path described by the perimeter of the grinding wheel describes a part toroidal or donut shaped surface as the grinder is pivoted about the pivotal connections to its mounting frame 704.

[0064] Back plate 702 is bolted or welded to the mounting plate 703. The mounting plate 703 remain static relative to the clamp, whereas the lower plate 719 of the mounting assembly 704 slides backwards and forwards towards and away from the clamp arrangement. The mounting plate 703 and lower plate 719 are connected by an adjustable sliding mechanism which has a Vernier gauge with graduated rotatable end wheel 710, such that rotation of the hand operated end wheel in a first rotational direction moves the mounting plate and consequently the mounting frame 704 and grinding wheel further towards the clamp and towards the main central axis of the clamp, and rotation of the end wheel in a second, opposite rotational direction moves the mounting frame 704 further away from the clamp and further away from the axial centre of the clamp, thereby moving the grinding wheel radially outwards away from the main central axis of the clamp, which in use coincides with the main central axis of the axle. The Vernier gauge may be lockable with a hand operated locking lever 713 so that the position of the mounting frame relative to the backplate in a direction radial to the main geometrically central axis passing through the aperture formed by the clamp is lockable at any Vernier gauge position.

[0065] The slidable mounting frame 700 for is movable such that the whole of the motorised grinder is movable in a direction towards the main central axis which is symmetrically central to the clamp and which coincides with the main central axis of the axle in use, and in an opposite direction away from the main central axis through the clamp, and therefore away from the main central axis of the axle.

[0066] In the preferred embodiment prototype as shown in Figures 7 to 11 herein, the grinder is known commercially available electric powered angle grinder. However in other embodiments, the angle grinder may be replaced by a specifically designed motorised housing with replaceable grinding wheel, with provision for the motorised housing to be rocked or tilted backwards and forwards within the mounting frame, so as to scan the rotating perimeter of the grinding wheel in an arc so that the rotating edge of the grinding wheel travels an arcuate path relative to the main central axis of the axle which is being ground.

[0067] The grinder is turned on and off by an electrical switch mounted on the disc grinder. Typically the grinder will be used with a grinding disc or wheel which is between 3mm and 8mm in thickness, and typically uses commercially available 110mm or 150 mm diameter grinding wheels for grinding metal. In other embodiments, larger grinders having larger diameter grinding wheels may be used.

[0068] Preferably the grinding tool is of a size and weight which can be comfortably carried by a single person without straining. In the best mode embodiment, the grinding tool weighs less than 25kg and preferably weighs less than 15kg.

[0069] In the embodiment shown, the clamp arrangement comprises a first clamp shell 711 to which the backplate is rigidly mounted; and a second opposing clamp shell 712 which lies opposite the first clamp shell, there being a passage way therebetween into which the axle can fit. The first and second clamp shells are connected to each other by a set of four bolts 730 -733 extending between the clamp shells, such that the clamp shells and the bolts form a passage through which the axle shaft can pass. The second clamp shell is fully removable from the first clamp shell by undoing all four bolts, or can be loosely retained to the first clamp shell by one or more bolts. The first and second clamp shells can be tightened around the axle shaft using the set of four bolts which connect the first and second clamp shells to each other.

[0070] Rigidly connected to the second clamp shell 712 there is provided a tube connector 740 into which a leverage bar or tommy bar 741 may be fitted. The tube may be threaded to accept a corresponding threaded end of a tommy bar, or in other variations, the tube may have a smooth internal circular cylindrical surface to accept a smooth circular cylindrical outer surface of a leverage bar, which can easily be slid in and out of the two connector. Other arrangements, such as a bayonet fixing may be used in other embodiments.

[0071] In the prototype embodiment shown, the clamp comprises two sections of opposing angle iron or steel, each comprising first and second plates arranged substantially 90° to each other. Each shell has a substantially flat sheet liner a softer material, for example plywood or a plastics sheeting material to provide grip onto the outer surface of the axle shaft when the clamp is fitted around an axle.

[0072] In variations of the prototype embodiment, the clamp can be constructed as first and second clamp shells which are hingedly connected to each other and tightened and released by means of one or more bolts extending between the first and second clamp shells, or alternatively the first and second clamp shells can be retained to each other by as few as two bolts, one each side of each clamp shell.

[0073] Referring to Figure 8 herein, there is shown the grinding tool in view from one end, showing the electric grinder device mounted within the spaced apart mounting arms 720, 721 about a pair of pivotal connections. As viewed in the end direction, along said main central axis through the clamp, the perimeter of the grinding disc 706 can be moved towards and away from the main central geometric axis running through the clamp, which is coincident with the main central axis of the axle when the clamp is fitted to the axle.

[0074] Referring to figure 9 herein, there is illustrated schematically the grinding tool in view from a second side, opposite to the first side.

[0075] Referring to Figure 10 herein, there is illustrated the grinding tool in view from the second end, showing the radial movement control wheel 710 and the back of the backplate 702.

[0076] Referring to Figure 11 herein, there is illustrated schematically in perspective view, the grinding tool from the second end and first side, where the grinding tool has a leverage bar 1100 inserted into the lever bar holder. The leverage bar extends outwardly of the first clamp shell 711 on an opposite side of the clamp to the grinder and mounting plate so that user can turn the whole grinding tool either clockwise or anticlockwise by grasping in one hand the lever bar, and in the other hand, the radially protruding grinder and mounting assembly, thereby balancing the physical effort required, on the human operator's body to turn the threading tool.

Threading Tool Construction [0077] Referring to Figures 12 to 15 herein, there is shown the views of the threading tool 601, being a specific embodiment according to the present invention.

[0078] Referring to Figure 12 herein, there is illustrated schematically a view of the threading tool 601 as viewed from a first side. The threading tool comprises an annular body assembly 1200 having an inner annular tubular sleeve 1201 and a concentric outer annular tubular sleeve 1202, the inner tubular sleeve 1201 having an outwardly facing helical screw thread which engages with an inwardly facing corresponding helical screw thread on an inner surface of the outer tubular sleeve 1202; a radially protruding mounting plate 1204 for mounting a sliding adjustable plate assembly 1205; mounted to the adjustably slidable plate assembly 1205, there being a cutting tool mounting plate 1206 to which the cutting tool holder 1207 as attachable; and a cutting tool 1208 having a cutting tip mounted to the cutting tool holder 1207.

[0079] The body assembly, comprising the inner and outer annular sleeves, and the mounting plate which is rigidly secured to the outer sleeve is an interchangeable part, which can be selected from a set of such bodies, each having a different pitch of thread between the inner and outer sleeves. Different internal diameter inner sleeves may be selected for different vehicle axles having different outside diameters. The pitch of the thread determines the axial travel of the outer sleeve with respect to the inner sleeve per each revolution of the outer sleeve with respect to the inner sleeve, and therefore, for the cutting tool tip which is fixed to the outer sleeve via the mounting plate, the pitch of the helical path of the cutting tip is determined to be the same as the pitch of the thread between the inner and outer sleeves. To create a thread of a particular pitch on the end of the axle shaft requires selection of a body comprising the sleeve set having the same thread pitch between the inner and outer sleeves as the axle end thread which it is required to cut.

[0080] The inner sleeve of the sleeve set aligns coaxially with the outer sleeve of sleeve set, with the outer sleeve being rotatable with respect to the sleeve, rotation of the outer sleeve around the inner sleeve causing axial movement of the outer sleeve relative to the inner sleeve.

[0081] The peak to trough height of the resulting thread which the cutting tool creates on the end of the axle is determined by the shape of the tip of the cutting tool, which is selected to match the shape of the required thread profile corresponding to the new retaining nut, and by the extent of the radial direction of travel of the cutting tool tip which is controlled by the slidable Vernier plates and hand operated micrometer gauge.

[0082] An inner surface of the annular tubular circular cylindrical inner sleeve 1201 comprises a smooth circular cylindrical face, of a diameter selected to slide over the outside of the relatively larger diameter part of the axle shaft. For example, where the axle shaft has a largest outside diameter of 90mm, a set of sleeves for that diameter of axle should have an internal aperture bore diameter which is a sliding fit over the axle shaft. Similarly, sets of sleeves for different axles of other different outside diameters have sets of sleeves which closely fit around the maximum outer diameter of the shaft portion of those axles.

[0083] Preferably the threading tool is of a size and weight which can be comfortably carried by a single person without straining, and preferably the weight of the threading tool is less than 25kg, and preferably weighs less than15kg.

[0084] Referring to figure 13 herein, there is illustrated schematically in view of the threading tool from a second side.

[0085] Referring to Figure 14 herein, there is illustrated schematically a view of the cutting tool from one end showing the concentric annular inner sleeve 1201 and surrounding annular outer sleeve 1202 in view along the main axial direction at a geometric centre of the sleeve assembly.

[0086] At an outer perimeter of the outer sleeve, there is provided first and second mountings 14001, 1401, each for mounting one end of a corresponding respective lever bar. In the preferred embodiment, the mountings each comprise a threaded bore into which a male threaded end of a lever bar may be inserted. The mountings are diametrically opposed to each other on opposite sides of the outer sleeve, so that when the levers are inserted into the mountings, the levers extend substantially radially outwards from a main geometric centre line of the sleeve assembly.

[0087] As shown in Figure 14, the line of inward and outward movement of the tip of the cutting tool which cuts the thread in the axle end is perpendicular to the main central axis of the bore of the sleeve, which coincides with the main central axis of the axle.

[0088] Referring to Figure 15 herein, there is illustrated schematically a view of the threading tool from a second, opposite end, showing a worm screw 1500 which is rotated by control 1214 which moves the tool mounting plate 1206 in a direction towards and away from the central bore of the inner sleeve. 1.5

[0089] As seen in Figure 15, the line of movement towards and away from the main central axis of the inner sleeve is along a line which is parallel to a diameter through the main central axis.

[0090] Referring to Figure 16 herein, there is illustrated schematically in view from one side a further sleeve assembly for the threading tool. A set of sleeve assemblies may be provided with a threading tool in which each sleeve assembly has an inner sleeve, and outer sleeve, one or more mounting positions 1602 for attaching a lever bar to assist in rotation of the outer sleeve about the inner sleeve; the inner sleeve having an outwardly facing mail thread 1603, and the outer sleeve having an inwardly facing female thread which engages the male thread of the inner sleeve, so that as the outer sleeve is rotatable with a sleeve, the outer sleeve moves in a direction of rotation and axially along the inner sleeve at a rate of distance per full revolution which is dictated by the pitch of the threads on the inner and outer sleeves.

[0091] The inner sleeve has a plurality of securing means 1604, 1605 four securing the inner sleeve to the outer surface of an axle. In this case, securing means comprise three threaded apertures spaced angularly equidistantly from each other, each having a bolt which protrudes through a respective aperture, and which to the surface on the axle. Release of the inner sleeve from the axle is achieved by doing the bolts.

[0092] In a set of sleeve assemblies each having a specific having the same internal bore diameter of the sleeve to match a particular outside diameter axle, for each internal diameter of the sleeve there may be more than one sleeve assembly, each having a different thread pitch, so that different thread pitches can be applied to the same diameter axle, and that different diameters of axles have threads applied.

Method of Operation [0093] A method of operation of the axle thread repair apparatus will now be described.

[0094] Typically the grinding tool 600 and threading tool 601 can be used as part of a mobile axle repair apparatus comprising a portable electrical welding apparatus, the conventional toolkit having a range of spanners, torque wrenches and other known hand or power tools, and a portable electrical generator to provide electrical power to the electric welder and grinding tool 600.

[0095] A repair operator arrives on site at a vehicle having a seized or damaged axle bearing, and proceeds to remove the road wheel from the end of the axle having a damaged bearing. The end retaining nut and the screw thread on the end of the axle will typically become inevitably damaged when removing the end retaining nut due to over tightening of the nut onto the axle by the inner race of the bearing.

[0096] Once the axle shaft has been stripped of the wheel, the wheel mounting and roller bearings, so that only the substantially circular cylindrical axle remains exposed on the vehicle, the basic stages of axle repair whilst the axle is still on the vehicle are as follows: * The human operator strips off the end cap from the axle to reveal the end retaining nut which holds the wheel hub onto the axle; * The operator loosens the end retaining nut which holds the wheel hub on the axle. This is the stage which damages the thread on the attainment and on the end of the axle; * The vehicle is jacked up, or the axle is otherwise raised to lift the road wheel off the ground; * The maintenance operator removes the end retaining nut. During this stage, the end nut strips the thread on the end of the axle; * The operator removes the wheel hub from the axle end; * With the axle end exposed and with the axle remaining on the vehicle, the operator fits the grinding tool over the main shaft of the axle, and grinds away the damaged thread portion on the end of the axle to achieve a substantially circular cylindrical surface which may be recessed relative to the outer diameter of the end portion of the axle, or maybe at the same outer diameter as the end portion of the axle, or which may stand proud of the nominal outer diameter of the the axle; * The operator removes the grinding tool and builds up the region where the thread has been ground down with weld in order to increase the diameter of the end of the axle where the thread is to be replaced so that there is enough metal material to cut a new thread of the required diameter; * The operator re-attaches the grinding tool and starts to make the end of the shaft circular cylindrical using the grinding tool to a diameter equal or slightly greater than the maximum diameter of the intended thread; * The operator grinds away an annular clearance channel at an axial location adjacent to the diameter step of the axle to provide a clearance channel between the intended position of the thread and the diameter step change of the axle between the end portion of the axle and the main shaft portion; * With the grinding wheel spinning, the operator sweeps the grinder about its pivot axis on the mounting frame so that the perimeter of the grinding wheel sweeps across the threaded end portion of the axle. The operator rotates the grinding tool around the axle and works their way round the threaded end of the axle rotating the grinding tool around the axle, with the clamp of the grinding tool rotating about the larger diameter shaft portion of the axle; * The operator uses the radially adjustable mounting plate and rotatable wheel control to gradually grind away the weld, working their way around the end of the axle by rotating the grinding tool around the shaft of the axle, and rocking the grinding tool about its pivot point on the grinder mounting, to achieve an approximately circular cylindrical surface.

* Periodically, the operator may slide the grinding tool off the end of the axle and apply an external caliper measuring tool with a graduated scale to measure the outside diameter of the end of the axle. Alternatively, the operator may rely on the micrometer gauge on the grinding tool to determine the diameter of the end of the axle * By working the grinding tool around the end of the axle and by rocking the grinder backwards and forwards in its pivot mounts, and incrementally moving the grinder towards and away from the main central axis of the axle an accuracy of radius of the end of the axle of around plus or minus 0.1mm can be achieved, and in other embodiments, accuracies in the range 0.05mm to 0.2mm may be achieved.

* The operator removes the grinding tool and attaches the threading tool to the main shaft of the axle, after first having checked that the correct threading tool sleeve assembly having the correct pitch for the required thread to be cut has been selected; * The operator measures the outer diameter of the ground circular cylindrical end of the axle shaft, where the thread is to be cut, using outside caliper gauge, and uses the micrometer gauge on the threading tool to control the depth of the cutting tool.

* The operator manually rotates the thread cutting tool around the end of the axle, to cut a thread in the circularised weld region.

* It has been found that the threading tool is best rotated through a part revolution in a first direction resulting in cutting of the thread in the axle end, and is then reversed in an opposite rotational direction, in order to allow clearance of material from the cutting tool, and gradually working axially along the end of the axle cutting in stages towards the central shaft part of the axle, with regular reversals of rotational direction of the cutting tool, rather than attempting to cut a thread in a single rotational direction movement; * The operator removes the threading tool to leave the completed repaired axle end.

* The operator fits a new bearing into the wheel hub and replaces the wheel hub on the axle shaft, applies the correct amount of lubricant and fits a new end retaining nut having a thread diameter and pitch matching the thread diameter and pitch of the newly re-threaded axle end, and refits the end cap and road wheel.

Operation of the grinding tool [0097] Referring to Figures 17 to 19 herein, there is illustrated schematically use of the grinding tool.

[0098] The clamp assembly is slid over the axle and moved axially along the length of the axle until it surrounds the main larger diameter shaft portion of the axle, with the outer perimeter of the grinding wheel facing opposite the outer surface of the region of the axle end to be ground down. The bolts of the clamp are tightened up using a spanner so that the grinding tool is rigidly held to the axle shaft.

[0099] Using the rotating adjustment wheel which moves the slidable mounting plate, the grinding wheel is gradually moved radially inwards towards the axial centre of the axle, and the operator grasps the end of the grinder and rocks the grinder about its pivot points in the grinder mounting so that the perimeter of the grinding wheel grinds away part of the threaded portion of the axle end, with passes or sweeps of the perimeter of the rotating grinding wheel sweeping about a pivot axis which is substantially perpendicular to and spaced apart from the main central axis of the axle.

[00100] The operator grinds an annular channel at the intersection between the diameter change of the axle, to provide a clearance channel.

[00101] In some cases, where the surface of the axle is toughened, when carrying out re-threading of the end of the axle, the cutting tool may vibrate or skip over the surface of the circularized weld, due to the mixture of the original toughened thread and the weld material, of the same material type, but not being toughened.

[00102] In this case, there are two options: * Firstly, for a toughened surface axle, when grinding the threaded region, the region is ground down to a diameter slightly lower than the valley of the original thread, so that when the region is built up with weld, the valley in the thread cut into the weld does not encounter any of the original toughened metal surface of the axle.

* Secondly, if the weld has already been built up in the threaded region, without grinding the original damaged thread down below the level of the original toughened surface, then instead of using a static thread cutting tip on the threading tool, the threading tool can be mounted with a motor -driven rotating "V" shaped diamond tipped wheel which takes the place of the thread cutting tip. Operation of the threading tool is the same as previously described, with the operator rotating the rotating cutting edge around the end of the shaft, to cut a thread, and with the threaded portion between the inner sleeve and the outer sleeve determining the pitch of the thread being cut. This requires modification of the threading tool to accommodate a motor -driven rotating cutting tool.

[00103] Referring to Figure 20 herein, after grinding away the damaged thread portion, the end of the axle is built up with weld as shown. There is illustrated schematically in perspective view one end of a circular cylindrical axle shaft having a damaged thread, where the end of the thread has been built up by adding drops of welded metal to the end of the shaft. The added weld needs to be thick enough such that there is sufficient metal material added in the radial direction that when the welded portion is ground down to a circular cylindrical shape, the metal is thick enough to accommodate the full height of the screw thread which is to be applied to the added material.

[00104] After the weld build -up stage, operation of the grinder to grind down the welded region to a sub-substantially circular cylindrical surface is similar as described above. The operator moves the grinding tool axially along the axle shaft, and also moves the grinding wheel inwards towards the welded region to be ground away to make a substantially circular cylindrical outer surface which has been built up from weld, and ground down to a circular cylindrical surface.

Operation of the threadinq tool [00105] Referring to Figures 21 to 23 herein, there is shown operation of the threading tool 601 being used for cutting a thread on the end of an axle, with the axle in situ on the vehicle.

[00106] Referring to Figure 22 herein, there is illustrated schematically in perspective view the threading tool fitted to end of axle in a first rotational position, with the cutting tip engaged within a thread groove of the axle end.

[00107] The inner sleeve of the threading tool is slid over the end of the axle shaft and is rigidly secured to the outer surface of the axle shaft by tightening up the three radially extending bolts 1210 -1213 at a first end of the inner sleeve. With the cutting tool moved radially outwardly so that it is clear of the end of the axle to be threaded, the inner and outer sleeves are contracted to their maximum extent so that the inner sleeve is drawn within the outer sleeve to its maximum extent.

[00108] The cutting tool holder 1207 is moved radially inwards towards the main centreline of the sleeve assembly to a position where it just touches the outer surface of the ground down weld section on the end of the axle, and then using the rotatable control wheel 1214 the tool holder is moved slightly outward radially, for example by a distance of 0.1mm, and the operator rotates the outer sleeve relative to the inner sleeve around the axle, using first and second lever arms attached to the outer sleeve, so as to begin a first pass of the cutting tool over the ground down welded section of the axle.

[00109] Rotation of the outer sleeve with respect to the inner sleeve causes both rotational and axial movement of the cutting tip relative to the outer surface of the ground down welded portion of the axle. The cutting tip follows a helical path around the axle end, scoring out a helical groove in the end of the axle, being the beginning of the thread formed in the ground down welded portion.

[00110] If the cutting tool has been set too far inwardly towards the central axis of the sleeve assembly, making rotation of the outer sleeve difficult, the user may use the control wheel 1214 to bring the cutting tool out radially so that the groove cut by the tool is not as deep. The operator starts off with a relatively shallow groove, making a first pass along the axle to cut a helical groove or channel in the end of the axle. After a first pass of the cutting tool, the operator may then measure the external diameter of the peaks of the thread using an external caliper Vernier gauge or like measuring instrument.

[00111] The operator moves the cutting tool radially outwardly so as to clear the thread and then winds the outer sleeve back to its original home starting position where the inner sleeve is fully contracted to the outer sleeve.

[00112] The operator proceeds to move the cutting tool holder incrementally inwards towards the axial centre of the axle, which is coincident with the axial centre line of the sleeve assembly, when the sleeve assembly is secured to the axle, and checks the radial distance of the cutting tool tip using the micrometer measuring scale and the control wheel 1214. The operator then makes a further (second) pass of the cutting tool along the previously made groove, rotating the outer sleeve relative to the inner sleeve as described previously, and the cutting tool cuts the groove or channel in the axle deeper.

[00113] The above processes are repeated, with periodic checks for measurement of the outer diameter of the thread, and of the depth of the thread (peak to valley depth) using a thread depth measuring instrument.

[00114] The Vernier gauge on the threading tool is movable towards or away from the geometric centre of the axle to which the threading tool is attached in increments of 0.1mm or less.

[00115] Once the operator is satisfied that they have formed a thread of the correct depth and having the correct maximum outer diameter peak to peak, the operator winds the cutting tool holder radially outwards using the control wheel 1214 so that the cutting tool tip is clear of the thread, and then uses a spanner or socket to loosen the securing bolts 1210 -1212 which frees the inner sleeve from the outer surface of the axle.

[00116] Axles are manufactured in standardized outer diameter sizes, and the inner sleeve can be manufactured so that it has an inner diameter which is a sliding fit over the outer surface of a standard [00117] Referring to Figure 22 herein, there is illustrated schematically in a further perspective view the threading tool fitted to end of axle in the first rotational position, with the cutting tip engaged within a thread groove of the axle end.

[00118] Referring to Figure 23 herein, there is illustrated schematically the threading tool fitted onto the axle, without the external lever bars attached and with the outer sleeve located partway along the inner sleeve in the axial direction, during part of a rethreading process.

[00119] Referring to Figure 24 herein, there is illustrated schematically in view from one side, a repaired axle having a repaired and re threaded end using the apparatus and methods described herein above. Visually, the repaired axle end is substantially identical to a new axle, having a thread of the same pitch, outside diameter and minor the same valley wall shape as the original thread of the axle. The thread is made up of metal welded to the end of the axle, and differs from the original thread in that the repaired thread may not have been toughened or hardened.

Advantages [00120] Specific embodiments and methods according to the invention as disclosed herein allow repair of a damaged axle shaft end or spindle end on a road vehicle, without the need to remove the axle or spindle from the road vehicle. This reduces the stripping down time for removing an axle or spindle from vehicle.

[00121] The apparatus and methods disclosed herein can be operated by a single person, provides an advantage over the prior art method of replacing or repairing a damaged axle shaft end spindle end.

[00122] Using apparatus and methods herein, there is no need to remove the axle from the road vehicle, and no need for turning of the axle spindle on a workshop lathe. The axle does not need to be sent to a workshop.

[00123] The items of apparatus disclosed herein are small enough and light enough to be portable by a single person, and can fit into a van or commercial vehicle, meaning that axle end repair can be carried out as a mobile service without the need for full workshop facilities.

[00124] All of the toolkit including toolbox, spanners, the grinding apparatus disclosed herein, the threading apparatus disclosed herein, a small electric generator for powering the grinding tool, an electric welder or small gas welder and all the welding rods and welding supplies needed will fit into small commercial vehicle such as a van or pickup truck.

Claims

Claims 1. A method of repairing a stripped thread of a vehicle axle, whilst said axle remains in situ on the vehicle, said method comprising, whilst the axle remain on the vehicle: attaching a grinding tool to said axle, said grinding tool comprising a rotatable grinding surface; moving said grinding surface along and around a perimeter of said axle to create a substantially circular cylindrical end of said axle; attaching a threading tool to said axle, said threading tool comprising a cutting head; and moving said cutting head around a perimeter of said substantially circular cylindrical end of said axle to put a thread in said end of said axle.
2. The method as claimed in any one of the preceding claims, wherein said stage of attaching said grinding tool to said axle comprises clamping said grinding tool to said axle.
3. The method as claimed in any one of the preceding claims, wherein said stage of moving said grinding surface around said axle comprises manually rotating the whole of said grinding tool around said axle.
4. The method as claimed in any one of the preceding claims, wherein said stage of moving said cutting head around a perimeter of said axle comprises manually rotating said cutting head around said axle.
5. The method as claimed in any one of the preceding claims, wherein said step of attaching a threading tool to said axle comprises sliding an inner collar of said threading tool over an end of said axle, and securing said inner collar to said axle.
6. The method as claimed in any one of the preceding claims, wherein said grinding tool is removed from said axle prior to fitting said threading tool to said axle.
7. The method as claimed in any one of the preceding claims, wherein said stage of rotating said grinding surface around a perimeter of said axle comprises moving a centre of rotation of said rotatable grinding surface towards a geometric central axis of said axle.
8. The method as claimed in any one of the preceding claims, wherein said stage of rotating said grinding surface around a perimeter of said axle comprises moving a centre of rotation of said rotatable surface towards an outer surface of an end region of said axle.
9. The method as claimed in any one of the preceding claims, wherein said centre of rotation of said rotatable grinding surface is moved towards or away from said perimeter of said axle by a distance increment in the range 0.05mm to 0.2mm.
10. The method as claimed in any one of the preceding claims, wherein a distance of a tip of said thread cutting tool is moveable towards a geometric central axis of said axle or spindle by a distance increment in a direction radially outwards said geometric central axis in the range 0.05mm to 0.2mm.
11. The method as claimed in any one of the preceding claims, comprising building up an end portion of said axle or spindle with weld to provide a mass of metal for grinding and threading.
12. The method as claimed in any one of the preceding claims, wherein the grinding tool has an overall weight of less than 25kg.
13. The method as claimed in a one of the preceding claims, wherein said threading tool has an overall weight of less than 25kg.
14. A tool for grinding an axle shaft of a road vehicle, said tool comprising: a clamp for attaching to a circular cylindrical outer surface of said axle shaft; a rotatable grinding wheel; a movable mounting for mounting said rotatable grinding wheel; an electric motor for driving said rotatable grinding wheel.
15. The grinding tool as claimed in claim 14, wherein said movable mounting comprises a mounting which is slidable in a directions towards and away from said clamp.
16. The grinding tool as claimed in claim 14 or 15, wherein said movable mounting comprises a first plate having an elongate channel, and a second plate having a protruding carriage portion which slides along said elongate channel.
17. The grinding tool as claimed in any one of claims 14 to 16, wherein an axis of rotation of said rotatable grinding wheel is spaced apart from a main geometric central axis surrounded by an internal surface of said clamp.
18. The grinding tool as claimed in any one of claims 14 to 17, wherein said rotatable grinding wheel is pivotally mounted on said mounting about a pivotal axis which is perpendicular to and spaced apart from an axis of rotation of said grinding wheel.
19. The grinding tool as claimed in any one of claims 14 to 18, wherein said rotatable grinding wheel is pivotally mounted on said mounting about a pivotal axis, such that a perimeter of said grinding wheel describes a substantially toroidal segment path as said grinding wheel is pivoted about said pivotal axis.
20. A threading tool for cutting a thread onto a vehicle axle in situ on a vehicle, said tool comprising: a tubular inner sleeve for fitting over said axle; a tubular outer sleeve for fitting over said inner sleeve; an mounting plate mounted to said tubular outer sleeve; and a cutting tool holder mounted to said adjustable mounting plate.
21. The threading tool as claimed in claim 20, further comprising a slidably adjustable plate assembly which is removably attachable to said mounting plate.
22. The threading tool as claimed in claim 20 or 21, wherein said tubular inner sleeve comprises an outwardly facing thread on an outer surface of said sleeve.
23. The threading tool as claimed in claim any one of claims 20 to 22, wherein said tubular outer sleeve comprises an inwardly facing thread.
24. The threading tool as claimed in any one of claims 20 to 23, wherein said tubular inner sleeve comprises an outwardly facing thread; and said tubular outer sleeve comprises an inwardly facing thread; wherein said outwardly facing thread of said inner sleeve engages said inwardly facing thread of said outer sleeve so that when said outer sleeve is rotated relative to said inner sleeve, said outer sleeve moves both rotationally and axially with respect to said inner sleeve.
25. The threading tool as claimed in any one of claims 20 to 24, wherein said cutting tool holder is movable towards and away from a main geometrically central length axis of said inner sleeve.
26. The threading tool as claimed in any one of claims 20 to 25, wherein said tubular inner sleeve comprises a plurality of threaded apertures extending in a direction radially towards a geometric central axis of said tubular inner sleeve; and a plurality of threaded bolts, located in said threaded apertures.
27. A sleeve assembly for a threading tool for cutting a thread onto a vehicle axle in situ on a vehicle, said sleeve assembly comprising: a tubular annular inner sleeve having a first externally presenting threaded portion; a tubular annular outer sleeve having an inwardly facing threaded portion of a same pitch as said externally presenting threaded portion; and a radially extending mounting plate rigidly secured to said outer sleeve.
28. The sleeve assembly as claimed in claim 27, wherein said inner sleeve comprises a smooth circular cylindrical central bore.
29. The sleeve assembly as claimed in claim 27 or 28, wherein said outer sleeve comprises an externally presenting mounting for mounting a lever to said outer sleeve.
30. The sleeve assembly as claimed in any one of claims 27 to 29, wherein said inner sleeve comprises at least one radially extending screw capable of extending and contracting in a radial direction towards and away from a main geometric central axis of said inner sleeve.
31. A set of sleeve assemblies, each as claimed in any one of claims 27 to 30, wherein each individual sleeve assembly has a different internal bore diameter to each other sleeve assembly in the set.
32. A set of sleeve assemblies each as claimed in any one of claims 27 to 30, wherein each individual sleeve assembly has a said externally presenting threaded portion and a said inwardly facing threaded portion of a pitch which is different to a pitch of the externally facing an inwardly facing threads of each other sleeve assembly of said set.