The object of the invention is a ditch excavator provided with a caterpillar mounting, the excavator comprising an excavating unit secured to the mounting and supporting legs fastened to the mounting to support the ditch excavator during the digging.

To improve forest growth, ditches have been dug and are still dug in forests to remove water. When a forest grows, tree stand also grows at the edges of ditches, and the ditches are gradually blocked by runoff material and moss growing in the ditches, as well as by tree stand and other vegetation growing at the edges of ditches. To make the ditches work as desired, they should be cleaned and any extra earth and vegetation should be removed therefrom. In dense forests, it may also be necessary to dig new ditches in areas where the tree stand is dense.

Generally, digging of ditches is carried out by means of normal excavating equipment, which is rather heavy and large in size. In dense forests, an excavator like this needs a space that is several metres in width so as to be capable of working. Consequently, in connec¬ tion with cleaning of old ditches a large number of growing trees in good condition should be chopped down from the edges of ditches merely to enable the excavator to move, which brings about unnecessary economic loss. Further, moving of a normal excavator like this in a forest brings about a need for a passage as the machine moves from one ditch to another and also otherwise damages the undergrowth and terrain. Furthermore, use of a heavy excavator like this is rather expensive.

A plurality of different apparatuses has been developed to treat or dig ditches. British Patent 1,545,316 discloses an apparatus comprising a frame

equipped with two wheels and a supporting wheel fastened with an articulated arm transverse to the frame, the frame and the supporting wheel being situated on the opposite sides of the ditch to be dug, and the ditch being capable of being dug with a bucket fastened to the frame and moving transverse to the ditch. The solution requires that the vegetation and other obstructions be removed from both sides of the ditch to be dug in order that the apparatus might move. Furthermore, so far as small and narrow forest ditches are concerned, it is rather cumbersome and slow to dig a ditch with a trans¬ verse excavating structure, wherefore the apparatus cannot be used effectively for digging or cleaning forest ditches. British Patent Application 2,134,565 discloses a solution including a ditch cleaner progressing along the ditch bottom, the cleaner comprising a separate power unit in a carriage-like frame and, in front of it, a working unit provided with cutters shearing material on both sides. The working unit shears earth and mater¬ ial from the edges of a ditch and the carriage-like power unit following the working unit levels the mater¬ ial to the ditch and the edges thereof. To move the apparatus, it is secured to an anchor point with a winch cable and pulled forward with the winch while the cutters rotate. It is impossible to apply this solution to treatment of ditches to be cleaned or to digging of new ditches since in both cases extra material has to be removed from the ditches and not only levelled to the bottom of the ditch. In addition, the solution concerned requires that for each transfer, a cable should first be secured to an anchor point, whereafter it is possible to move the apparatus but not further than the cable can reach. Neither is the apparatus capable of moving from one ditch to another or from a road to a ditch

without a separate pallet, which also prevents the use thereof in normal cleaning or digging of a ditch.

German Offenlegungsschrift 3,106,113 discloses a solution with an excavator digging in the transverse direction of the ditch, the frame of the excavator moving on successive wheels or on a caterpillar combina¬ tion along the ditch bottom or the edge of the ditch, the excavator comprising a train of supporting wheels fastened to the frame at the end of an arm and moving along the edge or the slope, supporting the frame unit and preventing it from falling over. This apparatus is rather clumsy and cumbersome and requires that a moder¬ ately wide passage be cleared e.g. at one edge of the ditch so as to enable the apparatus to clean or dig. The apparatus is also otherwise big and clumsy, and cumber¬ some or practically impossible to use in dense forests for cleaning forest ditches.

Finnish Patent Application 761,791 discloses a mounting of a ditching machine, comprising a frame unit essentially of the shape of the ditch and driving wheels mounted pivotally about the longitudinal axis of the apparatus such that the apparatus can be driven on the wheels to the ditch, whereafter it is lowered to rest on the frame thereof at the ditch bottom and pulled forward with a bucket as the digging progresses. This apparatus is rather clumsy and cumbersome since the mobility thereof is, as a whole, rather limited. It is also difficult to control it in the ditch and it is extremely difficult to move the apparatus by means of the bucket only, particularly in a situation where the apparatus should be turned to a direction deviating from that of the ditch.

The object of the present invention is to pro¬ vide a ditch excavator with which new ditches can be easily cleaned and dug also in dense forests without

causing unnecessary damage and without needing a wide passage therefor. Another object of the invention is to provide a ditch excavator that has a simple structure and is yet capable of digging a ditch and moving the necessary distances in a stable and controlled manner essentially without damaging the forest or terrain even during the transfer. It is characteristic of the ditch excavator according to the invention that the cater¬ pillar mounting comprises a relatively narrow frame and underneath a caterpillar unit essentially of the same width as the frame, the apparatus moving on the unit, that the excavating unit is secured to one end of the caterpillar mounting in the longitudinal direction thereof, that the excavator has two supporting legs that are mounted pivotally, in the transverse direction of the excavator, on both sides of the end of the cater¬ pillar mounting facing the excavating unit, and that the foot means at the outer ends of the supporting legs are such that the supporting legs function as lateral supports to the excavator when the excavator moves.

The essential idea of the invention is that the ditch excavator comprises a light frame with a track or a pair of tracks underneath for moving and transport¬ ation of the apparatus, the tracks being not wider than the frame of the apparatus, and an excavating unit secured to one end of the frame, the unit comprising a boom and a bucket for digging and supporting legs at the excavating end of the frame, the supporting legs supporting the ditch excavator at the forward end thereof during the digging and also providing lateral support for keeping the apparatus in an upright position during both digging and moving. An advantage achieved with the apparatus according to the invention is that the total weight of the apparatus, including the excavator, is fairly small, whereby the track thereof

causes very little damage to the ground the apparatus moves on. Another advantage of apparatus according to the invention is that the overall structure of the apparatus is very narrow, wherefore it can also move in a very narrow space in dense forests and old ditches without damaging the tree stand or other vegetation around it. Further, the combined digging / moving supporting structure also makes handling of the apparatus reliable and yet simple since the number of functions that are to be controlled during the use is fairly small. Furthermore, it is quick and effective to dig a ditch with the apparatus according to the inven¬ tion since clearing and cleaning of a passage as well as other extra operations needed with normal digging apparatuses are not necessary.

The invention is described more closely in the attached drawing, wherein

Figure 1 shows a side view of the ditch excavator according to the invention, Figure 2 shows, in the longitudinal direction, a frame unit of the ditch excavator according to the invention on essentially even ground during transfer or digging of a new ditch,

Figure 3 shows the frame unit of the ditch excavator according to the invention in a ditch during the cleaning of the ditch,

Figure 4 shows a schematic top view of the ditch excavator according to the invention during the cleaning of the ditch, Figure 5 shows a schematic cross-sectional view of the frame unit of the ditch excavator, and

Figure 6 shows another embodiment of the supporting leg of the ditch excavator.

The ditch excavator according to the invention comprises a frame 1 with a motor 2 as well as fuel and

hydraulic oil tanks (not shown in detail) at the rear end thereof. At the rear end of the frame is also a winch 3 which is operated by a hydraulic motor (not shown) driven by the motor of the apparatus. To the frame 1, to the front of the motor is secured a seat 4, and to the front end of the frame 1, a connecting unit 5, control levers 6 projecting toward the seat 4 from said connecting unit. To the front of the connecting unit 5 is secured an excavating unit 7, and to the sides of the connecting unit 5, on both sides of the frame, are fastened supporting legs 8, which are mounted pivotally, at one end thereof, on the frame 1 about the longitudinal axis 8a thereof. At the other end of the supporting leg 8 is a foot means 9, which is pressed against the ground when the supporting legs are used. Between the supporting legs 8 and the connecting unit 5 are supporting cylinders 10 by means of which the supporting legs 8 can be turned to a desired position at the sides of the frame 1 to support the frame and to keep it in an upright position. Under the frame 1 is a caterpillar unit or a train of wheels 11 comprising pairs of wheels 12 in the longitudinal direction of the frame. The pairs of wheels 12 are mounted on both sides of the auxiliary frame shown in greater detail in Figure 5 such that the wheels of a pair of wheels are situated essentially symmetrically in the lateral direction of the frame 1. In addition to the pairs of wheels, drive sprockets 14 are fastened to a frame 13, the drive sprockets being toothed wheels connected at one end thereof by means of a drive chain (not shown) to rotate the motor 2. About the pairs of wheels and the drive sprockets runs a caterpillar track 15, which moves the excavator forward by means of a motor and on which the total weight of the excavator rests when the excavator moves. The width of the track is essentially equal to

that of the mounting or frame 1, whereby it may be slightly broader or narrower. It is essential that the weight affecting the track via the train of wheels is on the track when the apparatus moves, whereas during the digging the main load rests on the supporting legs 8 and a foot means 9 thereof. In the longitudinal direc¬ tion of the apparatus, the track 15 may be longer or slightly shorter than the frame. With regard to control¬ lability of the apparatus, it is important that the weight of the mounting in relation to the front wheel 12 is greater than the weight of the excavating unit 7 on the other side of said wheel in ^* order that the apparatus might be driven and excavated with. The excavating unit 7 is an excavator known per se, having a boom element 17 turning about a vertical axis 16 in the horizontal direction and turning and folding about horizontal articulations in the vertical direction, the boom element having a bucket 18 at one end thereof. It is generally and fully known to use an excavating unit 7 for digging, and so are the structure and components thereof, wherefore they are not described in greater detail herein.

Figure 2 shows the frame unit of an excavator in a situation where it moves on normal ground when transferred from transportation to digging. Here the ditch excavator is moved by a motor rotating the track 15. To keep the excavator in an upright position, the supporting legs 8 are turned out by supporting cylinders such that the foot means 9 thereof are close to the ground. Should the ditch excavator tilt, it would be balanced by the foot means 9 and not fall over. As terrain varies, the foot means 9 can be adjusted, by supporting cylinders, to a different distance from the ground 10 either simultaneously or only one at a time. During transfer, situations arise where the travel

direction of the apparatus must be changed. This is carried out by stopping the ditch excavator for a while and by turning the frame thereof by means of the excavating unit 7, whereafter the excavating unit is lifted off the ground and the ditch excavator can again be moved forward. At a ditch to be cleaned the ditch excavator is driven to the ditch, supporting it with the supporting legs 8 and turning it by the excavating unit 7, whereafter the supporting legs 8 are pressed by the supporting cylinders 10 into the ditch bank or against the edge of the ditch and the ditch can be dug by the excavating unit. When the distance within the reach of the excavating unit has been dug, the ditch excavator is moved backward by the motor 2 and the track 15 and possibly also by the boom and bucket of the excavating unit 7 if the terrain is cumbersome or difficult. When the apparatus has moved backward an appropriate dis¬ tance, another section of the ditch within the reach of the excavator is dug, and by alternately digging and moving the ditch excavator the ditch can be cleaned fairly fast and effectively. As shown in Figure 4, the ditch excavator according to the invention can pass quite near the trunks without causing any damage to them and without their really disturbing the digging and moving of the apparatus in the ditch. As shown in Figure 4, the supporting legs 4 are situated quite at the front end of the apparatus, whereby the mounting or frame 1 of the ditch excavator, the motor 2 and the train of wheels 11 may be moderately light as a whole and yet provide sufficient counterweight for the boom element 17 of the excavating unit 7, the bucket 18 and the earth and other material in the bucket.

Figure 5 shows a schematic cross-sectional view of a mounting of a ditch excavator by way of example. The mounting comprises a frame unit 1 comprising beams

or other suitable structures, a motor 2 and fuel and hydraulic fluid tanks being secured thereto. Downward from the frame unit 1 are connecting means la, which extend outside the track 15 and turn from under the track 15 between successive pairs of wheels 12 under¬ neath the frame 1. The connecting means la are fastened to the auxiliary frame 13, which is a beam-like unit in the longitudinal direction of the mounting extending over the entire length of the train of wheels 11. Each pair of wheels 12 and the drive sprockets 14 are mounted essentially symmetrically on the auxiliary frame 13. A toothed wheel 14a with a chain' 14b running about it is attached to the axle at the end of one of the drive sprockets 14. The chain 14b, in turn, passes on to a chain wheel 14c attached to the axle of the hydraulic motor (not shown) driven by the motor 2 such that when the hydraulic motor rotates the chain wheel 14c rotates the chain 14b and thereby, via the chain wheel 14a, the train of drive sprockets 14. Consequently, the track 15 rotates about the drive sprockets 14 and the entire train of wheels thus moving the ditch excavator.

Figure 6 shows an embodiment for carrying out the foot means 9 of the ditch excavator. It shows an opening in the middle of the foot means 9 and an extra supporting wheel 9a adjusted above the foot means 9. In relation to the foot means 9 the supporting wheel 9a is mounted such that when the apparatus is moved, it may lean on the ground by means of the supporting wheel 9a, which facilitates the moving thereof on harder ground. However, in connection with digging, the supporting leg 8 may be firmly pressed against the ground, and when the ground is soft, the supporting wheel 9a is pressed into the ground as far as the foot means 9, whereafter the foot means 9 receives most of the supporting force. The specification and the figures describe the

invention only by way of example and the invention is not in any way restricted thereto. The ditch excavator according to the invention may be built such that the excavating unit 7 is a separate excavator known per se as additional equipment for tractors and other such apparatuses, the excavator being secured to the mounting of the ditch excavator with conventional connecting means for digging a ditch. The excavating unit 7 may also be secured permanently to the ditch excavator, whereby the supporting legs, which are a fixed part in conventional excavators used as additional equipment, do not unnecessarily load the apparatus or increase the number of operating parts. The supporting legs need not be essentially transverse to the mounting of the ditch excavator in the manner disclosed but they may also turn forward in the longitudinal direction of the mounting of the ditch excavator such that during the digging the supporting legs 8 support the excavator at the front end thereof facing the digging point, whereby the mounting may weigh less than before and yet provide sufficient counterweight during the digging. The wheels of the pairs of wheels 12 may be solid or filled with air, and they may rotate independent of one another or the wheels on the same axle may be attached to their axle such that they are immobile with respect to one another.

The track 15 may be uniform or formed of two parts next to each other, as long as the parts together form a track with essentially the same width as the mounting, on which track the apparatus may move. In the latter case, the auxiliary frame 13 may also be secured to the frame of the mounting between the tracks, if so desired.

Although in theory two narrow tracks next to each other make it possible to turn the apparatus by driving the tracks at different speeds, this is not

particularly advantageous with this track width, where¬ fore even in this case it is the most advantageous that the movements of the tracks are similar and mutually dependent and that the apparatus is turned by means of the excavating unit. Thereby a large number of extra hydraulic connections and one extra hydraulic motor can be dispensed with.