Individual wheel gear set The invention concerns a single wheel transmission unit, comprising a drive gear coupled with a drive shaft, said drive gear coupled via at least one intermediate 5 gear with a driven gear, that for the purpose of driving a wheel is connected with a driven shaft in a form-locked manner, while for the purpose of achieving a greater ground clearance the drive shaft is vertically offset relative the driven shaft. 10 A single gear transmission unit of the type described in the introduction is known from DE 36 40 947 C2. In this case one deals with a transmission unit with load equalisation for a steerable wheel of a motor vehicle. This transmission unit has at least two intermediate gears, which have two stages having different outside diameters and are joined with one another rotationally fixed. The stage with the 15 large outside diameter engages the input gear and the stage with the small outside diameter engages a hollow gear, whereby the hollow gear, the input gear and the intermediate gears are arranged within the axial extension of the wheel and wherein the input gear as well as the stages meshing with the hollow gear have cantilevered mounting. For the accomplishment of the transmission unit six 20 gears altogether are required, while one gear is constructed as a hollow gear and consequently its manufacture is expensive. In the case of the known embodiment a twofold reduction is carried out, in fact first from the input gear to the first stage of the intermediate gear with the greater 25 outside diameter and then from the second stage of the intermediate gear with the smaller outside diameter to the hollow gear. Therefore one deals here with a "slow running one" that can be used only for specially adapted drive transmissions and differentials. 30 In DE 21 16 441 B2 an axle transmission for motor vehicles with gantry axle is described. In the case of such an axle transmission the driving power is transmitted from the vehicle drive to the final gear provided on the peripheral drive shaft via a gear box and a compensating transmission to the right and left axle shafts and from them via a reducing transmission within each of the final 35 drive housing, that comprises a fixed transmission with spur gears having 2 external teeth. At the same time the reducing transmission is provided within the downward protruding portion of the housing of the gantry axle. DE 197 17 866 Al describes a driving train for a cross-country vehicle. Instead of 5 the mechanical combination of pairs of wheels conventionally used for cross country vehicles and working machinery having more than four wheels, a suspension of the wheels with a hydraulically supported rocker arm is suggested. The ground clearance, toe-in, balancing out when travelling inclined etc. is compensated for by the hydraulics. 10 DE 1 895 981 U1 discloses an axle in a floatable and cross-country vehicle. The vehicle has wheels, within the wheel rims of which a transmission is provided. The drive shafts of same are situated above the axis of the wheel. The central axle piece with a differential, to the drive shaft of which disc brakes are joined on 15 both sides, is directly connected with the chassis of the vehicle. In both cases the wheels are connected with the vehicle's box or frame via wishbones, while in the case of the floatable vehicle the lower wishbone is supported by a spring, whereas in the case of the cross-country vehicle the upper wishbone is held by an adjustable pneumatic spring. 20 DE 10 2004 003 644 Al describes a gantry axle for vehicles with low floors. In this connection a gantry transmission comprises a driving bevel gear, that is effectively meshing with a first bevel gear of the transmission, said bevel gear joined rotationally fixed with a second bevel gear of the transmission that is 25 effectively meshing with a driving bevel gear. The vertical distance of the axis of rotation of the driving bevel gear to the ground is less than the vertical distance of the bevel gears of the transmission to the ground. AT 184 451 discloses an agricultural towing and working machine with a variable 30 driving mechanism. The driving mechanism is characterised in that for the mounting of the driven parts of the driving train (caterpillars or wheels) in the housing of the differential easily exchangeable gantry axles of various lengths are used and that the steerable wheels can be fastened at various positions of their support axles. This embodiment, however, is not spring mounted.
3 DE 38 43 689 Al describes a wheel suspension for vehicles with variable ground clearance. In this connection the wheel suspension is adjusted relative the vehicle together with the spring support. Due to this in the case of single wheel suspensions the result is unfavourable kinematic conditions and for the driven 5 wheels problems with the bending angles on the drive shafts. An adjusting mechanism is so connected with the wheel support, that when an adjusting movement of the wheel support is carried out by the actuating device the wheel support remains in its position and the wheel axle changes its position in the vertical direction. 10 DD 86 561 B discloses an agricultural tractor as a transport tractor. Instead of a rear axle planetary drive a pivotably arranged rear axle gantry transmission with reduced number of revolutions of the drive is so constructed, that the centre of the wheel lies in the vicinity of or in the turntable point and a rear wheel axle 15 gantry transmission with a bracket and a rear axle bridge with an outrigger is constructed to mount the resilient and height-adjustable devices. The gantry transmission itself is not resiliently mounted. From AT 215 830 an axle, in particular a driving axle for agricultural motor 20 vehicles, is known. In the case of this embodiment one deals with an essentially rigid axle also, the support of its driving wheel, for the purpose of altering the ground clearance of the vehicle, can be pivoted about an axis coinciding with the axis of the driving axle of the wheel or of the axle tube. Each axle tube, joined with a wheel support, can be pivoted relative the body of the vehicle by using an 25 adjusting device and be secured in various positions, while the wheel support is rotationally elastically supported relative the wheel support or by springs in an end position of the pivoting range. DE 10 2004 003 731 Al discloses an arrangement of the actuating device of the 30 braking device for a gantry axle. In the case of this device the brake callipers of the braking device can rotate about the axis of the wheel in such a manner that the actuating device, constructed as an axial cylinder the axis of which is parallel with the axis of the wheel, can be arranged with its open side in a hole provided in the gantry housing or in a U-shaped recess of the gantry housing.
4 All aforementioned single wheel transmission units have been designed for a special application and can only be used for that particular vehicle. EP-A-1 418 068 describes a vehicle with an increased freight space. In the case 5 of this vehicle one deals with a vehicle with a low floor, wherein the drive axle is provided vertically below the wheel axle so that to obtain in this manner an as large as possible freight space. The transmission is connected via a wishbone with spring elements, which are connected with the vehicle housing. 10 From FR-A-2 726 230 an arrangement and a system for the motor drive for cars is known. In this system an electric or hydraulic motor is directly integrated into the single wheel suspension. The motor is coupled with the driven shaft via a transmission. The motor or transmission housing is joined to the chassis via a wishbone. 15 US-A-6 131 919 discloses a method for the automatic adjustment of a tractor to a horizontal position and a device to carry out the method. The transmission is exclusively designed for tractors and consequently is not suitable for the conversion of road vehicles. 20 WO-A-01/03963 describes an axle preferably to operate a bus with a low floor. This has also an axle bridge that is provided at a distance from the wheel axle. The housing of a drive motor is connected with the axle bridge on the one side and with the suspension elements on the other. 25 All aforementioned single wheel transmission units have been designed for a special application and can only be used for that particular vehicle. From the state-of-the-art further conventional, all-wheel drive vehicles are known, 30 the wheels of which are directly connected with a drive shaft of the vehicle. It is, however, often desirable to make such all-wheel drive vehicles suitable to be driven on land by increasing the ground clearance.
S Transmissions of the type mentioned in the introduction are unsuitable for these tasks, since they are constructed for a special application. Until now it was customary to develop new constructions for each type of vehicle, that is time consuming and 5 consequently expensive. When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or 10 components. The above references to and descriptions of prior proposals or products are not intended to be, and are not to be construed as, statements or admissions of common general knowledge in the art in Australia. 15 Embodiments of this present invention further develop a single wheel transmission unit of the type mentioned in the introduction in such a manner that a conversion of a conventional vehicle to a cross-country vehicle with an increased ground clearance will be simplified. 20 According to an aspect of the invention, there is provided a single wheel transmission for a cross-country vehicle with high ground clearance, comprising a drive gear coupleable via a drive shaft with a cardan shaft at the vehicle side, said drive gear coupled via at least one intermediate gear with a driven gear, which for the purpose of driving a rim of 25 a wheel is connected form-fittingly with a driven shaft, said driven shaft being offset in height relative to the drive shaft for achieving a high ground clearance, wherein the drive gear is engaged with the driven gear via one single intermediate gear, with the drive gear, the intermediate gear and the driven gear are arranged offset to each other in plane such that their centers form a triangle, that the drive gear, the intermediate gear and the driven 30 gear are arranged as a gantry transmission in a gantry housing designed as a retrofittable kit, comprising a first gantry housing component with a first attachment point for a spring-shock absorber element and with a second attachment point for at least one wishbone as well as a second gantry housing component designed as a cover and with 5a attachment points at the wheel side, to which attachment points are attachable a brake unit as well as a wheel bearing unit and that the rim of the wheel is capable to receive the gantry housing at least in sections. One embodiment provides a single wheel transmission unit that is a component of a single wheel suspension for converting conventional road vehicles to cross-country vehicles with high ground clearance, that the single wheel transmission unit has a gearbox to accommodate the drive gear, the at least one intermediate gear and the driven gear, that 10 the gearbox has a first attachment point with which it can be connected via a spring-shock absorber element to an unaltered attachment point on the side of the vehicle that the gearbox has a second attachment point via which the gearbox can be connected by means of a wishbone element with an unaltered attachment point for the wishbone element on the side of the vehicle and that on the other side of the wheel the gearbox has attachment 15 points for brake units and/or wheel bearing units. By virtue of the construction of the singe wheel transmission unit according to the invention a retrofittable single wheel reduction is made available while retaining the original direction of rotation of the wheel. 20 A preferred embodiment provides that a drive shaft on the vehicle's side is coupled with the drive gear via the drive shaft in a form-locking manner, said drive gear meshing via a single intermediate gear with the driven gear, that is coupled with the driven shaft in a form-locking manner, By doing so, the drive gear, the intermediate gear and the driven 25 gear preferably lie in one plane. Due to this, when compared with the state-of-the-art, a particularly compact construction 30 35 6 is achieved, that after the retrofitting of the single wheel transmission unit widens only insignificantly the track width of the vehicle. The transmission can be constructed with freely selectable reduction or step-up, 5 whereby the reductions or step-ups are possible in the range of 0.5 to 2.5. To enable an individual adaptation to suit an existing single wheel suspension of a road vehicle the transmission housing has a two-part construction, comprising a gantry housing part with a first attachment point for a spring-shock absorber unit 10 and a second attachment point for at least one wishbone as well as a gantry cover, on which attachment points are fastened for a braking device, like brake callipers. By virtue of this a retrofitting without constructive alterations is possible for almost any vehicle. 15 To achieve further ground clearance the at least one wishbone element may have a crank. Furthermore, the single wheel transmission unit can be constructed as a height adjustable gantry transmission. The gantry transmission preferably has an input 20 gantry half, that is rigidly joined with the spring-shock absorber unit at a fixed angle and an output gantry half, that is pivotably arranged relative the input gantry half. This construction makes the variable adjustment of the ground clearance of the cross-country vehicle possible. 25 A further preferred embodiment is characterised in that the height-adjustable gantry transmission has a drive gear joined in form-locking manner with the drive shaft, said drive gear coupled with a first of two intermediate gears mounted on a shaft and wherein a second of the two intermediate gears is coupled with the driven gear. In this embodiment the drive gear with the first intermediate gear lies 30 in a first plane and the second intermediate gear with the driven gear in a second plane that is parallel with the first plane.
7 In the case of this embodiment the cross-country vehicle can be shifted by means of lever devices manually, hydraulically or electrically from a low road position to a higher cross-country position. 5 The single wheel transmission unit can be constructed as a gear transmission, traction belt transmission or a chain transmission. For the purpose of completely covering the gantry drive or the gantry transmission on the one hand and to only insignificantly increase the track width 10 of the vehicle by the retrofitting of the gantry on the other, a rim is provided in which the gantry transmission is accommodated and the inside screw-on surface of the rim dish is provided outside the rim well. For the purpose of optimising the transmission with regard to noise, the individual 15 gears may have helical teeth. For the drive gear, intermediate gear and the driven gear metallic and non-metallic materials may be used, for example as contact surfaces. Further details, advantages and features of the invention become apparent not 20 only from the claims, the features obtainable from them, individually and/or in combination with each other, but also from the following description of the preferred embodiments which become apparent from the drawing. They show in: 25 Fig.1 - a three-dimensional illustration of a single wheel suspension with gantry transmission, Fig.2 - a side view of the single wheel suspension with gantry transmission, 30 sectioned, Fig.3 - a front view of the single wheel suspension, sectioned, d Fig.4 - a schematic illustration of a height-adjustable gantry transmission, in side view, Fig.5 - a schematic illustration of the height-adjustable gantry transmission, in top 5 view, and Fig.6 - a schematic illustration of the gantry transmission as a traction means gantry, wherein the traction means is a chain or a toothed belt. 10 Fig.1 is a perspective illustration of a single wheel suspension 10 with a gantry type construction. The single wheel suspension 10 is chosen purely as an example without limiting the invention by this embodiment. The single wheel suspension 10 comprises the single wheel transmission 12 with 15 a gantry housing 14 that according to the invention is constructed as a retrofitted sub-assembly, the gantry housing being covered by a gantry cover 16. The gantry housing 14 is joined via a first attachment point 18 with a spring-shock absorber unit 20 and via a second attachment point 22 with a wishbone 24. By doing so the second attachment point 22 is provided on an underside of the 20 gantry housing 14 and the first attachment point 18 on an upper side of the gantry housing 14. The attachment points 18, 22 are so arranged, that the retrofitting is possible for almost all vehicles, while no constructive modifications of the vehicle are 25 necessary. For the fastening of the brake callipers 26 further attachment points 28, 30 are provided on the gantry cover 16. 30 In the embodiment illustrated the drive is carried out mechanically via a drive shaft 32. Alternatively, the drive can be carried out by hydraulic or electrical means.
9 Fig.2 shows a longitudinal section through the single wheel suspension illustrated in Fig.1. The drive shaft 32 is coupled with a drive shaft 34, that is joined with a drive 5 pinion 36 by form-locking. The drive pinion meshes with an intermediate gear 38, resulting in a reversed direction of rotation. The intermediate gear 38 further meshes with a driven gear 40, that via a form-locked joint drives a driven shaft 42, in fact in a direction opposite that of the intermediate gear 38. Thus in each case of an odd number of gears 36, 38 42 the direction of rotation of the drive 10 shaft 34 is retained on the driven shaft 42. Consequently a single wheel reduction with freely selectable reduction or step-up is possible as retrofitting for almost all vehicles because the direction of rotation of the wheel is retained and no constructive modifications of the vehicle, in particular of the transmission or the differential, is necessary. 15 Generally speaking the entire vehicle is retained, while merely the driving train, the wheels and the brakes are replaced. Fig.3 shows a cross-section of the single wheel suspension 10, wherein it can be 20 seen that the torque flow is transmitted from the drive shaft 34 to the driven shaft 42 and thus to the bearing hub 44. Furthermore, the wishbone 24 has a crank 46, that greatly contributes to the ground clearance in the vehicle's width and thus contributes to the full use of the elevation of the gantry. Furthermore the compact construction, whereby the drive gear 36, the intermediate gear 38 and the driven 25 gear 40 are arranged in one plane, becomes obvious. A brake disc 48 is further joined with the bearing hub 44, the brake disc rotating inside the brake callipers 26. Fig.4 shows purely schematically a second embodiment of a single wheel 30 transmission unit 50, that is constructed as a height-adjustable gantry. The height-adjustable gantry 50 comprises an input gantry half 52 that, for example, is rigidly joined with the shock-absorber leg 20 at a fixed angle. An output gantry half 54 is pivotably mounted with the input gantry half and can be fixed. In the case of this embodiment the torque flow is transferred from the drive gear 36 to 10 two intermediate gears 38.1, 38.2 mounted on a common axle 56, to the driven gear 40 and finally to the driven shaft 42. A top view of this arrangement is illustrated in Fig.5. 5 Thus from the setting illustrated with maximum travel height, i.e. in cross-country mode, a low position for road operation can be converted in the direction of arrow 58. In this connection the conversion can be carried out manually or hydraulically or electrically by adjusting means (not illustrated). 10 Instead of a gear transmission a drive traction means drive may be used, which is illustrated by the embodiment in side view in Fig.6. On this occasion the traction means 58 can be a chain or a toothed belt that couples the drive gear 36 with the driven gear 40. 15 Figs.7 and 8 show an embodiment of a rim 60 suitable for a gantry transmission unit 12. In the case of this rim an inside screw-on surface 62 of the rim dish 64 is provided outside the rim well. Thus the gantry drive or the gantry transmission unit 12 is completely covered on the one hand and the track width of the vehicle will be only insignificantly widened after the retrofitting of the gantry transmission 20 unit 12 on the other. The step-up or reduction of the gantry transmission unit 12 can be freely selected and set and is preferably chosen in the range of 0.5 to 2.5.