The present invention concerns a tool for use in the le- velling of an under layer, i. e. for use in the levelling of sand and gravel in the laying of tiles or paving stones or the like, and comprising at least two straight support rails which can be placed in or on an under layer for supporting the ends of a levelling rail which can be placed on the sup- port rails for levelling of the under layer in between the support rails, said levelling rail consisting of a straight rail with a front side, a rear side and a levelling edge.

Such tools are well-known and are used wherever a fortification of the ground surface is to be established in the form of tiles or paving stones or the like which are laid out on a layer consisting of sand or fine-grained gravel, which is levelled-off to a predetermined level and with a predetermined slope. There do not exist any tools of truly simple configuration for the execution of the levelling work, and therefore use has hitherto been made of materials at hand in the form of iron pipes, which are typically used as side support rails, and a board or iron rail or the like with at least one reasonably straight side as levelling rail.

The problems connected with the use of the above- mentioned means for the levelling of an under layer are typi- cally that it is necessary for the pipes which are used as side support rails to be buried down in the under layer, so that the upper side of the rails lies on a level with the fi- nished levelling layer. The placing of the rails in the e under layer can be a very time consuming operation, particularly if the rails are also to be placed with a predetermined, desired degree of slope.

The work of establishing under layers for the lay- ing of tiles or paving stones or the like, including the le- velling of the under layer, is often carried out by one per- son, which obviously involves a great consumption of time in connection with the positioning of the iron pipes at the cor- rect height before the levelling of the under layer is car- ried out.

From publication DK 163311 B, there is known a dra- wing-off element with supporting rollers which is operated by two men, this comprising a transverse cutting edge with an inclined slide surface which leads up to a collection chamber for the levelling material, whereby the drawing-off element also serves as transport carriage for the levelling material.

As mentioned, however, the operation of this drawing-off ele- ment requires two men, the result being that this element is more applicable for use by professional firms who are requi- red to carry out paving work on a really large scale, and is thus not for single-man operation.

However, with the invention it has been realised that the above-mentioned problems can be solved with a new levelling system of the kind disclosed, which is characteri- sed in that the levelling rail consists of a straight rail with a front side and a rear side and a levelling edge, and having ends which are provided with slide pieces inserted in the ends of the levelling rail from which they extend out- wards in the longitudinal direction of the rail, the undersi- des of said slide pieces in the position of use being in con- tact with the supporting rails, and where the levelling edge lies below the underside of the slide blocks.

The advantages herewith are firstly a quite simple levelling system, whereby the work involved in the levelling of the under layer is made considerably easier, in that the supporting rails do not need to be buried down in the under layer, but merely have the ends hereof placed on top of this at a point which has locally been levelled to the desired fi- nal levelling height, or merely on top of the under layer, after which the levelling layer within the area in between the rails is subsequently levelled by means of the levelling rail sliding on the upper edge of the supporting rails.

The levelling rail can with advantage consist of a profile, the side of which opposite the levelling edge com-

prises a cavity at least in the area at the ends of the le- velling rail, and the outwardly-extending parts on the level- ling rail can with advantage consist of slide blocks, the one end of which is inserted in the cavities in the ends of the levelling rail, and the free ends of which constitute the outwardly-extending parts.

The advantage herewith is that it is hereby possi- ble to produce the levelling rail in one operation, for exam- ple by extrusion, and subsequently mount the extending parts/slide blocks in the ends of the levelling rail.

With the view to being able to establish the level- ling layer in different thicknesses over the level for the under layer, with the supporting rails placed on top of this, the slide blocks can be interchangeable with slide blocks of varying heights in that part which extends outside the ends of the levelling rail and down towards the levelling edge. It is hereby achieved that when the slide blocks are changed, a variation in the height of the levelling edge over the under layer can be obtained. Moreover, in the ends of the levelling rail, blocks of different heights can be placed on the downwards-extending part, whereby the under layer can be le- velled with a predetermined, desired slope P in the transver- se direction in between the supporting rails.

With the view to being able to achieve an adequate under-supporting of the supporting rails, and a good sliding surface for the slide pieces, the supporting rails can with advantage consist of profiled tubes with rectangular or quadratic cross-section, the height Sv of which corresponds substantially to the distance SA between the under side of the slide blocks and the lower edge of the levelling rail.

With the view to being able to continue levelling of the levelling layer by the laying of the one levelling rail out on the edge of the under layer already levelled, and thus that it is necessary only to set a slide rail at the

correct height in the levelling of an area at the side of the immediately preceding levelled area, the height Sv of the straight supporting rails associated with the system can with advantage correspond to the distance SA between the under si- des of the slide blocks and the levelling edge, so that this extends flush with the under side of the supporting rails.

With the view to being able to carry out the level- ling of an under layer closely up against vertical surfaces, the side edge of the levelling rail facing towards the under layer can be wedge-shaped, so that the breadth of the level- ling rail decreases in towards the front.

The advantage is hereby achieved that the levelling rail can be used in the levelling of an under layer right up against house walls, in that it is possible to maintain a good grip on the levelling rail by letting the inclined side of the wedge shape section come into contact with the house wall. A further advantage of the wedge-shaped section is that a narrow side edge is provided for use in the levelling of the under layer.

The narrow side edge also offers an advantage in that the levelling rail is furthermore even especially usable as a straight rail which is used to check the building con- struction, for example in checking the uniformity of a wall, which means that even very narrow cracks e. g. in between a wall and the levelling rail are revealed, as opposed to the use of a straight rail with rectangular cross-section, where the shadow effect results in small deviations not being reve- aled.

With the object of obtaining a good finger-grip du- ring use of the levelling rail, the rear side, and/or the front of the rail can be provided with a corrugated surface, preferably in the form of longitudinal finger grooves.

With the object of being able to use the levelling system for the levelling of the under layer all the way from

and including the underlying support layer to and including the levelling layer, and moreover to be able to level these layers with a preferred slope in both the lateral direction and the longitudinal direction of the supporting rails, the tool according to the invention can also comprise a number of ground spikes with associated bearing brackets for the sup- port of the supporting rails, said bearing brackets being ad- justable and securable in a displaceable manner in the longi- tudinal direction of the spike. By means of the levelling sy- stem, it is hereby possible to carry out the levelling of any individual support layer in a desired thickness, and thus that this is provided with the preferred degree of slope for the fortification which is placed on top of the finally le- velled under layer.

To assist in the quick adjustment of the slope of the supporting rails, the ground spikes for the bearing brackets can also be provided with a measuring scale.

In the following, an example embodiment of the le- velling system according to the invention is explained in mo- re detail with reference to the drawing, where fig. 1 is a perspective view of a levelling rail according to the invention, seen obliquely from the rear, fig. 2 is a detail perspective view of an end of the levelling rail, fig. 3 is a perspective view of two supporting rails, fig. 4 shows the levelling system according to the invention during its use, fig. 5 is a detail view of the transition between the levelling rail and the supporting rail, fig. 6 is a section of the levelling system in use, with the use of slide blocks of different heights, and fig. 7 is a perspective view of a ground spike with bearing bracket.

The preferred embodiment of the levelling rail 2 according to the invention shown in fig. 1 consists of a rec- tangular, hollow aluminium profile 5 with a front side 4 and a rear side 6, and having a lower part 8 which is wedge- shaped towards a levelling edge 10. In the ends of the level- ling rail 2 there are inserted slide blocks 12, and as will appear from fig. 1 the wedge-shaped section of the levelling rail 2 starts from the under side 14 of the slide blocks 12.

As will appear from fig. 2 and fig. 6, the slide blocks 12 are changeable, and as will appear from fig. 6 the height of the slide blocks at the part 12,14 which extends outside the ends of the levelling rail and down towards the levelling edge can vary. It is hereby achieved that with the changing of the slide blocks, a variation can be obtained in the height of the levelling edge above the under layer. More- over, blocks with different heights at the downwards- extending part can be inserted in the ends of the levelling rail, whereby the under layer can be levelled with a prede- termined, desired slope P in the transverse direction between the supporting rails, cf. fig. 6.

The levelling system also comprises at least one pair of supporting rails 16, cf. fig. 3-6, which consist of profiled tubes of quadratic cross-section, and the height Sv of which corresponds to the distance SA between the under si- de 14 of the slide blocks 12 and the levelling edge 10 on the levelling rail 2.

The levelling system is used by placing the ends of the supporting rails 16 at the final levelling height, and with a distance between them which corresponds to the length of the levelling rail 2 which is used for the levelling of the under layer. Hereafter, the levelling rail 2 with slide blocks 12 is placed resting on the upwardly-facing side of the supporting rails 16, after which a levelling of the under layer 18 is carried out by pulling on the levelling rail 2 (in the direction as indicated by the arrow D), supported by the slide blocks 14, which in turn are supported on the sup- porting rails 16, as is shown in fig. 4. There is hereby a- chieved a simple and practicable working operation in con-

nection with the levelling of the under layer 18, and which can very easily be carried out by a single person.

The wedge-shaped section 8 on the back 6 of the rail makes the levelling of the under layer 18 close to house walls 20 and the like considerably easier, in that the wedge- shaped section 8 is allowed to come into contact with the preferably vertical house wall 20, whereby there will be a good possibility of achieving a good grip around the upward- ly-facing side of the levelling rail at the beginning of the levelling work.

The part 8'of the back 6 of the levelling rail 2 can also be provided with a corrugated surface, preferably in the form of longitudinal finger grooves 9.

The levelling system also comprises a number of ground spikes 22, which in the example embodiment shown con- sist of galvanized steel, cf. fig. 7. The ground spikes 22 are provided with a bearing bracket 24 which is fastened to the spike in a displaceable manner by means of a clamping screw 26. The bearing brackets 24 constitute a knee-like bea- ring saddle 28 which accommodates and supports a supporting rail 16. When use is made of the ground spikes 22 with asso- ciated bearing brackets, it will be possible to use the le- velling system for the levelling of different support layers from datum line to and including the final levelled layer 18 for the laying down of tiles, flagstones or paving stones 21 or the like.

The use of the ground spikes 22 is effected by ham- mering them down into the ground and with a distance between them which is less than the length of the supporting rails, and such that the distance between the supporting rails 16 matches the length of the levelling rail. Hereafter, the saddles 28 on the bearing brackets are placed at the prefer- red heights and the supporting rails 16 are placed on the saddles. The area to be levelled is then filled with material and roughly smoothed out, after which a fine regulation of the surface is carried out by means of the levelling rail 2, as shown in fig. 4. Hereafter, a stamping-down of the materi- al can possibly be carried out, after which the bearing

brackets are moved to a higher level and the filling and le- velling process can be repeated until the under layer is rea- dy for the laying of tiles, flagstones, paving stones or the like.

The levelling system is hereby used not only for the levelling of the final layer of sand and gravel, but in the total building-up of the under layer, which hereby beco- mes uniform in its structure. The thicknesses of the layers will be well-defined in that with the use of the levelling system the bearing brackets are easy to adjust, in that the levelling height is identical to the level of the bearing saddle, which is a consequence of the distance SA between the under side 14 of the slide blocks 12 and the levelling edge 10 on the levelling rail 2 being identical to the side length Sv of the supporting rails.

The new levelling system disclosed here is thus of the kind which to a wide extent will ease the work involved in the levelling of an under layer for the laying of tiles etc., and with the greatly improved possibilities regarding adjustment of the heights of the bearing brackets, the user will be more inclined than has previously been the case to carry out the levelling of deeper-lying support layers with subsequently better results. Furthermore, the levelling sy- stem has the great advantage that it can easily be used by a single person.