Tractor-drawn forming tool for making concrete slabs on the ground

A forming tool made to be drawn by tractor-feeder means of any type. The tool comprises two arms mounted to pivot by their front ends on the tractor-feeder. At the back end of the arms is mounted a needle ramp for immersion vibration so as to keep the concrete delivered and distributed by the tractor-feeder in the liquid state before its forming. The forming means comprise an upper element which has a front part in the form of a shield for the regulation of the amount of concrete introduced under the form, and a back part serving as forming upper plate and simultaneously as back reference and support means for levelling the tool, the latter being entirely carried by the formed concrete layer. Side forming plates are also provided.

FIELD OF THE INVENTION 
The present invention relates to tools for making concrete slabs for roads 
or the like, and more to particularly to a forming tool of the sliding 
form type. 
BACKGROUND OF THE INVENTION 
Machines known as sliding form machines are already known in the art in 
which a predetermined amount of cement concrete is deposited on the ground 
by feeder means, then subjected to a forming under vibration using upper 
and side form plates mounted solid with the frame. 
However, in this type of machine the concrete layer is made between the 
supports of the machine, which requires the use of a tractor unit of the 
straddling type, whose side bulk is disadvantageously great. This type of 
machine therefore imposes a limit on the width of the slab to be made 
which is compatible with the tractor path itself, except for major 
mechanical interventions. 
Moreover, this type of requires a complex altimetric guide system with a 
minimum of four height-adjusting jacks which act as rigid connections 
between the sliding form and the frame of the machine. These jacks are 
provided to compensate for the defects of the traveling surface of the 
tractor unit, by preventing these defects from impacting on the quality, 
or smoothness, of the layer of concrete formed. In particular, such a 
system is most often poorly suited to compensating for sudden movements or 
impacts, both vertical and horizontal, exerted on the machine. 
SUMMARY OF THE INVENTION 
It is an object of this invention to alleviate these drawbacks and to 
provide a molding tool of the sliding form type with which a concrete slab 
exhibiting a satisfactory smoothness can be made simply and efficiently. 
Another object of this invention is to provide a piece of equipment for 
molding with sliding form which can be easily adapted to any 
tractor-feeder unit whatsoever, and particularly nonstraddling type. 
Therefore, slabs of any width can be made totally independent of the 
crosswise dimensions of the tractor-feeder unit. 
For this purpose, this invention relates to a forming tool of the sliding 
form type made to be tractor-drawn by any tractor-feeder unit able to 
deposit the concrete on the ground in a predetermined amount, 
characterized in that it comprises: 
two hitching arms able to be mounted to pivot at their front end, for 
traction; 
immersion vibration means mounted downstream from the tractor-feeder unit 
and made to subject the concrete to a vibration; and 
forming means resting by their own weight on the formed concrete slab, 
comprising side elements for confinement of the concrete and an upper 
element consisting of a front part mounted rigidly in the region of the 
back end of the arms downstream from the immersion vibration means and 
forming a regulator of the amount of formed concrete, and of a back part 
simultaneously forming an upper molding plate and back reference and 
support means for carrying said tool, which is thus carried by the formed 
concrete slab.

With reference to the drawing, and first in FIG. 1, a molding tool for 
making concrete slabs, particularly for roads and the like, is shown in 
the form of a unit made to be tractor-drawn by a tractor-feeder piece of 
equipment of any type whatsoever, not shown. Purely by way of example, the 
tractor-feeder piece of equipment will be able to take the form of a road 
machine having a cement concrete receiving hopper, conveyor or other means 
for conveying the concrete to the ground at the back of the machine, and 
means for spreading or distributing the concrete in a relatively uniform 
way on the ground, for example, with crosswise Archimedes' screws. 
Thus the unit or moding tool according to the invention comprises two 
longitudinal side hitching arms 24 which are made to insure the connection 
between the frame of the tractor-feeder device with which it is associated 
and the actual elements of the tool. More precisely, and also with 
reference to FIG. 2, each hitching arm 24 exhibits at its front end, on 
the left in FIG. 1, hooking means consisting of a longitudinal tie rod 26 
which goes through a vertical slide 28 made in an angle bracket 30 which 
is either integral with the frame of the above-mentioned device, or added 
to it and fastened in place by any suitable means such as welding, 
bolting, etc. Tie rod 26 comprises two parts 31, 32 in side projection and 
longitudinally separate, between which angle bracket 30 is held, 
projecting part 31 of course being removable and fastened in place after 
the insertion of the free end of tie rod 26 in slot 28. Thus, for purposes 
explained in detail later on, a hitching is defined (the traction being 
performed by cooperation between projecting part 31 and slide 28) provided 
with certain degrees of freedom vertically and horizontally. Further, 
close to part 32 is provided a fork 33 (FIG. 2) for mounting the lower end 
of a height-adjusting jack 34 (FIG. 1), whose upper end will be fastened 
to the frame of the tractor-feeder device. In certain cases, jack 34 can 
be replaced with a simple height-adjusting device such as a crank or the 
like. 
The forming tool itself consists of the following elements: 
immersion vibration means which is this embodiment exhibit the form of a 
vibration needle ramp, diagrammatically indicated as 40, said ramp being 
fastened to the back end region of hitching arms 24 with suitable 
standards 41; these needles 40, no longer desribed in detail because they 
are standard, are made to keep the cement concrete in the liquid state 
just before its molding by means described below; and 
molding a mold or sliding mold which comprises an upper horizontal molding 
element 42 and, in this example, two side molding plates 44a and 44b. 
Upper molding element 42, as FIG. 3 shows more in detail, has a front part 
46 which exhibits the form of a rigid shield exhibiting a lower leading 
edge, or front nose 47, made as will be seen in greater detail below to 
regulate the introduction of concrete, accumulated in sufficient amount at 
45, in the molding means. Front shield 46 is mounted rigidly on the back 
part of hitching arms 24 by two vertical standards 50, welded and/or 
bolted on the arms. 
Upper molding element 42 further comprises a back plate-shaped part 48 
which performs the forming itself. Back plate 48 is made to be able to 
take a certain longitudinal inclination in relation to the rigid part of 
shield 46, for purposes explained below. This degree of freedom of 
articulation can be assured in any manner (not shown in detail). For 
example, there can be provided between the back edge of part 46 and the 
front edge of part 48 a hinge mechanism, diagrammatically indicated as 49 
in FIG. 3. Another possibility, shown in FIG. 4, consists in designing 
parts 46 and 48 as one piece, providing, however, at the connection of 
said parts a zone of thickness sufficiently small to allow a certain 
angular clearance of part 48 in relation to rigid part 46. 
Between back plate 48 and the back end of hitching arms 24 are provided 
support means, made to keep said plate 48 in correct alignment in relation 
to molded concrete layer 51 (FIG. 3), to give the tool according to the 
invention its self-supported characteristic. However, it is understood 
that the vertical distance between this back plate 48 and the back ends of 
arms 24 varies when the angle between shield 46 and plate 48 varies. 
Therefore, for the support means there will be provided a device with 
hydraulic jacks, indicated as 52, or further, a device with compression 
springs, so that this support (more precisely the transmission to arms 24 
of the reaction force exerted on the tool by freshly deposited concrete 
layer 51) is assured regardless of the vertical distance mentioned above. 
As has been mentioned, the molding means comprise in this embodiment two 
side molding plates 44a and 44b. As FIG. 1 shows, side plate 44a is 
approximately rectilinear, while plate 44b exhibits a set back, indicated 
as 44b', thus extending the mold laterally to the outside in relation to 
the associated arm. This illustrates the fact that the side molding plates 
can take any desired shape to obtain a form of any width, greater or less 
than the space between the two hitching arms 24. 
Each side plate 44a, 44b is mounted on the tool with vertical play, for 
purposes explained below. More specifically, the front part of each side 
plate has a small tongue 56 directed upward and made to slide vertically 
in an associated housing made in an intermediate region of associated arm 
24. Further, diagrammatically indicated as 58 are assembly means with 
vertical sliding of the back region of each side plate 44a, 44b on the 
side of rigid shield part 46 of the upper forming element. Of course in 
the case of widening a road, the molding plate located on the side of the 
existing road will be eliminated, its role then being performed by the 
side edge of said road. 
Finally, and optionally, the concrete tool according to the invention 
comprises altimetric guide means in the form of a crank feeler 66 which is 
mounted to swivel in a stationary box 68 mounted to project in relation to 
associated arm 24 by two standards 70 and 72 arranged in a "V." A guide 
wire (not shown) is stretched along the entire path that the tool 
associated with its tractor-feeder device must travel and cooperates with 
feeler 66, in a standard way, to provide constantly in real time position 
information representative of the variations in height of the front part 
of the hitching arms in relation to the reference height defined by the 
guide wire, to act, for example by a standard associated chain, on the 
height of the hitching point of associated arm 24 on the frame of the 
tractor-feeder device, by jack 34 described about. In case it is provided, 
this altimetric guide means could either be rounded out by an identical 
means (not shown) associated with the other arm, or by a swinging device 
(also not shown because it is standard). 
The concrete tool as described above functions in the following way: 
First, a tractor-feeder device of any type, to which the tool is hitched, 
deposits and distributes upstream from this latter a suitable amount of 
concrete cement, indicated as 45 in FIG. 3. The hitched tool advancing in 
the direction of arrow 18, while being drawn as has been said by its two 
arms 24, the concrete is first subjected to the action of immersion 
vibration needles 40, in a standard manner, to keep it in a relatively 
liquid state until the time of molding. Then the concrete is introduced 
into the molding part itself, consisting of upper element 42 and side 
plates 44a and 44b. For this purpose, front nose 47 serves as a device for 
metering or regulating the amount of concrete introduced into the mold, to 
give the tool a self-levelling characteristic. Actually, with reference to 
FIG. 3, it is understood that any lowering of the hitching point of arms 
24, for example when a descent is begun, causes a corresponding lowering 
of shield 46, and therefore of solid front nose 47 (positions in broken 
lines indicated as 46' and 47'), thus to reduce gradually the thickness of 
formed concrete layer 51. 
Moreover, during all these movements of part 46 of upper forming element 
42, whether they are planned or accidental (for example, during the 
presence of unevennesses on the traveling path of the tractor-feeder 
device), it is understood that the angular clearance mentioned above 
between parts 46 and 48 makes it possible for part 48, which constitutes 
the upper molding part itself of the tool, to maintain an orientation that 
is approximately parallel to the upper surface of concrete layer 51, to 
assure satisfactorily the support of the tool simply by said layer 
(self-supporting or floating characteristic), by support means 52 with 
compensation for variation in height as described above. Moreover, this 
solution makes it possible to make a concrete slab of extremely 
satisfactory smoothness, no defect being able to be created at its upper 
surface by unwanted movements of said back molding plate 48, on the 
contrary in addition to serving as a means of support for the tool on the 
concrete layer, serving as a means for smoothing said layer. 
The tool according to this invention thus appears in the form of a 
self-supporting and smoothing form, thanks to the specific shape used for 
upper molding element 42. 
Moreover, it can be noted that the possible longitudinal impacts to which 
the device which pulls the tool will be subjected will advantageously not 
be transferred to the tool itself, thanks to the horizontal play mentioned 
above which is allowed by the design itself of the elements for attaching 
the arms to said device. Also, the vertical clearance allowed for side 
plates 44a and 44b advantageously makes it possible to free the form from 
the unevennesses of the ground in the region of the contact, by gravity, 
of said plates with the ground. 
Of course, this invention is absolutely not limited to the embodiment 
described in detail above, but includes any variant or modification that a 
person skilled in the art can bring to it. 
In particular, the tool can easily be adapted to making concrete slabs of 
any crosswise shape, particularly roof or gutter shape. In this case, an 
upper molding element having a shield in two parts slightly inclined to 
one another will be provided. The unwanted gap which then can appear 
between the two corresponding parts of the back plate for certain relative 
longitudinal inclinations can be prevented by the use of a continuous, 
flexible sheet, of plastic or the like, which will extend along the entire 
lower surface of the upper forming element and will advantageously smooth 
out the various unevennesses that can be present on said low surface 
because of the deformable character of said upper element. 
Of course, such a flexible sheet can also be used in the tool as described 
above. In particular, it will make it possible to prevent an excessive 
inclination between the two parts 46 and 48 from damaging the upper 
surface of the formed concrete layer, by rounding the edge associated with 
such an inclination. 
Moreover, the tool as described, and more particularly needle ramp 40, 
upper forming element 42, and side forming plates 44 can be designed in 
modular fashion to be able to cause its width easily to vary by simple 
addition or elimination of sections of elements bolted to one another. 
Further, the self-levelling ability in certain cases makes it possible to 
do without the altimetric guide means as described above. 
It will be noted that the internal vibration means as described above can 
be replaced by any suitable external vibration device. 
Finally, according to a variant embodiment, the crosswise position of the 
forming tool can be made to vary in relation to the feeding tractor device 
by installing, for example on an arm 24 as indicated in FIG. 1, a jack 74 
whose end 76 is secured to the tractor device. Jack 74 is controlled by a 
guide wire (or any other longitudinal reference system)--not shown 
here--which makes it possible for the mold, according to the same 
operating principle as said combination of elements 34 and 66, to follow a 
different path from that of the tractor device. This improvement makes it 
possible, during the placing on the ground of concrete slabs, to assure a 
very precise joint between two adjacent slabs.