GB2051703A

GB2051703A - Articulated height adjustable vehicle

Info

Publication number: GB2051703A
Application number: GB8019611A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-06-20
Filing date: 1980-06-16
Publication date: 1981-01-21
Also published as: GB2051703B

Abstract

In an articulated vehicle for use in off the road locations such as in forestry work, a chassis having a first and second portion 12, 14 pivotally connected together has a steering mechanism connected between the first and second portions, and two wheel assemblies 22 mounted on each portion of the chassis are adjustable to vary the distance a wheel of each wheel assembly projects below the chassis. The vehicle is therefore capable of maintaining a horizontal attitude on severe gradients. <IMAGE>

Description

SPECIFICATION An articulated vehicle This invention relates to an articulated vehicle, and more particularly, to an articulated vehicle which is suitable for use in off the road locations.

During use of vehicles in off the road locations such as, for example, when a vehicle is utilised in forestry work, the vehicle often has to traverse uneven terrain. Furthermore, it is necessary at certain times for the equipment carried by such a vehicle to be brought into operation whilst the vehicle is standing on severe gradients and work has to be carried out on trees which normally grow vertically. It is therefore extremely beneficial if the vehicle is capable of maintaining a horizontal attitude on such severe gradients.

The object of this invention is to provide a vehicle whose attitude in respect of the terrain on which the vehicle stands is capable of being varied.

According to this invention, an articulated vehicle comprises a chassis having a first and a second portion pivotally connected together, a steering mechanism connected between the first and the second portions of the chassis, and at least two wheel assemblies mounted on each portion of the chassis, wherein the distance a wheel of each wheel assembly projects below the chassis is adjustable.

Preferably, the distances which the wheels of the assemblies project below the chassis are independently adjustable to vary the attitude of the vehicle.

Preferably, also, the wheel of each assembly is driven, and the wheel is, preferably, driven by a hydraulic wheel motor. Preferably, a power unit is mounted on the chassis and may include a hydraulic pump which is, preferably, connected to the hydraulic wheel motors via a control means.

Alternatively, the wheel of each wheel assembly is driven by mechanical means. The power unit mounted in the chassis is, preferably, connected via gearing to the wheels of each assembly.

Preferably, also, the chassis is provided on its lower surface with skid portions on which, in soft ground, the vehicle can rest. The skid portions on the first and the second portions of the chassis are, preferably, spaced-apart from the pivotal connection between said portions of the chassis.

Preferably, each wheel assembly is connected to the chassis by a piston-and-cylinder assembly, and the distance the wheel of each wheel assembly projects below the chassis is adjusted by extending or contracting the associated piston-and-cylinder assembly. Preferably, also, the piston-and-cylinder assemblies extend vertically relatively to the plane of the chassis. The upper end of each piston-andcylinder assembly may be connected to the chassis by spring means and/or a hydraulic or pneumatic accumulator to provide a spring suspension and/or shock absorbing facility for the vehicle.

A preferred embodiment of this invention will now be described, by way of example only, with reference to the accompanying drawings of which: Figure 1 is a diagrammatic side elevation of the vehicle; Figure 2 is a diagrammatic plan view of the vehicle shown in Fig. 1 with parts omitted for the sake of clarity; Figure 3 is a perspective view of the vehicle shown in Fig. 1; Figure 4 is a side elevation of the vehicle shown in Fig. 1 in the operative position; and Figure 5 is a schematic side elevation of a modified vehicle.

Referring now to Figs. 1 to 4 of the drawings, an articulated vehicle which is particularly suitable for use in off the road conditions such as, for example, during use in forestry work where uneven terrain is encountered, comprises a chassis indicated generally at 10 formed of tubular steel members. Alternatively, the chassis can be formed of steel pressings or any other suitable construction.

The chassis 10 consists of a front portion 1 2 and a rear portion 1 4 which are pivotally connected together by two spaced-apart vertically aligned hinge assemblies 1 6 and 18 so that the front portion 1 2 and the rear portion 14 of the chassis 10 are capable of pivotal movement relatively to each other about a vertical pivotal axis. The front portion 1 2 and the rear portion 1 4 of the chassis 10 have a piston-and-cylinder 20 connected therebetween, extension or contraction of which varies the angle between the front portion 1 2 and the rear portion 1 2 of the chassis 10 to effect steering of the vehicle.

The front portion 1 2 and the rear portion of the chassis 10 are each provided with two transversely spaced-apart wheel assemblies indicated generally at 22. Each wheel assembly 22 comprises a road wheel 24 inside which is fitted a rotatably driven hydraulic wheel motor (not shown). A stub axle 26 of the hydraulic wheel motor is connected to the lower end of a slide 27 which in turn is connected to a piston-and-cylinder 28 mounted vertically in the associated chassis portion 1 2 or 1 4. The lower end of the slide 27 is supported between two guide rollers 30 and 32 and is further supported by the profile of the associated chassis portions 1 2 or 1 4 throughout its retracted length.

The upper end of the piston-and-cylinder 28 is connected via a spring (not shown) and/or a hydraulic or pneumatic accumulator 34 to the chassis 10. The spring assembly and/or the pneumatic or hydraulic accumulator 34 provides the vehicle with a spring suspension and shock absorbing facility.

The extension or contraction of the pistonand-cylinders 28 associated with the wheel assemblies 22 provide adjustment of the distance which each road wheel 24 projects below the chassis thus enabling the attitude of the vehicle to be varied. Control means (not shown) is provided for controlling the extension or contraction of the piston-and-cylinders 28 so that the vehicle is maintained in a horizontal attitude irrespective of the gradients encountered by the vehicle during movement over rough terrain. The control means (not shown) may include a pendulum type of switch (not shown) which senses variations in the inclination of the vehicle relative to the horizontal and operates the piston-and-cylinders 28 to maintain the vehicle in a horizontal attitude.

The lower surfaces of the front portion 1 2 and the rear portion 1 4 of the chassis 10 are provided with relatively flat surfaces which are adapted to form skid portions 38 thereon and the skid portions 38 are arranged to be spaced-apart from the location of the hinge assembly 1 8. When the vehicle is traversing extremely soft ground such as, for example, mud, the road wheels 24 can be retracted until the vehicle rests upon the skid portions 38 of the chassis 10.

A prime mover in the form of a diesel engine 40 is mounted in the rear portion 1 4 of the chassis 10 and is arranged to drive a hydraulic pump 42 which supplies fluid under pressure to the wheel motors (not shown) which rotate the road wheels 24. Each road wheel 24 is thus independently driven giving the vehicle a maximum tractive effort which makes the vehicle particularly suitable for traversing rough terrain.

A side panel 43 extends upwardly above each wheel assembly 22, and an arcuate passageway 45 is formed within each panel 43. When a wheel 24 is retracted, the hoses (not shown) which carry fluid from the hydraulic pump 42 to the associated wheel motor (not shown) are accomodated within the associated passageway 45 to prevent the hoses from becoming punctured or unduly bent as the wheel 24 is retracted.

When the vehicle encounters extremely soft ground such as, for example, mud, and the road wheels 24 are retracted until the vehicle is resting upon the skid portions 38 as described above, the road wheels can then be drivably rotated and in effect act as paddles to propel the vehicle slidably forward on the skid portions 38.If this form of driving arrangement is insufficient to propel the vehicle forward in extremely soft conditions, and alternative method of propulsion can be provided by actuating the piston-and-cylinder 20 to form an acute angle between the front portion 1 2 and the rear portion 1 4 of the chassis 10, driving the front road wheel 24 which is adjacent to the acute angle formed between the portions 1 2 and 1 4 of the chassis and also driving the diammetrically opposed rear road wheel 24; then applying full opposite lock to change the angle between the front portion and rear portions 1 2 and 1 4 of the chassis 10 and driving the two opposite road wheels 24.This action, in effect produces a snake-like movement of the vehicle, which propels it forward over terrain such as mud.

Referring now to Fig. 5 of the drawings, the prime mover in the form of the diesel engine 40, is arranged to drive a mechanical gear box 44 which is connected via gearing 46 to the road wheels 24 thus replacing the hydraulic pump 42 and the hydraulic wheel motors of the vehicle described with reference to Figs. 1 to 4 of the drawings.

It will be appreciated that the above described vehicle is particularly suitable for use in forestry work where it is often necessary to carry out tree felling or pruning operation on trees which although themselves normally grow vertically are disposed on steeply inclined hillsides and the attachment of equipment to this type of vehicle enables the attitude of the vehicle to be brought into a horizontal plane even when the vehicle is resting upon inclined hillsides by virtue of the use of the adjustment provided therein for varying the distances which each of the road wheels 24 project below the chassis 10 of the vehicle. This is shown particularly clearly in Fig. 4 of the drawings.

It is intended that the vehicles as described above should in use, face down hill so that the weight of the engine 40 and any timber (not shown) carried on the rear portion 14 is arranged to stabilise the vehicle on a hillside rather than increasing the tendancy of the vehicle to topple over backwards as would be the case if the vehicle faced uphill. The engine 40 is set at an angle of about 10" to the horizontal axis of the rear portion 14 as clearly shown in Fig. 4 to enable the engine to function correctly even when the vehicle (facing downhill) is inclined steeply to the vertical. If the engine were to be mounted in line with the horizontal axis of the rear portion 14, then the oil feed to the engine would become disrupted when the vehicle was inclined downwardly on a steep slope, which could result in the engine functioning incorrectly or ceasing.

Tractive force between the road wheels 24 and the ground can be greatly reduced when the vehicle is mounted on a steep slope, with the result that the wheels 24, and consequently the vehicle, tend to slide down the slope. To counter-act this latter tendancy, a winch (not shown) may be connected to the vehicle so that the vehicle can be held by the winch and restrained from sliding down the slope, or can be slowly raised or lowered relatively to the slope by operation of the winch.

Claims

1. An articulated vehicle comprising a chassis having a first and a second portion pivotally connected together, a steering mechanism connected between the first and second portions of the chassis, and at least two wheel assemblies mounted on each portion of the chassis, wherein the distance a wheel of each wheel assembly projects below the chassis is adjustable.

2. An articulated vehicle as claimed in Claim 1, in which the distances which the wheels of the assemblies project below the chassis are independently adjustable to vary the attitude of the vehicle.

3. An articulated vehicle as claimed in Claim 1 or Claim 2, in which the wheel of each assembly is driven.

4. An articulated vehicle as claimed in Claim 3, in which the wheel of each wheel assembly is driven by a hydraulic wheel motor.

5. An articulated vehicle as claimed in any one of the preceding claims, in which a power unit is mounted on the chassis.

6. An articulated vehicle as claimed in Claim 5, in which the power unit includes a hydraulic pump.

7. An articulated vehicle as claimed in Claim 6 when dependent from Claim 4, in which the hydraulic pump is connected to the hydraulic wheel motors via a control means.

8. An articulated vehicle as claimed in Claim 3, in which the wheel of each wheel assembly is driven by mechanical means.

9. An articulated vehicle as claimed in Claim 5, in which the power unit is connected via gearing to the wheels of each wheel assembly.

1 0. An articulated vehicle as claimed in any one of the preceding claims, in which the chassis is provided on its lower surface with skid portions on which, in soft ground, the vehicle can rest.

11. An articulated vehicle as claimed in Claim 10, in which the skid portions on the first and the second portions of the chassis are spaced-apart from the pivotal connection between said portions of the chassis.

1 2. An articulated vehicle as claimed in any one of the preceding claims, in which each wheel assembly is connected to the chassis by a piston-and-cylinder assembly, and the distance the wheel of each wheel assembly projects below the chassis is adjustable by extending or contracting the associated piston-and-cylinder assembly.

1 3. An articulated vehicle as claimed in Claim 12, in which the piston-and-cylinder assemblies extend vertically relatively to the plane of the chassis.

1 4. An articulated vehicle as claimed in Claim 1 2 or Claim 13, in which the upper end of each piston-and-cylinder assembly is connected to the chassis by spring means and/or a hydraulic or pneumatic accumulator to provide a spring suspension and/or shock absorbing facility for the vehicle.

1 5. An articulated vehicle constructed arranged and adapted to operate substantially as herein described with reference to Figs. 1 to 4, or Fig. 5 of the accompanying drawings.

16. An articulated vehicle as claimed in Claim 15, and as illustrated in Figs. 1 to 4, or Fig. 5 of the accompanying drawings.