GB2301569A

GB2301569A - A running gear for a tracked vehicle

Info

Publication number: GB2301569A
Application number: GB9611443A
Authority: GB
Inventors: Harald Becker; Piotr Dudzinski; Michael Ketting
Original assignee: Intertractor AG
Current assignee: Intertractor AG
Priority date: 1995-05-31
Filing date: 1996-05-31
Publication date: 1996-12-11
Anticipated expiration: 2016-05-31
Also published as: ITMI961091A1; JPH0930458A; FR2734782B1; GB9611443D0; ITMI961091A0; GB2301569B; FR2734782A1; DE19620759A1; IT1282762B1

Abstract

A suspension system for tracked vehicles, in particular for vehicles having chains or belts 1 made of a resilient material, comprises a chassis 2, drive wheels 3, leading wheels 4, and track rollers 5. The track rollers 5 are mounted on rocker arms 6 either individually (Figure 1) or in pairs (Figure 3). Control elements 7 such as hydraulic cylinders are connected at one end to the chassis 2 and at the other end to a point between the ends of the rocker arms 6 to control the rotational movement of the track rollers 5. A number of the control elements 7 of each track are interconnected so that constant ground pressures of the track rollers 5 are achieved over varying ground conditions. A further hydraulic control element 11 may be used to lock the suspension, or to reduce the length L2 of the contact surface of the track 1 to allow a reduction in the turning resistance of the vehicle.

Description

A running aear for tracked vehicles, in particular for vehicles having chains or belts made of resilient material The present invention relates to a running gear for tracked vehicles, in particular agricultural machinery, which in particular have chains or belts made from resilient material, such as rubber, rubber substitutes, elastomers or mixtures thereof, comprising a chassis having drive wheels, leading wheels and track rollers, wherein the track rollers of each track are mounted on rocker bars or arms either individually or in sets and are swivellable on the chassis around articulated axles disposed transversally to the longitudinal axis of the chassis.

With such running gears different suspensions of the track rollers are known. Thus, it is known to support such track rollers or pairs of track rollers on the chassis by means of resilient elements. An adequate compensation for uneven terrain is achieved by this construction, with the result that an accordingly equipped vehicle can travel over uneven ground with only slight inclination of the body.

Such systems are however relatively expensive and moreover uniform pressure distribution cannot be achieved between the belt or chain (crawler) and the sub-soil.

Proceeding from this prior art, the aim of the present invention is to create a running gear of a generic kind, in which a uniform pressure between the crawler and sub-soil is achieved even when travelling over uneven ground.

Accordingly, the present invention provides a running gear for tracked vehicles, comprising a chassis, drive wheels, leading wheels, track rollers, wherein the track rollers of each track are mounted on rocker arms and are swivellable on the chassis around articulated axles disposed transversally to the longitudinal axis of the chassis, and control elements mounted or articulated on the chassis side and articulated on the rocker arms in a region between the track roller side end and the chassis side end of each rocker arm, by means of which the swivel movement of the track rollers is sprung, whereby all or some of the control elements of each track are effectively connected to one another so that in use constant ground pressures of the track rollers are achieved with varying ground factors.

By the fact that the control elements, which are preferably hydraulic control elements, are effectively coupled to one another, constant ground pressures of the track rollers are achieved with varying ground factors and ground unevenness. Thus, a uniform specific pressure is achieved between the crawler and the sub-soil. In addition' a good resiliency is ensured.

It is preferred that hydraulic cylinders are provided as hydraulic control elements, with the hydraulic cylinders of each track being hydraulically connected to one another.

By connecting the hydraulic cylinders hydraulically to one another it is guaranteed that the same force acts on the track rollers independently of any ground unevenness.

In a preferred embodiment the hydraulic control elements are hydraulically connected to a hydraulic pump or a hydraulic tank, preferably a bladder-type accumulator.

A sensitive spring action is achieved with this construction.

In a further preferred embodiment each hydraulic control element has an associated hydraulic tank. With this construction a particularly sensitive response is achieved and only slight oscillations in the hydraulic system are produced. In addition, lower load peaks occur, since only short lines are required between each tank and hydraulic control element.

Preferably, the running gear further comprises a throttle element associated with each hydraulic control element. More preferably, the throttle elements are adjustable throttle valves. An adjustable damping action is achieved by the throttle elements, in particular by the adjustable throttle valves, such that an excellent spring and damping property of the suspension is ensured. In this case spring action is performed substantially via the tank or tanks, which is or are preferably a bladder-type accumulator, while the damping is achieved via the throttle elements in the hydraulic circuit.

Preferably, the running gear further comprises a further hydraulic control element associated with each support carrying a track roller or set of track rollers, by means of which the swivellability of the track rollers can be restricted or prevented. The further hydraulic control element preferably consists of a hydraulic cylinder attached, for example, to the chassis, having a piston, the piston rod of which is articulated to the rocker arm of the track roller or the set of track rollers. The cylinder chambers above and below the piston of the hydraulic cylinder are connected to a fluid (oil) tank, which enables a free flow of the hydraulic fluid. In this case a socalled "soft" travel of the running gear is provided.If the connection between the chambers below and above the piston of the hydraulic cylinder is blocked, for example by means of a valve, movement of the hydraulic cylinder is locked to achieve a rigid behaviour of the mounting/bearing.

Preferred embodiments of the present invention will now be described hereinbelow by way of example only with reference to the accompanying drawings, in which: Figure 1 shows a side elevational view of a running gear in accordance with a first embodiment of the present invention, with only one track being shown; Figure la shows a schematic representation of a preferred arrangement of the control elements of the running gear of the present invention; Figure 2 shows a side elevational view of a running gear in accordance with a second embodiment of the present invention, with only one track being shown; Figure 3 shows a side elevational view of the embodiment of Figure 2 in another operating position; and Figure 4 shows a side elevational view of a running gear in accordance with a third embodiment of the present invention, with only one track being shown.

A running gear for tracked vehicles, in particular for agricultural machinery, having chains or belts 1 made of resilient material, such as rubber, rubber substitutes, elastomers or mixtures thereof, is shown in the drawings.

The running gear comprises a chassis 2, and on each side of the chassis 2 a drive wheel 3, a leading wheel 4 and track rollers 5. The track rollers 5 of each track are mounted on rocker arms 6 either individually (as in the embodiment of Figure 1) or in pairs (as in the embodiments of Figures 2 to 4), and are pivoted on the chassis 2 around articulated axles extending transversally to the longitudinal axis of the vehicle.

The running gear further comprises control elements 7 which are articulated to the chassis 2 and a respective rocker arm 6. In the described embodiments the control elements 7 are hydraulic control elements. The pivot point of these control elements 7 on the rocker arms 6 lies in each case between the end on the track roller side and the end on the chassis side. The control elements 7 are preferably articulated about the mid-point of the rocker arms 6. The swivel movement of the track rollers 5 and associated rocker arms 6 is sprung by means of these control elements 7, with the control elements 7 of each track being coupled effectively to one another in such a manner that constant ground pressures of the track rollers 5 are achieved with varying ground factors and ground unevenness.

As mentioned, in the described embodiments, hydraulic cylinders are provided as the hydraulic control elements 7, wherein the hydraulic cylinders of each track are hydraulically connected to one another, as can be seen from the schematic representation in Figure la. The hydraulic control elements 7 are each connected to a hydraulic tank 8, preferably a bladder-type accumulator, and in a preferred embodiment one tank 8 is associated with all of the hydraulic control elements 7. A throttle element 9 is associated with each hydraulic control element 7, wherein the throttle element 9 is preferably adjustable, in particular from the control console of the driver's cab which is disposed on the chassis 2.

In the embodiments of Figures 2 to 4, a further hydraulic control element 11 is additionally associated with the track roller support 10, by means of which the swivellability of the track roller 5 or set of track rollers 5 can be limited or prevented. In the driving state the hydraulic control elements 11 are not locked, so that free movement of the hydraulically sprung rocker arm 6 and the track roller 5 or set of track rollers 5 connected therewith is permitted. In the event of difficult terrain conditions, it may be necessary to lock the suspension, for the purpose of which the hydraulic control element 11 is then also locked, so that the spring action is blocked.

A desired damping action is achieved by the combination of each throttle element 9 and tank 8. Instead of the arrangement in the illustrated embodiments, the combination of a tank with several hydraulic control elements 7, to which one throttle element 9 is associated in each case, is also possible. The provision of several tanks 8, which are preferably accumulators, is however advantageous in so far that a more sensitive response is achieved and hence smaller oscillations in the hydraulic system are produced and lower load peaks occur, as only a short hydraulic line has to be run from each tank 8 to the corresponding hydraulic control element 7.

Overall, with the construction according to the present invention an important requirement of tracked vehicles having rubber chains or the like is essentially met. Namely, the present invention provides a uniform distribution of pressure between chains (crawlers) and the sub-soil, good compensation for unevenness with the smallest possible inclination of the body, quiet running of the running gear at high speed and also low susceptibility to failure. A single wheel suspension is virtually produced, which enables a uniform distribution of pressure to the sub-soil. In addition, by the provision of the hydraulic control elements 11 in the embodiments of Figures 2 to 4, the chambers above and below the piston 12 of the associated hydraulic cylinder being connected to a fluid (oil) tank, enables a free flow of the hydraulic fluid.

Provided that this flow is blocked by a controllable valve, the spring action is locked, with the result that virtually a rigid suspension is achieved. By virtue of a hydraulic suspension in a running gear with a crawler running-in angle as employed by the embodiments of Figures 2 to 4, the length L1 of the contact surface of the crawler can be shortened to the length L2 shown in Figure 3, which results in a reduction in the turning resistances of the vehicle.

This may be achieved by corresponding pressurization of the hydraulic control element 11, by means of which the pair of track rollers 5 in the left-hand region of the running gear, according to the schematic representation, is swivelled out of the position shown in Figure 2 into the position shown in Figure 3, from which the corresponding shortening of the contact surface of the chain or belt 1 respectively results.

As is evident in particular from the diagrammatic representation in Figure la, the chambers 14, which are located above the pistons 13, of the cylinders of all of hydraulic control elements 7 are connected to one another by lines, with a throttle element 9 being connected in front of each hydraulic control element 7 and a bladdertype accumulator 8 being associated therewith.

Consequently, a hydraulic connection of the hydraulic cylinders of one track is consequently achieved in a simple manner.

It will be understood that the present invention is not limited to the exemplified embodiments, but can be modified in many different ways within the scope of the present invention as described in the appended claims.

Claims

CLAIMS:

1. A running gear for tracked vehicles, comprising a chassis, drive wheels, leading wheels, track rollers, wherein the track rollers of each track are mounted on rocker arms and are swivellable on the chassis around articulated axles disposed transversally to the longitudinal axis of the chassis, and control elements mounted or articulated on the chassis side and articulated on the rocker arms in a region between the track roller side end and the chassis side end of each rocker arm, by means of which the swivel movement of the track rollers is sprung, whereby all or some of the control elements of each track are effectively connected to one another so that in use constant ground pressures of the track rollers are achieved with varying ground factors.

2. A running gear according to claim 1, further comprising chains or belts made of resilient material.

3. A running gear according to claim 2, wherein said chains or belts comprise rubber, rubber substitutes, elastomers or a mixture thereof.

4. A running gear according to any of claims 1 to 3, wherein said track rollers are articulated individually to the chassis.

5. A running gear according to any of claims 1 to 3, wherein said track rollers are articulated in multiple sets to the chassis.

6. A running gear according to any of claims 1 to 5, wherein the control elements are articulated centrally on the rocker arms.

7. A running gear according to any of claims 1 to 6, where the control elements are hydraulic control elements.

8. A running gear according to claim 7, wherein the hydraulic control elements comprise hydraulic cylinders, with the hydraulic cylinders of one track being connected hydraulically in series.

9. A running gear according to claim 7 or 8, wherein the hydraulic control elements are hydraulically connected to a hydraulic pump or a hydraulic tank.

10. A running gear according to claim 7 or 8, wherein each hydraulic control element is associated with a hydraulic tank.

11. A running gear according to claim 9 or 10, wherein the hydraulic tank comprises a bladder-type accumulator.

12. A running gear according to any of claims 7 to 11, further comprising a throttle element associated with each hydraulic control element.

13. A running gear according to claim 12, wherein the throttle element is an adjustable throttle valve.

14. A running gear according to any of claims 7 to 13, further comprising a further hydraulic control element associated with each support carrying a track roller or a set of track rollers, by means of which the swivellability of the track rollers can be restricted or prevented.

15. A tracked vehicle, in particular an agricultural machine, incorporating a running gear according to any of claims 1 to 14.

16. A running gear substantially as hereinbefore described with reference to Figure 1, Figures 2 and 3, or Figure 4, optionally taken in conjunction with Figure la of the accompanying drawings.