TECHNICAL FIELD

The present invention relates to a bogie comprising at least two pairs of wheels and intended for off-road loaders.

BACKGROUND ART

Machines which are fitted with a plurality of wheels and intended for work in more or less difficult ter¬ rain, for instance forest clearing work, transporta- tion of timber etc., are known to the art. For reasons of economy, there is a tendency to produce these machines in progressively larger dimensions with the result that they become progressively more energy demanding in operation. One result of this development is reflected in the increase in wear and tear on the machine carrying surface (forest ground) and the ma¬ chines themselves, and there is now a demand for technical improvements that will reduce these draw¬ backs for environmental and economical reasons.

The object of the present invention is to provide for machines and loaders that are intended particularly for off-road work bogies which are so constructed as to considerably reduce these drawbacks.

DISCLOSURE OF THE INVENTION

A bogie constructed in accordance with the invention comprises at least two pairs of wheels where each wheel pair is pivotal or tiltable on a shaft which extends at right angles to the wheel axles (horizontal on flat ground) and the two wheel pairs are together rotatable about a further shaft which extends at right angles to

the first-mentioned shaft. A bogie of this construc¬ tion can be used as a basic unit for the construction of more complex bogeys which together include 4, 8, 12, 16, 32 wheel pairs and so on, which are so con- structed and arranged that each unit will function independently with maximum adaptation to the underly¬ ing driving surface, which results in minimum puncti- form loading (the pressure is distributed evenly on the ground) and minimum energy consumption, i.e. the wear and tear on the driving surface is reduced, terrain accessibility is improved and the useful life of the machines is extended.

The characteristic features of different types of bogie are set forth in the following Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to the accompanying drawings, in which Figure 1 illustrates a bogie having two pairs of wheels and adapted for barrow-type loaders; Figure 2 illustrates a bogie having four pairs of wheels; Figure 3 illustrates a bogie having eight pairs of wheels; Figure 4 illustrates a loader and a power unit, each having eight pairs of wheels; Figure 5 illustrates from above a loader having twelve pairs of wheels; and

Figure 6 is a side view of the loader illustrated in Figure 5.

DESCRIPTION OF PREFERRED EMBODIMENTS

The bogie illustrated in Figure 1 comprises two wheel pairs 11 and 12 of which two wheels 11 are mounted on a common axle ill and two wheels 12 are mounted on a common axle 121 (one wheel of each pair

being hidden behind the visible wheel). Each wheel is mounted for pivotal movement on a respective shaft 13 which extends at right angles to the respective wheel axles 111 and 121. The total angle of pivot of each wheel pair from one extremity (SW-NE) to the opposite extremity (SE-NW) is about 30°.

The two wheel pairs 11 and 12 are together mounted for rotation on a second shaft 14 which extends at right angles to the shaft 13. Mounted underneath the barrow 10 is a mechanical bearing block which is common to the shafts 13 and 14.

When the barrow is driven conventionally in rough terrain, the wheels will adjust to the surface condi¬ tions of the terrain and enable the barrow to be driven across ground which would be inaccessible to conventional barrows.

The bogie illustrated in Figure 2 includes two mutual¬ ly identical units, each having two wheel pairs 21, 22 and 21'', 22' respectively.

Each of the wheel pairs 21, 22 is mounted forindividual pivot or tiltable movement on a shaft 23, while each of the wheel pairs 21 and 22' is mounted for individual pivotal or tiltable movement on a shaft 23', with the total pivotal angle of each wheel pair reaching to about 30°. The wheel pairs 21, 22 and 21', 22' are mounted individually for rotation about a shaft 24 which is fitted mechanically to the underside of the loader. The loader is intended for connection to a power unit.

The bogie illustrated in Figure 3 comprises two mutu¬ ally identical units, each having four wheel pairs 31, 32, 31', 32' and 33, 34, 33', 34' respectively with each wheel pair mounted individually for pivotal movement on a shaft 35, 35', 37, 37' which extends at

right angles to the axle direction of respective wheel pairs, with the total pivot or tilt angle reaching to about 30°. The wheel pairs are mounted for rotation, two and two, about a second shaft 36 and 38 respec¬ tively, extending at right angles to the first- mentioned shaft 35, 35' and 37, 37' respectively. The shafts 36, 38 are mounted mechanically on the under¬ side of a loader. The loader is intended for connec¬ tion to a power unit.

Figure 4 illustrates a bogie which comprises two sub- bogeys, namely a sub-bogie 400 which is fitted to a power unit and a sub-bogie 410 fitted to a loader 40.. Each sub-bogie has eight wheel pairs, similar to the Figure 3 illustration, wherein each wheel pair is mounted for pivotal or tilting movement on a shaft (parallel to the plane of the paper) and the wheel pairs are mounted for rotation, two and two, about shafts (right angles to the plane of the paper) which extend at right angles to the first-mentioned shaft.

The two units 40 and 41 are pivotal relative to one another about an axis y-y (in the plane of the paper) at right angles to the axle directions of respective wheel pairs, partly about an axis x-x (at right angles to the plane of the paper) parallel with the axle directions of respective wheel pairs. In this regard, the pivotal movement between said units is such that an angle between the longitudinal directions 401 and 411 of the upper sides of respective bogeys 40, 41 will always be > 180°.

Figures 5-6 illustrate a loader which has twelve wheel pairs with six wheel pairs on a respective side assembly 51 and 52, which are, in turn, movably mount¬ ed to a central unit 50 which carries the actual loading device. The central unit is provided on one end thereof, to the right of the Figures, with power unit attachment means 501.

The wheel pairs have the same construction as those wheel pairs earlier described. The side units 51, 52 are self-adjustable (autopivotal) so as to adapt to the nature of the ground independently of one another.

The invention is not limited to the basic exemplifying embodiments. The system can be extended to include larger and larger units, wherein the number of wheels provided shall be divisible by four.