TECHNICAL FIELD The invention relates to a device on lorries with rear axles arranged in the form of a bogie, said device being intended for axle pressure equalization and stabilization.

BACKGROUND OF THE INVENTION Vehicles with driven rear axles arranged in the form of a bogie have hitherto, in Sweden, not been dominating among vehicles equipped with tipping devices and intended e.g. for the transportation of sand and/or stones. Such vehicles have generally been equipped with only one driven rear axle and a supplementary liftable rear axle.

A bogie with all wheels driven presents obvious advantages, which has induced manufacturers of vehicles to give priority to such designs. It has, however, been established that under the circumstances prevailing on Swedish roads and under working conditions prevailing in Sweden, which in international comparison may be considered to be generally efficient and requiring little labour, that vehicles with two driven rear-axles arranged in a bogie without any possibilities for axle pressure equalization (transfer of part of the axle load on one axle of a bogie to the other axle) often have a tendency to tilt in con- nection with driving on roads of less good quality and in connection with tipping. In connection with tipping, the drivers of such vehicles have experienced a lack of stability of the vehicle, which has involved reduced efficiency of work or alternatively inadequate risks. It is one purpose of this invention to eliminate or at least to reduce these disadvantages on lorries with double driven rear axles arranged in the form of a bogie.

STATE OF THE ART

Devices for stabilization and stabilization and/or transfer of axle load are known i.a- through the German published patent application DE-A1-2800 549 and the US-patent No. 4,324,417.

The German paper of disclosure describes a device including a conven¬ tional U-shaped stabilizer, which by means of an intermediary axis can be adjusted in different positions. By means of an adequate displace¬ ment of the intermediary axis, the function of the stabilizer can be adapted to different conditions of load or speed of the vehicle. The device in question involves an intermediary axis and means for the displacement of the intermediary axis. This device has the disadvan¬ tage that it involves a plurality of components and thus is rather expensive and complicated. The device is mainly intended for motor cars.

Through the US-patent No. 4,324,417 a device is known which includes a funtion of transfer of axle load in combination with a U-shaped bow, which has a stabilizing function. The transfer of axle load, in such a way that one pair of wheels takes all the axle load and the other pair of wheels is lifted from the ground, is carried out by the device according to the US-patent in order to introduce a spring suspension between the pair of wheels carrying the load and the chassis of the vehicle. This is achieved by means of a bar, which is rotatable and arranged transverse in relation to the chassis, which bar has its ends provided with arms parallel to each other and perpendicular to the bar, which arms press down the front end or the rear end of the bogies. In the centre of the bar, an arm perpendicular to the bar is provided, which is connected to a pressure cylinder, which permits the bar to be pivoted in such a way that the perpendicular arms will press down the bogies and one pair of wheels is lifted from the ground. The spring action is obtained by means of a gas receptacle, functioning as a gas spring, connected to the pressure side of the hydralic cylinder. The transversal bar with perpendicular arms has in this connection a stabilizing function.

The device according to the US-patent No. 4,324,417 has the disadvan¬ tage that it cannot be used together with vehicles with spring sus¬ pended rear axles arranged in the form of a bogie in order to stabi- lize a vehicle with a tipping device for tipping e.g. gravel. Further¬ more, the device is comparatively space consuming due to the gas

receptacle, which also contributes to making the device more compli¬ cated and expensive in connection with aquisition and maintenance.

The device according to the said US-patent furthermore has the disad- vantage that the lowering of the wheels must be equal on both sides of the vehicle. When tipping gravel on a sloping surface, the device cannot be used to level the chassis in order to stabilize the vehicle.

BRIEF DESCRIPTION OF THE INVENTION The purpose of the invention is to provide a device with improved general stability, specially for lorries with bogies with four driven wheels, in combination with tilt stabilization, as well as the possi¬ bility of axle pressure equalization.

These and other objectives can be achieved with the device according to the invention, which is characterized by, in combination, at least one power and movement generator, a stabilizer between the spring sus¬ pended and the non-resilient system of the vehicle and connected to one of the spring suspended bogie-axles of the vehicle, power trans- mission means firmly connected to the stabilizer between the stabi¬ lizer and the power and movement generator and means for connecting and disconnecting, as required, said at least one power and movement generator to and from the stabilizer, said at least one power and movement generator being arranged to influence the position of at least one of the rear axles, and the chassis of the vehicle, respec¬ tively, via said power transmission means.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following description of a preferred embodiment, reference will be made to the following figures, of which

Fig. 1 shows a side view of a lorry with two driven rear wheel axles arranged in the form of a bogie, and a device according to the present invention mounted on the lorry; ^{■ ■}

Fig. 2 shows a top view of the lorry shown in Fig. 1 with the device according to the present invention mounted on it;

Fig. 3 shows a perspective view of a device according to the inven- tion mounted on a lorry;

Fig. 4 shows a alternative arrangement of the power transmission from the power and movement generator; and

Fig. 5 shows another alternative arrangement of the power trans¬ mission.

DESCRIPTION OF A PREFERRED EMBODIMENT

A lorry with a device according to the invention is shown in Fig. 1-4. The device consists of a transversal cylindrical bar 2, which is pivotably supported by two bearings 5a, 5b. The ends of the bar 2 are firmly connected to two arms 3a, 3b, which are parallel to each other, each arm being pivotably connected via a link 6a, 6b to the non- resilient system 8, which includes the utmost rear axle of the lorry.

The differential and axles including wheels and tyres are in this connection considered as the non-resilient system. This non-resilient system is spring connected to the chassis, which is considered as the spring supported system, by means of a plate spring package.

Each one of the links 6a, 6b is pivotably connected to ear shaped holders 7a, 7b, which holders are firmly connected to the non- resilient system consisting of the utmost rear axle. The device con¬ sisting of the bar 2, the arms 3a, 3b, the bearings 5a, 5b and the links 6a, 6b forms a non-disconnectable stabilizer with sides, which are pivotably connected to each other, the stabilizer acting upon the non-resilient system as well as upon the spring supported system with forces, which tend to keep the wheel axle parallel to e.g. a plane defined by the upper flanges of the beams of the frame. Side tilting is counter-acted by means of said stabilizer.

The device according to the invention includes, apart from the stabi¬ lizer, also a device working in combination with the stabilizer and intended to further stabilize the lorry.

The bar 2 is thus provided with two additional arms 4a, 4b, which are parallel to each other and perpendicular to the bar 2, to which they are firmly fastened. The arms 3a, 3b are fixed at the ends of the bar 2 and are thus placed outside the longitudinal beams of the chassis frame. The arms 4a, 4b are, however, placed on the bar 2 in such a way that they are located between the longitudinal beams of the frame, the left arm being preferably placed as close as possible to the left beam and the right arm being placed as close as possible to the right beam. For said stabilization, and for the previously mentioned transfer of axle load, the device according to a preferred embodiment of the in- vention also includes two hydraulic cylinders la, lb, which preferably are mounted on the inside of the vertical parts of the longitudinal beams. The cylinders la, lb are placed in such a way that the pistons of the cylinders, when they are moved outwards and backwards, will act on the end portions of the arms 4a, 4b in such a way that said end portions also will move backwards, and the arms 3a, 3b will move up¬ wards lifting the rearmost axle. A precondition is that the arms 3a, 3b point forwards and that they are approximately horizontal when there is a normal load on the vehicle. Furthermore, the arms 4a, 4b are fastened on the bar 2 in such a way that they are mainly vertical or somewhat inclined forwards, e.g. 10-20° when there is a normal load on the vehicle.

The rear axle of the bogie can thus be lifted if the bar 2 is influenced by the hydraulic cylinders la, lb.

It is possible to work either with both hydraulic cylinders la, lb in the same degree, with both cylinders synchronized, or with one of the cylinders either la or lb, or with one of the cylinders in a higher degree than the other. In the first case, the rearmost axle of the bogie will be lifted in the same degree on both sides. In the second and in the third case, one side of the rearmost axle will be lifted.

The cylinders la, lb can be manoeuvred by the driver by means of valves which can be located in the driver's cabin or at any other suitable place.

Alternative, both cylinders la, lb can be replaced by only one cylin¬ der, which in this case can be located in the centre of the chassis to act on an upstanding arm at the centre of the bar 2. In this case, it is, however, not possible to achieve a redistribution of the kind described above working individually with one of the cylinders.

In the embodiment according to Fig. 4, the arms 4a, 4b have been pro¬ vided with a pin 10, and the piston rods of the cylinders have been provided with long holes, eyes or similar long hole means 11. When the respective bogie's rear axle shall be lifted, the cylinders la, lb are activated in such a way that the piston rods are pressed backwards and the rear axle of the bogie is lifted.

The interaction of the cylinders la, lb and the arms 4a, 4b can also be arranged as shown in the embodiment according to Fig. 5, the arms 4a, 4b and the cylinders la, lb being linked together by means of an articulated connection. The cylinders la, lb can then be intercon¬ nected and a damping function can be introduced by means of overflow and strangulation.