AU627808B2

AU627808B2 - Vehicle

Info

Publication number: AU627808B2
Application number: AU46529/89A
Authority: AU
Inventors: Derek William Foster; Derek Arthur Prime; Jeremy Richard Thake
Original assignee: JC Bamford Excavators Ltd
Current assignee: JC Bamford Excavators Ltd
Priority date: 1988-11-17
Filing date: 1989-11-17
Publication date: 1992-09-03
Anticipated expiration: 2009-11-17
Also published as: CA2003254A1; DK171790A; GB2224982A; WO1990005815A1; EP0396731A1; GB2224982B; GB8926043D0; DK171790D0; AU4652989A

Description

Title: "Vehicle"

This invention relates to a vehicle having a first pair of ground engageable means carried on a first oscillating member which is pivotable about a generally horizontal axis e.g. horizontal or inclined to the horizontal up to about 15 relative to a second oscillating member which carries a second pair of ground engageable means. The generally horizontal axis permits the pairs of wheels to twist relative to each other when driving over uneven ground so that the pairs of ground engageable means can conform to the shape of the ground.

Such vehicles are known which have at least one of the first and second osculating members provided by an "oscillating axle", That is, an axle which is connected to a respective chassis part by means of a connection which permits the axle to oscillate relative to the chassis part about a generally horizontal axis e.g. horizontal or inclined to the horizontal up to about 15 to enable the vehicle to travel over rough terrain, the chassis part being rigid with a further chassis part about a generally horizontal axis. Alternatively, the chassis parts themselves may be connected for pivotal movement about a generally horizontal axis with the wheels being carried bv the respective chassis parts without provision for pivotal movement about a generally horizontal axis.

More particularly, but not exclusively, the invention relates to a vehicle comprising a front chassis part and a rear chassis part which are articulated for steering about a generally upright axis e.g. vertical or inclined to the vertical up to about 10º . Such a vehicle will hereinafter be referred to as "an articulated vehicle".

Particularly when such an articulated vehicle is provided with a loaded work implement which projects forwardly or rearwardly of the chassis parts, stabilisation of the vehicle, especially when cornering bv articulating the front and rear chassis parts relative to one another, is a design consideration. However, the very nature of such an oscillating axle or oscillating chassis parts can contribute to instability of an articulated vehicle, especially on cornering since, particularly when the vehicle has a loaded work implement projecting from a chassis part, a moment is produced tending to overturn the vehicle. An object of the invention is to provide α new and improved vehicle. According to the present invention, we provide a vehicle comprising a first pair of ground engageable means carried on a first oscillating member which is pivotable about a generally horizontal axis relative to a second oscillating member which carries a second pair of ground engageable means and a stabilising system, the stabilising system comprising fluid operated actuator means, connected hetween the oscillating members to control oscillation therebetween about said generally horizontal axis, passage means to enable fluid to flow to and from a chamber of the actuator means in response to oscillation of the members and valve means to control the flow of fluid along the passage means in a direction to control oscillation between said members, said valve means being actuated by a control signal dependent on a ground engaging force transmitted by a ground engageable means of the vehicle.

Flow of fluid through the passage means from a chamber of the actuator means, which is operative to control rising of one of the first pair of ground engageable means carried by the first oscillating member, is controlled by a valve means provided with a control signal derived from said force transmitted by one of the second pair of ground engageable means which is diagonally opposite, as herein defined to said one of said first pair of ground engageable means.

By 'diagonally opposite' we mean a ground engageable means which is disposed on the opposite side of a fore and aft line of the vehicle and which is disposed towards the opposite .end of the vehicle to the end adiacent which is disposed said ground engageable means which is tending to rise.

The valve means may prevent transfer of fluid relative to the actuator chamber to control said oscillation.

Alternatively, the valve means may permit transfer of fluid relative to the actuator chamber against a resistence to fluid flow to control said oscillation.

The invention is particularly, but not exclusively, for use where the vehicle is an articulated vehicle as herein defined.

In this case the flow of fluid is controlled so as at least to resist relative pivotal movement between the oscillating members to counteract rising of one oscillating member relative to the other on the same side as the direction in which the one oscillating member has been articulated for steerina. The oscillating members may comprise, in a preferred embodiment, an oscillating axle and an associated chassis part but may comprise two oscillating chassis parts.

Where the oscil lating member is an oscillating axle, and the vehicle is an articulated vehicle, the oscillating axle may be provided either on a front or rear chassis part, or both the front and rear axles may be oscillating axles, in which case both the front and rear axles may have a stabilising system if required.

It will be appreciated that as the vehicle moves over the ground, particularly when the vehicle is cornering, the load carried by the loading implement affects the stability of the vehicle. Hence by "load" we mean the effect of the load on the stability of the vehicle.

The vehicle may have a boom carrying a loading implement such as forks or a bucket, which boom and loading implement may be operated by a power system, such as a fluid operated system, to enable the loading implement to be loaded. However, the invention may be applied to any other type of vehicle which hσs an oscillating member.

A single acting fluid operated actuator may be provided on each side of the axis of oscillation of the members, a passage means connecting each actuator chamber to a source of fluid under pressure and the valve means controlling flow of fluid along the passage means.

In an alternative, a double acting fluid operated actuator may be provided on one or each side of the axis of oscillation of the members, the passage means connecting the chambers on opposite sides of the or each actuator to a source of fluid under pressure and the valve means controlling flow of fluid along the passage means.

In each case the passage means may connect the actuator chambers together so that fluid ejected from one chamber is transferred towards the other and vice-versa.

Means may be provided to supply fluid to an actuator to force the associated side of an oscillating member carrying a ground engageable means downwardly.

The fluid may be supplied from a hydraulic circuit which supplies hydraulic fluid to a loader operating means of the vehicle.

Said control signal may be provided by a sensing means adapted to sense a parameter which varies in dependence on variation in said ground engaging force. Said sensing means may provide an electrical control signal.

Said sensing means may provide a fiuid control signal.

Said sensing means may be operable to sense deflection of a part of an element of a rear axle of the vehicle having said ground engageable means mounted thereon.

Said sensing means mav be operable to sense movement of a part carried by an element of the rear axle of the vehicle having said ground engageable means mounted thereon.

Said sensing means may be operable to sense strain of a chassis part on which is mounted a part of a rear axle of the vehicle having said ground engageabie means mounted thereon.

Said element may comprise a casing of the axle.

Said deflection mav be sensed by sensing the distance between a part of said element of the axle and a reference member connected in cantilever to another part of the axle or to the chassis part.

The reference member may be disposed within the ax'e casing.

The reference member may be fixed to the axle ad'acent the mid-point thereof and the reference member may extend in cantilever and parallel to the axis of rotation of the ground engageable means carried by the axle.

The distance may be measured by measuring the movement of a probe which is movably carried bv a mounting member fixed to the axle and the probe being movable with the reference member.

Means may he provided to ensure that the axle and reference member are uniformly heated to avoid significant variation in said distance sensing due to differential thermal expansion.

Means may be provided to distribute oil within the axle over the whole or substantially the whole of the internal surface thereof and of the reference member so that, in use, the temperature of the axle and reference member is uniform or substantially uniform.

The reference member may be tubular, one end of the tube being fixed to the axle and the distance between the axle and a portion adjacent the other end of the tube being sensed.

The tubular reference member may be provided with openings at least in an upper part thereof to enable oil to pass therethrough.

The tubular reference member may encircle a drive shaft to the ground engageable means and the shaft may drive an oil distributing means to dis tribute oil onto an upper part of the inner surface of the tube and, through said openings, onto the axle casing.

Alternatively the sensing means may comprise a fluid operated ram, connected so as to be driven by relative movement between a part of the rear axle having said ground engageable means mounted thereon and a chassis part, displacement of fluid relative to said ram providing said control signal to the valve means.

The invention will now be described with the aid of the accompanying drawings in which:

FIGURE I is an illustrative side view of a vehicle which embodies the invention.

FIGURE 2 is a view looking forwards at the rear of the front axle of the vehicle of Figure I showing part of a stabiliser system according to the invention,

FIGURE 3 is a diagrammatic illustration of the hydraulic circuit of the stabilising system of the vehicle of Figures 1 and 2,

FIGURE 4 is a diagrammatic illustration of the electric circuit of the stabilising system of Figure 3 showing the vehicle in plan view,

FIGURE 5 is a diagrammatic illustration of an alternative hydraulic circuit,

F1GUP.E 6 is a fragmentary cross-sectional view through part of the rear axle of the vehicle of Figure 1 , and

FIGURE 7 is a fragmentary view showing a modification of the vehicle shown in Figure 1 .

Referring first to Figure 1 , a vehicle 10 of the articulated type has a vehicle body 1 1 comprising a front chassis part 1 2 and a rear chassis part 1 3, and a pair of loading arms 14 which together comprise a loading boom, carried on the front chassis part 12.

The vehicle 10 is driven and the loading arms 14 are controlled, from within an operator's cab 15 which is mounted on the rear chassis part.

The body 1 1 carries two pairs of ground engageable means comprising wheels 17, 18. The wheels 17 are termed hereinafter "the front wheels" and are carried on a front axle 30 on the front chassis part 12. The wheels 1 8 are termed hereinafter "the rear wheels" and are mounted on a rear axle 200 carried by the rear chassis part 13

An engine to provide power to drive the vehicle 10 and a hydraulic operating system of the vehicle 10, is mounted beneath a bonnet 1 9. The loading arms 14 are pivotally mounted at one end at 20 to the front chassis part 12, and carry at an opposite end a loading implement comprising in this example, a loading bucket 22. The loading arms 14 can be moved about a pivot 20 by a pair of hydraulic actuators 23 connected in a loader lift arm circuit, although only one of these can be seen In Figure 1 of the drawings. The bucket 22 can be pivoted relative to the loading arm 14 for movement about a generally horizontal axis 25, by a further pair of hydraulic actuators 26 (only one of which can be seen) mounted between the loading arms 14 and the bucket 22.

Thus the vehicle 10 can be loaded and unloaded by manipulating the arms 14 and bucket 22, as is well known In the art. If desired, any other means for manipulating the arms and the bucket mav be provided.

The vehicle 10 can be steered by articulating the front chassis part 12 relative to the rear chassis part 13, about a generally vertical axis 27, by means of linear hydraulic actuators which are provided to effect this articulation, although alternatively any other hydraulically powered or other slewing means could be provided.

Referring now to Figure 2, there is shown the front axle 30, which in use carries the front wheels 17, although the wheels 17 themselves are omitted from Figure 2.

The wheels 17 are mounted on hubs 31 at each end of the axle 30 and the hubs 31 are driven via half shafts within the axle 30 from a crown wheel and pinion gear mounted in a housing 32 of the axle, drive being transmitted thereto from a gearbox G via drive shafts H.

The axle 30 is of the oscillating type and is mounted relative to the front chassis part 12 by trunnions 34 received by bushed openings of the chassis front part 12 so that the axle 30 may oscillate about a generally horizontal pivotal axis 35. There is a tendency for this oscillation to permit of overturning of the vehicle in certain circumstances. For example, when the loading bucket 22 is transporting a load and the chassis parts have been articulated about the axis 27 for steering, the reaction with the ground preventing overturning occurs at the contacting point of the inside rear wheel 18 and the pivot axis 35 at the centre of the axle 30. The load being offset, in the direction of steering, from a projection of a line joining these points, creates a turning moment.

To stabilise this oscillation, an actuator means comprising a pair of single acting hydraulic actuators 138, 139, is mounted between the axle 30 and the front chassis part 12 externally of the chassis side plates 12g of the first chassis part 1 2. One actuator 1 38 is provided to one side of the axis 35 and the other actuator 1 39 is provided on the other side of the axis 35. The connections between the actuators 138, 1 39 and the axle 30 and between the actuators 138, 139 and the front chassis part 12, permit of pivoting movement about the axis 35 as the axle 30 oscillates.

Referring now to Figures 3 and 4, the actuators 138 1 39, are each part of an axle stabilising system 140 of the vehicle 10.

The actuators 138, 139 have a piston 1 38g, I 39g, slidoble in a cylinder 1 38b, 139b to provide a variable volume chamber 1 38c, 1 39c. T he chambers 138c, 139c are inter-connected by a passage means 141 and fluid to the stabilising system is provided from a make-up line 150 through which hydraulic fluid is fed to the passage means 141 from a hydraulic pump P provided on the vehicle which also provides fluid under pressure to the other services S of the vehicle, such as the loader arms The pressure in the line 1 50 is reduced to a low pressure e.g. 14 Bar by a pressure reducing valve 152 and limited to a slightly higher pressure, e.g. 17 Bar by a pressure release valve 1 53.

The free flow of fluid along the passage means 141 , to transfer fluid relative to the respective actuator chamber, is control led by a respective valve 142, 143, one of which is associated with each of the actuators 138. 139. The valve 142 is provided on the chassis adjacent to the actuators 1 38, 129 but may be incorporated as an integral part of the actuators if desired. The valves 142, 143 are of a known type which can be opened, to permit of free passage of fluid therethrough, or closed, to prevent of passage of fluid therethrough, in a direction away from the associated actuator, by means of an electrical control signal supplied to the valve. The valves are provided with a suitable check valve arrangement which allows fluid to flow through the valve 142. 143 towards the associated actuator at all times. In addition, check valves 142', 143' are provided to prevent excess pressure being developed in the actuators 138, 139.

The passage means 141 is also provided with a restrictor and check valve assemblies 144, 145 associated with each actuator 1 38, 1 39 respectively, to permit of restricted flow of fluid away from the associated actuator and free flow of fluid in the direction towards the associated actuator. The electrical control signal is provided by a suitable electrical circuit which includes sensors 170, 171 which sense the load on each rear wheel 18g, 18b as hereinafter to be described.

The electrical control circuit includes a controller 176 comprising a micro-processor and is arranged

a) to close the valve 142 when the sensor 170 associated with a diagonally opposite rear wheel 18a senses that the load on the rear wheel 18g has fallen below a predetermined level whilst the valve 143 is signalled to remain open by the sensor 171 associated with a diagonally opposite rear wheel 18b, senses that the load on the rear wheel 18b is above a predetermined level, or

b) to close the valve 143 when the sensor 171 senses that the load on the diagonally opposite rear wheel 18b has fallen below a predetermined level whilst the valve 142 is signalled to remain open by the sensor 170 associated with the diagonally opposite wheel 18g , sensing that the load on the wheel 18g is above a predetermined level.

It is preferred that the load which causes a previously closed valve to open is a higher load than that which caused the valve to be closed. The higher load to cause opening of a previously closed valve avoids operation of the stabilising system when the vehicle encounters a temporary unstable condition, for example if a rear wheel encounters a pothole or other localised surface irregularity.

The switches which are used to provide the sensing means to controller 176 may comprise a set of relays instead of a micro-processor.

Operation of the stabiliser system 142 will now be described.

As the vehicle travels, normally the front axle 30 will oscillate and fluid will be expelled from an actuator 138 or 139, as the associated axle side rises, and be fed to the other actuator 139 or 138 respectively, with the flow being restricted by the associated restrictor and check valve assembly 144, 145 respectively, to limit the speed of oscillation of the axle 30.

As the vehicle corners, by articulating the front chassis part 12 relative to the rear chassis part 13 then under certain circumstances, for example when the loader arms are extended and/or carry a heavy load, the outside rear wheel tends to become unloaded and can, in the absence of the present invention, lift from the ground. In accordance with the present invention, when the load on the outside rear wheel falls below a predetermined level, this is sensed by the relevant sensor 170, 1 7 1 to provide a signal to the diagonally opposite control valve 1 42, 143 respectively to cause that valve to be closed and hence prevent flow of fluid from the associated actuator 138, 1 39 and therefore prevent the associated axle side rising, thus preventing the load on the diagonally opposite rear wheel falling further and hence preventing the rear wheel from lifting from the ground. The check valve permits fluid to flow to the ram if the axle assembly oscillates in the reverse direction to cause the actuator to be extended.

If desired, in a modification shown in Figure 5, the electrical circuit provides a signal to the valves, 142 or 143 to close the relevant valve to prevent the fluid flow therethrough and to open a further valve 142a or 143a to supply fluid under pressure, from the loader lift arm hydraulic circuit C, in which the actuators 23 are connected, to the associated ram 138, 139. Consequently, the associated side of the axle is forced downwardly and thus actively maintains the diagonally opposite rear wheel on the ground.

It will be appreciated that as the vehicle is loaded, for example as soil is loaded into the bucket 22, the pressure in feed lines 50 feeding hydraulic fluid to the actuators 23 to lift the loading arm 14 will increase. This increase in pressure in the loader lift arm circuit C is transmitted to the actuators 138, 139 when a valve 142a, 143a is opened and the restoring force will thus be increased by an amount depending upon the magnitude of the load.

Thus the restoring force of the oscillating axle 30 relative to the front chassis part 12 will change depending upon the magnitude of the load carried by the loader arm. The greater the load, the more pressure is provided via the valves 142a, 143a and so the greater the restoring force which is applied to the oscillating axle 30.

If the pressure obtaining in an actuator 138, 139 due to a load imposed thereon as a result of oscillation the axle 30, exceeds the pressure obtaining in the loader lift arm circuit hydraulic fluid will not flow from an actuator 1 38, 139 to the loader lift arm circuit C because of the provision of a check valve means in the valves 142a and 143a, thereby avoiding any possibility of oscillation of the axle occurring as a result of the pressure in the actuator 138, 139 causing lifting of the loader arms

The electric circuit is preferably arranged so that the valves 142, 143 (and 142g, 143g when provided) occupy the positions illustrated In Figures 4 and 5 when no electric current is supplied thereto, thereby blocking flow of fluid from the rams, should the electrical supply fail. Hence the arrangement is "fail-safe".

In a further modification the electrical circuit may provide a signal to the valves 142, 143 and the valves may be arranged to permit fluid flow between the actuators 138, 139, but against a resistence sufficient to stabilise the vehicle as described hereinbefore.

The pump P supplying fluid under pressure by the pipe 150 may be an independent pump provided for the purposes of the stabilising system and independent of the fluid circuit for the loader arms 14 or the fluid in the pipe 150 may be supplied from the loader arm circuit.

Instead of the pair of single acting actuators 138, 139, one disposed on either side of the oscillating axis 35, the actuator means may comprise a double acting actuator which may be provided on one or each side of the axis In this case, the passage means connects the chambers on opposite sides of the piston of the or each double acting actuator so that the stabilising system operates substantially as described above, but with suitable arrangements provided to compensate for the different volumes of the two chambers due to the presence of a piston rod In one chamber. For example, a valve means may be associated with a chamber provided at each side of the piston of the or each double acting actuator rather than with each of a pair of single acting actuators.

In the embodiments described above, the means for sensing the load on each rear wheel 18a, 18b comprises a specially adapted rear axle 200 comprising a central housing part 201 which houses a conventional differential drive 202 and crown wheel and pinion. A pair of generally tubular casings 203 are bolted to opposite sides of the housing 201. As best shown in Figure 6, each casing 203 has at its outer end an inner race 204 of a roller bearing 205, an outer race 206 of which mounts a hub 207 and a wheel 18g, or 18b is mounted on the hub 207. The hub 207 is driven by a half shaft 208 which extends within the casing 200 parallel to a central axis X-X thereof and is adapted, at its inner end, to be driven by the differential 202. The half shaft 208 has a sleeve 209 fixed thereto which is engaged with a multi-plate brake 210 disposed within an inner part 21 1 of the casing 703. Also mounted within the casing 203 is a tubular reference member 212 which is fixed to a flange 21 3 mounted within the casing 203. Thus the tubular reference member 21 2 is mounted in cantilever on the flange 2 1 3. A distance sensing device 214 is bolted to a part 220 of the casing 203 and has a probe 21 5 which engages a surface part 216 of the tube 212 adiacent a free end 21 7 thereof. In the present example the measuring device 2 14 comprising a voltage splitting potentiometer, the movable contact of which is moved in accordance with the position of the probe 2 15.

If desired, any other form of sensing device may be provided, such as a variable inductance or capacitance device, a strain gauge or an optical sensing device.

The tube 212 is provided with three rows of circular apertures 218, the central row being disposed at the top of the tube 21 2 and the other two rows being disposed as shown in the upper half of the tube. The tube is also provide with two further circular apertures 219 at the bottom adjacent the inner end of the tube.

In use, as the load on a wheel 1 8g or 18b varies, it will cause the associated axle casing 203 to deflect so that the distance between the part 21 6 of the reference tube 212 and the adiacent part 220 of the casing 203 will vary since the reference tube 21 2 will not deflect with variation in wheel load, whilst the casing will. Therefore, by measuring the change in the distance between the parts 220 and 216, a measure of the ground engaging force transmitted by the wheel 18a or 18b is achieved.

In conventional manner the casing 203 is partially fi lled with oil and, in use, the oil heats up and consequently the part of the casing 203 and the tube 212 immersed in the oil would be of a higher temperature to the parts of the casing 203 and tube 21 2 not immersed in the oil. Due to difrerential thermal expansion effects, the accuracy of the load measurement wi ll be affected since the distance between the two parts 220 and 21 6 would varv due to thermal differential effects, irrespective of variation in load.

To avoid this problem the apertures 21 8 are provided, together with a paddle device 221 fixed to rotate with the half shaft 208 and which serves to throw oil into contact with the upper part of the tube 21 2 and, through the apertures 2 18 into contact with the upper surface of the casing 203, thus causing the temperature of the tube 212 and casing 203 to be substantially uniform throughout their circumferential extent, thereby avoiding the above mentioned differential thermal expansion effects It has been found that when the vehicle is stationary, so that the oil falls to the bottom part of the casing 218 and the paddle 221 is inoperative, the upper parts of the casing 203 and of tube 212 cool similarly so that on cooling there is no unacceptable variation In the spacing between the parts 216 and 220 .

It has been found that if the reference member 212 is cut away completely in an upper part, for example, above the central axis of the tube, so that the maiority of the tube, except for cylindrical parts, is, for example, of semi-cylϊndrical shape, then whilst the paddle 212 serves to keep the axle casing 203 at a uniform temperature in service and the reference member 212 is maintained at the same temperature, since the majority of it is immersed in the oil in the lower part of the casing 203 so that differential thermal expansion effects are not a problem during normal use of the vehicle, when the vehicle was stationary then the reference member 212 stayed at the same temperature as the oil whilst the upper part of the casing 203, which is not immersed in the oil cooled causing differential thermal expansion effects to occur, leading to a variation in the distance between the parts 220 and 216. It has therefore been found necessary to make the reference member 212 of the above described configuration where there is a portion of the wall of the tube above the central axis of the tube or at least above the part of the tube which is normally in contact with the oil, so that on cooling a similar distortion pattern occurs in the upper parts of the casing 203 and reference member 212.

The apertures 219 are provided to enable oil to pass between the casing 203 and the interior of the tube 212 to enable oil to be circulated through the brake 210. If desired, the reference member 212 may be provided with apertures throughout its circumference and indeed may comprise a generally perforated member.

Although a generally cylindrical tuκular member has been described as the reference member 212, if desired the reference member 212 may be of other configuration, for example it may comprise a latticework construction, or it may comprise a plurality of parallel members, for example, three members arranged in a equilateral triangle or other configuration with appropriate connecting members, or may be of any other desired configuration consistent with avoiding the above described differential thermal expansion effects.

If desired, other means for detecting deflection of the axle casing 203 may be provided. For example, a reference member may be provided fixed relative to the housing 201 and extending in cantilever parallel to the axis X- x but disposed externally of the casing with appropriate sensing means similar to the means 214 described hereinbefore provided to sense variation in the distance between a part of the reference member adjacent a free end thereof and an adjacent part of the casing 203. Such an externally disposed reference member is not, however, preferred since it is liable to damage and to be interfered with by foreign bodies.

If desired, whether provided internally or externally, the reference member may be mounted in cantilever at the outer end of the casing 203 and extend inwardly so that its free end is adjacent the housing 201. In this case a sensing means similar to the sensing means 214 would be provided adjacent the housing 201.

Further alternatively, the reference member may be mounted in cantilever at any desired position along the length of the casing 203 and may extend therefrom so that its free end is directed inwardly or outwardly relative to the housing 201 so long as the reference member is of sufficient length for there to be a change in distance between it and the casing for accurate measurement.

If desired, any other suitable sensor to sense the load on each rear wheel 18g. 18b may be provided. For example, as shown in Figure 7 a displacement sensing means 180, such as a transducer or micro-switch, senses displacement d of an upper end 181 of a bar 182 fixed, at its lower end 183, for example by welding, to a bracket 1 84 carried by the axle 173.

Alternatively, as shown in dotted line in Figure 4, the sensors may comprise a strain gauge 170', 171' provided on flanges 172 that mount the rear axle 173 on the rear chassis part 13.

Further alternatively, instead of providing an electrical circuit to sense the load on the rear wheel and to provide a signal to the control valve 142, 143, (and valve 142a, 143a, when present) if desired, a pair of single or double acting hydraulic rams or one double acting hydraulic ram may be connected between the rear chassis part and the rear axle, which may itself be mounted for oscillation on the rear chassis part and the flow of fluid from and/or to these rams may be used to provide a signal to control hydraulical'y actuated valves corresponding to the electrically operated valves 142, 143 ( 142a, 143g).

In the embodiments described, the stabilising system is applied to an oscillating member comprising an axie. Where rigid axles are provided on an artlculated vehicle, the stabilising system may be provided between the oscillating chassis parts in which case the oscillating member would be one of the chassis parts, and the actuator or actuators would be connected between the chassis parts. If desired each of the first and second pairs of wheels may be carried on an oscillating member which can pivot relative to an associated chassis part and the chassis parts may themselves be pivotally interconnected about a generally horizontal axis in which case an appropriate number of stabilising systems may be provided for each pair of oscillating parts. Appropriate sensing means to sense the ground engaging force transmitted by an appropriate ground engageable means of the vehicle, e.g. one diagonally opposite to the respective actuator.

Various modifications may be made without departing from the scope of the Invention.

It will be appreciated that although the stabilising system 140 is described in relation to an articulated loading vehicle, the Invention may be applied to any other load carrying vehicle, and many other types of articulated and non-articulated vehicle as required which may have an oscillating axle.

As described, the vehicle 10 only has a stabilising system associated with the axle 30 carried on the front ground wheels 17, which is an oscillating axle. The axle carrying the rear ground wheels 18 is rigid. However, in another type of vehicle, both the axles carrving the front wheels 17 and the rear wheels 18 may be of the oscillating type and mav each have a stabilising system associated therewith.

Alternatively, if a rear axle were of the oscillating type and the front axie rigid, only the rear axle would require a stabilising system. In each case a control signal dependent upon the load carried by a suitable wheel of the vehicle is provided.

Whereas, preferably, in a vehicle such as a vehicle shown at 10 in Figure I, the axles carrying the front and rear wheels 17, 18 are driven so that the vehicle is a four-wheel drive vehicle, it will be appreciated that the stabilising system may be applied to a vehicle in which drive is transmitted through only two wheels so that the hubs 21 , for example, may not be driven.

Where the invention is applied to a vehicle which is not of the articulated type, but has an oscillating axle, the hub 31 of the front wheels and/or the corresponding hubs on the rear wheels may be movable to effect sfeerina of the vehicle. Whilst in the illustrated embodiments a single wheel is mounted ad acent the end of each axle, if desired a plurality of wheels may be provided adjacent the end of each axle. For example, there may be two wheels side bv side rotating about the same axis. Alternatively there may be two wheels disposed in tandem, i.e. rotating about axes which are parallel and spaced apart in a fore and aft direction of the vehicle; in such a case the wheels may be carried on a sub-frame mounted on the axle and again each such wheel may have another wheel or wheels disposed side by side. Further alternatively the vehicle may be provided with endless tracks commonly known as "caterpil lar tracks". A discrete endless track or tracks in tandem and/or side by side may be provided adjacent the end of each axle or an endless track or tracks may be common to the ends of the axles on each side of the vehicle. The term "ground engageable means" is used herein to encompass all such arrangements.

Although the actuators described herein are linear actuators if desired other forms of actuator may be provided such as rotary actuators.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, or a class or group of substances or compositions, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS:

1. A vehicle comprising α first pair of ground engageable means carried on a first oscillating member which is pivotabfe about a generally horizontal axis relative to a second oscillating member which carries a second pair of ground engageable means and a stabilising system, the stabilising system comprising fluid operated actuator means, connected between the oscillating members to control oscillation therebetween about said generally horizontal axis, passage means to enable fluid to flow to and from a chamber of the actuator means, in response to oscillation of the members and valve means to control the flow of fluid along the passage means in a direction to control oscillation between said members, said valve means being actuated by a control signal dependent on a ground engaging force transmitted by a ground engageable means of the vehicle.

2. A vehicle according to Claim 1 wherein flow of fluid through the passage means from a chamber of the actuator means, which is operative to control rising of one of the first pair of ground engageable means carried by the first oscillating member, is controlled by a valve means provided with a control signal derived from said force transmitted by one of the second pair of ground engageable means which is diagonally opposite, as herein defined, to said one of said first pair of ground engageable means.

3. A vehicle according to Claim 1 or Claim 2 wherein the valve means prevents transfer of fluid relative to the actuator chamber to control said oscillation.

4. A vehicle according to Claim 1 or Claim 2 wherein the valve means permits transfer of fluid relative to the actuator chamber against a resisfence to fluid flow to control said oscillation.

5. A vehicle according to any one of the preceding claims wherein the vehicle is an articulated vehicle, as herein defined.

6. A vehicle according to Claim 5 wherein the flow of fluid is controlled so as at least to resist relative pivotal movement between the oscillating members to counteract rising of one oscillating member relative to the other on the same side as the direction in which the one osci l lating member has been articulated for steering.

7. A vehicle according to any one of the preceding claims wherein the oscillating members comprise an oscil lating axle and an associated chassis part.

8. A vehicle according to any one of Claims 1 to 6 wherein the oscillating members comprise two oscillating chassis parts.

9. A vehicle according to Claim 7 when dependent upon Claim 5 or Claim 6 wherein the oscillating axle is provided either on a front or a rear chassis part.

10. A vehicle according to Claim 7 when dependent upon Claim 5 or Claim 6 wherein both the front and rear axles are oscil lating axles.

1 1. A vehicle according to Claim 10 wherein both the front and rear axles have a stabilising system.

12. A vehicle according to any one of the preceding claims wherein the vehicle has a boom carrying a loading implement, which boom and loading implement are operated by a power system to enable the loading implement to be loaded.

13. A vehicle according to any one of the preceding claims wherein a single acting fluid operated actuator is provided on each side of the axis of oscillation of the members, a passage means connecting each actuator chamber to a source of fluid under pressure and the valve means controlling flow of fluid along the passage means.

14. A vehicle according to any one of Claims 1 to 12 wherein a double acting fluid operated actuator is provided on one or each side of the axis of oscillation of the members, the passage means connecting the chambers on opposite sides of the or each actuator to a source of fluid under pressure and the valve means controlling flow of fluid along the passage means.

15. A vehicle according to Claim 13 or Claim 14 wherein the passage means connects the actuator chambers together so that fluid ejected from one chamber is transferred towards the other and vice-versa.

16. A vehicle according to any one of the preceding claims wherein means are provided to supply fluid to an actuator to force the associated side of an oscillating member carrying a ground engageable means downwardly.

17. A vehicle according to Claim 16 wherein the fluid is supplied from a hydraulic circuit which supplies hydraulic fluid to a loader operating means of the vehicle.

18. A vehicle according to any one of the preceding claims wherein said control signal is provided by a sensing means adapted to sense a parameter which varies in dependence on variation in said ground engaging force.

19. A vehicle according to Claim 18 wherein said sensing means provides an electrical control signal.

20. A vehicle according to Claim 18 wherein said sensing means provides a fluid control signal.

21. A vehicle according to any one of claims 18 to 20 wherein said sensing means is operable to sense deflection of a part of an element of a rear axle of the vehicle having said ground engageable means mounted thereon.

22. A vehicle according to Claim 18 wherein said sensing means is operable to sense movement of a part carried by an element of the rear axle of the vehicle having said ground engageable means mounted thereon.

23. A vehicle according to Claim 18 wherein the sensing means is operable to sense strain of a chassis part on which is mounted a part of a rear axle of the vehicle having said ground engageable means mounted thereon.

24. A vehicle according to Claim 21 wherein said element comprises a casing of the axle.

25. A vehicle according to Claim 21 or Claim 24 wherein said deflection is sensed by sensing the distance between a part of said element of the axle and a reference member connected in cantilever to another part of the axle or to the chassis part.

26. A vehicle according to Claim 25 w hen dependent upon Claim 24 wherein the reference member is disposed within the axle casing.

27. A vehicle according to Claim 25 or Claim 26 wherein the reference member is fixed to the axle adjacent the mid-point thereof and the reference member extends in cantilever and parallel to the axis of the ground engageable means carried by the axle.

28. A vehicle according to any one of Claims 25 to 27 wherein the distance is measured by measuring the movement of a probe which is movably carried by a mounting member fixed to the axle and the probe being movable with the reference member.

29. A vehicle according to any one of Claims 75 to 28 wherein means are provided to ensure that the axle and reference member are uniformly heated to avoid significant variation in said distance sensing due to differential thermal expansion.

30. A vehicle according to Claim 29 wherein means are provided to distribute oil within the axle over the whole or substantially the whole of the internal surface thereof and of the reference member so that, in use, the temperature of the axle and reference member is uniform or substantially uniform.

31. A vehicle according to any one of Claims 25 to 30 wherein the reference member is tubular, one end of the tube being fixed to the axle and the distance, between the axle and a portion adiacent the other end of the tube, being sensed.

32. A vehicle according to Claim 31 when dependent upon Claim 30 wherein the tubular reference member Is provided with openings at least in an upper part thereof to enable oil to pass therethrough.

33. A vehicle according to Claim 32 wherein the tubular reference member encircles a drive shaft to the ground engageable means and the shaft drives an oil distributing means to distribute oil onto an upper part of the inner surface of the tube and, through said openings, onto the axle casing.

34. A vehicle according to Claim 20 wherein the sensing means comprises a fluid operated ram, connected so as to be driven by relative movement between a part of the rear axle having said ground engageable means mounted thereon and a chassis part, displacement of fluid relative to said ram, providing said control signal to the valve means.

35. A vehicle substantially as hereinbefore described with reference to Figures 1 to 6 or Figure 7 of the accompanying drawings.

36. Any novel feature or novel combination of features disclosed herein and/or shown in the accompanying drawings.