Abstract:
The invention relates to a method for smoothing or leveling a ground surface, wherein a smoothing or leveling material is laid on a ground surface in that a box-like device filled with material is moved forwards, the material being allowed to exit a plate-adjustable rear opening in the box-like device and to come to lie in a strip, and a blade mounted on the box-like device after the opening spreads the material on the ground surface, the blade being capable of being raised and lowered together with the plate, the blade is raised and lowered with an adjustable reduction ratio relative to the plate, by means of a lever/parallelogram arrangement which connects the blade and the plate.

Description:
CLAIM OF PRIORITY 
   This application is the U.S. National Phase of PCT/NO02/00350 filed Oct. 1, 2002 and claims priority to Norwegian Patent Application No. 200114763 filed Oct. 1, 2001, which are hereby incorporated herein by reference in their entirety. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a method for leveling a ground surface. 
   2. Description of the Related Art 
   It is known (GB 2226839) to use a box at the rear end of which there is a plate-adjustable opening for the discharge of material as the box is moved forwards on the ground surface. In a known box of this kind, it is also known to raise and lower the plate so as to regulate the amount of material that exits through the opening as the box is moved forwards. Mounted behind the plate is a blade which can be raised and lowered relative to the plate. 
   SUMMARY OF THE INVENTION 
   The invention relates to a method for levelling a ground surface wherein material is laid on the ground surface in that a box-like device filled with levelling material is moved forwards, the levelling material being allowed to exit through a plate-adjustable rear opening in the box-like device and to come to lie in a strip, and a blade mounted on the box-like device after the opening spreads the material on the ground surface, the blade being capable of being raised and lowered with the plate. 
   The invention also relates to an apparatus for levelling a ground surface, comprising a box-like device which has two side walls and a front and a rear end wall, where the rear end wall has an opening at the bottom, with a plate in the opening that can be raised and lowered to regulate the amount of material that exits through the opening as the box filled with levelling material is moved forwards, and with a blade or plough behind the plate and mounted so as to be capable of being raised and lowered together with the plate. 
   The object of the invention is to permit an accurate and desirable spreading and levelling of the levelling material or smoothing material in order to provide an optimally levelled ground surface for elements that set stringent requirements as regards precise location. Examples of such elements are railway cable pits, water pipes, drop pipes, cables etc. 
   Other areas of use may be the smoothing of footpaths/cycle tracks, pavements and the laying of kerbstones and bedding for flagstones and paving stones. 
   One particular object is to allow spreading and levelling of a material in areas of restricted space where it would be difficult to work with huge machines, e.g., road graders and the like, and it is also a particular object to provide an apparatus that is highly suitable for spreading and levelling material on such areas of restricted space. 
   A particular object of the invention is to permit the laying of a smoothing or levelling material in a desired width using one and the same box-like device. 
   Another particular object of the invention is to make possible an apparatus which in a simple manner can be altered to give the box-like device greater width, or can be made narrower. 
   According to the invention, the basic idea is that a certain amount of smoothing material will flow out through the plate-adjustable opening as the box-like device is moved forwards on the ground surface that is to be smoothed or levelled. The blade at the back is used to spread the smoothing material out to the desired width, equal to or greater than the width of the box (box opening). 
   According to the invention a method as set forth in claim  1  is therefore proposed. 
   It is especially advantageous if the height of the blade is registered by a levelling system, in particular a laser system, and registered deviation from a set value is compensated by raising/lowering the plate and thus the blade until the levelling system registers/indicates the correct blade height. 
   According to the invention an apparatus according to claim  3  is also proposed. 
   The adjustable reduction ratio can be obtained in many ways, e.g., by a gear coupling, but it advantageous for the apparatus to be constructed so that the blade and the plate are mutually interconnected to a lever arrangement where the blade is adjustably mounted on a lever. 
   It is particularly advantageous for the blade to be supported so as to be adjustably mounted in a parallelogram arrangement where the lever and the blade supporting part form a respective parallelogram side. 
   For levelling, the blade can be fixedly connected to a laser reflector. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described in more detail with reference to the drawings, wherein: 
       FIG. 1  is a purely schematic illustration of how the apparatus may be constructed, the figure showing three different settings between the plate and the blade; 
       FIG. 2  is a purely schematic illustration of a parallelogram embodiment for blade suspension; 
       FIG. 3  is a schematic perspective view of the embodiment in  FIG. 2 ; 
       FIG. 4  is a side view of a practical embodiment of an apparatus according to the invention; 
       FIG. 5  is an enlarged detail section from the embodiment in  FIG. 4 ; 
       FIG. 6  is a side view of the detail section in  FIG. 5 ; 
       FIG. 7  is a side view like that in  FIG. 6  of a modified embodiment; and 
       FIG. 8  is a purely schematic illustration of a variant; 
       FIG. 9  is a purely schematic illustration of another variant; 
       FIG. 10  shows a possible variant of the invention; 
       FIG. 11  shows the embodiment in  FIG. 10  in a position for refilling the box with material; 
       FIG. 12  is a purely schematic illustration of another possible embodiment; and 
       FIG. 13  is a purely schematic illustration of yet another possible solution. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  shows a box-like device  1 , see also  FIG. 3 , where in a rear end wall  2  there is an opening  3  the exit area of which can be adjusted by means of a plate  4  that is capable of being raised and lowered. The end wall  2  is the rear wall of the box  1  because during smoothing or levelling the box is moved in the direction of the arrow (to the left on the drawings). 
   The plate  4  can be raised and lowered by using non-illustrated means, for example, one or more hydraulic working cylinders. This will be shown and discussed in more detail below in connection with  FIGS. 4–7 . 
   One (or for example two) supporting arms  5  project backwards from the box  1 . As shown, the supporting arm  5  is angular and forms an articulated support  6  for a rod  7  the other end of which is articulately supported on the plate  4  at  8 . At the articulated support  8  there is indicated a certain scope for telescopic movement to compensate for changes in length when the plate  4  is moved up and down, thereby swinging the rod  7  in the vertical plane about the articulated support  6  on the arm  5 . In some cases the joints  6  and  8  could be made so slack that this in itself would provide the necessary length compensation. 
   The rod  7  supports a blade  9 . The blade  9  is supported by the rod  7  via a sleeve  10  that can be moved on the rod  7  in the longitudinal direction of the rod and fixed at a desired point on the rod, continuously or optionally in steps (locking pin holes). 
   In the top illustration and in the centre illustration of  FIG. 1 , the blade  9 , i.e., the supporting sleeve  10 , is placed close to the joint  8  and thus close to the blade  4 . At the top in  FIG. 1  the plate  4  is shown in a lowered position, i.e., in a position in which it blocks the opening  2 . The blade  9  is at the same level as the lower edge of the plate  4 . When the plate  4  is raised a distance a, as shown in the centre illustration of  FIG. 1 , the blade  9  will also be raised, but depending on the distance between the sleeve  10  and the joint  8 , the length b that the blade is lifted will differ from the lifting length a of the plate. This is due to the leverage that is provided between the plate and the blade. 
   In the bottom illustration in  FIG. 1  the blade  9  is shown displaced to about the middle of the rod  7  and fixed in that position. It can be seen that when the plate  4  is lifted a distance a, the blade  9  will only be lifted a distance b which corresponds to half the lifting distance a of the plate. 
   Thus, by moving the blade  9  along the rod  7 , it is possible to set a reduction ratio between the plate  4  and the blade  9 . This means that in, for example, the setting shown at the bottom of  FIG. 1 , smoothing material will flow out through the discharge opening  3  when the box  1  is moved forwards in the direction of the arrow, and this material will be spread out in a larger width by the blade  9 , as determined by the setting between the movement of the plate and the movement of the blade. Of course, the blade  9  is made having a width corresponding to the width that is to be laid, and which thus is larger than the width defined by the box  1 . 
   Using one and the same box  1  it is thus possible to lay different, desired widths of smoothing or levelling material on a ground surface  11  on which the box  1  is advanced. 
   To obtain a parallel displacement of the blade  9 , the parallelogram solution shown in  FIG. 2 , see also  FIG. 3 , may optionally be used. In  FIG. 2  a parallel rod  12  is arranged parallel to the rod  7  and is articulately supported in the supporting arm  5  at  13 . The blade  9  is attached to a rod  14  that is pivotally connected to a respective sleeve  10 ,  15  which can be moved along the rod  7  and the parallel rod  12  respectively and fixed there in the same way as discussed earlier. 
     FIG. 3  is a purely schematic illustration of an advantageous embodiment in which two parallel supporting arms  5  are used. A construction of this kind is particularly advantageous because the whole apparatus can thereby be made symmetrical about the longitudinal axis of the box. By changing the transverse dimension of the box, i.e., by changing the non-illustrated front wall of the box and the rear end wall of the box with the plate  4 , the width of the box can be changed, keeping the supporting arms  5  and the equipment suspended thereby. 
   From a purely practical point of view, the apparatus according to the invention can, for example, be made as shown in  FIGS. 4–6 . The apparatus shown in  FIGS. 4–6  is a leveller comprising a box-like device which has two side walls  16  (only one side wall is shown in  FIG. 4 ), a front end wall  17  and a back end wall  2  (the same reference numerals are used here as in the schematic  FIGS. 1–3 ). 
   A smoothing material  18  is placed in the box-like device  1 . The box-like device  1  may optionally be bottomless, or have a partial bottom or a complete bottom (not shown). The longitudinal side walls  16  are optionally braced by non-illustrated transverse bars. 
   The rear end wall  2  has an opening that extends upwards from the bottom edge and whose discharge opening  3 , as previously mentioned, can be adjusted by means of a plate  4  that is capable of being raised and lowered. In  FIG. 5  a levelling material  18  is indicated in the box  1 , but for clarity, the material has been omitted in the bottom part of  FIG. 5 , i.e., the area close to the discharge opening  3  and the blade  9 . 
   Two parallel supporting arms  5  are welded in place at the top of the box  1 , i.e., that the illustrated practical embodiment is made in the same way as the basic embodiment shown in  FIG. 3 . A rod  7  is supported in each supporting arm  5 . 
   As shown in  FIGS. 5 and 6  each rod  7  is telescopic, and in the exemplary embodiment the rod consists of a rectangular tube that is supported in the supporting arm  5  at  6  and accommodates a rectangular rod  7 ′. The rod  7 ,  7 ′ is articulately connected at  19  to a lever arm  20  which in the middle is tiltably supported in the plate  4  by means of a swing bolt  21 . 
   Above the supporting arms  5  there is provided a platform structure  22  on which necessary hydraulic equipment  23  for working cylinders  24  is placed. Two working cylinders  24  are shown in the exemplary embodiment. As shown in  FIG. 5 , a working cylinder  24  is found at one end of the lever arm and is connected to the lever arm by means of a yoke  25  formed on the end of the working cylinder piston rod  26 . A similar working cylinder with piston rod is arranged at the other end of the lever arm  20 , next to the other supporting arm  5 . 
   When the working cylinders  24  are actuated, they will work opposite one another and cause a swinging or tilting of the lever arm  20 . Thus, the articulated connection  19  of the arm  7 ,  7 ′ is moved up and down, and the two supporting arms  7  are then swivelled correspondingly about their respective articulated support  6 . In this way, the blade  9  can be tilted or adjusted to compensate for irregularities. 
   Actuation of both working cylinders  24  in the same direction will allow the plate  4  to be raised and lowered. Of course, the pivot point  21  of the lever arms  20  is thus also raised and lowered, and the two arms  7 , 7 ′ are also moved correspondingly in their respective vertical planes. 
   The blade  9  is suspended from two rods  14  (only one is shown). The rod  14  is articulately connected at  28  and  27  to respectively a sleeve  10  and a sleeve  15  which are slidably arranged on the rod  7  and the parallel rod  12  respectively. In the rod  7  and the parallel rod  12  there are locking pin holes  29 , designed for cooperation with a respective locking pin  30 ,  31  in the sleeve  10  and  15  respectively. In this way, the sleeve  10  and  15  can be moved on the respective rod  7 ,  12  and fixed step by step in accordance with the holes  29 . 
     FIG. 7  shows a modified embodiment, where the working cylinders  24 ,  26  are connected directly to the plate  4  and where the two parallel rods  7  are articulately connected directly to the plate  6  as indicated by  8 . 
   For smoothing or levelling, the box  1  is moved in the direction of the arrow. The smoothing material  18  will flow out through the discharge opening  3  and will be spread by the following blade  9  in a width larger than the width of the discharge opening  3  and which is determined by the leverage between plate  4  and blade  9 . 
   Advantageously, the blade  9  can be connected to a levelling system, in  FIGS. 4 and 5  indicated as a laser reflector  33 . Laser beams are sent from an installed laser transmitter to the reflector  33 , and deviation from the desired levelling will be detected and signalled to a suitable device which will cause the working cylinder or the working cylinders  24 ,  26  to be actuated in a desired direction and distance. 
     FIG. 8  shows a variant with two blades  9 ,  9 ′ arranged one after the other and at a different height above the ground. A compactor  35  is suspended from the bar  7  between the two blades  9 ,  9 ′. 
     FIG. 9  shows a variant where the blade  9 ″ is slidingly suspended on a bent bar  36 . In an embodiment of this kind the blade can be tilted in the horizontal plane. 
     FIGS. 10 and 11  show an embodiment in which a box  1 ′ is towed by a small crawler  37  which includes a loading box  9  tiltable by working cylinder  38 . The loading box  39  contains material, which can be transferred to the box  1 ′ by tilting ( FIG. 11 ) the loading box. 
   The new apparatus according to the invention permits a rapid and accurate smoothing/levelling. The apparatus can be towed or can be self-propelled, for example with crawler belts. 
   The apparatus can optionally be provided with a device (not shown) for laying sheeting or the like, before or after the levelling operation. 
   In the exemplary embodiments it is shown that the plate is raised and lowered by suitable means, preferably one or two hydraulic working cylinders. A person skilled in the art would know that the working cylinder/cylinders could instead act on the levers/rods  7  or on the parallel rods  13 , and thus act indirectly on the plate. 
     FIG. 12  is a purely schematic illustration of another preferred embodiment where a blade  9  is suspended in a parallelogram arrangement comprising a supporting arm  5  where a parallel rod  12  is articulately supported at  13 . The parallel rod  12  runs parallel with the rod  7 , which is supported at  6 . The blade  9  is attached to a rod  14  that is pivotally  40 ,  41  connected to a respective sleeve  10 ,  15  that can be moved along the rod  7  and the parallel rod  12  respectively and can be fixed there in the same way as discussed earlier. There is a parallelogram arrangement of this kind on each blade side (see, e.g.,  FIG. 3 ). 
   A working cylinder  42  is connected to the parallel rods  12  for raising and lowering the blade  9 . 
   The two rods  7  are extended in the direction of the plate  4 , which can be raised and lowered by a working cylinder  43 . 
   Suspended from the supporting arms  5  is a control device  44  for activation of the movement of the working cylinders  43 . The control device is actuated by a light beam  45  which passes between the two ends of the rods  7  facing the plate  4 . The light beam  45  forms an indirect connection between the rods  7  and actuates the control device  44 . If the light beam moves up, the control device  44  is actuated and causes the working cylinder  43  and the plate  4  to move up, and conversely, if the light beams  45  moves down, the plate  4  moves down in the set situation. 
     FIG. 13  is a purely schematic illustration of how the rods  7 , instead of having an indirect connection (the light beam  45 ), can be connected directly to an elastic band  46  which actuates a switch  47  in the box (the control device)  44 . 
   The embodiments in  FIGS. 12 and 13  can also be made as pure lever embodiments (as for example in  FIG. 1 ).