Levelling device for producing a smooth surface

A levelling device for producing a smooth surface on a sett paving bed is constructed, with a view to easy handling and neat working, so that the rule can lift the excess material with a cutting action by a projecting cutting edge and a rising ramp surface. With a collecting trough and with rollers to support the levelling rule, a transport truck for excess material can be provided at the same time.

The invention relates to a levelling device for producing a smooth surface. 
Levelling boards of wood or metal are typically used for levelling a 
surface for sett paving work, these being displaced, transversely to 
themselves, along the top of the previously compacted formation. In this 
case, guiding laths must previously be sunk in the formation so that their 
upper edge lies at the level of the smooth surface to be produced. Working 
with these levelling boards is inconvenient and arduous if only because 
the bed material for the sett paving, such as sand for example, has to be 
pushed out from a crouching or kneeling working position. 
Levelling devices have also been developed already which can be handled by 
means of handles and are accordingly intended for use in an upright 
working position. 
Finally, levelling boards have already been developed for mounting on 
mechanical implements but these presuppose corresponding mechanical 
expenditure and in addition cause special problems with deformation of the 
subsoil as a result of the weight of the implements on the formation. 
In each of the known cases, problems result, in particular, with the excess 
material which is pushed onto the compacted material and has to be removed 
from there so that regions of unequal density easily result. As a result, 
the necessity for finishing work often arises. Filling in and touching up 
are also regularly necessary after guiding laths have been taken out of 
the finished formation. 
It is the object of the invention to provide a levelling device which is 
easy to handle and enables a smooth surface to be produced in a rapid 
procedure which makes finishing work largely superfluous. 
The present invention is a levelling device for producing a smooth 
formation on a sett paving bed, having a levelling rule which is movable 
transversely to itself along guiding laths or the like levelling aids, the 
levelling rule comprising a cutting edge on a ramp surface which extends 
upwardly from the cutting edge to a collecting trough. 
The levelling device according to the invention departs from the 
traditional levelling with a substantially perpendicular levelling surface 
and changes over to a cutting or paring removal motion to which the 
material of the bed for the sett paving offers considerably less 
resistance. Furthermore, it is provided that the excess material is not 
pushed up in front of the levelling rule where it therefore offers 
additional resistance but is lifted up and received in a collecting 
trough. 
Apart from the reduction in the forces to be applied during the levelling 
movement, this has the particular advantage that the precompacted rough 
formation is not covered with loose material and that compacted material 
is also lifted during the removal of pushed-up excess material. The 
material here remaining behind the levelling device is, instead, of a 
uniform density. 
It is particularly advantageous to support the levelling rule on rollers 
which make it easier to carry away excess material, which has accumulated 
in the collecting trough, with the levelling device. The rollers may also 
facilitate support on guiding laths or the like levelling aids during the 
levelling movement. 
For the support on guiding laths, provision may appropriately be made for 
the rollers to be adjustable in height in relation to the levelling rule, 
the adjusting range usually being such that the roller as a whole lies 
above the cutting edge of the levelling rule. Guiding laths can then be 
arranged on the surface of a rough formation so that the cutting edge 
extends below the lower edge of these guiding laths. Similarly, guiding 
laths can also be laid on a strip of smooth formation which has already 
been finished, on sett paving already present or the like - the adjustment 
in height enables a smooth formation to be produced at the desired level. 
The latter also applies in the case where, during the production of a 
smooth formation strip by strip, there is a rough formation on one side 
and a smooth formation which is already finished at the other side or 
where kerbstone edges at one side serve as a reference level and levelling 
aid.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The levelling device, which is designated as a whole by 1 in the drawing, 
comprises a levelling rule 2 which is typically extended over several 
meters and the centre portion is only shown broken away for reasons of 
illustration. The levelling rule is supported, at each of its two lateral 
ends, on a supporting device 3 or 4 respectively, each of which comprises, 
at the back, a roller 5 or 6 respectively which is mounted in a frame 7 or 
8 respectively which extends in a predominantly horizontal plane and forms 
a sensing edge 9 or 10 at the front. The supporting devices 3 and 4 are 
each connected to the levelling rule 2 for adjustment in height through a 
column 11, 12 which is directed predominantly vertically and has a spindle 
13, 14 and a crank handle 15, 16 at the top for the spindle. The frames 7, 
8 are further connected, through links 17, 18, to handles 19, 20 at the 
ends, which enable the device to be handled in an upright attitude. 
The levelling device can now be moved over guiding laths 21, 22, similarly 
to a conventional levelling board, in order, on movement in the direction 
of an arrow 23, to form out of a rough formation 24 in front of the 
levelling device, a smooth formation 25 behind this. Certainly it is no 
longer necessary for the guiding laths or other levelling aids to be sunk 
below the required level of the smooth formation and instead the elevated 
arrangement of the rollers 5, 6 and in particular of the sensing edges 7, 
8 also renders possible the use of higher reference edges. Accordingly, 
the edges of the sett pavements which have already been laid, kerbstone 
edges extending parallel and the like may also be used. The offsetting in 
height between the upper edge of the smooth formation and the upper edge 
of the guiding lath 21 or 22 can be seen, inter alia, from FIGS. 2 and 3, 
and the laths do not need to lie at the same height and instead reference 
heights offset in relation to one another can also be used--particularly 
with various levelling aids. 
During work, both the sensing edge 9 or 10 and the roller 5 or 6 of the 
supporting devices 3, 4 lie on the associated guiding lath 21 or 22, the 
sensing edge 9 or 10 determining the adjustment in height because it is 
adjacent to the lowest region of the levelling rule. In the example of 
embodiment illustrated, the sensing edge executes a scraping movement 
which has the advantage over the rolling motion possible as an alternative 
that sand or the like material of the bed of the sett paving is stripped 
off the guiding lath 21 or 22 on which it is lying. It is understood that 
a two-point support at both sides with levelling rule and roller can also 
be replaced by a single-point support, whether scraping or rolling, 
provided this is arranged substantially perpendicular to the lowest region 
of the levelling rule. Certain variations in the setting angle then do not 
have an appreciable effect on the level of the smooth formation. 
FIG. 2 shows the advantageous shape of the levelling rule which is made 
from a metal plate bent at an angle, particularly for reasons of weight. 
On movement in the direction of the arrow 23, contact of the levelling 
rule 2 is first made by a cutting edge 26 behind which the plate, rising 
obliquely, offers a ramp surface 27. Thus it is possible to lift the sand 
or other bed material of the sett paving above the level line without the 
material being pushed or rolled forwards. A collecting trough 28, which is 
bounded at the back by a back plate 29 set steeply, is formed behind the 
ramp surface 27 to receive the material lifted up. Thus the material can 
be picked up and does not fall back onto the freshly prepared smooth 
formation. 
As soon as the trough is full, the levelling device 1 can be used as a 
whole as a truck and can be moved on the rollers 5, 6 in order to convey 
the excess bed material of the sett paving away. 
The levelling device thus provided is relatively easy to construct as a 
whole, particularly as the middle region of the levelling rule 2, which is 
broken away in the drawing for reasons of illustration, determines the 
greater part of the dimensions. Such a device, which is operated by hand, 
has proved advantageous because it renders easy and neat work possible so 
that the use of mechanical levelling aids, which lead to special problems 
from the point of view of expense and net weight, can be dispensed with. 
The levelling rule can be subdivided in length, the sectional shape 
facilitating an inherently stable, areal connection. The possibility is 
thus also afforded of pushing the divided shaped plates together or 
pulling them apart in order to produce different widths. A preferred form 
of embodiment provides for a trisection of the plates so that a 
symmetrical construction with a centre portion and two lateral portions 
arranged symmetrically in relation to this results for the levelling rule 
2. The connection can be effected by conventional screw connections or 
other clamping devices. It is also possible, however, to fit bracing 
behind the back plate for a spindle or cable line adjustment.