GB2311967A - A variable-track, four wheel steering agricultural vehicle with active suspension - Google Patents

A variable-track, four wheel steering agricultural vehicle with active suspension Download PDF

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Publication number
GB2311967A
GB2311967A GB9607397A GB9607397A GB2311967A GB 2311967 A GB2311967 A GB 2311967A GB 9607397 A GB9607397 A GB 9607397A GB 9607397 A GB9607397 A GB 9607397A GB 2311967 A GB2311967 A GB 2311967A
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United Kingdom
Prior art keywords
steering
vehicle
wheels
wheel
hydraulic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Application number
GB9607397A
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GB9607397D0 (en
Inventor
Richard John Bateman
Jason John Bateman
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BATEMAN ENGINEERING Ltd
Original Assignee
BATEMAN ENGINEERING Ltd
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Publication date
Application filed by BATEMAN ENGINEERING Ltd filed Critical BATEMAN ENGINEERING Ltd
Priority to GB9607397A priority Critical patent/GB2311967A/en
Publication of GB9607397D0 publication Critical patent/GB9607397D0/en
Publication of GB2311967A publication Critical patent/GB2311967A/en
Withdrawn legal-status Critical Current

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60BVEHICLE WHEELS; CASTORS; AXLES FOR WHEELS OR CASTORS; INCREASING WHEEL ADHESION
    • B60B35/00Axle units; Parts thereof ; Arrangements for lubrication of axles
    • B60B35/02Dead axles, i.e. not transmitting torque
    • B60B35/10Dead axles, i.e. not transmitting torque adjustable for varying track
    • B60B35/1036Dead axles, i.e. not transmitting torque adjustable for varying track operated with power assistance
    • B60B35/1054Dead axles, i.e. not transmitting torque adjustable for varying track operated with power assistance hydraulically
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60BVEHICLE WHEELS; CASTORS; AXLES FOR WHEELS OR CASTORS; INCREASING WHEEL ADHESION
    • B60B35/00Axle units; Parts thereof ; Arrangements for lubrication of axles
    • B60B35/02Dead axles, i.e. not transmitting torque
    • B60B35/10Dead axles, i.e. not transmitting torque adjustable for varying track
    • B60B35/1072Dead axles, i.e. not transmitting torque adjustable for varying track by transversally movable elements
    • B60B35/109Dead axles, i.e. not transmitting torque adjustable for varying track by transversally movable elements the element is an axle part
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60GVEHICLE SUSPENSION ARRANGEMENTS
    • B60G21/00Interconnection systems for two or more resiliently-suspended wheels, e.g. for stabilising a vehicle body with respect to acceleration, deceleration or centrifugal forces
    • B60G21/02Interconnection systems for two or more resiliently-suspended wheels, e.g. for stabilising a vehicle body with respect to acceleration, deceleration or centrifugal forces permanently interconnected
    • B60G21/06Interconnection systems for two or more resiliently-suspended wheels, e.g. for stabilising a vehicle body with respect to acceleration, deceleration or centrifugal forces permanently interconnected fluid
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B62LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62DMOTOR VEHICLES; TRAILERS
    • B62D49/00Tractors
    • B62D49/08Tractors having means for preventing overturning or tipping
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B62LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62DMOTOR VEHICLES; TRAILERS
    • B62D7/00Steering linkage; Stub axles or their mountings
    • B62D7/20Links, e.g. track rods
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B60VEHICLES IN GENERAL
    • B60YINDEXING SCHEME RELATING TO ASPECTS CROSS-CUTTING VEHICLE TECHNOLOGY
    • B60Y2200/00Type of vehicle
    • B60Y2200/20Off-Road Vehicles
    • B60Y2200/22Agricultural vehicles

Abstract

A variable-track vehicle, such as an agricultural vehicle, has front and rear wheels, on opposite sides of the vehicle, carried by axle portions (1, 2) displaceable outwardly and inwardly by hydraulic drive means (3). Linkwork 7, 7a ensures that the displacements on opposite sides are equal and opposite. The wheels are steerable about respective vertical axes and mounted on respective swinging arms (8) pivotally connected to the vehicle chassis. Each wheel is steered by a radius arm (12) pivotally connected with a steering rod (11) extending parallel with the respective swinging arm (8) so that the steering geometry is substantially unaffected by track width adjustments. A hydraulically lockable linkage arrangement (Fig. 2) is provided whereby the rear wheels can, at choice, be locked against steering movements or can be steered in conjunction with the front wheels. An active hydraulic suspension system (Figure 4) for the vehicle lends stability when working across a slope.

Description

DESCRIPTION OF INVENTION Title: "Improvements in or relating to agricultural and the like vehicles" THIS INVENTION relates to wheeled vehicles and is particularly, but not exclusively concerned with heavy duty agricultural vehicles, but may be applicable, in at least some of its aspects to other cross-country vehicles, or to earth moving or other vehicles used in the construction industry or mineral recovery industries, for example.
The invention, in some of its aspects relates to improvements in track adjustment means and steering systems for such vehicles.
An important requirement for agricultural vehicles for many uses, particularly those used by contractors, is for safe and ready adjustment of the track width of the wheels. Such track width adjustment is often achieved by having wheel rims which are mounted on offset brackets which are in turn carried on dished wheel centres such that a range of discrete track widths is obtainable by mounting of the brackets on the inside or outside of the dished centre, by reversal of the wheel centres and by interchange of wheels from side to side. These changes, however, are laborious, time-consuming and have an element of danger to the operator, particularly with heavy wheels. In another arrangement, the wheel hubs are arranged for sliding along protruding axle shafts, but with this arrangement the overall width of the vehicle remains fixed and relatively large even when the track is set to a width less than the maximum. Another arrangement uses overlapping sections of axle members bolted together by two or more bolts on each side through a range of holes, whereby selection of different holes provides several discrete wheel tracks.
All the above known arrangements involve jacking up the vehicle, necessitating good standings to effect the work safely. When steered wheels are to be adjusted for track width, it is usually also necessary for adjustments to be made to the steering mechanism, for example to the length of a steering track rod and possibly also to a drag link from the steering gearbox. Such time-consuming operations militate against frequent changes and possibly against the use of optimum track widths for the jobs in hand.
An object of the present invention in one of its aspects is to provide, in a wheeled vehicle, an improved arrangement for adjustment of track width.
According to this aspect of the invention, there is provided a wheeled vehicle having at least one pair of transversely aligned wheels mounted on opposite sides of the vehicle, said wheels being carried by axle portions displaceable outwardly and inwardly of the vehicle by drive means to vary the track width.
Preferably said drive means comprises hydraulic drive means.
In the preferred embodiment of the invention, the track width can be varied steplessly by the application of hydraulic power without the need to jack the axles up, by operation of controls at the driver's seat, for example whilst the machine is moving slowly.
Preferably said wheel pair of adjustable track width are steerable, each said axle portion having associated therewith a respective swinging arm having one end pivotally connected with the axle portion, for pivoting about a first vertical axis, the other end of the swinging arm being pivotally connected with the vehicle chassis for pivoting about a second vertical axis, the wheel carried by said axle portion being rotatably mounted on a hub or mounting assembly which is pivotable about a vertical axis relative to the respective axle portion and is steerable by means of a radius arm extending from said hub or mounting assembly and pivotally connected with a steering rod extending generally parallel with the swinging arm, the axis of the pivotal connection between said radius arm and said steering rod being substantially coincident with said first vertical axis in a neutral steering position, said steering link at its opposite end being pivotally connected with a steering member for pivoting about an axis which, in said neutral steering position, corresponds substantially with said second vertical axis, whereby the angular position of each said steerable wheel relative to the longitudinal axis of the vehicle is substantially unaffected by track-width adjustment.
It is another object of the invention to provide a four-wheeled vehicle having an improved steering arrangement.
According to this aspect of the invention, there is provided a wheeled vehicle having a front pair of wheels steerable by means of a front steering member pivoted about one vertical axis fixed with respect to the body of the vehicle, a rear pair of wheels steerable by means of a rear steering member pivoted about another, generally parallel axis fixed with respect to the body of the vehicle, first selectively operable coupling means coupling said front and rear steering members to provide four wheel steering and selectively operable locking means operable to hold the rear steering member stationary, relative to the vehicle, to provide front wheel steering, steering driving means for pivoting the front steering member whereby with said selectively operable coupling means in a condition to couple said front and rear steering members and said selectively operable locking means in an inoperative condition, steering movements imparted to said frame steering member by said steering driving means for steering the front wheels will also be imparted to said rear steering member for steering the rear wheel pair, providing four wheel steering, whilst with said selectively operable coupling means in a condition to uncouple said front and rear steering members, and said selectively operable locking means in its condition to hold the rear steering member stationary relative to the vehicle steering movements imparted to said front steering bar by said steering driving means are not also imparted to said other steering bar, providing exclusively front wheel steering.
It is an object of the invention, in another of its aspects, to provide a wheeled vehicle having an improved suspension.
According to this aspect of the invention there is provided a suspension arrangement for a vehicle comprising a pair of front wheels and a pair of rear wheels, a respective hydraulic or pneumatic piston and cylinder unit associated with each said wheel and wherein the cylinders associated with the rear wheels have pressurised chambers providing a bias forcing the rear wheels downwardly with respect to the vehicle chassis, and the pressurised chambers of the rear wheel suspension cylinders are connected by fluid conduits with respective chambers of the piston and cylinder units associated with the respective diagonally opposite front wheels such that pressurisation of the last-mentioned chambers of said front suspension piston and cylinder units provides a bias tending to urge the respective front wheels upwardly with respect to the vehicle chassis, the suspension arrangement including means for providing a bias tending to urge said front wheels downwardly with respect to the vehicle chassis, against the first mentioned bias.
An embodiment of the invention is described below by way of example with reference to the accompanying drawings, in which: FIGURE 1 is a highly schematic fragmentary perspective view showing a track width adjusting arrangement and associated steering arrangement of a vehicle embodying the invention, FIGURE 2 is a highly schematic fragmentary plan view of part of the vehicle showing the track width and steering arrangement, FIGURE 3 is a schematic view of part of the steering arrangement, FIGURE 4 is a diagrammatic illustration of a suspension system of the preferred embodiment, and FIGURES 5 to is a diagrammatic illustration of part of the suspension system of Figure 4.
The preferred embodiment of the invention described below takes the form of a self-propelled four-wheeled agricultural vehicle, which may be a dedicated-purpose vehicle or may be a multi-purpose vehicle adapted to carry any of a selection of fitments, e.g. for crop-spraying, soil cultivation etc. or to tow further vehicles. The specific purpose of the vehicle in any configuration is not relevant to the invention and will not be discussed further.
The vehicle comprises, in known manner, a body or chassis (shown only fragmentarily in the figures) supported on four wheels, comprising a front pair of steerable wheels carried at opposite ends of a front axle, 1, 2, and a rear pair of steerable wheels carried at opposite ends of a similar rear axle 1,2 (not shown in Figure 1).
In the preferred embodiment, the four wheels are driven by respective hydrostatic hydraulic motors carried at the respective ends of the respective axles, in manner known per se, said motors, in manner known per se, being connected via flexible hydraulic fluid lines and control valves, etc. with a source of pressurised hydraulic fluid, such as a large hydropneumatic accumulator which is kept charged with hydraulic fluid by hydraulic pump means driven by an internal combustion engine, the hydraulic motor likewise being connected, in manner known per se, with a low pressure hydraulic reservoir or tank from which the hydraulic pump referred to drawings its hydraulic fluid.
Referring to Figure 1, the front axle comprises two co-axial horizontal tubes 1, 2, one slidable telescopically within the other under the action of a hydraulic piston and cylinder unit 3 and each providing a respective end of the axle. Each tube 1, 2 carries at its outer end a wheel mounting assembly 4 which is supported, from the axle end, by a kingpin arrangement 10, for pivoting, for steering purposes, about a generally vertical axis relative to the axle end. The respective wheel, not shown, is rotatably mounted on the outer side of the mounting assembly 4 by means of a respective hydrostatic hydraulic motor (not shown) also mounted on assembly 4 and supplied (as noted above), with hydraulic fluid by means of flexible lines not shown, extending, via control valves, etc. in manner known per se, from a central hydraulic pumping facility powered by the vehicle engine. For ease of illustration, in Figure 1, only the swinging arm 8 on one side of the vehicle is shown, in Figure 1, and likewise only the arm 13 on one side of the vehicle is shown in Figure 1. These components are, of course, as illustrated in Figure 2, duplicated on the other side of the vehicle, as are the wheel mounting assembly 4, hydraulic motor, radius arm 12, etc. the suspension and steering arrangement for the front wheels exhibiting substantial symmetry about the longitudinal centre line of the vehicle. Likewise, in the preferred embodiment, and as shown in Figure 2, the suspension and steering arrangement for the rear wheels is to a large extent a duplication of that for the front wheels and like references associated with the rear wheels in Figure 2 denote like parts.
The vehicle chassis or body is supported from the axles by hydraulic struts (not shown in Figures 1 to 3 but indicated schematically at 70 in Figure 4), each said hydraulic strut having its lower end pivotally connected, for example, with a bracket fixed to the respective axle tube 1, 2 adjacent the free end of the axle tube and having its upper end pivotally connected, for example, with a bracket fixed to the vehicle body or chassis. Thus, as the axle parts 1, 2 are moved outwardly or inwardly, each strut 70 swings in a respective transverse vertical plane. In the preferred arrangement shown in Figures 1 and 2 in which, as described below, each axle is connected with a pair of swinging arms 8 and varies slightly in position along the longitudinal axis of the vehicle, the connection of each end of said hydraulic strut with the vehicle body and the respective axle end is preferably by way of a respective ball joint or other universal articulation.
As shown in Figure 1, each axle tube 1, 2 is pivotally connected, for pivoting about a vertical axis, with one end of the respective swinging arm 8 which at its other end is pivotally connected, at 8A, via a ball joint or other universal articulation, with the vehicle body or chassis. In the arrangement shown, said one end of the arm 8 carries a fork 8B providing upper and lower horizontally extending jaws between which the respective axle end extends and through which pass the ends of a pivot pin 8C passing vertically through the respective axle end. Each steerable wheel is steered by the action of a respective longitudinal steering rod 11 pivotally connected at one end, at llA, with the inner end of a radius arm 12 fixed to the respective wheel mounting assembly and extending inwardly from the assembly generally along the respective axle. The point llA of pivotal connection of the rod 11 with the radius arm 12 is such that in a "neutral" steering position of the steering assembly (i.e. a position in which the steering is set for straight-ahead movement of the vehicle), said point llA lies substantially on the axis of the pivotal connection between the arm 8 and the respective axle. The rod 11, at its opposite end, is pivotally connected, at llB, with a further radius arm 13 which is pivotally connected at one end to the vehicle chassis for pivoting about a vertical axis and extends inwardly from that axis. The point llB of pivotal connection of rod 11 with arm 13 is spaced inwardly from the pivotal axis of arm 13 and the arrangement is such that in said "neutral" steering position, the point llB lies substantially on the axis of the pivotal connection at 8A of the arm 8 with the chassis. Because of the disposition of the pivot points llA and llB on the vertical axes of the pivotal connection of opposite ends of the arm 8 with the axle tube and the vehicle chassis at 8C and 8A respectively, in the "neutral" steering position, the inward or outward movement of the axle ends for track adjustment, in the "neutral" steering position, does not give rise to steering, toe-in or toe-out movements of the vehicle wheels relative to the axles. In the arrangement illustrated, the radius arm 12 extends above the axle 2, 1 and the fork 8B and the pivotal connection llA with the rod 11 lies directly above the upper end of fork 8B whilst the arm 13 extends above the pivotal connection 8A, the rod 11 thus lying over the arm 8 and parallel therewith.
As noted above, the longitudinal position of the axle tube 1 within the co-axial axle tube 2 is adjusted by means of a double-acting hydraulic piston and cylinder unit 3, which may be connected between brackets on the tubes 1 and 2 or may be connected between the associated opposite swinging arms 8 or (having regard to the equalising arrangement referred to below) may be connected between the chassis and one arm 8. The hydraulic piston and cylinder unit 3 is connected via appropriate control valves operable from the driver's cabin (not shown) with the hydraulic pump means (not shown) carried on the vehicle body.
In order to ensure that the wheels on each axle of the vehicle are extended equally on opposite sides of the vehicle, the two axle halves 1, 2 (or, which is functionally equivalent, corresponding locations on the opposing swinging arms 8) are connected by an equalising arrangement comprising respective tie rods 7 pivotally connected at 7A with the respective axle halves 1, 2 or with the arms 8 and pivotally connected at 7B to opposite ends of a rocking lever 5 pivotally connected at its midpoint, at 5A with the vehicle chassis. As, in the preferred embodiment, each axle 1, 2 is movable vertically with respect to the vehicle chassis in operation of the suspension system, each tie rod 7 is connected at each end 7A with the respective axle part or arm 8, on the one hand, and at end 7B with the respective end of the rocking lever 5, on the other hand, by a ball-joint or other universal articulation allowing the rods 7 to swing up and down as the suspension operates, the rocking lever 5 also serving, by pivoting about its pivot 5A, to compensate for the effective changes in horizontal extent of the tie rods 7 as a result of upward and downward swinging of the rods 7.
As noted above, due to the angular movement of swinging arms 8 during outward or inward movement of the axle parts 1 and 2 to alter track width, there is, with such adjustment, a slight movement of axle 1, 2 in the fore and aft direction with a concomitant slight inequality of lateral adjustment of the wheels on the two axle halves relative to the vehicle centre line at the extremes of such adjustment but, with the limited range of track adjustment relative to the other vehicle dimensions in the preferred embodiment, this slight inequality is imperceptible. It will be understood that other equalising arrangements may be utilised instead of that comprising rocking lever 5 and rods 7. A further equalising arrangement, not shown, is provided to ensure equality between the inward and outward movements of the front wheels and rear wheels, such as a mechanical linkage (e.g. of the Panhard type) connecting respective parts of the front and rear axles or swinging arms 8.
By the means described it is possible to adjust the track width of the wheels from the driver's position whilst the vehicle is in motion, the steering of the wheels being unaffected by such adjustment, the system automatically accommodating to the changes in wheel position.
As best shown in Figure 2, for four-wheel steering the steering of the rear wheels is accomplished by use of a similar arrangement of links and levers and in Figure 2 the same references are used for corresponding parts associated with the front wheel steering and with the rear wheel steering.
Figure 2 is a schematic plan view from above of the vehicle, parts corresponding to parts in Figure 1 likewise having the same references. The chassis of the vehicle is indicated in Figure 2 schematically by longitudinal members 25 shown in broken lines and by fragments 27, 28, 30. As best shown in Figure 2, the inner end of each radius arm 13 is pivotally connected to one end of a respective rigid link 14 the other end of which is pivotally connected to a respective end of a steering bar. Thus, the two links 14 for the front wheel steering are so connected to the opposite ends of a front steering bar 15 and the two links 14 for the rear wheel steering are so connected to the opposite ends of the rear steering arms 15'. Each steering bar 15, 15' is pivotally connected at its mid-point to the chassis (27, 28) for pivoting about a respective vertical axis lying in the longitudinal vertical central plane of the vehicle, the arms 15, 15' extending transversely of the vehicle and parallel with one another. The opposite ends of the two arms 15, 15' may be regarded as forming the four vertices of a quadrilateral. Connected across a diagonal of this quadrilateral is a selectively operable hydraulic stay 34 described below in more detail with reference to Figure 5, the stay being pivotally connected at one end to one end of steering arm 15 and being pivotally connected at its opposite end to the diagonally opposite end of the steering arm 15'. The vehicle is operable in two steering modes, namely a four-wheel steering mode and a front-wheel steering mode. In the four wheel steering mode, the stay 34 is in an operative condition in which it acts as a rigid stay so that steering movements imparted to arm 15' are imparted via stay 34, to the steering arm 15 to cause the latter to pivot through the same angle as, but in the opposite sense from, the steering arm 15'. In the frontwheel steering mode, the stay 34 is in an inoperative condition in which it can be extended and retracted by negligible longitudinal forces, whilst the steering arm 15 is held immobile by a selectively operable hydraulic stay 36, similar in function and operation to the stay 24, the stay 36 being in its inoperative condition when the stay 34 is in its operative condition and vice versa.
Referring to Figure 5, which illustrates the stay 34 or stay 36 together with a control valve 42 therefor, each stay 34, 36 comprises, in effect, two double-acting piston and cylinder units arranged back to back as shown, with the rod end of one cylinder and the piston head end of the other cylinder connected with a hydraulic line 38 and with the other ends of the two cylinders connected with a hydraulic line 40. With the lines 38, 40 connected respectively via a control valve such as illustrated at 42, for example, with the source P of hydraulic fluid under pressure and with the low pressure hydraulic fluid reservoir T respectively the stay is placed in its operative state in which, as shown, the piston 35 of one cylinder is fully extended and the piston 37 of the other cylinder is fully retracted and is maintained in this state by the applied hydraulic pressure. With both line 38 and line 40 connected with the low pressure reservoir T, for example, and possibly, as indicated, also connected together, the stay is in its inoperative state in which each piston 35, 37 is free to reciprocate under comparatively low axial forces, between its extreme positions, allowing the stay to readily lengthen and contract relative to its effective length in its operative state.
The steering movements of the steering arm 15' are preferably imparted thereto by two double acting hydraulic piston and cylinder units 46 and 48 each having one end pivotally connected to a respective end of the arm 15' and each being pivotally connected at its opposite end to the vehicle chassis. The piston and cylinder units 46 and 48 are connected with the hydraulic system of the vehicle via a control valve arrangement, illustrated in Figure 3, which allows the "gearing" of the steering to be changed automatically, for example between front wheel steering and four-wheel steering modes. Referring to Figure 3, lines 50 and 52 extend from a hydraulic steering facility, known per se, such as an Orbitrol or similar system controlled by a steering wheel in the vehicle cabin and which, in effect, supplies an appropriate volume of hydraulic fluid to one such line 50 or 52 according to the controlling displacement applied to the steering wheel or other steering control by the machine operator, or supplies such hydraulic fluid at a rate which depends upon the difference between a "set" steering displacement applied to the steering wheel and an actual steering displacement sensed by appropriate sensing means for example, in manner known per se.
As shown, the piston head end of piston and cylinder unit 46 is connected to a port 54 of a six-part spool valve 51, the piston rod end of unit 46 is connected to port 56 of valve 51, the piston head end of unit 48 is connected to port 58 of valve 51 and the piston rod end of unit 48 is connected to port 60 of valve 51. Ports 62 and 64 of the valve 51 are connected together and to the low-pressure reservoir of the hydraulic system. In one position of valve 51, the valve connects port 58 with port 60 and port 54 with port 56 and disconnects ports 62 and 64 from any of the other ports. In this first position of valve 51, the steering is effectively in a low geared condition.
Supposing, for example, that the steering control system, (represented for simplicity, by a valve 53 in Figure 3 is supplying hydraulic fluid under pressure via line 50, with the line 52 being connected to the low pressure reservoir T, the pressure fluid from line 50 is supplied to the piston head end of unit 46 and the piston rod end of unit 48, the opposite ends of the two units being connected, via line 52 to the low pressure reservoir, so that both units 46, 48 apply a respective turning moment to the steering bar 15' and absorb part of the hydraulic fluid supplied via line 50. (If, in this condition of valve 51, pressurised fluid is supplied instead via line 52 and is exhausted via line 50, the same low-gearing conditions apply, except, of course, that the pressure is applied to the opposite ends of units 46 and 48 and the bar 15' is turned in the opposite direction). In the alternative, second position of the valve 51, the ports 54 and 58 are each disconnected from any of the other ports whilst the port 56 is connected with port 62 and the port 60 with the port 64. Thus, in this second position of valve 51, pressurised hydraulic fluid is supplied via line 50 or 52, only to the piston head end of the unit 46 or 48 respectively connected directly to the pressurised line 50 or 52, all other connections to units 46 and 48 being connected directly or indirectly to exhaust. Consequently, the resulting movement of the steering arm 15' is substantially greater for a given quantity of pressurised fluid supplied via line 50 or 52 than when the valve 51 is in its first position, the force thus applied to arm 15' being correspondingly lesser. This second position of valve 51 is the position occupied by valve 51 in the front wheel steering mode.
Figure 4 is a schematic diagram of the preferred active suspension system for the vehicle. The purpose of the suspension system is to provide a relatively stable chassis although the vehicle may be traversing variable terrain. It will be understood that the suspension system described below is not confined in its applicability to the vehicle described as the preferred embodiment but may be adapted to a variety of load-carrying or other vehicles, for agricultural or other uses. As noted above, a respective hydraulic suspension strut 70 is provided for each wheel, each said suspension strut being connected between the respective axle end adjoining the respective wheel and a respective mounting on the vehicle body. In Figure 4, the front left and front right wheels are referenced FR and FL respectively and the rear left and rear right wheels RL and RR respectively. In Figure 4, the individual suspension units are indicated by the reference 70 with the suffix FL, FR, etc. according to the vehicle wheel with which they are associated. Each suspension strut comprises a double-acting hydraulic piston and cylinder unit with the free end of the piston rod pivotally connected, as described above, with the respective axle part and with the head of the cylinder pivotally connected with the vehicle body (not shown in Figure 4). In the front wheel units 70 FL and 70 FR the chambers in the respective cylinders above the respective pistons are connected by a common line 74 which is connected with the output of a hydraulic sensor valve FA the function of which is described in more detail below and which is common to both front struts. In each of the rear suspension struts 70 RL and 70 RR the space within the respective cylinder above the respective piston is connected via a respective line 78L or 78R with a respective hydraulic sensor valve RAL or RAR. Furthermore, the cylinder chamber above the piston in the left rear suspension unit 70RL is connected by a line 80 to the cylinder chamber beneath the piston in the front right suspension unit 70FR whilst the cylinder chamber above the piston in the rear right suspension unit 70RR is connected by a line 82 with the cylinder chamber below the piston in the front left suspension unit 70FL.
Each of the sensor valves FA, RAR, RAL, is connected with the source of hydraulic pressure P and the low pressure reservoir T. Each sensor valve FA, RAR, RAL has a body secured to the vehicle chassis and an actuating element connected by a linkage (not shown) with the respective axle or axle end and operates to connect the outlet of the valve with either the pressure source P or the low pressure reservoir T in order to admit pressurised fluid to the respective strut or struts 70, or release fluid from the respective strut or struts 70 according to whether the height of the vehicle body above the respective axle or axle end, as sensed by the sensor valve and linkage, is less than or greater than a respective predetermined nominal height so that if the respective chassis part falls below its nominal level pressurised hydraulic fluid is admitted to the respective strut or struts to raise the respective chassis part and conversely if the respective chassis part rises above its nominal level, hydraulic fluid is released from the respective strut or struts to lower the respective chassis part. The sensor valve FA, and its associated linkage, are located in such positions that the sensor valve FA is effectively responsive to the vertical spacing between the vehicle chassis and a point at the middle of the front axle 1, 2, that is to say a point mid-way between the wheels FL and FR and thus may be regarded as sensing, at any instant, the mean of the positions of the front left wheel and the front right wheel. Because of the direct connection, via line 74 of the upper chambers of the front suspension struts and because of the sensor valve arrangement just described, when the vehicle chassis is substantially level with the horizontal, the front suspension arrangement provides the effect of a centre pivot axle, since the rocking of the axle with respect to the chassis is accommodated by movement of the supporting oil from the top of one cylinder to the top of the other. The upper chambers of the front suspension struts are also connected to a hydropneumatic accumulator to provide a springing effect. The rear sensor valves RAL and RAR, on the other hand, are mounted adjacent the sides of the vehicle with their respective linkages being connected with the rear axle parts 1 and 2, of the vehicle at points adjacent the outer ends of the axl pistons, in the units 70 RL and 70 RR will be determined by the loading on the rear wheels of the vehicle, (assuming for simplicity that the chambers below these pistons are at atmospheric pressure) whilst the common (in static conditions) pressure in the chambers above the pistons in the front suspension units 70 FL and 70 FR is determined jointly by the loading placed on the front wheels by the vehicle and by the counteracting pressure in the chamber beneath the respective piston in the respective front suspension unit which counteracting pressure is (in static conditions) equal to the pressure in the respective diagonally opposite rear suspension unit. This arrangement lends stability to the vehicle when working across, sloping terrain, i.e. in circumstances in which the left wheels of the vehicle are higher in level than the right wheels or vice versa. The effect of the resulting tilt of the vehicle is to place a higher load on the downhill wheels of the vehicle than on the uphill wheels so that the downhill rear sensor valves RAR or RAL must maintain a higher pressure in the upper chamber of the downhill rear suspension unit than if the vehicle were on level ground to maintain the preset spacing of the downhill rear wheel with respect to the chassis. Likewise, a lower pressure than if the vehicle were on level ground will be maintained in the uphill rear suspension unit. Because of the diagonal connection of the front and rear suspension units via lines 80 and 82, there will consequently be a higher counteracting pressure in the lower chamber of the uphill front suspension unit and a lower counteracting pressure in the lower chamber of the downhill front suspension unit with, consequently, a higher net force being exerted between the vehicle chassis and the front downhill wheel by the downhill front suspension unit and a lower net force applied between the uphill front wheel and the vehicle chassis by the uphill front suspension unit. As a result, the suspension system tends, in these conditions, to hold the axles parallel with those parts of the chassis which, on level terrain, would normally lie horizontally transversely of the vehicle. This arrangement alleviates a stability problem which is encountered in cross-slope working in conventional agricultural vehicles in which, typically, the front axle is merely pivotally connected at its middle with the vehicle chassis and thus provides no corrective moment tending to counteract the tendency of the vehicle to topple over on the downhill side.
The bottoms, or rod ends of the two rear cylinders 70 RR and 70 RL, are connected together by a line 90 and to a hydropneumatic accumulator (not shown). If the pressure in this part of the circuit rises above a first predetermined value a relief valve 92 opens to permit the release of pressure. If it falls below a second, lower, predetermined value another valve 94 opens to admit o l from the main hydropneumatic accumulator or pressure source. The effect of this provision is that if the vehicle is working across critically sloping terrain, such that the load imposed by the vehicle on the uphill wheels drops or may drop to zero, the tendency of the vehicle chassis to tilt or roll downhill is also counteracted to some extent by the weight of the uphill rear wheel, which, in view of the predetermined pressure maintained beneath the respective rear wheel piston, must be lifted from the ground before, or in the course of, such tilting of the vehicle chassis.

Claims (13)

1. A wheeled vehicle having at least one pair of transversely aligned wheels mounted on opposite sides of the vehicle, said wheels being carried by axle portions displaceable outwardly and inwardly of the vehicle by drive means to vary the track width.
2. A vehicle according to claim 1 wherein said drive means comprises hydraulic drive means.
3. A vehicle according to claim 1 or claim 2 including operating means operable to ensure that the transverse displacements, relative to the vehicle, of said wheels on opposite sides of the vehicle are equal and opposite.
4. A vehicle according to any preceding claim wherein said wheel pair of adjustable track width are steerable, each said axle portion having associated therewith a respective swinging arm having one end pivotally connected with the axle portion, for pivoting about a first vertical axis, the other end of the swinging arm being pivotally connected with the vehicle chassis for pivoting about a second vertical axis, the wheel carried by said axle portion being rotatably mounted on a hub or mounting assembly which is pivotable about a vertical axis relative to the respective axle portion and is steerable by means of a radius arm extending from said hub or mounting assembly and pivotally connected with a steering rod extending generally parallel with the swinging arm, the axis of the pivotal connection between said radius arm and said steering rod being substantially coincident with said first vertical axis in a neutral steering position, said steering link at its opposite end being pivotally connected with a steering member for pivoting about an axis which, in said neutral steering position, corresponds substantially with said second vertical axis, whereby the angular position of each said steerable wheel relative to the longitudinal axis of the vehicle is substantially unaffected by track-width adjustment.
5. A wheeled vehicle having a front pair of wheels steerable by means of a front steering member pivoted about one vertical axis fixed with respect to the body of the vehicle, a rear pair of wheels steerable by means of a rear steering member pivoted about another, generally parallel axis fixed with respect to the body of the vehicle, first selectively operable coupling means coupling said front and rear steering members to provide four wheel steering and selectively operable locking means operable to hold the rear steering member stationary, relative to the vehicle, to provide front wheel steering, steering driving means for pivoting the front steering member whereby with said selectively operable coupling means in a condition to couple said front and rear steering members and said selectively operable locking means in an inoperative condition, steering movements imparted to said frame steering member by said steering driving means for steering the front wheels will also be imparted to said rear steering member for steering the rear wheel pair, providing four wheel steering, whilst with said selectively operable coupling means in a condition to uncouple said front and rear steering members, and said selectively operable locking means in its condition to hold the rear steering member stationary relative to the vehicle steering movements imparted to said front steering bar by said steering driving means are not also imparted to said other steering bar, providing exclusively front wheel steering.
6. A vehicle according to claim 5 wherein each said steering member comprises a respective steering bar pivotally connected intermediate its ends to the vehicle body for pivoting about the respective axis, said selectively operable coupling means comprising a selectively operable hydraulic strut pivotally connected at each end to a respective said steering bar at a position spaced from the respective axis.
7. A vehicle according to claim 5 or claim 6 wherein said locking means comprises a selectively operable hydraulic strut pivotally connected at one end to the vehicle body and at its opposite end to said rear steering arm.
8. A vehicle according to claim 6 or claim 7 wherein the or each said hydraulic strut comprises a pair of pistons working in respective cylinders fixed with or respect to one another and wherein, in the operative position of said strut one of these pistons is forced by hydraulic pressure to a fully extended limiting position in its cylinder and the other is forced by hydraulic pressure to a fully retracted limiting position in its cylinder, thereby fixing the length of the stay at a length intermediate is minimum and maximum lengths, in an inoperative condition of the strut each said piston is free to move, without significant biasing pressure, in its respective cylinder.
8. A vehicle according to claim 6 or claim 7 wherein said front steering bar is pivotally connected with the vehicle body midway between its ends and said steering driving means comprises two substantially parallel doubleacting hydraulic piston and cylinder units each pivotally connected at one end to the vehicle chassis and pivotally connected at its other end to a respective end of said front steering bar, means for supplying hydraulic fluid under pressure to said piston and cylinder units, and valve means which in one position connects one end of each said hydraulic cylinder with said means for supplying hydraulic fluid under pressure and in another position connects only one of said cylinders with said means for supplying hydraulic fluid under pressure and connects the other of said hydraulic cylinders with a low-pressure reservoir, whereby the effective steering gearing can be changed by operation of said valve means.
9. A suspension arrangement for a vehicle comprising a pair of front wheels and a pair of rear wheels, a respective hydraulic or pneumatic piston and cylinder unit associated with each said wheel and wherein the cylinders associated with the rear wheels have pressurised chambers providing a bias forcing the rear wheels downwardly with respect to the vehicle chassis, and the pressurised chambers of the rear wheel suspension cylinders are connected by fluid conduits with respective chambers of the piston and cylinder units associated with the respective diagonally opposite front wheels such that pressurisation of the last-mentioned chambers of said front suspension piston and cylinder units provides a bias tending to urge the respective front wheels upwardly with respect to the vehicle chassis, the suspension arrangement including means for providing a bias tending to urge said front wheels downwardly with respect to the vehicle chassis, against the first mentioned bias.
10. A suspension arrangement according to claim 9 wherein said cylinders associated with the rear wheels have said pressurised chambers thereof pressurised under the control of respective level-sensing devices means associated with the respective rear wheels to provide said bias forcing the rear wheels downwardly.
11. A suspension means according to claim 9 or claim 10 wherein said piston and cylinder units associated with the front wheels are double acting, each having a first said chamber providing a bias urging the respective front wheel upwardly and a second said chamber providing a bias urging the respective front wheel downwardly and wherein said second chambers are pressurized under the control of level sensing means common to the two front wheels and sensing the mean of the levels of the two front wheels.
12. A wheeled vehicle substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
13. Any novel feature or combination of features disclosed herein.
GB9607397A 1996-04-10 1996-04-10 A variable-track, four wheel steering agricultural vehicle with active suspension Withdrawn GB2311967A (en)

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GB2311967A true GB2311967A (en) 1997-10-15

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GB2339761A (en) * 1998-07-25 2000-02-09 Bamford Excavators Ltd Load handling apparatus
GB2356331A (en) * 1999-08-31 2001-05-23 Reekie Mfg Ltd Universal tool carrier
GB2382056A (en) * 2001-11-20 2003-05-21 Applied Sweepers Ltd Sweeping machine with variable wheel tracking
GB2375332B (en) * 2001-04-05 2004-05-12 Nigel Howard Mckrill Wheel restraint system
EP1529722A2 (en) 2003-11-07 2005-05-11 Hardi-Evrard Adjustable tread device for wheels of the same axle
WO2005056308A1 (en) * 2003-12-11 2005-06-23 Singapore Technologies Kinetics Ltd Wheel track adjustment system
US7063706B2 (en) 2001-11-19 2006-06-20 Wittenstein Ag Distraction device
EP1908674A1 (en) * 2006-10-06 2008-04-09 Oto Melara S.p.A. Variable configuration vehicle
CN102442341A (en) * 2011-12-15 2012-05-09 徐浩钟 Hydraulic plunger type steering transmission device
EA018272B1 (en) * 2008-08-20 2013-06-28 Дир Энд Компани Device and method for reducing tire wear on an agricultural vehicle
WO2015179936A1 (en) * 2014-05-29 2015-12-03 Marchesan Implementos E Máquinas Agrícolas Tatú S.A. A turn system applied to the four wheels of a sugar-cane harvester
US9930821B2 (en) 2015-02-18 2018-04-03 Cnh Industrial America Llc Agricultural vehicle support frame
US10183542B1 (en) 2017-12-11 2019-01-22 Cnh Industrial America Llc Suspension control system providing orientation control for an agricultural machine
US10436622B2 (en) 2017-12-11 2019-10-08 Cnh Industrial America Llc Suspension control system providing closed loop control of hydraulic fluid volumes for an agricultural machine
US10569612B2 (en) 2017-12-11 2020-02-25 Cnh Industrial America Llc Suspension control system providing tire height corrections for an agricultural machine
US10730359B2 (en) 2017-12-11 2020-08-04 Cnh Industrial America Llc Suspension control system providing suspension height corrections for an agricultural machine

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GB1558007A (en) * 1975-12-23 1979-12-19 Jlg Ind Inc Aerial lift platform
GB2082926A (en) * 1980-09-03 1982-03-17 Maxim John Conductive fluid activated devices
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Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2339761A (en) * 1998-07-25 2000-02-09 Bamford Excavators Ltd Load handling apparatus
GB2356331A (en) * 1999-08-31 2001-05-23 Reekie Mfg Ltd Universal tool carrier
GB2375332B (en) * 2001-04-05 2004-05-12 Nigel Howard Mckrill Wheel restraint system
US7063706B2 (en) 2001-11-19 2006-06-20 Wittenstein Ag Distraction device
GB2382056A (en) * 2001-11-20 2003-05-21 Applied Sweepers Ltd Sweeping machine with variable wheel tracking
US7735176B2 (en) 2001-11-20 2010-06-15 Tennant N.V. Sweeping machine with variable wheel tracking
FR2862022A1 (en) * 2003-11-07 2005-05-13 Hardi Evrard DEVICE FOR DISENGAGING TWO WHEELS FROM THE SAME AXLE
EP1529722A2 (en) 2003-11-07 2005-05-11 Hardi-Evrard Adjustable tread device for wheels of the same axle
EP1529722A3 (en) * 2003-11-07 2005-12-28 Hardi-Evrard Adjustable tread device for wheels of the same axle
WO2005056308A1 (en) * 2003-12-11 2005-06-23 Singapore Technologies Kinetics Ltd Wheel track adjustment system
EP1908674A1 (en) * 2006-10-06 2008-04-09 Oto Melara S.p.A. Variable configuration vehicle
EP2156724A3 (en) * 2008-08-20 2016-01-27 Deere & Company Device and method for reducing tire wear on an agricultural vehicle
EA018272B1 (en) * 2008-08-20 2013-06-28 Дир Энд Компани Device and method for reducing tire wear on an agricultural vehicle
CN102442341A (en) * 2011-12-15 2012-05-09 徐浩钟 Hydraulic plunger type steering transmission device
WO2015179936A1 (en) * 2014-05-29 2015-12-03 Marchesan Implementos E Máquinas Agrícolas Tatú S.A. A turn system applied to the four wheels of a sugar-cane harvester
US9707997B2 (en) 2014-05-29 2017-07-18 Marchesan Implementos E Maquinas Agricolas Tatu S.A. Turn system applied to the four wheels of a sugar-cane harvester
AU2015268112B2 (en) * 2014-05-29 2018-07-26 Marchesan Implementos E Maquinas Agricolas Tatu S.A. A turn system applied to the four wheels of a sugar-cane harvester
US9930821B2 (en) 2015-02-18 2018-04-03 Cnh Industrial America Llc Agricultural vehicle support frame
US10183542B1 (en) 2017-12-11 2019-01-22 Cnh Industrial America Llc Suspension control system providing orientation control for an agricultural machine
US10436622B2 (en) 2017-12-11 2019-10-08 Cnh Industrial America Llc Suspension control system providing closed loop control of hydraulic fluid volumes for an agricultural machine
US10569612B2 (en) 2017-12-11 2020-02-25 Cnh Industrial America Llc Suspension control system providing tire height corrections for an agricultural machine
US10730359B2 (en) 2017-12-11 2020-08-04 Cnh Industrial America Llc Suspension control system providing suspension height corrections for an agricultural machine

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