The present invention relates to an arrangement in a drivable excavator comprising a wheel or caterpillar supported under¬ body with a cab and a digging arm comprising a digging beam which is linked to said underbody, a digging arm which is linked to the free end of said beam and has a digging bucket provided on its outer end, and wherein the movements of said arm and bucket are caused by hydraulic working cylinders.

It is a problem in connection with most wheel and caterpillar excavators, especially excavators with the upper chassis swinging 360°, that the location of the beam and digging arm will cause such a high center of gravity that transport on roads is made difficult. This location of the digging aggre¬ gate also causes difficulties in maneuvering the machine in narrow spaces, since the digging aggregate projects outside the underbody of the machine. Because of this, such machines have a limited range of application, commonly limited to the work carried out by digging aggregate and, possibly, a share.

It is an object of the present invention to provide an exca¬ vator, where the above mentioned problems and disadvantages are eliminated, to provide the machine with a lower center of gravity and, thus, make it more suitable for transport along a road, and where the digging aggregate may be maneuvered in such a manner that it does not project outside the underbody of the machine. In this manner it will be possible to use the machine for other tasks, e.g. as a front loader, for a three- point mounted tool, draw hook, and the like.

According to the invention, this is achieved in a drivable excavator of the kind mentioned above with the characteriz¬ ing features of the invention being that the points of attachment of the working cylinder for the digging beam are provided to permit said beam to be turned from a digging position across its upper dead centre to a lowered horizontal folded up position, and that the beam foot is, in a manner

known per se, pivoted laterally of the cab.

A preferred embodiment of the invention is characterized by the fact that said beam is angular with the apex of said angle facing backwards, i.e. away from the digging bucket, and that the beam foot is pivoted in a bracket projecting upwards from said underbody with the turning axis at a distance above said underbody which is equal to or slightly larger than the arm of the angle that is located closest to said turning point.

Further details of the invention will appear from the depen¬ dent claims and from the following disclosure with reference to an embodiment shown in the drawing, wherein

Figure 1 shows an excavator turned 360 in the digging posi¬ tion,

Figure 2 shows the machine in a first step of folding up the digging aggregate into a transport position,

Figure 3 shows a second step of folding up said digging aggregate,

Figure 4 shows said digging arm means completely folded up on the underbody, and

Figure 5 shows the machine with a folded up digging aggregate according to Figure 4 in a plan view,

Figure 6 is a view in perspective of said excavator with supporting feet which are used as lifting arms for a three- point mounted tool, ^" and

Figures 7 and 8 show alternative embodiments of the location of the working cylinder moving the digging beam.

The excavator of the shown embodiment is a machine running on wheels and providing a rotation of 360 , with a cab 1, and

machine housing 2 being mounted for 360 rotation on a drivable chassis 3 with wheels 4 and 5. Machine housing 2 is provided on an underbody in the shape of a circular plate 7, on which a bracket 8 is mounted to carry digging aggregate 9. The lat¬ ter comprises an angular digging beam 10 having a short leg 11 which at its free end is pivoted in upper end of bracket 8 about axis 12. Beam 10 can be turned in a vertical plane by the aid of a cylinder 13, which is attached to bracket 8 at a point 14 located below and in front of axis 12. The other end of the cylinder attacks at a point 15 on beam 10. A digging arm 16 is pivoted in the outer free end of beam 10 and is movable by the aid of a hydraulic cylinder 17, via linked arms 18. At the free outer end of digging arm 16 a turnable digging bucket 19 is provided, and is movable by the aid of a hydraulic cylinder 20, via linked arms 21.

When said machine is to be moved from a digging position as shown in Figure 1, to a transport or driving position, cylin¬ der 13 is activated to turn beam 10 with arm 16 and bucket 19 upwards, i.e. counterclockwise, until both securing points 14 and 15 of cylinder 13 are aligned with securing point 12 of the beam on bracket 8. Digging arm 16 with bucket 19 is pull¬ ed adjacent to beam 10, as shown in Figure 3, and the centre of gravity TP of the entire digging aggregate is then moved behind turning point 12, permitting the digging aggreagate to be laid down on top of the underbody, as shown in Figure 4, by easing out cylinder 13. As will appear clearly from Figure 5, the digging aggregate will then be positioned horizontally on the udnerbody of the machine, at the side of the cab and machine housing. In this position the digging aggregate will not project outside the underbody of the machine in a rear¬ ward direction and the centre of gravity of the entire machine will have a low position, providing a favourable position of transport for the machine to be driven on a road.

As will appear from Figure 6, this machine may also be pro¬ vided with a telescopic front loader which is mounted on chassis 3. Additionally, a three-point suspension with top

stays 22 and pull stay members 23. is provided, and a tool 24, in the shown embodiment a rotary cultivator, is mounted on said three-point suspension. Supporting feet which may be used during digging operations or when said front loader is utilized, may be mounted to said pull stay members 23.

In Figure 7 an alternative manner of attaching cylinder 13 is shown. Beam 10 is secured to a bracket 8 ,as in the above em¬ bodiment. Cylinder 13 is secured to beam 10 at the apex of its angle, and the other end 14 is attached to said circular plate 7 behind said digging aggregate in its digging position.

In Figure 8 another arrangement for turning said beam 10 is shown. This arrangement comprises a working cylinder 13' which with one of its ends is secured to plate 7 at the front end of bracket 8. The other end of working cylinder 13' is attached to the free end of a rocking lever 25 , one end of which is pivoted to upper end of bracket 8. A second working cylinder 13" has also one end attached to the free end of rocking lever 25, and its other end is attached to the under¬ side of beam 10. This arrangement is somewhat more complicat¬ ed, but it permits turning said beam across its dead centre without any need of manipulating digging arm and bucket.

The essential advantages of the invention are, as mentioned above, a low position of the center of gravity when the ma¬ chine is driven, as well as compact exterior dimensions when the digging aggregate is lowered,and that said digging aggre¬ gate does not impair visibility in this position during driving operations or when other tools are used.

Furthermore, a simple and sturdy structure is provided which is not more expensive in production than conventional digging aggregates. Changeing over from a digging position to a transport position is a very rapid operation.

The invention is not limited to the embodiment disclosed above and shown in the drawing. Said digging beam may, e.g. be a straight member, even though the angular shape has

great advantages.

It will also be possible to arrange the point of rotation 12 of beam 10 vertically above point of attachment 14 of cylin- der 13, even though this will result in a less advantageous moment when beam 10 is rotated, and the beam, then, cannot be turned as far rearwards as in the embodiments shown in Figures 1-5.