The working machines operating on crawler tracks are generally very slow and, thus, even relatively short-distance transfers of such machines are preferably covered by using separate carriages or wheel systems mounted on the working machine. Such a latter type of apparatus is prior known e.g.

from GB Patent publication 1,044,074.

In the apparatus disclosed in GB Patent publication 1,044,074, a working machine is secured to a wheel system, wherefor the chassis of the working machine must be fitted with separate coupling elements, which may result in major costs. The prior known apparatus involves drawbacks in terms of its use as well. The use is inconvenient and slow, as it requires special mea- sures and, in addition, the working machine operator must step out of the cab of a working machine for locking the wheel system in place or, respec- tively, for releasing the wheel system.

An object of the invention is to provide an apparatus, which is simply and quickly attachable to a working machine and which apparatus does not necessitate any modifications to the working machine.

According to the invention, this object has been achieved and an apparatus of the invention is characterized in that a working machine is adapted to be

driven onto a load platform, said load platform being provided with a guard for stopping the advancement of the working machine at a desired spot on the load platform and said guard being fitted in such a manner that, as the working machine is in contact with the guard, the mass of said working machine delivers to the load platform a moment that forces the load platform to pivot against the bottom surface of a crawler track of the working machine, and that the load platform is provided for each crawler track with at least one gripping element for eliminating a relative slippage between the crawler track and the load platform and for locking the working machine against the guard.

When using an apparatus of the invention, a working machine can be brought very quickly to a transfer condition and respectively to an operating condition without forcing the driver to step out of the cab. Neither is it neces- sary for the driver of a tractor vehicle to step out of his or her vehicle since, when transferring an excavating machine, for example, it is sufficient that the bucket of the excavating machine be propped against the platform of the tractor vehicle.

The invention will now be described in more detail with reference made to the accompanying drawings, in which: fig. 1 is a side view, showing an apparatus of the invention in a condition, wherein the apparatus is ready to receive a working machine to be driven onto the same.

Fig. 2 shows a working machine in a transfer condition, propped on the one hand against an apparatus of the invention and on the other hand against a tractor vehicle through the intermediary of the bucket of the working machine.

Fig. 3 shows from behind an apparatus according to a first embodi- ment of the invention, with a working machine in a transfer condition.

Fig. 4 shows from behind an apparatus according to a second em- bodiment of the invention, with a working machine in a transfer condition.

Fig. 5 shows an apparatus of the invention in a side view and partially sectioned, the section along a iine V-V in fig. 6.

Fig. 6 shows a section along a line VI-VI in fig. 5.

Fig. 7 shows an apparatus according to the first embodiment of the invention in a plan view.

The apparatus, designated generally in the drawings with reference numeral 1, is intended for transfer rides of a working machine 3, especially an exca- vating machine, movable on crawler tracks and provided with an excavating mechanism 2 or some other lifting means.

The apparatus 1 includes at least 2 spaced-apart wheels 4 mounted for a free rotation and a load platform 5 fitted therebetween.

The load platform 5 comprises a trough-like carrier, the floor of which is constituted by a number of spaced-apart beams 12 which are welded at the ends thereof securely to sheets that make up side walls 10 for the load platform 5, to which is in turn securely welded a plate-like rear wall and/or a beam 13 connecting the side walls 10 together at the upper portions thereof in the rear of the load platform 5.

The wheels 4 are mounted in a per se known manner on the side walls 10 of the load platform 5. The point of attachment is selected such that, as a result of gravity, the load platform 5 has its leading edge always pressing against the ground or floor, whenever the apparatus 1 stands freely in an unloaded condition on the ground (fig. 1), the working machine 3 being derivable onto

the load platform 5 in such a manner that one end of the working machine will rest on the load platform 5.

The load platform 5 is provided with a mechanical guard 7, which in the example of fig. 5 comprises a beam 13, for stopping the advancement of the working machine 3 at a desired spot on the load platform 5. The guard 7 is fitted in such a way that, when a working machine is in contact with the guard 7, the mass of the working machine 3 delivers to the load platform 5 a moment which forces the load platform 5 to pivot against the outer surface of a crawler track 8 of the working machine 3.

The load platform 5 has a bearing surface which is provided for each crawler track 8 with at least one gripping element 9 for eliminating a relative slippage between the crawler track 8 and the load platform 5 and for locking the working machine 3 against the guard 7. In the example of fig. 5, the gripping element 9 included in the load platform 5 is constituted by a protrusion, sticking out of the bearing surface of the load platform 5 and designed to match a respective gripping element 11 included in the crawler track 8.

Naturally, the gripping element 9 may also be constituted by a recess, in which the respective gripping element of the crawler track takes hold of and prevents a relative slippage between the crawler track 8 and the load plat- form 5.

Depending on the weight and size of the transferable working machine 3, the apparatus 1 of the invention can be designed as depicted in fig. 4, with both crawler tracks 8 of the working machine 3 propped on the same appara- tus 1. Especially when dealing with heavy-duty working machines 3, the exemplary embodiment shown in fig. 3 is more preferable, with each crawler track 8 provided with its own apparatus 1. In this case, both pieces of appa- ratus 1 are designed as independent units, separated from each other and only coupled together by the working machine 3 itself. In order to prevent a toe-out or toe-in from developing between the wheels 4 of the separate pieces of apparatus 1, the load platforms 5 have an internal width which is

dimensioned to be just slightly more than the width of the crawler track 8, whereby the load platform 5 always sets itself substantially in alignment with the crawler track 8.

In the solution of fig. 3, which uses two pieces of apparatus 1, the side walls 10 of the load platform 5 are adapted to diverge from each other when progressing upwards from the bearing surface of the load platform 5. Thus, the apparatus 1 is freely inclinable when performing transfers on uneven terrains.

In one preferred embodiment of the invention, the apparatus 1 is fitted with wheels 4 which lock automatically upon the removal of a load off the load platform 5. Such a brake mechanism secures the immobilization of the apparatus 1 also on an inclined surface, thus facilitating the use of the apparatus 1.

In the exemplary embodiment shown in figs. 5-7, the brake mechanism comprises a lever 14 articulated in the middle to the external surface of a side wall of the load platform 5. One of the legs, the bottom one, of the lever 14 is pivotably fitted with a plate spring 15 or the like. In an unloaded condi- tion, the plate spring 15 is in the position depicted with dash-and-dot lines in fig. 6, the other, upper leg of the lever 14 leaning against the wheel 4 and blocking its rotation. In order to bend the spring 15, the load platform 5 is provided with a clack 16, pivotably journal led at its leading edge and pressed down by the crawler track 8 and, respectively, lifted up by the spring 15 whenever the clack 16 is not subjected to a laid.

The apparatus of the invention operates as follows.

In the first condition shown in fig. 1, the working machine 3 is driven up to rest on one or two pieces of apparatus 1 all the way until the crawler track 8 collides with the permanent guard 7 included in the apparatus 1. Thereafter, the track 8 may still slightly slip relative to the load platform 5 until said track

grabs the gripping element 9. At this point, the apparatus 1 and the working machine 3 are completely locked to each other.

Following this, the excavating mechanism 2 of the working machine 3 is turned from the position of fig. 1 through 1800 around the vertical axis, thus bringing the excavating mechanism 2 onto the load bed of the tractor vehicle 6 and lifting the crawler tracks 8 of the working machine 3 off the ground by means of the excavating mechanism 2, whereafter the working machine 3 is ready for a transfer.

If necessary, the working machine 3 can be used for braking action by adjusting the excavating mechanism 2 in such a way that the crawler tracks 8 touch the ground at the leading end of the working machine 3.