Various methods are known for mounting axles in simpler forms of vehicle, such as bicycles. The axles are normally demountable to allow removal of wheels for the purpose of tyre repair or replacement or for substitution of a different wheel and tyre unit. To ease demounting, it is common practice, particularly in the case of bicycle rear wheels, to locate the wheel axle in slots, known as a'drop out', in a support frame. The axle has threaded ends and is retained simply by tightening nuts on the ends against surfaces of the frame with interposition of slip-resisting washers or similar. In this conventional system, removal of the axle is a relatively slow procedure, the retaining force achieved by the nuts is variable and an exactly repeatable location of the axle in a specific axial position is not possible. Quick-action mounting systems have accordingly found favour to simplify and accelerate axle removal, especially for specialised bicycles where wheel replacement may be carried out as matter of course to adapt the bicycle to different uses or requirements.

In one such system, the wheel hub has short axle spigots which engage in frame slots and a spindle which passes through the hub and protrudes from the spigots. The spindle has, at its ends, adjustable clamping heads tightened against surfaces around the slots. To tighten the heads against these surfaces, one of the heads is displaceable on the spindle towards the other head by way of a cam operated by a lever with an over-centre action.

The clamping effect of the heads is cancelled by operation of the lever in reverse sense to move the heads apart.

This quick-action system satisfies the requirement for quick release of the axle, but the comparatively small diameter of the axle spigots and the low clamping forces generated by the heads acting on surfaces interrupted by slots have the consequence that the structure composed of wheel unit, axle and associated part of the frame is not particularly rigid. A large amount of wheel-to-frame flex is present, which is undesirable in bicycles intended for rough terrain use. In addition, for reasons of universal use the axle spigots on commercially supplie hub and axle assemblies are normally threaded, which militates against precise and repeatable location of the axle in the slots. Accurate location is, however, desirable in view of the growing use of disc brakes, which are less tolerant of wheel misalignment.

Mounting assemblies allowing quick release of axles are also known in connection with other vehicles, such as motorcycles. In one such assembly, the axle is located by end stubs in hinged clamps. The parts of each clamp are tightened around the respective axle stub by a setscrew bearing against a surface of one part and threaded into a swivel pin in the other part. A slot in the first part allows the setscrew, when loosened, to be moved clear by swivelling of the pin. The clamp can then be opened for release of the stub. This system depends on use of a specially designed axle and cannot accommodate an axle of the kind described above, that is to say an axle having short, threaded end spigots, without giving rise to the mentioned problems of uncertain location and wheel-to-frame flexing.

It is accordingly the primary object of the invention to provide an axle mounting assembly which may enable relative secure and repeatable location of an axle, but permit quick release of the axle. A further object is to provide an assembly which al ! ows rigid mounting of wheel axles having short, threaded end spigots, so that the assembly can accept existing forms of bicycle wheel axle. A related object is the provision of a vehicle incorporating an axle mounting assembly with these capabilities.

Other objects and advantages of the invention will be apparent from the following description.

According to a first aspect of the invention there is provided an axle mounting assembly comprising an openable and closable clamp which is intended for mounting on part of a vehicle and which in a closed state defines a bore, a removable bush located in the bore and having an internal passage for reception of axle means to be secured therein against rotation relative to the bush, and releasable securing means for securing the clamp in the closed state with the bush clamped at its circumference in the bore, the bush being provided with locating means for locating the bush in a predetermined axial position in the bore and the clamp being openable through release of the securing means to define an opening permitting withdrawal of the bush together with such axle means in radial direction with respect to the axis of the bore. In such an assembly, the axle means is received in a bush and can be secured therein against relative rotation, so that the bush and axle means combine to form a rigid unit. The bush, which can have an appreciably larger diameter than the axle means and thus provide a greater support area, is clamped at its circumference in the bore and located in a predetermined axial position by locating means, which ensure a repeatable positioning of the axle means relative to a vehicle part, such as a bicycle frame, on which the clamp is mounted. The clamp is openable to define an opening through which the bush together with the axle means can be radially withdrawn as a unit, thus duplicating the quick-release capability of the known system employing slots, but without the attendant disadvantage of reduced rigidity due to reliance on clamping against interrupted surfaces. The clamping action at the circumference of the bush provides a particularly firm seat for the unit composed of bush and axle means and this in turn contributes stiffness to the supporting part of the vehicle, which results in improved wheel location. The passage in the bush can be shaped to provide a seat for the threaded axle spigot of existing forms of bicycle wheel hubs, but the assembly as a whole can be adapted to differing axle types by modification of the bush.

Preferably, the clamp is openable by relative movement of two hinged parts thereof which define the bore in the closed state of the clamp and the opening in an open state of the clamp. in this arrangement, the clamp constitutes a unit and does not require division into two completely separate parts to allow removal of the bush. Consequently, refitting the bush and axle means is quick and simple.

For preference, the locating means comprises a respective projection provided at at least one axial end region of the bush and co-operable with the clamp. The or each projection, which can be in the form of a flange, can bear against an adjacent surface of the clamp to provide defined axial positioning of the bush. If such a flange is provided at each end of the bush, the flanges can axially locate the bush without the need for application of any axially directed force to the bush.

In order to accommodate existing bicycle axle designs, the passage in the bush can be stepped to form a narrower diameter portion for locating a spigot of the axle means and a larger diameter portion for receiving fastening means for the axle means. The narrower diameter portion can thus provide a firm seat for the spigot and the larger diameter portion can serve to receive, for example, the threaded end of a spindle passing through the spigot and a nut tightenable on the threaded end to urge the bush against, for example, a collar adjoining the spigot. To assist firm seating of the bush in the clamp, the diameter of the bore in the clamp is preferably at least substantially twice the diameter or maximum diameter of the passage in the bush. The larger diameter of the bore and consequently of the effective external circumference of the bush, i. e. excluding any flange or flanges, resists any tendency of the bush to rock in the clamp notwithstanding any transverse thrust exerted on the axle means.

The securing means for securing the clamp in the closed state is preferably a quick-action device, which can open and close the clamp by rotation. Such a device can take the form of, for example, a cam co-operable with a cam follower to tighten the clamp around the bush. Thus, in the case of a two-part hinged clamp, a cam in the form of a rotatable body with a cam track can be journalled in one of the parts and a cam follower in the form of a ball able to run on the track can be fixed to the other one of the parts, the ball leaving the track when the parts are pivoted to form the withdrawal opening for the bush. Other forms of securing means are possible, however. It is of advantage, if the securing means comprises retaining means for automatic retention in a setting in which the clamp is in the closed state. Such retaining means can be provided by an over-centre action or by suitable detent means. The automatic retention of the securing means enhances the quick-action character of the securing procedure.

According to a second aspect of the invention there is provided a vehicle, for example a two-wheel vehicle such as a bicycle, provided with a wheel having axle means and with an axle mounting assembly according to the first aspect of the invention, the axle means being mounted in the assembly. In that case, the axle means preferably comprises an axle spigot seated in the passage in the bush and secured against rotation relative to the bush.

The vehicle can be provided with two such axle mounting assemblies and the axle means can comprise a respective axle spigot extending at each side of the wheel and seated in the passage in the bush of a respective one of the assemblies. The axle means may then also include a spindle extending through both the spigots and into the passages in the bushes, the spindle being provided with fastening means fastening the spindle in the bushes and tightening the bushes against respective surfaces adjoining the spigot. Such an axle means represents, with modification of the spindle, an existing form of bicycle rear axle, which is retained more securely and more precisely than in the case of existing retention systems and which provides enhanced rigidity of the bicycle wheel relative to the bicycle frame.

If, as in the case of a bicycle, the vehicle is chain-driven, the clamp of the mounting assembly or one of the assemblies can comprise a part fixed to a body or frame structure of the vehicle and a part movable relative to the fixed part for opening and closing the clamp, the movable part being provided with a carrier for guide means of a chain of the chain drive. Such a guide means can be the sprockets of a derailleur mechanism of a gear system and the carrier can incorporate actuating elements of the mechanism.

An embodiment of the present invention will now be more particularly described by way of example with reference to the accompanying drawings, in which: Fig. 1 is a schematic exploded perspective view of an axle mounting assembly embodying the invention, together with part of a wheel hub and axle unit to be mounted by the assembly; Fig. 2 is a schematic cross-section, along the line ii-ll of Fig. 3A, of the assembly with mounted axle; Fig. 3A is a schematic, partly-sectioned elevation, to a reduced scale, of part of the assembly with a clamp thereof in a closed and secured state; Fig. 3B is a view similar to Fig. 3A, with the clamp closed but unsecured and ready for opening; and Fig. 3C is a schematic eievation similar to Figs. 3A and 3B, but with the clamp opened.

Referring now to the drawings there is shown an axle mounting assembly 10 intended for, in particular, mounting the axle of a rear wheel of a bicycle, especially an off-road or 'mountain'bicycle. Such a rear wheel has, as shown in Figs. 1 and 2, a hub 11 rotatably supported by bearings (not shown) on an axle tube 12. Threaded end portions 12a, which conventionally have a diameter of 10 millimetres, of the tube protrude from each side of the hub. A hardened steel collar 12b with a radially serrated outer face is screwed onto each threaded end portion 12a. Finally, a spindle 13, which is illustrated in Fig. 1 with exaggerated length and which has a diameter of 5 millimetres, with threaded ends extends through and protrudes from the axle tube 12. The wheel with its hub and integrated axle tube forms a unit of conventional construction, with the threaded end portions 12a of the tube serving as axle spigots and being securable, in some conventional applications, by nuts screwed directly onto the spigot threads.

A respective mounting assembly 10 is normally provided at each side of the wheel hub for each end portion 12a of the axle tube 12, only one such assembly being illustrated in the drawings and described below. The assembly comprises a clamp 14 composed of a fixed first part 15 with a flat mounting face 15a intended to be rigidly attached, preferably by welding, to one of the arms of a rear wheel fork of the bicycle, and a movable second part 16 pivotably connected to the first part by a hinge pin 17. The two clamp parts 15 and 16 have complementary part-cylindrical surfaces which, in a closed state of the clamp as illustrated in Figs. 3A and 3B, co-operate to define a cylindrical bore 18. In an open state of the clamp, achieved by pivoting the movable part 16 away from the fixed part 15 into the position shown in Fig. 3C, the two parts bound an opening 19 having a minimum width greater than the diameter of the bore 18.

The assembly 10 further includes a cylindrical bush 20 with axial end flanges 20a. The bush is preferably made of aluminium. The diameter of the effective outer circumference of the bush 20, that is to say between the flanges 20a, corresponds with that of the bore 18 and is considerably larger, for example 20 millimetres, than the diameter of the end portion 12a of the axle tube. The axial length of the bush between the flanges corresponds with the dimension of the clamp 14 in the axial direction of the bore 18 plus a small tolerance, so that the bush is securely seated in the bore in the closed state of the clamp as shown in Fig. 2 but can be removed from and refitted to the clamp in the open state thereof without undue force. The mutually facing surfaces of the two flanges 20a bear against the respectively adjacent flanks of the clamp to provide a precisely defined axial location of the bush 20 in the bore 18.

In its interior the bush 20 has a stepped passage 20b with a narrower diameter portion providing a firm seat for the threaded end portion 12a of the axle tube 12 and a wider diameter portion accommodating a washer 21 and a nut 22 engageable on the threaded end of the spindle. By tightening the nut 22, with the washer 21 bearing against the step between the two portions of the passage 20b and with the spindle 13 fixed at its other end relative to the hub 11, the bush 20 can be firmly clamped against the serrated face of the collar 12b.

The assembly 10 is completed by a quick-action securing device 23 for securing the clamp in a closed state with the surfaces of the bore 18 bearing on the circumference of the inserted bush 20 to firmly clamp it in place. The securing device 24 comprises a rotary body 24, which is journalled in the fixed part 15 of the clamp and which is provided with a cam track 24a and operating lever 24b, and a cam follower ball 25, which is engageable in the cam track and carried by a pin shank 25a adjustably mounted, by screw-threading, in the movable part 16 of the clamp. The ball 25 can enter and exit the cam track 24a via a slot 26 in the part 15. The cam track 25a is shaped so that in one rotational setting of the rotary body 25, as shown in Fig. 3B, the ball 25 can freely enter and exit the track and in another rotation setting, shown in Fig. 3A, the ball is held by the cam track with the clamp closed and the surfaces of the bore 18 pressurably bearing against the circumference of the bush 20. The securing device 23, in particular the rotary body 24, can have an over-centre action to provide automatic retention of the body in the setting shown in Fig. 3A. The over-centre action can act to similarly retain the body in the setting of Fig. 3B, i. e. with the clamping effect cancelled.

The movable part 16 of the clamp is provided with an extension 16a for carrying a derailleur mechanism (not shown) for a rear wheel gear system of the bicycle. Such a mechanism conventionally includes oppositely-acting deflecting sprockets for the bicycle drive chain. In the fully open state of the clamp shown in Fig. 3C, the derailleur mechanism is moved clear of the path for the bush 20 through the opening 19, but in that case induces a tension in the chain tending to move the clamp parts 15 and 16 together.

This tendency effectively produces a light closing force for the clamp.

In use of the described axle mounting assembly 10, the clamps 14 of two such assemblies (only one with a derailleur mechanism) are permanently fixed by their mounting faces 15a to the arms of a rear wheel fork of a bicycle. The clamps are disposed with the bores 18 in alignment. This fixing process represents a step in the manufacture of the bicycle. In similar manner, the bushes 20 of the assemblies 10 are located on the threaded end portions 12b of the axle tube 12 of a wheel unit consisting of a wheel with hub 11, tube 12 and spindle 13, and the washers 21 and nuts 22 are fitted to the ends of the spindle within the passages 20b of the bushes. On tightening of the nuts 22, the bushes 20 are firmly clamped against the collars 12b of the axle tube to form a rigid subassembly with the wheel unit. In that case, the serrations of the collars bite into the aluminium material of the bushes to resist relative rotation. The axial spacing of the bushes 20 can be adjusted, for precise adaptation to the spacing of the clamps 14, by adjustment of the position of the collars 12a on the axle tube 12 and/or by use of shims or spacers. The subassembly can now be mounted in the clamps 15 in the reverse sequence illustrated by Figs. 3A to 3C.

Thus, with the clamp parts 15 and 16 pivoted apart as shown in Fig. 3C, each bush 20 is moved into a position in which its circumference is engaged by the part-cylindrical surface of the fixed part 15 of the associated clamp and the clamp is closed by movement of the movable part 16-assisted, in the case of the assembly with the derailleur mechanism, by the tension of the drive chain-into the closed position shown in Fig. 3B. In that position, the part-cylindrical surfaces of the clamp parts 15 and 16 define the bore 18 for the bush and the ball 25 of the securing device 24 enters the cam track 24a of the rotary body 24. On movement of the rotary body 24 by the lever 24b into the setting shown in Fig. 3A, the ball runs on the cam track and is drawn into the clamp part 15 in the sense of pulling the clamp parts 15 and 16 together and tightening the clamp around the bush. Precise setting of the clamping pressure can be effected by prior adjustment of the ball shank 25a in the clamp part 16. The mentioned over-centre action retains the rotary body 24 in the setting illustrated in Fig. 3A, thus with the bush firmly clamped in the clamp and the wheel unit mounted in the bicycle frame.

Release of the wheel axle is by repetition of the described steps in opposite sequence.

When the clamp is opened as shown in Fig. 3C, the clamp parts 15 and 16 define the withdrawal opening 19, which is of such a width that the bush can be removed in radial direction with respect to the axis of the bore 18.

The axle mounting assembly embodying the invention combines the features of quick release of the wheel unit, rigid support of the unit and precise and repeatable axial location of the wheel. The rigidity of the axle mounting enhances the stiffness of the rear part of the bicycle frame and provides improved conditions for use of a disc brake. A removed wheel unit can be subject to maintenance as required or replacement by a substitute unit prefitted with additional bushes, the bushes being simple and inexpensive components.

The assembly accepts existing axle designs and can, for example by modification of the bush passage, be adapted to different designs, including an extended axle tube able to be directly secured without use of a through spindle. Other modifications are possible, including axial location of the bush by different methods, for example an interengaging rib and channel intermediate the bush ends, and use of other types of securing devices, for example threaded fasteners.