Abstract
A track drive cassette for a vehicle, comprising a drive motor adapted to power a drive sprocket, a continuous track having a portion adapted to engage with the drive sprocket, running wheels, and a return arrangement.
Claims
1. A track drive cassette for a vehicle, comprising a drive motor adapted to power a drive sprocket, a continuous track having a portion adapted to engage with the drive sprocket, running wheels, and a return arrangement.
2. A cassette according to claim 1, adapted to be a discrete module removably attachable to a vehicle.
3. A cassette according to claim 2, wherein the cassette is attached to a chassis of a vehicle by way of a support arm, or wherein the cassette is attached to a chassis of a vehicle by way of two arms extending between the cassette and the chassis, the arms being arranged to form substantially a parallelogram with an edge of the cassette and an edge of the chassis being parallel to one another and the arms being parallel to one another, and wherein one or both arms is attached to a hydraulic ram.
4. A cassette according to claim 3, wherein the support arm is substantially permanently fixed to the said vehicle and releasably attachable to the cassette.
5. (canceled)
6. (canceled)
7. A cassette according to claim 2, further comprising means for receiving power from the main chassis.
8. A cassette according claim 1, comprising one or more running wheels each attached to a discrete wheel station, wherein each wheel station is provided with a suspension arrangement, each suspension arrangement being substantially independent of other suspension arrangements of other wheel stations.
9. (canceled)
10. A cassette according to claim 8, wherein the suspension arrangement comprises an idler and the suspension arrangement is adapted to move the idler backwards or forwards to maintain track tension, or wherein the suspension arrangement comprises a swing arm having a wheel end which is in turn connected to a running wheel axle and a pivot end, the swing arm being pivotable about the pivot end to move the wheel end.
11. (canceled)
12. A cassette according to claim 8, wherein the suspension arrangement further comprises a suspension drive means.
13. A cassette according to claim 12, wherein the suspension drive means further comprises a lever adapted to create a mechanical disadvantage.
14. A cassette according to claim 12, wherein the suspension drive is moved by an air bag, pneumatic cylinder, hydraulic cylinder, electric actuator.
15. A cassette according to claim 1, comprising an idler substantially identical in form to the drive sprocket.
16. A cassette according to claim 15, wherein the idler is attached to the cassette by way of a linkage comprising a piston attached to a cam which is in turn connected to an axle for the idler.
17. (canceled)
18. A cassette according to claim 1, characterised in that the length of a guided path of the continuous track can be varied.
19. A cassette according to claim 1, comprising track links having a track horn which has an approximately triangular profile, and wherein the track horn is as long at its base as the track link on which it is formed and wherein the track horn is hollowed on one side.
20. (canceled)
21. (canceled)
22. A cassette according to claim 1, having a sprocket formed of two or more separable sprocket components.
23. A cassette according to claim 1, wherein sprockets are provided with a guide therebetween.
24. A cassette according to claim 1, further comprising one or more of a power generator; an idler provided with braking means; a support arm arrangement for a return roller having a support arm and a sub-carrier releasably connectable to each other, the support arm being rotatable about the sub-carrier in use; and a track link comprising a track pad generally disposed on the part of the link which will engage with the ground, in use.
25.-27. (canceled)
28. A cassette according to claim 24, wherein the track pad is detachably attached to the track link at two points, the track pad is wider than the track link, and the track pad has one or more chamfered underside faces.
29. (canceled)
30. (canceled)
31. A cassette according to claim 28 wherein the track pad has a void formed within the one or more chamfered faces.
32. A cassette according to claim 24, wherein adjacent track pads are arranged so that front and leading edges of pads meet and compress against each other at the point the pads are being laid on the ground in use.
33. A cassette according to claim 1, further comprising track pins, wherein the track pins comprise bearings.
34. A cassette according to claim 33, wherein the bearings comprise pass through bearings having “O” rings at either end of bearing housings.
35. A vehicle comprising at least one track drive cassette according to claim 1, the vehicle characterised in that the wheelbase width of the vehicle can be varied proactively in use.
36. (canceled)
Description
DETAILED DESCRIPTION OF THE INVENTION
[0130] Examples of certain aspects of the present inventive concept will now be described with reference to the accompanying drawings, in which:
[0131] FIG. 1 shows a perspective view of a track drive cassette for a vehicle;
[0132] FIG. 2 shows a side view of a track drive cassette for a vehicle;
[0133] FIG. 3 shows a perspective view of an arrangement of two cassettes connected to a chassis;
[0134] FIG. 4 shows a perspective view of a single cassette and means for connecting it to a chassis;
[0135] FIG. 5 shows a section through a wheel station;
[0136] FIG. 6 shows a perspective view of the wheel station of FIG. 5;
[0137] FIG. 7 shows a further perspective view of the wheel station of FIG. 5 showing some internal components;
[0138] FIGS. 8 and 9 show perspective views of parts of an adjustment linkage arrangement;
[0139] FIG. 10 shows a perspective view of parts of a track, track links and a return roller;
[0140] FIG. 11 shows a side view of parts of a track, track links and a return roller;
[0141] FIG. 12 shows parts of a track link;
[0142] FIG. 13 shows a track pad;
[0143] FIG. 14 shows an exploded view of a sprocket;
[0144] FIG. 15 shows an exploded view of a support arm arrangement;
[0145] FIGS. 16A, 16B, 16C, 16D shows a vehicle with exemplary cassettes in different states;
[0146] FIGS. 17A, 17B shows a cassette in different states
[0147] FIG. 18A shows a track link, and FIG. 18B shows the same track link in a partially exploded view;
[0148] FIGS. 19A, 19B show a track pad in various states when interacting with spoil on a surface to be traversed; and
[0149] FIG. 20 shows how debris can be removed from the track by its arrangement during operation.
[0150] Certain elements of the inventive concept are shown in certain drawings without being labelled explicitly, to aid clarity.
[0151] Turning to FIGS. 1 and 2, a track drive cassette 10 for a vehicle has a drive sprocket 12 which engages with a continuous track 14. The drive sprocket 12 is adapted to be powered by a drive motor (not shown), the continuous track 14 having a portion adapted to engage with the drive sprocket 12. The cassette 10 further comprises running wheels 16, idler 18 and return rollers 20. The cassette 10 is adapted to be a discrete module removably attachable to a vehicle. The track 14 comprises a series of track links 22, the track links having track horns 24 attached thereto. The cassette 10 also has a linkage 26 connected to the idler 18.
[0152] FIG. 3 shows two cassettes 10 mounted either side of a chassis 100. Arms 11 (partially obscured in FIG. 3) connecting the cassettes 10 to the chassis 100 are fully closed minimising the vehicle's width for road use or transport. In this drawing the cassettes 10 are raised to their maximum suspension height—as may be used for travelling at speed. Each cassette 10 can be individually extended or retracted from the chassis 100 and suspension heights are similarly independently variable between cassettes 10. This enables significant advantageous shifts in the vehicle's overall centre of gravity allowing it access across side and longitudinal slopes impassable to other vehicles.
[0153] FIG. 4 shows the an individual releasably attachable cassette 10 attached by arms 11 on one side the chassis 100. On the other side of the chassis 100 from the cassette 10, arms 11 are shown without a cassette attached.
[0154] The cassette 10 comprises a series of wheel stations 28, an individual wheel station being shown in more detail in FIGS. 5, 6 and 7. Wheel station 28 provides a linkage 30, having a swing arm 30A, the linkage 30 being arranged between a running wheel 16 and a suspension arrangement 32. The suspension arrangement 32 has an air bag 34 connected to one end of a drive arm 43 of the linkage 30. The air bag 34, the drive arm 43 and the linkage 30 form a suspension drive means. The drive arm 43 and linkage 34 are joined by a detachable bearing arrangement 37. The air bag 34 provides resilience to the linkage 30. The suspension arrangement 32 can thus mitigate vertical movement of the running wheel 16. Furthermore, proactive extension or retraction of the air bag 34 (by inflation, for example) enables the vertical displacement of the running wheel 16 with respect to the rest of the wheel station 28 to be varied.
[0155] FIG. 6 further shows a return roller 20, as part of the wheel station 28. The linkage 30 has a swing arm with a pivot point 37. The return rollers 20 of the wheel station 28 are located directly above the bearing arrangement 37 of the swing arm. The return rollers 20 carry and guide the returning track. The wheel station also has three rubber bump stops 39 for the swing arm. The wheel station 28 has fixing points 41 are seen as lugs with holes and set in a plane around the other edges of the wheel station 28.
[0156] FIG. 7 shows the wheel station 28, in which an airbag 34 can extend and contract within a cage 31. The airbag 34 is anchored at one end against a reaction matrix 33 part way along the wheel station 28) through which the cage 31 passes to allow it to engage with the drive lever 35. As the airbag 34 expands it pushes the right hand end of the cage 31 further from the reaction matrix 33 whilst pulling its left hand end closer to the matrix. Since the left hand end of the cage 31 is attached to the drive lever 35, which in turn pivots around the linkage 30, the suspension height is raised as the airbag 34 expands.
[0157] FIGS. 8 and 9 show a portion of the cassette 10 from a different perspective, showing the linkage 26 which is connected to the idler (not shown in FIGS. 8 and 9). The linkage 18 has a cam 36 attached to a piston 38. The idler is attached to the cam 36 in such a configuration that when the piston 38 extends or retracts, in use, the cam 36 rotates about an axis 40 so that an axle of the idler moves with respect to the cassette 10. In FIG. 9 it can be seen that in the region of the idler, for example, track pads 46 separate to form gaps therebetween. Thus, any sealed relationship between track pads 46 is broken at that stage. This is likely also to occur when track links move into other rotational phases.
[0158] FIGS. 10 and 11 show portions of the track 14, the track 14 has track links 22, each of which has a track horn 24 attached thereto. The track horns 24 are sized and shaped to fit between discs 60 of the return roller 20 of the wheel station (not shown in full) and between discs of the running wheel (not shown). The track horns 24 are restricted by the discs, and thus track movement laterally is restricted by the track horns and discs. Track links 22 are attached to one another by track clamps 23.
[0159] FIGS. 10, 11 and 15 also show a support arm arrangement for the return roller 20 which has a support arm 61 and a sub-carrier formed by a tube 62 which is arranged coaxially within a tube 63 of the support arm 61, so that the tubes 62, 63 are releasably connectable to each other. The tube 62 of the sub-carrier is mounted on and projecting from the side of the cassette (not shown). The support arm 61 can thus be rotated around the sub-carrier 62 when in a released state, and rotationally fixed thereto in a fixed state. In use, removing a support arm 61 can be then simply rotated around the sub-carrier 62 to disengage the return roller fully from the weight of the track. The support arm 61 can then be drawn axially away from the sub-carrier 62 without requiring any physical support from a user, until the support arm 61 is fully drawn away.
[0160] FIG. 12 shows a track link 22 having bearings 42 engaging track pins 44. Bearings 42 enable the track links 22 and track pins 44 to be stripped, refurbished, and reused. This is useful because the track links and track pins are expensive to manufacture. Prior art arrangements generally require all components to be scrapped when some components are worn. Track links 22 can be attached to one another using clamps (not shown) which attach to track pins 44 of adjacent track links 22. The track link 22 has a track horn 24 projecting therefrom.
[0161] FIG. 13 shows a track pad 46. The track pad 46 has two gravel cavities 48, one at each side of the track pad 46. A central cavity 50 is designed to accommodate bespoke inserts. The track pad 46 may be chamfered on their underside side faces (in use) to assist them to sledge over the top of any spoil displaced by the vehicle when turning. This largely avoids the generation of any potentially damaging wave of spoil being generated during turns. Additionally, a cavity may be set into the underside of the pad's chamfered face which may trap a portion of any accumulating spoil. As a vehicle turn continues, spoil trapped by such a cavity becomes compressed as more spoil is forced into it. Since the track pad 46 may be manufactured from a semi-flexible material and with nowhere else to go, this additional pressure forces it upwards causing a further increase in the angle presented to the incoming spoil and enhancing its sledging effect.
[0162] The leading and trailing faces of adjacent pads may be designed to be slightly oversized for the space they should occupy in relation to the length of track they need to cover. Consequently their leading and trailing edges become compressed by one another when laid horizontally on the ground during use. This produces a compressive seal between adjoining pads that resists the ingress of aggregates whilst presenting the faces of the track pads in contact with the ground as an effectively unbroken surface ensuring maximum possible contact area.
[0163] Such a seal may also assist the prevention of aggregates reaching the track's bearing seals so extending their lives. Where aggregates do penetrate the seal between adjacent pads they are encouraged to be ejected in use as this seal is reopened as the link moves from its horizontal plane of contact with the ground—to the longer curved path around the sprocket or idler.
[0164] FIG. 14 shows an exploded view of a sprocket 70 which comprises three sprocket components 70A, 70B, 70C each having teeth for engagement with the track of the cassette as described (not shown). The sprocket 70 is connected for use with a sprocket rim 72 by a plurality of threaded bolts 74 and dowels 76. The bolt connection between the sprocket components 70A, 70B, 70C and the sprocket rim 72 enable individual sprocket components to be removed for maintenance and/or replacement without the whole sprocket requiring removal. Thus in use the track need not be dismantled in order to maintain and/or replace sprocket components 70A, 70B, 70C.
[0165] FIG. 15 shows an exemplary view of a support arm arrangement.
[0166] FIG. 16A shows a vehicle having two cassettes, with both cassettes being set in a raised state. FIG. 16B shows the same vehicle with both cassettes being in a mostly lowered state. FIG. 16C shows the same vehicle with one cassette (on the left-hand side) being in a raised state and the other cassette (on the right-hand side) being in a lowered state. In the state shown in FIG. 16C the vehicle is arranged to traverse an angled surface while maintaining the cab of the vehicle substantially horizontally. FIG. 16D shows the same vehicle with one cassette (on the left-hand side) being in a raised state and extended away from the vehicle and the other cassette (on the right-hand side) being in a lowered state and drawn into the vehicle. In the state shown in FIG. 16D the vehicle is arranged to traverse a maximally angled side-slope.
[0167] FIG. 17A shows a cassette in a raised state. FIG. 17B shows a cassette in a mostly lowered state. Track tension is maintained in different states and during transition between states as described herein.
[0168] FIGS. 18A and 18B show a track link 22. Certain features are not labelled to aid clarity. The track link 22 has bearings 42 engaging track pins 44. The bearings 42 have “O” rings 43 and washers 47 (only one of each labelled to aid clarity) arranged between the track link 22 and a track link clamp 45. The bearings 42, “O” rings 43, washers 47 and track link clamps 45 may be replaced, enabling the track link 22 to be reused after repair or rejuvenation. The track link 22 has a track horn 24 projecting therefrom. The track horn 24 is formed with a hollow or indented side. A hollow sided track horn 24 presents the same front and rear profile to the road wheels but saves weight by using fewer materials so reducing costs, and improving fuel economy. The hollow sides also provide an open volume for spoil to be temporarily accommodated so keeping the mechanism's operation smooth should it enter.
[0169] In FIG. 19A, a track pad 46 is shown with a chamfered edge 80. In the first state, a void V forms under the chamfered edge 80. In the second state as the track pad 46 slides sideways during a turn it sledges over gravel and other spoil S, which builds up under the chamfered edge 80 and is accommodated by the space under the chamfered edge. A chamber 82 or recess (shown in FIG. 19B) is formed in the underside of the track pad 46. The chamber 82 forces the spoil S to accumulate. This increases the pressure within the chamber 82 and beneath the chamfered edge 80 of the track pad 46 so lifting it and providing or augmenting a “sledging” effect. As seen in the third stage, repeated or prolonged turns cause spoil S to accumulate within the chamber 82 forcing the chamber upwards and so increasing the sledging.
[0170] In FIG. 20, a series of track links 22 are shown (not all labelled to aid clarity). As track links 22 move from horizontal to rotate around the sprocket (not shown) the gap between the triangular track horns 24 (not all labelled to aid clarity) narrow encouraging hard debris such as rocks R to be squeezed out and ejected before engagement with the sprocket. Tracks pads 46 (not all labelled to aid clarity) are longer than the track links 22 and when aligned with each other, as shown, they are pressed together forming a seal that resists water and grit so protecting the track links 22. As track pads 46 rotate around the sprocket they leave horizontal alignment so re-opening the seals and ejecting any accumulated debris.
