[0001] The present invention concerns an improved dowel device for a concrete machine, in
particular a concrete machine for leveling concrete, of the type whereby poured concrete
is distributed over a pre-determined width and this concrete is skimmed off at a certain
thickness.
[0002] Such concrete machines are used, as is known, for spreading out and smoothing concrete
in order to form a floor, slab, road or the like, whereby specific molded patterns
can be provided in the formed road - either or not simultaneously - such as a gutter,
a standing edge, a concrete guard rail or the like.
[0003] It is known that such concrete machines are usually built of a mobile chassis, under
which a number of tools are fixed, which are designed among others to distribute the
concrete poured in front of the machine, to more or less even it, vibrate it and finally
smooth it out, such that, after the concrete machine has passed, an entirely finished
road is obtained, whereby one only has to wait for the concrete to harden and possibly
provided expansion joints must be filled.
[0004] It is known to equip such concrete machines with a dowel device as well for providing
dowels in the concrete, usually at the expansion joints. Such dowels are reinforcement
rods, usually having a length of about half a meter, which are provided in the longitudinal
direction of the road. Usually, a whole series of such dowels are provided next to
one another, at mutual distances of 20 to 30 cm.
[0005] The dowel devices used hereby are devices which make it possible to provide dowels
at a certain depth in the concrete near vibrating needles with which the concrete
machine is equipped, as a result of which the dowels are embedded well in the concrete.
[0006] Such concrete machines and dowel devices are known from
EP 1.284.323, whereby dowels are loaded in upward directed insertion elements, which insertion
elements are situated at mutual distances from each other and are distributed over
de width of the concrete machine, and whereby the dowels are pushed out of the above-mentioned
magazines into the concrete via an output pipe at the bottom of every insertion element
by means of a push-out mechanism.
[0007] Although these known dowel devices give good results in practice, they are disadvantageous
in that they are relatively complex and sensitive to blocking, due to the fact that,
on the one hand when loading the insertion elements, the falling motion of the dowels
cannot be controlled and, consequently, the dowels can block in the insertion elements
in a slanting position, and on the other hand, the push-out mechanism of every insertion
element does not always exert an axial and centered push-out force on the dowels,
due to the long lever arm of the push-out mechanism on the other hand, as a result
of which obstructions may occur in this case as well.
[0008] Another disadvantage is that with the known dowel devices, the insertion elements
are open at the top, as a result of which dirt and other unwanted elements may fall
in the insertion elements, which may lead to obstructions or blockings.
[0009] The present invention aims to remedy one or several of the above-mentioned and other
disadvantages.
[0010] To this end, the invention concerns an improved dowel device for a concrete machine
which consists of a mobile chassis to which the dowel device is or can be fixed, which
mainly consists of a series of insertion elements for dowels which are erected widthwise
at a distance from one another in the concrete machine, and which consist of a housing
directed upward and in the driving direction of the concrete machine with a first
compartment in which dowels can be stacked and which is provided with an output pipe
for dowels, and a second compartment in which a push-out mechanism for dowels is provided
at the bottom, and whereby both compartments are connected at the bottom via a passage,
characterized in that the push-out mechanism of each insertion element is formed of
a chain which is guided over two chain wheels placed on top of one another and a flexible
blade which is fixed to the chain with one far end and which is provided with a pressure
piece on the other far end, whereby the blade is guided over a guide at the bottom
of the second compartment which bends off the blade through the above-mentioned passage
in the direction of the output pipe.
[0011] An advantage of such a dowel device according to the invention is that it has a relatively
simple construction and occupies relatively little space in the driving direction
of the concrete machine, as a result of which more space remains for other tools.
[0012] Another advantage is that, thanks to the construction of the push-out mechanism,
the forces exerted by the push-out mechanism on the lower dowel in the first compartment
are always axially directed according to the longitudinal axis of the dowel and in
line of the output pipe, as a result of which can be avoided that a dowel might get
stuck in the insertion element while being pushed out.
[0013] The improved dowel device according to the invention is preferably provided with
an automatic loading system to load the dowels in the insertion elements, whereby
this loading system contains a mobile trolley provided widthwise in relation to the
concrete machine above the insertion elements.
[0014] An advantage of such an automatic loading system is that the insertion elements can
be loaded quickly and automatically.
[0015] According to a preferred embodiment, a valve is provided in each insertion element,
at the top, which can receive a dowel falling from the trolley in the insertion element
concerned and which can subsequently drop this dowel in a controlled manner in the
insertion element concerned.
[0016] This valve offers the advantage that the fall of the dowel is interrupted and that
the dowel is first received on this valve so as to stabilize it first and to subsequently,
when it lies still on the valve, be lowered in a soft and controlled manner in the
insertion element, as a result of which the dowel is prevented from getting stuck
in the insertion element during its free fall.
[0017] The valve is preferably a stop valve which can stop up the insertion element so as
to prevent dirt from falling in the insertion element.
[0018] Said valve is also preferably provided with a control element which can work in conjunction
with the above-mentioned trolley, such that when the trolley passes over an insertion
element, a dowel falls in the insertion element.
[0019] The invention also concerns a concrete machine which is equipped with an improved
dowel device as described above.
[0020] In order to better explain the characteristics of the invention, the following preferred
embodiment of an improved dowel device according to the invention and of a concrete
machine which is provided with such a dowel device is given as an example only without
being limitative in any way, with reference to the accompanying drawings, in which:
Figure 1 is a schematic side elevation which represents a partial section of a concrete
machine provided with an improved dowel device according to the invention;
figure 2 represents the section of the dowel device indicated by the frame F2 in figure
1 to a larger scale;
figure 3 represents a section as that in figure 2, but for another position;
figures 4, 5 and 6 represent sections according to the respective lines IV-IV, V-V
and VI-VI of figure 2.
[0021] As is represented in figure 1, the invention concerns a machine, in particular a
concrete machine 1 for forming a concrete road 2 provided with dowels 3.
[0022] The concrete machine 1 mainly consists of a frame 4 which either or not is telescopic
in the width and/or in the length and which is mobile thanks to for example supporting
elements 5 situated on the angular points, which are provided for example with caterpillar
tracks 6, which can be driven by means of engines that are not represented in the
figures.
[0023] To the frame 4 and/or to the supporting elements 5 are in this case fixed several
tools for realizing the concrete road 2.
[0024] Depending on the application, several tools are either or not used.
[0025] In the example of figure 1, these tools respectively consist of schematically indicated
means 7 for spreading concrete 8 poured in front of the concrete machine 1, an improved
dowel device 9 according to the invention for the insertion of the dowels 3, means
10 for vibrating the concrete, one or several moulds 11 and a finishing element 12.
[0026] The means 7 can be of different nature and they may consist for example of a plow
for spreading the concrete 8 and/or of a driven element, such as an Archimedean screw,
for distributing the concrete 8.
[0027] The means 10 for vibrating the concrete preferably consist, as is represented in
figures 1 and 2, of a series of known vibrating needles 13 which reach into the concrete
8 while processing the concrete 8, preferably up to underneath the mould 11.
[0028] The mould 11 actually consists of a large jig with which the concrete is pressed
into a certain shape and is simultaneously provided with a smooth surface. When manufacturing
a conventional concrete road, the mould is made straight, for example as a profile
with a section as represented in figure 1, which extends over the working width of
the concrete machine, in other words over the width of the concrete road to be built.
It is clear that this can have special shapes as well and can be composed of several
parts, for example so as to form a gutter, a standing edge or the like at a concrete
road.
[0029] Moreover, several of such moulds 11 can be used which can be moved along each other,
such that the working width can be adjusted. When discussing a mould 11 hereafter,
it is clear that this also applies to embodiments whereby several of such moulds are
present.
[0030] The finishing element 12 in figure 1 consists of a smoothing board which can be systematically
moved over the formed surface 14 of the concrete road 2.
[0031] Naturally, the means 7 and the finishing element 12 are optional.
[0032] In the given example, the dowel device 9 is situated, according to the driving direction
V of the concrete machine 1, in front of and/or near the mould 11 while concreting.
[0033] As is clearly visible in figure 2, the dowel device 9 contains a tray 15 or U-shaped
guide with a bottom 16 and standing side edges 17, whereby this tray 15 is fixed to
the frame 4 or is suspended to it and extends widthwise in relation to the concrete
machine, and whereby grooves 18 are provided in the bottom 16 which extend widthwise
in relation to the concrete machine 1, in other words crosswise in relation to the
concrete road 2 to be realized, at regular distances from each other, and which are
evenly distributed over the width of the above-mentioned tray 15.
[0034] The dowel device 9 contains a series of insertion elements 19 for dowels 3 which
make it possible to insert dowels 3, when forming the concrete road 2, in the liquid
concrete 8, whereby each of these insertion elements 19 is provided under an above-mentioned
groove 18.
[0035] The insertion elements 19 and the vibrating needles 13 are alternately erected next
to each other, as is clearly represented in figure 4.
[0036] As is represented in the figures 2, 5 and 6, the insertion elements 19 consist of
upward directed elements, each with a housing 20 of a limited width which extends
mainly in a vertical plane, parallel to the driving direction V of the concrete machine
1, whereby every insertion element 19 is fixed to the above-mentioned bottom 16 of
the tray 15, at the top, via a conical part 21.
[0037] The insertion elements 19 are fixed to the tray 15 in such a manner that, while the
concrete machine 1 is in use, at _least during the periods in which dowels 3 must
be provided in the concrete 8, they extend into the concrete 8 more particularly they
are situated with their bottoms 22 of the housing 20 in the concrete 8.
[0038] Said insertion elements 19 each contain two compartments, a first compartment 23
on the one hand which serves as a magazine and in which dowels 3 can be horizontally
stacked, and a second compartment 24 on the other hand which is connected to the first
compartment 23 via a passage 25 at the bottom.
[0039] The first compartment 23 is provided at the bottom on the back wall 26 of the housing
20 of each insertion element 19 with an output pipe 27 which mainly extends in the
driving direction V of the concrete machine 1 and which forms a passage through which
the dowels 3 can be axially pushed from the first compartment 23 into the concrete
8.
[0040] On the free end of the output pipe 27 is provided a bush 28 which is provided at
its inner wall with a silicone coating 29 which can form a sealing around a dowel
3 which is pushed outward, in order to prevent concrete 8 from penetrating into the
insertion element 19 via this output pipe 27.
[0041] In the second compartment 24 of each of the insertion elements 19 is provided a push-out
mechanism 30 which makes it possible to push the dowels 3 out of the first compartment
23 via the output pipe 27 into the liquid concrete 8.
[0042] The push-out mechanism 30 in this case consists of a chain 31 which is guided over
two chain wheels 32 and 33 placed on top of each other, in this case vertically on
top of each other, which are each bearing-mounted in the housing 20 in a rotating
manner, and whereby a flexible blade 34 is fixed to the outside of the chain 31, for
example made of spring steel, in this case by means of screws or bolts 35 which are
screwed through the far end of the blade 34 and through the chain 31 in a stop block
36.
[0043] The above-mentioned blade 34 made of spring steel extends vertically against the
chain 31 and is guided with its free end, which is provided with a pressure piece
37 over a bent guide 38 at the bottom of the second compartment 24, such that this
free end extends horizontally opposite the passage 25 between the first and the second
compartment, 23 and 24 respectively, as is represented in figure 2 and bends off the
blade 34 through the passage 25 in the direction of the output pipe 27, in particular
in the direction of the extension of the output pipe 27, preferably in a direction
in the extension of the bottom 22 of the insertion element 19.
[0044] On the inside of the chain 31 is provided a stop slat 39 with two stop-forming far
ends 40 and 41, such that the chain 31 with its stop block 36 can move to and fro
between these two stop-forming far ends 40 and 41, in particular between a first farthest
position, as represented in figure 2, whereby the stop block 36 is situated against
the top stop-forming far end 40, and the blade 34 is entirely withdrawn in the second
compartment 24, and a second farthest position where the stop block 36 touches the
bottommost stop-forming far end 41 and the blade 34 extends horizontally with its
free end over a certain length in the first compartment 23 as represented in figure
3, preferably with the pressure piece against or practically against the output pipe
27.
[0045] The push-out mechanism 30 comprises, as represented in figure 6, a drive 42 which
in this case is common to all insertion elements 19 and which is formed of a common
shaft 43 which is in this case formed of a series of pieces connected to each other
and which extends in the width of the tray 15 through the second compartments 24 of
the insertion elements 19 and onto which the topmost chain wheel 32 of each of these
insertion elements 19 is fixed.
[0046] The above-mentioned shaft 43 is driven via a central motor 44 and one or several
drive belts or chains 45, whereby this motor 44 is electrically connected to a control
box 46 which can drive the motor 44 in both directions of rotation.
[0047] In the front wall 47, in the extension of the above-mentioned output pipe 27, is
provided a control opening 48 which can be sealed by means of a stop 49.
[0048] The dowel device 9 is further provided with an automatic loading system 50 in the
form of a trolley 51 with wheels 52 provided in a mobile manner in the above-mentioned
tray or gutter-shaped guide 15 and which can be moved to and fro between the standing
side edges 17 of this tray or guide 15, widthwise in relation to the concrete machine
1, whereby this trolley 51 is provided with a drive which is not represented in the
figures and whereby the standing side edges 17 form a guide for the trolley 51.
[0049] The trolley 51 is made tub-shaped with standing walls 53 and a bottom 54 which slants
down widthwise in relation to the concrete machine 1 which is fixed with one end to
an above-mentioned standing wall 53 and which rests with its other end on a key-shaped
element 55 whose width A is larger than the width B of the grooves 18 and which, together
with the trolley 51, moves over or right above the bottom 16 of the tray 15.
[0050] The trolley 51 is provided, on the lower edge of the slanting bottom, with a groove-shaped
outlet 56 whose width essentially corresponds to the thickness of the dowels 3 and
through which the dowels 3 can fall out of the trolley 51 via the above-mentioned
grooves 18 on the bottom 16 of the tray 15 in the insertion elements 19.
[0051] The groove 56 is in this case formed between the free edge of the bottom 54 and the
opposite standing wall 53 onto which, above this groove 56, is provided a guiding
strut 57 with a triangular cross section.
[0052] In each of the insertion elements 19 is provided a valve 58 to collect dowels 3 falling
from the trolley 51 in the insertion element 19 concerned, to stabilize them and subsequently
drop them in a controlled manner in the insertion element 19.
[0053] In the given example, the valve 58 is a stop valve in the form of an angle section
with legs 59 and 60 which is hinge-mounted in its longitudinal direction around a
shaft 61 and which can hinge between two extreme positions, namely a first position
in which, as is represented in figure 5 for the left insertion element, the first
compartment 23 is sealed by means of the leg 59 and the leg 60 is directed upward,
and a second position in which, as is represented for the other two insertion elements
of figure 5, the leg 59 is tilted downward so as to open the compartment 23, whereby
the first compartment 23 is sealed in this position by means of the other leg 60.
[0054] Thus, in both positions, the compartment 23 is sealed, thus preventing dirt from
falling in this compartment 23, which would entail the risk for the dowels 3 to become
blocked in an unwanted position in the insertion element 19 due to the dirt.
[0055] The valve 58 is provided with a control element 62 in the form of a lip which can
work in conjunction with the trolley 51 so as to move the valve between the above-mentioned
extreme positions and which is positioned such that it rests on the bottom 16 of the
tray 15 in the first position of the stop valve 58 and that it is directed upward
in the second position of the stop valve 58 and extends above the bottom 16 of the
tray 15 so as to be able to work in conjunction with the key-shaped element 55 of
the trolley 51.
[0056] Further, the dowel device 9 of the concrete machine 1 can be equipped with a detection
device which is not represented in the figures and which can work in conjunction with
elements erected next to the concrete road 2 to be formed, for example pegs provided
especially to that end, and which can activate the drive 42 of the push-out mechanism
30 and the drive of the trolley 51 in an appropriate sequence.
[0057] The working of the concrete machine 1 and in particular of the dowel device 9 can
be easily derived from the figures and is mainly as described hereafter.
[0058] First, the trolley 51 is filled with a required number of dowels 3 which are stacked
on the downward slanting bottom 54 of the trolley 51.
[0059] Next, the compartments 23 of the insertion elements 19 are filled by moving the trolley
51 to and fro over the width of the tray 15, whereby, when the trolley 51 moves to
the right and the key-shaped element 55 moves over the insertion elements 19, the
stop valves 58 are tilted in their first position and whereby, when the groove 56
of the trolley 51 is situated above the insertion element 19 concerned, a dowel 3
falls onto the leg 59 which in this position seals the compartment 23 of the insertion
element 19.
[0060] When the trolley 51 moves further to the right, the control element 62 in the form
of a lip will no longer be stopped by the key-shaped element 55, and the leg 59 of
the stop valve 58 will be able to tip over due to the weight of the dowel 3, as a
result of which the dowel 3 concerned falls in the first compartment 23 of the insertion
element 19 in a controlled manner.
[0061] An advantage of this valve 58 is that, before the dowel 3 falls in the first compartment
23 of the insertion element 19, the dowel 3 is first stabilized on the valve 58, thus
preventing the dowel 3 from moving slantingly in the insertion element 19 during its
falling motion, thus blocking the lead-through of dowels 3.
[0062] Optionally, on the inside of the back wall 26, is provided a slanting guide 63 which
makes sure that the dowel 3 ending up on the bottom 22 is situated at a distance from
the above-mentioned back wall 26, so as to prevent that this dowel 3 might end up
on a dowel 3 which had been previously provided in the output pipe 27.
[0063] While loading the insertion elements 19, the blades 34 of the push-out mechanism
30 are entirely withdrawn in the second compartment 24, thus preventing the dowels
3 from ending up on the pressure piece 37 while they are being loaded, as a result
of which they would be directed slantingly, which would hinder the good working of
the dowel device 9.
[0064] It is clear that, thanks to a to-and-fro movement of the trolley 51, the insertion
elements 19 can systematically be filled with a required number of dowels 3.
[0065] The speed of the trolley 51 is selected such that each time an insertion element
19 is being passed, only one dowel 3 at a time ends up in the insertion element 19.
[0066] Once there are a sufficient number of dowels 3 in the insertion elements 19, the
push-out mechanisms 30 of the insertion elements 19 are moved to and fro once by activating
the motor 44 of the common drive 42.
[0067] To this end, the motor 44 is first activated in one sense of rotation, as a result
of which the shaft 43 is turned and the chains 31 of the push-out mechanism 30 are
driven, such that the blades 34 made of spring steel are pushed down by the chains
31 and the pressure piece 37 of each of said blades 34 is moved over the bottom of
the insertion elements 19 by the bent guide 38, thereby pushing the lower dowel 3
out of the compartment 23 in the output pipe 27.
[0068] The form of the pressure piece 37 is preferably such that it can hold the front end
of a dowel 3, in order to make sure that the lower dowel 3 which is moved by the push-out
mechanism is pushed in the axial direction in the output pipe 27, thus preventing
blockages.
[0069] After the dowel 3 has been pushed in the output pipe 27, the motor 44 is activated
in the other sense of rotation, as a result of which the blades 34 and the pressure
pieces 37 are withdrawn in the second compartment 24 in the reverse sense and as a
result of which the stacked dowels 3 drop to the bottom 22 of the insertion element
19.
[0070] This creates a condition which is ready for use as is represented in figure 3, whereby
two dowels 3 are situated in line, one after the other, one of which is situated in
the output pipe 27, ready to be inserted in the concrete 8.
[0071] When forming the concrete road 2, concrete 8 is poured in front of the concrete machine
1. This concrete 8 is first spread out roughly by the above-mentioned means 7, after
which, by means of the mould 11, the actual concrete road 2 is formed. By means of
the finishing element 13 can be carried out an additional smoothing operation.
[0072] As soon as the concrete goes under the mould 11, it is vibrated by means of the vibrating
needles 13, as a result of which the concrete is made compact and homogenized.
[0073] During the concreting, the insertion elements 19 slide through the concrete 8.
[0074] When a series of dowels 3 is to be inserted, this is done in the manner as is systematically
represented in the figures 2 and 3, whereby while moving the concrete machine 1 in
the driving direction V, the push-out mechanisms 30 of the insertion elements 19 are
simultaneously activated as described above.
[0075] As a result, the lower dowel 3 is pushed in the first compartment 23 of each insertion
element 19 in the output pipe 27, such that the dowel 3 which is situated in the output
pipe 27 at that time is in turn pushed out of the output pipe 27 into the liquid concrete
8.
[0076] The control box 46 is set such that the speed at which the drive 42 controls the
push-out mechanisms 30 is synchronized with the driving speed of the concrete machine
1, as a result of which the dowels 3 stay in place in relation to the environment
as if it were.
[0077] Thus, the released dowels 3 that are inserted in the concrete 8 are systematically
enclosed by the concrete in their longitudinal direction, whereby, partly due to the
effect of the vibrating needles 13, a sound compaction of the concrete 8 round the
dowels 3 is obtained.
[0078] After a first series of dowels 3 has been inserted, the common drive 42 of the push-out
mechanisms 30 is excited in the reverse sense, as a result of which the blades 34
of the push-out mechanisms are drawn back into the second compartment 24 and are prepared
to push a following series of dowels 3 in the concrete in an analogous manner as described
above, after the concrete machine 1 has moved somewhat.
[0079] It goes without saying that the concrete machine 1 and the dowel device 9 can be
operated manually, but that the whole operation of building a concrete road 2 is preferably
done entirely automatically, whereby the above-mentioned control box 46 will then
control the concrete machine 1 and the dowel device 9 in an appropriate manner as
a function of the signals of the above-mentioned detection device which can work in
conjunction with pegs that are erected at regular distances from one another along
the trajectory of the concrete road 2 to be built, so as to indicate in which places
dowels 3 must be inserted in the concrete 3.
[0080] Although the dowels 3 are preferably inserted parallel to the driving direction V
of the concrete machine 1, it is not excluded to realize this at a slight angle of
for example 15.
[0081] It is clear that the loading system 50 can be omitted in a simpler embodiment of
the dowel device 9 and that the insertion elements 19 can be manually preloaded with
a required number of dowels 3.
[0082] It goes without saying that the valve 58 can be realized in other forms and that
also the control thereof through the movement of the trolley 51 can be realized in
other ways.
[0083] Moreover, said valve 58 must not necessarily entirely seal the first compartment
23 of an insertion element 13, but it may be sufficient for the insertion element
19 to be sealed only partly, but to a sufficient degree so as to be able to collect
a dowel 3 from the trolley 51 and to be able to stabilize it before it enters the
insertion element 19.
[0084] Naturally, instead of a trolley 51, use can also be made of a carriage for loading
the dowels 3.
[0085] The present invention is by no means limited to the embodiment given as an example
and represented in the accompanying drawings; on the contrary, such a dowel device
according to the invention and a concrete machine provided with such a dowel device
can be made in all sorts of shapes and dimensions while still remaining within the
scope of the invention.
1. Improved dowel device for a concrete machine which consists of a mobile chassis to
which the dowel device (9) is or can be fixed, which mainly consists of a series of
insertion elements (19) for dowels (3) which are erected widthwise in relation to
the concrete machine at a distance from one another, and which consist of a housing
(20) directed upward and in the driving direction (V) of the concrete machine (1)
with a first compartment (23) in which dowels (3) can be stacked and which is provided
at the bottom with an output pipe (27) for dowels (3), and a second compartment (24)
in which a push-out mechanism (30) for dowels (3) is provided, and whereby both compartments
(23-24) are connected at the bottom via a passage (25), characterized in that the push-out mechanism (30) of each insertion element (19) is formed of a chain (31)
which is guided over two chain wheels (32-33) placed on top of one another and a flexible
blade (34) which is fixed to the chain (31) with one far end and which is provided
with a pressure piece (37) on the other far end, whereby the blade (34) is guided
over a guide at the bottom of the second compartment which bends off the blade (34)
through the above-mentioned passage (25) in the direction of the output pipe (27).
2. Improved dowel device for a concrete machine according to claim 1, characterized in that one of the chain wheels (32-33) is provided with a drive (42) to move the pressure
piece (37) of the push-out mechanism (30) at least between a first extreme position
in which the blade (34) and the pressure piece (37) are entirely withdrawn in the
second compartment (24) and a second extreme position in which the blade (34) extends
in the first compartment (23) with the pressure piece (37) up against or practically
against the output pipe (27).
3. Improved dowel device for a concrete machine according to claim 2, characterized in that the above-mentioned extreme positions of the push-out mechanism (30) are determined
by a stop block (36) which is fixed to the chain and two stop-forming elements (40-41)
working in conjunction with it.
4. Improved dowel device for a concrete machine according to any one of the preceding
claims, characterized in that the top chain wheels (32) of the insertion elements (19) are provided on a common
shaft which is driven by a common drive (42).
5. Improved dowel device for a concrete machine according to any one of claims 2 tot
4, characterized in that the above-mentioned drive (42) is electrically connected to a control box (46) which
is such that when the drive (42) is activated for pushing out the dowels (3), the
speed at which the dowels 3 are pushed out of the insertion elements 19 is equal or
practically equal to the driving speed of the concrete machine (1).
6. Improved dowel device for concrete machine according to any one of the preceding claims,
characterized in that the form of the pressure piece (37) is such that it can hold a dowel (3) at its far
end.
7. Improved dowel device for a concrete machine according to any one of the preceding
claims, characterized in that the blade (34) is made of spring steel.
8. Improved dowel device for a concrete machine according to any one of the preceding
claims, characterized in that it is provided with an automatic loading system (50) for loading the dowels (3) in
the insertion elements (19).
9. Improved dowel device for a concrete machine according to claim 8, characterized in that the loading system (50) comprises a trolley (51) with a bottom (54) slanting down
widthwise in relation to the concrete machine (1) and a groove-shaped outlet (56)
for the dowels (3), which trolley (51) can be moved to and fro, widthwise in relation
to the concrete machine (1), on the bottom (16) of a tray or guiding gutter (15) which
is fixed or can be fixed to the concrete machine (1) and onto which the above-mentioned
insertion elements (19) are fixed, each time under a groove (18) in the bottom (16)
through which the insertion element (19) can be loaded.
10. Improved dowel device for a concrete machine according to any one of claims 8 or 9,
characterized in that in each insertion element (19) is provided a valve (58) at the top which can receive
a dowel (3) which falls from the trolley (51) in the insertion element (19) concerned
and which can subsequently drop this dowel (3) in a controlled manner in the insertion
element (19) concerned.
11. Improved dowel device for a concrete machine according to claim 10, characterized in that the above-mentioned valve (58) is a stop valve which seals the insertion element
(19) at the top.
12. Improved dowel device for a concrete machine according to any one of claims 10 or
11, characterized in that the valve (58) is formed of an angle section with legs (59-60) which is hinge-mounted
around a shaft (61) in its longitudinal direction and which is hinge-mounted between
a position in which the first compartment (23) is sealed by means of one leg (59)
and a second position in which this leg (59) is tilted downward and the other leg
(60) seals the first compartment (23).
13. Improved dowel device for a concrete machine according to claim 12, characterized in that the valve (58) is provided with a control element (62) which can work in conjunction
with the trolley (51) so as to move the valve (58) between the above-mentioned extreme
positions when the trolley (51) is moved over the insertion element (19) concerned.
14. Improved dowel device for a concrete machine according to claim 13, characterized in that the control element (62) is formed of a lip which is fixed to the valve (58) in such
a manner that, in the first position of the valve (58), it rests on the bottom (16)
of the tray (15), and in the second position of the valve (58) it is directed upward
and extends above the bottom (16) of the tray (15) so as to be able to work in conjunction
with the trolley (51).
15. Improved dowel device for a concrete machine according to claim 14, characterized in that the trolley (51) is equipped with an element (55) which moves over or right above
the bottom (15) and which can work in conjunction with the above-mentioned control
element (62).
16. Improved dowel device for a concrete machine according to claim 15, characterized in that the above-mentioned element (55) is a key-shaped element on which the above-mentioned
inclined bottom (54) of the trolley (51) rests.
17. Concrete machine, characterized in that it is provided with a dowel device (9) according to one or several of the preceding
claims.