GB2039572A - Apparatus for preparing ski slopes - Google Patents

Abstract

Apparatus for preparing ski tracks comprises a plane (20) for tearing up and mixing the covering of snow. The plane (20) is articulated for free pivoting through a traction gear (14) on a horizontal shaft (18) disposed transversely to the direction of travel (A) and in front of the plane (20). This shaft (18) is supported on a sled (1) disposed in front of the plane (20). In order to be able to select the lateral inclination of the track to be prepared largely independently of the lateral inclination of the terrain covered, the said shaft (18) and with it the traction gear (14) and the plane (20) can be tilted with respect to the sled (1) about a tilting axis (7) substantially parallel to the direction of travel (A) by means of guide rods (8). <IMAGE>

Description

SPECIFICATION Apparatus for preparing ski slopes The present invention relates to apparatus for preparing ski slopes, particularly ski-lift and downhill runs as well as cross-country tracks.

Apparatus of this kind is known from the DE-OS 25 33831. In this known apparatus called a 'track device', a connecting frame with two parallel longitudinal members is articulated directly on a sled about a horizontal pivot axis extending transversely to the direction of travel, as a traction gear. A scraper knife with a specific (adjustable) setting angle is suspended on the connecting frame as a plane, and a track sled which is articulately secured to the rear end of the connecting frame follows the scraper knife as a compacting member.

When a slope is covered with the known device at an angle to the line of steepest gradient (oblique slope travel), the front sled is inclined according to the inclination of the terrain. With this sled, however, the scraper knife and the following track sled are necessarily also inclined. Thus the plane of the track formed is always substantially parallel to the terrain covered. This is not always desired, particularly not for ski-lift tracks and cross-couhtry tracks. There the aim is that the track formed - seen transversely to the direction of travel - extends as horizontally as possible, that is to say that the later direction of travel of the skis coincides as far as possible with the line of the steepest gradient of the area of the prepared track, so that the skier does not always have to load the edges of the skis so as not to slip sideways.

In another device (DE-OS 26 27 893) which is likewise known, a plurality of plane members are provided which are each articulated through a pull rod on a horizontal shaft extending transversely to the direction of travel and which in turn are constructed on a traction frame which is supported on runners disposed in front of the plane members.

Here, too, the cutting edges of the planing knives are always parallel to that plane which is determined by two adjacent runners. Thus this device can likewise only prepare a track, the inclination of which corresponds substantially to the inclination of the terrain covered.

In a further known device (US-PS 3,926,262), the traction gear is formed by two parallel longitudinal members and this traction gear is directly articulated on a traction vehicle about a horizontal axis extending transversely to the direction of travel. Here, too, this has the consequence that the broaching blade rigidly secured to the traction gear with the following scraper blade necessarily remains parallel to the terrain covered by the vehicle. With an oblique slope travel (lateral inclination of the vehicle), here, too, the prepared track would be substantially parallel to the terrain covered.

It is an object of the present invention to obviate or mitigate these disadvantages.

The present invention is apparatus for preparing ski slopes, particularly ski-lift and downhill runs as well as cross-country tracks, having at least one plane mounted on traction gear which is articulated for free pivoting on a horizontal shaft disposd transversely to the direction of travel and in front of the plane, which shaft is in turn supported on a sled disposed in front of the plane in the direction of travel, said shaft and with it the traction gear and the plane being tiltable in relation to the sled about a tilting axis substantially parallel to the direction of travel.

As a result of the ability of the unit traction gear/plane to tilt in relation to the sled, during oblique slope travel this unit can be kept by the guide rods in that position which the resulting track is to have. The sled, on the other hand, always bears flat against the existing terrain.

The shaft on which the plane is articulated for free pivoting through the traction gear may be disposed at the rear end of a frame which in turn is articulated on the sled through the tilting axis disposed in the longitudinal centre of the sled. This frame may comprise two transverse struts which are disposed one behind the other and are connected to one another at their free ends through longitudinal members, which transverse struts are each arcticulated in their middle on a bearing on the sled, which bearings determine the tilting axis.

When the plane is tilted in relation to the sled disposed in front of it about the tilting axis, then the plane penetrates deeper into the covering of snow covered at one side than at the other. Thus more snow is removed at this side by the plane and the plane also has a greater resistance to overcome. In a preferred embodiment of the invention, therefore, the plane is secured to the traction gear through a vertical spindle about which the plane is pivotable to both sides against the action of a spring. The plane which normally extends with its cutting edge transversely to the direction of travel, in this form of embodiment, is deflected somewhat towards the rear, where the greter depth of penetration is, about the vertical axis against the action of the spring, that is to say where the greater resistance has to be overcome.With this form of embodiment, it is advisable to dispose sheet-metal guides extending substantially at right angles to the cutting edge of the plane at the top of the plane, the purpose of which, when the plane is tilted and consequently deflected, to displace the planed-off snow from one side, which is planed deeper, to the other side.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figures 1 and 2 are respectively diagrammatic side elevation and plan views of apparatus according to the present invention for preparing ski runs; Figure 2a shows, in plan view, a detail from Figure 2; Figures 3 and 4 show in front view different forms of the rubbing edge of a scraper blade disposed following the plane; and Figures Sand 6 show the use of the apparatus shown in Figures 1 and 2 for preparing a track extending horizontally in the transverse direction on an oblique slope.

The apparatus shown in Figures 1 and 2 for preparing ski tracks comprises a sled 1 which is supported on the ground, that is to say on the track 2 to be prepared. This sled carries a frame 3 which comprises two longitudinal members 4 extending parallel to one another in the direction of travel A and two transverse struts 5 connecting the latter to one another and V-shaped in construction. These transverse struts are secured to the sled by means of bearings 6 which determine a tilting axis 7 substantially parallel to the direction of travel A and rising slightly in this direction. The frame 3 can be tilted to both sides about this tilting axis 7 with respect to the sled 1. Fitted to the frame 3 are two parallel guide rods or shafts 8 which extend forwards in the direction of travel A and which serve in a manner to be described later for pulling and guiding the device.

At its rear end, each shaft is secured for adjustment in height to an attachment plate 9 fitted on the rear transverse strut 5. This adjustment in height of the attachment point of the shafts 8 is illustrated diagrammatically in Figure 1 and designated by 10. In addition, each shaft 8 is connected to a holder 13 for pivoting about an axis 12 by means of a collar 11, which holder is secured to the front transverse strut 5. When the rear end of the shaft 8 is adjusted in the attachment plate 9, the shaft 8 is pivoted about the axis 12 and so the inclination of the shaft is altered.

Connected to the frame 3 is a traction gear 14 which comprises an arm 15 extending towards the rear. At its front end, this arm 15 comprises a cross arm 16 which is pivotally connected to bearing plates 17 secured to the rear transverse strut 5. The pivotal axis 18 of the traction gear 14 determined by the bearing plates 17 extends at right angles to the direction of travel A and parallel to the track 2 to be prepared, that is to say in the horizontal position shown in Figure 1. Let into the arm 15 some distance behind this pivotal axis 18 is a bearing bush 39 in the bore of which, extending substantially vertically, a pivot pin 40 is mounted for rotation and secured against axial displacement by means of a nut 41. The pivot pin 40 is anchored at the upper end of a downwardly directed strut 19.The strut 19 includes a centering arm 42 which is directed towards the rear and which - see Figure 2a - engages between two compression springs 43 which are disposed substantially horizontally and act against one another.

Thus the compression springs 43 tend to hold the centering arm 42 aligned with the arm 15. The strut 19 also carries a plane 20 which comprises an attachment arm 21 fitted to the strut 19 and articulately connected to the strut 19 by means of a joint pin 22 and fixed in its position by a shear pin 23 transversing the strut 19. At its free end, the attachment arm 21 is provided with a knife carrier 24 which comprises an upwardly bent edge 25 at its rear end. Secured to the front end of the knife carrier 24 is a planing knife 26. This planing knife, which may comprise a straight or - as shown - a toothed cutting edge 26a, is inclined towards the rear in relation to the vertical, that is to say it has a certain angle of attack in relation to the plane of the track 2 to be prepared.

Secured to the rear end of the arm 15 is a scraper blade 28 which is pivotable about an axis 27 parallel to the pivotable axis 18 of the arm 15. The scraper blade 28 lies with its rubbing edge 29 on the ground, that is to say on the track 2. The inclination of the scraper blade 28 and hence also the height of its rubbing edge 29 with respect to the planing knife 26 can be altered by means of an adjusting device. This adjusting device 30 comprises a screw tube 31 which is articulately connected at one end, by means of a bearing eye 32 to the scraper blade 28. Engaged in this screw tube 31 is a threaded spindle 33 which is mounted in a bearing 34 secured to the arm 15. In order to turn the threaded spindle 33, this is provided with a crank 35 at its free end.By turning the stationary threaded spindle 33, the screw tube is adjusted in the longitudinal direction of the spindle 33 which leads to a pivoting of the scraper blade 28 about the pivotal axis 27. Thus the scraper blade 28 is held in its particular pivoted position by means of this adjusting device 30.

The rubbing edge 29 of the scraper blade 28 can be straight as shown in Figures 1 and 2. It is also possible, however, to construct or profile this rubbing edge 29 otherwise. As Figure 3 shows, which illustrates diagrammatically the under part of the scraper blade 28 in front view, projections 36 projecting from the rubbing edge 29 can be provided at the under side of the rubbing edge 29 which serve to form ski tracks when the devices shown in Figures 1 and 2 are pulled. It is naturally possible to provide more than two such projections 36 to form a plurality of ski tracks lying side by side.

In order to provide the whole device with a lateral guide means, guide runners 37 which project at both sides beyond the rubbing edge 29 may be provided on the scraper blade 28, as Figure 4 shows, which guide runners, when the apparatus is pulled, dig into the snow at the side of the track to be prepared and prevent slipping away sideways. The use and mode of operation of the device described is as follows: First, if necessary, the inclination of the scraper blade 28 and possibly also of the shafts 8 is adjusted.

By means of hooks 8a fitted at their front end, the shafts 8 are suspended, for example in the loop of a towing lift. An operator present between the shafts, guides the device and determines the tilting position of the frame 3 and of the traction gear connected to this with respect to the sled 1. During the towing of the device, the plane 20 digs into the snow as a result of the angle of attack of the planing knife 26, tears up the layer of snow and mixes the deeper layers of snow with the used uppermost layer. Since the plane 20 is freely pivotable about the pivot axis 18 through the traction gear 14, the arm 15 is pivoted downwards by this digging in of the plane 20. This pivotal movement of the arm 15 is transmitted to the scraper blade 28 rigidly connected to this, which as a result is pressed with its rubbing edge 29 against the track 2. Thus as a result of the penetration of the plane 20 a downwardly directed component of force results which is transmitted via the arm 15 to the scraper blade 28 as mentioned. As a result of the pressure which the scraper blade 28 exerts on the now loosened layer of snow, this it compacted again. In addition, the scraper blade 28 with its rubbing edge 29 causes a levelling of the prepared track. In addition, the scraper blade 28 serves as a baffle plate for the lumps of snow broken away by the planing knife 26, sliding away over the knife carrier 24 and thrown up by the bent up edge 25, which lumps impinge on the scraper blade 28 and are broken up.Because the scraper blade 28 is pressed against the track by the plane 20 digging in, the scraper blade ensures to some extent as a spatula a satisfactory compacting of the loosened snow without the scraper blade 28 having to be made particularly heavy for this purpose. On the other hand, assurance is also provided that the scraper blade 28 presses with its rubbing edge with a certain pressure on the track 2, so that a satisfactory distribution of the snow accumulating in front of the scraper blade is ensured for the necessary levelling.

The risk that the scraper blade might slide away over an accumulation of snow without exerting a distributing action is largely avoided in this manner. The scraper blade 28 supported on the track 2 also prevents the plane from penetrating too deeply into the track to be prepared so that the depth of penetration of the plane 20 is limited by the scraper blade 28. By adjusting the inclination of the scraper blade 28, the height of the rubbing edge 29 with respect to the plane 20 and hence also the depth of penetration of the plane can be altered - as already mentioned.

The free pivotability of the plane 20 with respect to the sled 1 has the advantage that the plane 20 does not necessarily have to follow the movements of the sled 1 in every respect. The plane 20 is therefore in a position, in the event of humps in the track to be prepared, to cut off the peaks of these humps effectively so that such irregularities can be entirely or at least mostly eliminated in one operation.

If the scraper blade 28 is provided with trackforming projections 36 on its rubbing edge 29, as already explained with reference to Figure 3, then in the course of compacting and levelling the track, one or more ski tracks can be formed which is of particular interest for cross-country tracks.

The operator is in a position, by raising or lowering both shafts 8, to alter their inclination with respect to the track 2. As a result, the height of the pivot axis 18 with respect to the track is also altered which leads to a corresponding alteration in the angle of attack of the planing knife and hence the depth of penetration of the plane 20. It is also possible for the operator to adapt the depth of penetration of the plane to the state of the unprepared track found during the journey, as required. By lateral tilting of the frame 3 about the tilting axis 7, that is to say by pressing down the one and/or raising the other shaft 8, the position of the planing knife 26 with respect to the sled 1 can likewise be altered. This is of importance when - as clearly shown in Figure 5 - a horizontal track 39 has to be produced in the transverse direction on an oblique slope.The sled 1 resting flat on the terrain covered assumes the inclination of the terrain covered, as shown in Figure 6. The traction gear 14 and hence the plane 20 and the scraper blade on the other hand can be held in a horizontal position by tilting about the tilting axis 7 so that a track is prepared, the lateral inclination of which does not depend on the lateral inclination of the terrain covered.

Now if, as described above, the plane 20 (and hence the scraper blade 28) is tilted with respect to the sled 1 by means of the shaft 8, then the plane 20 penetrates deeper into the layer of snow at one side than at the other. Therefore a greater resistance is also opposed to the plane 20 at this side. Since the plane 20 with the strut 19 is rotatable to a limited extent through the vertical pivot pin 40 and against the action of the compression springs 43, in this case it is deflected somewhat towards the rear at that side where there is the greater depth of penetration. The outline of the plane 20 in such a deflected position is illustrated in chain lines in Figure 2a.Secured to the upper side of the knife carrier 24 are sheet-metal guides 44 which are substantially at right angles to the cutting edge of the plane and the purpose of which is to push the snow broken away from the side with the greater depth of penetration of the plane towards the other side, before the levelling action of the scraper blade 28 begins. So long as the plane 20 is not deflected, however, these sheet-metal guides contribute to the straight guiding of the plane 20 (somewhat like the runners 37).

Instead of pulling the device by means of a towing lift as described, this can also be pulled by a towing vehicle. In this case, other suitable trailer members should be used instead of the shafts, the attachment points of which on the towing vehicle are adjustable individually in height.

In another embodiment of the device, the scraper blade 28 is not adjustable in its inclination. In order to adjust the depth of penetration of the plane 20, however, the scraper blade 28 is displaceable in height in the direction of the arrow C (Figure 1), as illustrated in broken lines in Figure 1. Forthis purpose, the strut 19 can be mounted on the arm 15 for adjustment in the direction of the arrow C and be held in its particular position by means of a locking device.

The device described is suitable not only for preparing ski-lift tracks but can also be used according to width - for preparing downhill runs and cross-country tracks.

Claims (8)

1. Apparatus for preparing ski slopes, particularly ski-lift and downhill runs as well as cross-country tracks, having at least one plane mounted on traction gear which is articulated for free pivoting on a horizontal shaft disposed transversely to the direction of travel and in front of the plane, which shaft is in turn supported on a sled disposed in front of the plane in the direction of travel, said shaft and with it the traction gear and the plane being tiltable in relation to the sled about a tilting axis substantially parallel to the direction of travel.

2. Apparatus as claimed in claim 1, in which said shaft is disposed at the rear end of a frame which in turn is articulated on the sled through the tilting axis disposed in the longitudinal centre of the sled.

3. Apparatus as claimed in claim 2, in which the frame comprises two transverse struts which are disposed one behind the other and are connected to one another at their free ends through longitudinal members and which, in their middle, are each articulated on a bearing on the sled, which bearings determine the tilting axis.

4. Apparatus as claimed in claim 3, in which the transverse members have the shape of an obtuse V open upwards.

5. Apparatus as claimed in any of claime 2 to 4, in which are provided towing shafts secured laterally to the frame and extending forwards.

6. Apparatus as claimed in any preceding claim, in which the plane is secured to the traction gear through a verticle spindle about which the plane is rotatable to a limited extent to both sides against the action of a spring.

7. Apparatus as claimed in claim 6, in which the plane comprises a planing knife secured to a knife carrier, and a plurality of sheet metal guides extending at right angles to the cutting edge of the plane are secured to the upper side of the planing knife and/or of the knife carrier.

8. Apparatus for preparing ski slopes substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.