GB2097733A

GB2097733A - Multi-wheel vehicle

Info

Publication number: GB2097733A
Application number: GB8202287A
Authority: GB
Original assignee: WESTABY JAMES RAYMOND LISTER
Current assignee: WESTABY JAMES RAYMOND LISTER
Priority date: 1981-02-19
Filing date: 1982-01-27
Publication date: 1982-11-10

Abstract

A multi-wheel low ground pressure vehicle for agricultural and other off-the-road use has four axles each provided with a pair of wheels (11), and all of the wheels are driven from the engine (12) via a longitudinal shaft (15) extending along the length of the vehicle and a counter shaft (16) individually connected to the axles by belt and pulley mechanisms (21, 22, 23). All of the wheels are steerable by interconnected rack and pinion mechanisms (24), or by rod and lever mechanisms (Figure 5, not shown). <IMAGE>

Description

SPECIFICATION Multi-wheel vehicle This invention relates to a multi-wheel vehicle and is particularly, though not exclusively, concerned with a so-called "low ground pressure vehicle" for agricultural and other off-the-road use.

As is well known, wheeled vehicles which have to travel off the road are usually provided with enlarged tyres so as to reduce the ground pressure and thereby to minimise the risk of the vehicle becoming "bogged down" in muddy conditions. For this reason, agricultural tractors, and wheeled earth moving equipment, are provided with very large tyres.

A light weight multi-wheel vehicle has been made for off-the-road use which is 6 or 8 wheeled and which comprises a moulded plastics shell supported by a chasis on which the wheels are mounted. The wheels are each mounted on a respective half-shaft and the front wheels are driven directly by the engine of the vehicle, whereas the remaining wheels take their drive from the half-shafts on which the front wheels are mounted. The drive is transmitted, down each side of the vehicle, from half-shaft to half-shaft via chain drive. The chassis is supported directly by the wheels, in that no springs or dampers are provided between the wheel mountings and the chassis. Also, all of the wheels are non-steerable wheels in the sense that none of the wheels can have its plane of rotation altered relative to the longitudinal axis of the vehicle.Steering is achieved by "skid-steer" in similar manner to the steering of an endless track vehicle, in that all of the wheels on a selected one of the sides of the vehicle are braked, so that the wheels on the other side, which are still driven, will pivot the vehicle until such time as the brakes are released on the wheels at the selected side.

It has been proposed to adapt this known light weight vehicle for agricultural use, particularly for fertiliser spreading and crop or ground spraying.

While conventional tractors have been used for fertiliser spreading and crop spraying for many years, it is becoming increasingly recognised that there is a need for a lighter ground pressure contact vehicle to carry out these tasks at certain times of the year. Thus, attack on slugs is usually required after a period of wet weather (when the slugs rise to the surface), and this is the one time when the use of conventional heavy tractors would cause the greatest damage to the soil. Also, the spraying of winter corn in the Autumn is generally not possible with conventional tractors.

The present invention has been developed primarily, though not exclusively, with a view to overcoming some of the drawbacks of the known light weight vehicles, when adapted for agricultural use.

In particular, the known vehicle suffers from five disadvantages. Firstly, the skid steer arrangement is not suitable for use in the spraying of crops, such as winter corn, in that when the vehicle is turned round when it reaches one end of a field, it will inevitably damage the crop as one side of the vehicle skids over the ground during skid steering. There will be a similar disadvantageous effect on the soil surface e.g. during slug treatment. Secondly, the rigid mounting of the wheels on the chassis means that very undulating ground surfaces can cause some of the wheels to come out of engagement with the ground surface. Thirdly, the use of chain drives between the axles is prone to breakdown and involves problems in installation and maintenance.

Fourthly, although a power take-off (P.T.O) facility is provided, this involves the use of a separate power plant with consequential additional expense. Fifthly, the known vehicle is considerably underpowered for agricultural use.

According to one aspect of the invention there is provided a multi-wheeled vehicle having a frame, n pairs of wheels mounted on the frame to support the vehicle, an engine mounted on the frame and in driving connection with all of the wheels, and a steering arrangement; in which n is equal to at least three and the driving connection between the engine and the wheels includes a shaft extending generally along the length of the vehicle.

Preferably, the steering arrangement is connected to all of the wheels for adjusting the planes of rotation of the wheels relative to the frame.

According to a further aspect of the invention, there is provided a multi-wheeled vehicle having a frame, n pairs of wheels mounted on the frame to support the vehicle, an engine mounted on the frame and having a driving connection with the wheels, and a steering arrangement; in which n is equal to at least three and the steering arrangement is connected to all of the wheels for adjusting the planes of rotation of the wheels relative to the frame.

Preferably, the driving connection comprises a main shaft which extends from the engine (provided preferably near one end of the vehicle) substantially throughout the remaining length of the vehicle to the opposite end thereof, and a counter shaft which extends throughout the greater part of the length of the vehicle and to which are connected individual drive trains for each pair of wheels.

Conveniently, the main shaft and the counter shaft are connected together drivingly via one or more belt and pulley connections, preferably ribbed belt and ribbed pulleys.

Each pair of wheels conveniently forms part of a sub-assembly of a differential, a pair of half-shafts to which the wheels are connected, and an input shaft projecting from the differential. The drive train to each sub-assembly preferably comprises belt and pulley type connections between each input shaft and the counter shaft.

When the vehicle is provided with four pairs of wheels (arranged on first, second, third and fourth axles provided throughout the length of the vehicle), the steering arrangment will be connected to the wheels in such a way that, when the vehicle is to be steered in a given direction, the wheels on the first and second axles will be turned in the given direction whereas the wheels on the third and fourth axles will be turned in an opposite direction. By connecting the steering arrangement to all of the wheels (which turn in the manner just described), the vehicle is very manoeuvrable, which renders the vehicle particularly suitable for agricultural use e.g.

spraying or fertiliser spreading, when the vehicle is required to turn through 1800 at the end of each traverse of a field. To facilitate steering of a vehicle with a view to minimising any damage to crops or the ground surface, it is preferred that the wheels on the first and fourth axles are pivoted through approximately the same angle (though in opposite directions) in a given steering setting, whereas the wheels on the second and third axles are pivoted through a smaller angle (also in relatively opposite directions).

To reduce still further the ground pressure, each axle may mount a pair of wheels at each end of the axles.

In order to minimise the transmission of shock loads to the driver, and as far as possible to maintain contact of the wheels with bumpy ground, it is preferred that spring and/or damper type mountings are provided for the wheels. It is particularly preferred that a Hydrolastic (Registered Trade Mark) type of support system should be provided.

The vehicle is particularly suitable for crop spraying and fertiliser spreading. Conveniently, a load platform is provided on which the necessary distribution apparatus is mounted, and drums or sacks of the material to be distributed are readily transported on the platform.

To provide a suitable drive means to operate the distribution apparatus, it is preferred that a P.T.O.

shaft is mounted on the vehicle at one end of the platform. Preferably, the P.T.O. unit is driven by the engine via a separate drive train to the drive for the main shaft, so that the P.T.O. shaft can be selectively operated, regardless of whether or not the vehicle is in motion.

The invention will now be described in detail, by way of example only, with reference to the accompaying drawings, in which: Figure 1 is a side view, partly diagrammatic, of a low ground pressure vehicle for off-the-road use; Figure 2 is a plan view of the vehicle; Figure 3 is a detail view showing part of the drive train to one of the wheel axles of the vehicle; Figure 4 is a schematic plan view illustrating the steering mechanism for the vehicle; Figure 5 is a schematic plan view of the vehicle with an alternative construction of steering mechanism; Figure 6 is a detail view illustrating the connections between the levers and the rods of the alternative steering mechanism; Figure 7 is a schematic plan view of another construction of steering mechanism; and Figure 8 is a detail side view of part of the steering mechanism shown in Figure 7.

Referring now to Figures 1 to 4 of the drawings, there is shown a multi-wheeled vehicle for off-theroad use having a frame 10, n pairs of wheels 11 (n = 4 in the illustrated embodiment) mounted on the frame 10to supportthevehicle, an engine 12 mounted on the frame 10 and in driving connection with all of the wheels 11, and a steering arrangement which is connected to all of the wheels 11 and has a steering wheel 13.

The engine 12 is in driving connection with all of the wheels 11 by means of a drive train which includes at least one shaft which extends generally along the length of the vehicle. Thus, the engine 12 drives a gearbox 14 which is coupled with a main shaft 15 (see Figure 2) extending along the longitudinal axis of the vehicle towards the rear end thereof.

The main shaft 15 is coupled with a counter shaft 16, which also runs longitudinally of the vehicle substantially throughout the length thereof, via a pair of belt and pulley arrangements 17. Each arrangement 17 comprises pulleys mounted on the main shaft 15 and on the counter shaft 16, and a ribbed belt which provides drive between the pulleys. Although not shown, the pulleys will have ribbed configuration in order to receive the ribs of the belts.

Each pair of wheels 11 forms part of an axle sub-assembly to which drive is transmitted from the counter shaft 16. The manner in which the drive is transmitted to a typical one of the sub-assemblies is shown schematically in Figure 3, in which the wheels 11 are mounted on the ends of half shafts 18 which receive drive from a central differential unit 19. An input shaft 20 projects from the differential unit 19 and has a ribbed pulley 21 mounted thereon to receive drive from the counter shaft 16 via a ribbed belt 22 driven by a ribbed pulley 23 mounted on the counter shaft 16. For ease of illustration, the transmission of drive from the counter shaft 16 to the wheels 11 is shown in Figure 2 only in respect of the two rearmost pairs of wheels. However, it should be understood that similar drive trains will be provided from the counter shaft 16 to the front two pairs of wheels 11.

The steering arrangement for the vehicle is shown in more detail in Figure 4, and comprises a set of chain drives which extend throughout the length of the vehicle in order to impart steering action from the steering wheel 13 to all of the wheels 11. Each pair of wheels 11 is arranged to be steered via a rack and pinion type arrangement 24 which is operated upon rotation of the steering wheel shaft 25. The steering shaft 25 operates the settering arrangement of the front pair of wheels (the left hand set in Figure 4) directly, whereas steering action is transmitted to the second set of wheels via a chain and sprocket arrangement 26, and then to the third set of wheels via a chain and sprocket arrangement 27. However, as will be seen from Figure 2, in which the wheels 11 are occupying a position so that the vehicle can carry out a left-hand turn during forward motion, the front two sets of wheels 11 are pivoted in one directon, whereas the rear two sets of wheels are pivoted in an opposite direction. In order to achieve the necessary reverse rotation of the two rear sets of wheels, a double set of sprockets 28 are provided for the third set of wheels, The necessary steering action is then transmitted to the fourth (rear) set of wheels via a chain and sprocket arrangement 29.

To achieve a satisfactory steering action with minimum adverse effect on the ground surface, it is preferred that the front and rear sets of wheels are steering through the same angle, though in opposite directions, whereas the second and third sets of wheels are turned through a slightly smaller angle, for a given setting of the steering wheel 13.

The vehicle illustrated in the drawings has four pairs of wheels 11. However, the vehicle may be provided with a minimum of three pairs of wheels, all of which are driven by the engine, and steerable by the steering arrangement. Also, if desired, a double set of wheels may be mounted at the end of each half shaft in order to reduce further the ground contact pressure.

In orderto minimise the transmission of shock loads to the driver, and as far as possible to maintain contact of the wheels 11 with bumpy ground, it is preferred that spring and/or damper-type mountings are provided for the wheels, although this is not shown in the drawings. If desired, Hydrolastic (Registered Trade Mark) type of support systems may be provided to mount the frame 10 on the wheels 11.

The vehicle as illustrated is particularly suitable for agricultural use. A box-frame 30 is provided to enclose to enclose the driver for safety purposes, and one or more seats 31 are arranged within the box frame 30 and mounted on frame 10. The frame 10 provides, behind the box frame 30, a loadplatform 32 on which can be mounted any desired piece of agricultural equipment. In particular, the vehicle is adapted to mount spraying and/or fertiliser spreading equipment, and drums or sacks of material to be distributed can readily be transported on the platform 32 as well. A fuel tank 33 is housed within the frame 10 at the rear end thereof. The gearbox 14 may be an automatic gearbox, and power assistance may be provided for the steering arrangement if required.

In order to provide an independent drive means for any distribution apparatus provided on the platform 32, a P.T.O. shaft unit 34 (see Figure 1) is mounted on the frame 10 and is arranged to receive drive directly from the engine 12, independently of the drive train to the wheels 11. This enables the P.T.O. shaft to be operated selectively, regardless of whether or not the vehicle is in motion.

Any suitable engine may be provided for the vehicle e.g. a petrol or diesel engine, and this should have a sufficient power output to drive the vehicle along the ground at any required speed, and also to operate any piece of agricultural equipment which may be mounted on the vehicle.

Referring now to Figures 5 and 6 of the drawings, the multi-wheel vehicle has four pairs of wheels 50, 51,52 and 53, and the wheels in each pair are independently driven by respective drive shafts 54 and are also steerable by operation of steering wheel 55.

In order to turn the vehicle, the front pair of wheels 50 and 51 will be pivoted in one direction, whereas the rear pair of wheels 52 and 53 will be pivoted in an opposite direction. In order to avoid "type scrub", the front pair of wheels 50 and the rear pair of wheels 53 are pivoted through slightly greater angles than the pair of wheels 51 and 52 respectively.

The steering mechanism comprises an arrangement of push rods and bell crank type levers, the push rods being reciprocated, following rotation of steering wheel 55, and pivoting respective bell crank levers which, in turn, apply thrust or tensil loads to link rods connected to the wheels.

The construction and operation of the steering mechanism will now be described, for the case in which the steering wheel 55 is rotated anticlockwise, so that the vehicle can carry out a left-hand turn.

(The linear motions are shown by arrows X). Evidently, for a right hand turn, the various linear and pivotal movements which will be described will be reversed.

Steering wheel 55 is connected by a steering shaft 56 and a steering box 57, and the output 58 of the steering box 57 is coupled with a connecting rod 58 so as to apply linear reciprocatory movement to the rod 58. The rear end of the rod 58 is connected to one arm 59 of a bell crank lever having a vertical pivot 60, and the other arm 61 is connected to a track rod 62 which extends between the wheels of the pair of wheels 10. Anticlockwise rotation of the steering wheel 55 causes rod 58 to move rearwardly so as to pivot the bell crank lever anticlockwise which, via its arm 61, moves track rod 62 so as to pivot the wheels 50 anticlockwise i.e. suitable for a left hand turn.

A further connecting rod 63 extends longitudinally of the vehicle between the wheels 50 and 51, and is connected at its forward end to the arm 59 of the bell crank lever, and at its rear end to a T-shaped lever arrangement 64. Linear reciprocation of connecting rod 63 imparts pivotal movement to the lever 64, which, in turn, applies linear reciprocation to track rod 65 in order to pivot the wheels 51.

The pivotal movement of the lever 64 also applies linear reciprocation to a connecting rod 66 which runs between the wheels 51 and 52, and is connected at its rear end to a similar T-shaped lever 67 which is connected to track rod 68 which controls the pivoting of the wheels 52. However, evidently, rearward linear movement of connecting 63 will apply, via lever 64, linearforward movementto connecting rod 66, so that the wheels 52 will be pivoted in opposite direction to the pivoting of wheels 51.

Finally, a connecting rod 69 extends between the wheels 52 and 53, and is connected at its forward end to the lever 67 and at its rear end to a bell crank lever 70. The bell crank lever 70 is connected to track rod 71 which applies pivotal movement to the wheels 53 in the same direction as the pivoting of the wheels 52. Thus, forward motion of connecting rod 66 applies, via lever 67, rearward linear motion to connecting rod 69. The arrangement of the bell crank lever 70 is such that the rearward movement of connecting rod 69 applies linear motion to track rod 71 in orderto pivot the wheels 53 in clockwise direction.

The arrangement of rods and levers provided a robust construction which is particularly advantageous, having regard to the difficult terrain over which the vehicle may be travelling. The vehicle may be provided with any one or more of the features (apart from the steering mechanism) shown in Figures 1 to 4.

Figure 6 is a detail view illustrating the connection between the levers and the rods of the steering mechanism. In Figure 6, there is shown a vertical round bar 72 which is mounted in bearings 73, and one of the levers is illustrated at 74, mounted near the upper end of bar 72. 75 designates the end of one of the longitudinally extending connecting rods (63, 66,69), and 76 designates a yoke which is connected to one of the track rods (62, 65, 68,71).

Referring now to Figures 7 and 8, there is shown a further construction of steering mechanism which may be provided in the vehicle. Figure 7 is a schematic plan view of the vehicle provided with the steering mechanism which is arranged to operate the pairs of wheels 80,81,82, and 83 provided on the front axle, the two intermediate axles, and the rear axle respectively. Each wheel is driven via a respective half shaft 84 from a differential 85, and drive to the differentials 85 is provided in any convenient manner from the motor (not shown) provided on the vehicle. Conveniently, drive is transmitted to the differentials in the manner described above with reference to Figures 1 to 4.

Each pair of wheels 80 and 83 is steerable and, to this end, a rack and pinion arrangement is provided for each pair of wheels. In respect of the wheels 80 and 81, a respective rack 86 is provided which is arranged so that its teeth face downwardly, whereas wheels 82 and 83 have a respective rack 87 having its teeth facing upwardly. The racks 86 are driven by pinions 88 which are arranged with their pivot axes extending generally horizontally and below the racks 86. The racks 87 are driven by pinions 89 which also extend horizontally, but are arranged above the racks 87.

The arrangement of the steering mechanism is such that, upon rotation of the steering wheel (not shown), the wheels 80 and 81 will both turn in the same direction, whereas the wheels 82 and 83 will turn in an opposite direction. Preferably, as in the other constructions of steering mechanism described above, the wheels 81 will turn through a slightly smaller angle than wheels 80, and similarly wheel 82 will turn through a slightly smaller angle than wheel 83.

The transmission of steering rotation to the pinions 88 and 89 is achieved by chain and sprocket connections with a longitudinal shaft 90 which runs generally throughout the length of the vehicle. At the front end of the shaft 90 there is a front sprocket 91 which is driven by a chain and sprocket connection from a forward extension (not shown) of the steering wheel shaft. Sprockets 92 are mounted along the length of the shaft 90 in order to transmit torque to the pinions 88 and 89 via coaxial sprockets fixedly connected to the pinions. Evidently, since the pinions 88 are located below racks 86 and engage the downwardly facing teeth thereof, whereas pinions 89 engage with the upwardly facing teeth of racks 87, rotation of shaft 90 in one direction will cause racks 86 to move linearly in a first direction, whereas racks 87 will move linearly in an opposite direction.Thus, wheels 80 and 81 will turn in, say, a clockwise direction, whereas wheels 82 and 83 will turn in an anticlockwise direction.

While it is preferred that the differentials 85 receive power from a common shaft running throughout the length of the vehicle (as described in more detail with reference to Figures 1 to 4), other means for transmitting drive to the half shaft 84 may be provided, if desired. Thus, for example, drive may be transmitted from the motor to a single differential which has a pair of projecting stub shafts, and then drive is taken from the half shafts in any convenient manner, e.g. by chain and sprocket connections, or an HTD belt and pulley arrangement, to the half shafts to the third axle. Direct drive may then be taken from the half shafts of the third axle to the fourth axle, in a rearward direction, to the second axle in a forward direction, and from the second axle to the first axle. These direction drive connections may be achieved by means of chain and sprocket connections, or HTD belt and pulley arrangements.

Alternatively, the single differential unit may transmit drive from its stub shafts jointly to the half shafts of the second and third axles, which, in turn, provide direct drive respectively to the first and fourth axles.

The alternative means for driving the wheels, described above, may be useful in certain situations in order to improve the quality of "ride" which is achieved by the vehicle when moving over land in which at least some of the wheels have only a loose grip with the ground surface. In such a situation, with a differential and half shaft drive for each pair of wheels, there may be a tendency for the wheels which are slipping to "dig-in", with adverse effect on the quality of the ride, and also the transmission of motion to the vehicle.

Claims

1. A multi-wheeled vehicle having a frame, n wheel axles mounted on the frame and each provided with a wheel at each of its ends to support the vehicle, an engine mounted on the frame and in driving connection with all of the wheels, and a steering arrangement; in which n is equal to at least 3 and the driving connection between the engine and the wheels includes a shaft extending generally along the length of the vehicle.

2. A vehicle according to claim 1, in which the steering arrangement is connected to all of the wheels for adjusting the planes of rotation of the wheels relative to the frame.

3. A multi-wheeled vehicle having a frame, n wheel axles mounted on the frame and each having a respective wheel at each of its ends to support the vehicle, an engine mounted on the frame, and having a driving connection with at least some of the wheels, and a steering arrangement; in which n is equal to at least 3 and the steering arrangement is connected to all of the wheels for adjusting the planes of rotation of the wheels relative to the frame.

4. Avehicle according to any one of the preceding claims, in which the driving connection comprises a main shaft which extends from the engine substantially throughout the remaining length ofthe vehicle, and a counter shaft which extends throughout the greater part of the length of the vehicle and to which are connected individual drive trains for driving the wheels of each axle.

5. A vehicle according to claim 4, in which the main shaft and the counter shaft are connected together drivingly via one or more belt and pulley connections.

6. A vehicle according to claim 5, in which the belt and pulley connections comprise ribbed belts and ribbed pulleys.

7. Avehicle according to any one of the preceding claims, in which each axle comprises a differential, a pair of half shafts connected at their inner ends to the differential, a wheel mounted on the outer end of each half shaft, and an input shaft projecting from the differential.

8. A vehicle according to claim 7, in which each input shaft is connected by a drive train to the counter shaft which comprises belt and pulley type connections.

9. A vehicle according to any one of the preceding claims and provided with first, second, third and fourth axles throughout the length of the vehicle, each axle being provided at each of its ends with at least one wheel, and in which the steering arrangement is connected to the wheels in such a way that, when the vehicle is to be steered in a given direction, the wheels on the first and second axles will be turned in the given direction whereas the wheels on the third and fourth axles will be turned in an opposite direction.

10. A Vehicle according to claim 9, in which the steering arrangement is such that the wheels on the first and fourth axles are pivoted through approxi matelythe same angle (though in opposite directions) in a given steering setting, whereas the wheels on the second and third axles are pivoted through a smaller angle (also in relatively opposite directions).

11. A vehicle according to any one of the preceding claims, in which each axle mounts a pair of wheels at each end of the axle.

12. A vehicle according to any one of the preceding claims, including spring and/or damper type mountings provided for the wheels.

13. A vehicle according to any one of the preceding claims, including a load platform on which is mounted crop spraying orfertiliserspreading equipment.

14. Avehicle according to claim 13, including a PTO shaft mounted on the vehicle at one end of said platform for driving said equipment.

15. A vehicle according to claim 14, in which the PTO shaft is arranged to be driven by the engine via a separate drive train to the drive for the main shaft, so that the PTO shaft can be selectively operated.

16. Avehicle according to any one of the preceding claims, in which the steering arrangement comprises an arrangement of sprockets and chains which are arranged to be driven by a steering wheel shaft and extend throughout the length of the vehicle, there being connections to individual steering rods associated with each axle in order to steer the wheels thereof.

17. A vehicle according to any one of claims 1 to 15, in which the steering arrangement comprises an arrangement of linearly reciprocable rods and levers which are connected to be driven by the steering wheel shaft and extend throughout the length of the vehicle, there being connections to individual steering rods associated with each axle for steering the wheels thereof.

18. Avehicle according to any one of claims 1 to 15, in which the steering arrangement comprises a longitudinal shaft extending throughout the length of the vehicle and arranged to be driven by the steering wheel shaft, and rack and pinion type mechanisms associated with each axle and arranged to be operated by said longitudinal shaft.

19. Avehicle according to claim 18, in which each rack and pinion mechanism is arranged to be driven from said longitudinal shaft by a respective chain and sprocket arrangement.

20. A vehicle according to claim 18 or 19, and having first, second, third and fourth axles, in which the pinions of the rack and pinion mechanism are arranged with their pivot axes extending generally horizontally, and the racks associated with the first and second axles are arranged with their teeth facing in one direction e.g. downwardly, and the racks associated with the third and fourth axles are arranged with their teeth facing in an opposite direction.

21. Avehicle according to claim 3, in which the driving connection from the engine to at least some of the wheels comprises a differential, stub shafts projecting from the differential, and direct drive connections from said stub shafts to one, or a pair of said axles.

22. Avehicle according to claim 21, including drive connections from said one axle of the other axles, or from each directly driven axle to an adjacent axle.

23. A multi-wheeled vehicle according to claim 1 or 3 and substantially as herein before described with reference to, and as shown in any one of the embodiments illustrated in the accompanying drawings.