Note: Descriptions are shown in the official language in which they were submitted.
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The invention relates to apparatus for transporting
and laying substantially slab-like road-surfacing elements.
Usually, slab-like road-surfacing elements are laid
on to a bed of sand which has previously been made level,
while maintaining the joints in relation to adjacent
elements as uniform as possible. Known laying apparatus
;-~ for transporting and laying slab-like road surfacing
elements has comprised a wheel-mounted frame carrying a
rocking arm from which ~s suspended tongs for gripping a
surface element or elements. Since it has been recognised
that the road-surfacing elements shoul~ be lowered to their
required positions as far as possible vertical;jr so that
more uniform joints may be established and impacts with
~ slabs which have already been laid are avoided, care has
; 15 been taken to have the pi~ot point of the rocking arm as
far as possible away from the tongs. As a result, the
lowering operation takes place with a relatively large
swinging radius.
However, it has been found in practice that even an
enlarged swinging radius does not permit neat, vertical
laying movement of the elements and consequently accurate
positioning of the slabs is not generally possible.
It is an object of the invention to provide trans-
porting and laying apparatus, which permits a satisfactory,
vertical lowering movement with the positioning of slab-
like road surfacing elements and the like.
Apparatus for transporting and laying road surfacing
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elements of substantially slab-like form comprises, accord-
ing to the invention, a wheel- or roller-mounted frame
capable of limited tilting movement about an axis of the
wheels or rollers; and outwardly extending cantilever arm
and a handle mounted on the frame at opposite ends thereof;
said arm being movable substantially vertically relative to
the frame; tongs for gripping the surfacing elements
carried by the cantilever arm; an energy storage device
mounted on the frame and connected to the cantilever arm so
that lowering of said arm by the weight of a surfacing
element carried by the tongs acts to store energy usable
for subsequently causing return upward movement of the arm
when the surfacing elenRnt has been released by the tongs;
and a control device on the handle for controlling vertical
movement of the arm.
It is by these means that, for the first time, a
working principle which has long been considered to be
desirable is achieved. The operator is now àble accurately
to position the apparatus with the slab which is carried
by the latter and deposit it exactly at the prescribed
position. This provides accurate joints and a clean laying
of the slabs, both as regards the lateral spacings of the
slabs and also horizontal alignment.
Several possibilities are offered as regards
carrying out in practice the solution provided by the
invention. In one constructional example which is explained
in the following description, the cantilever arm is guided
in a linear guideway and the tongs are directly arranged on
the free end thereof.
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In the preferred constructional form, a traction cable
may be connected at one end to the vertically movable canti-
lever arm and at the other end to the frame and guided
over a displaceably mounted pulley, which is coupled to the
;; energy-storing device. In this case, the mounting of the
~ pulley may guide the latter in the direction of the linear
; guideway.
The exchange of energy between the energy-storing device
and the arm may, for example, be effected by way of a
hydraulic transmission with a pair of hydraulic cylinders,
which are in communication with one another. One of the
` hydraulic cylinders may be combined with the displaceable
guiding means of the pulley and the other hydraulic cylinder
may be combined with the energy-storage device.
For retarding the movements which occur upon exchange of
energy between the arm and the energy-storage device, a
brake which is controlled by the control member may
advantageously be employed. By way of example, this brake
may be a friction brake, which is operative on a brake disc
driven from the guide means of the pulley. As an alternative,
the brake may also be formed as a throttle device in the
connecting pipe between the two hydraulic cylinders.
It is possible to employ self-clamping tongs of a
design known per se, in which the two clamping jaws are
fixed on the lower ends of intersecting arms of the tongs,
the arms being mounted to be rotatable about a common pivot
at a point of intersection connected to the cantilever arm.
According to another particularly preferred constructional
form of the invention, tongs are used of which the two
clamping jaws are each arranged on the bottom ends of tong
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arms which intcrsect which not being connected to each
other and which are rotatably mounted below the point of
intersection, each about its own individual pivot axis, the
pivots extending parallel to one another. In this con-
structional form, the upper ends of the tong arms are like-
wise so pivotally connected to the cantilever arm that the
clamping jaws, by a rotational movement about their own
pivots which are separate from one another, are moved
towards one another and clamp the element which is to be
laid. Preferably, the two individual pivots are positioned
relatively to one another by at least one connecting
rod with a spacing which is prescribed by the shape of the
surfacing element to be laid. For increasing the clamping
pressure, the pivots by which the connecting rod and the
arms of the tongs are pivotally connected to one another
are disposed near the clamping jaws of the tongs. As a
result, the distance covered by the clamping jaws for
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tightly clamping the element to be laid is reduced and the
clamping forces which become operative with this reduced
travel is increased. The clamping action can thereby be so
greatly increased that it is possible to pick up safely
and reliably composite slabs consisting of a number of
individual blocks which are interlocked. Such composite
slabs are usually manufactured in integral form with the
individual blocks secured temporarily together by readily
broken webs, in order to facilitate their transport and
laying, those webs being ruptured after laying; it may
happen that the composite blocks during transport may
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become broken into individual blocks or sets of blocks
when it becomes necessary to lay the blocks by hand. By
the use of the tongs of the invention, it is not only
possible to handle and lay an unbroken composite block,
but also a composite block which has become separated into
individual blocks or sets of blocks.
The invention will be more readily understood by way of
example from the following description of an embodiment of
a slab transporting and laying device in accordance
therewith, reference being made to the accompanying drawings,
in which
Figures 1 and 2 show the device in side view and in
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plan respectively, Figure 1 being partly in section,
Figure 3 is a perspective view on larger scale of
part of the device of Figures 1 and 2 and illustrates the
- brake, and
Figures 4 and 5 are respectively a side view and
a plan view of a particular constructional form of the tongs.
The transporting and laying device illustrated in
the drawings comprises a vertical frame 10 consisting
-~; essentially of two T-section girders 12 which are fixed
10 vertically on a base plate 13 and which are braced to one -~
another in suitable manner. The frame 10 can be tilted
at the front end about the axis of a pair of wheels 14
arranged on the base plate and is additionally supported
' towards the rear end by a caster 15. Disposed at a
distance behind the rear caster 15 which permits the
manipulation of the device are handles 16, which are rigidly
connected by upper and lower pairs of struts 18 to the
, frame 10.
Self-clamping tongs 30 of conventional design serve
for the gripping and laying of the paving elements which
are to be laid and which are in the form of heavy stone
slabs or the like. Tongs 30 are suspended from a beam 20
projecting forwardly from the frame 10 as a cantilever arm
r, and are displaceable together with the beam 20 in a
linear guideway 26 longitudinally of the frame 10. The
beam 20 consists essentially of a horizontally extending
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arm 21 and a substantially vertically extending guiding
section 22, which has at least one roller 24 at the top and
bottom ends in the vicinity of each of the two T-section
girders 12. In the present constructional example, the
guiding section 22 of the arm 20 has in all four of these
rollers 24, of which there are two on each side, and which
are guided in the U-section rails of the linear guideway 26
(see Figure 2). Obviously, the linear guideway for the
beam 20 may have a form different from that illustrated,
and may for example comprise ball bearings, ball guideways,
sliding tracks or the like.
The entire beam 20 is suspended from a traction
cable 33; this cable is connected by means of an eye 35
to the base of the arm 21 of the beam 20, is guided upwardly
over a freely rotatable roller 32 in the form of a cable
pulley and is fixed at its opposite end to an eye 34
forming part of the base plate 13. A bearing block which
carries the spindle of the pulley 32 is connected to the
closed end of a vertically disposed long-stroke hydraulic
cylinder 44 which is displaceable longitudinally of the
frame 10 on a piston rod 49. Piston rod 49 is drilled
longitudinally to form a flow duct and is fixed by means
of a stable base plate to the base plate 13 of the frame 10.
The long-stroke cylinder 44 is thus connected to the beam 20
by a transmission consisting of the traction cable 33 and
the pulley 32 in such a manner that the vertical displacement
of the beam 20 through a distance s is effected by a
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displacement of s/2 of the long-stroke cylinder 44 in
relation to the stationary piston rod 49.
The internal chamber of the long-stroke cylinder
44 is constantly in communication with the internal volume
of a hydraulic short-stroke cylinder 43 through a hydraulic
pipe 50 and the longitudinal bore of piston rod 49, and
the two chambers and communicating pipes are completely
filled with hydraulic liquid. The cylinder 43 is supported
at the rear of the device by the stays 18 and, in
conjunction with a compression spring 41, forms an energy-
storage device 40. The compression spring is clamped
between a movable plate 46 fixed on a piston rod 45 of
the short-stroke cylinder 43 and a fixed plate 47 connected
by stay bolts to the short-stroke cylinder in such a way
that it is urged to force the piston of the short-stroke
cylinder 43 with its piston rod 45 into the retracted end
position as shown in Figure 1. In this retracted end
position, the short-stroke cylinder 43 is substantially
emptied and the hydraulically connected long-stroke
cylinder 44 is positively forced out into its upper end
position. In this normal position of the apparatus, the
beam 20 with its tongs 30 assumes the upper end position
as shown in Figure 1.
The energy storage device 40, which is shown in
Figures 1 and 2 as a compression spring, may alternatively
consist of a gas accumulator; for example the cylinder 43,
extended in length if necessary, may contain a flexible
diaphragm above which is contained a trapped volume of gas. ~ -
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Associated with the beam 20 is a brake 60, which
holds the beam in a rest position thereof at any required
position along the linear guideway 26. As may best be
seen from Figure 3, the brake 60 includes a brake disc 62
which normally is clamped between a fixed brake plate 67
and a movable brake plate 68, the brake disc 62 having
fixed thereon a pinion 63 constantly in mesh with a
rack 65, which is connected fast to the guiding section 22
of the beam 20. In the same way as the shaft for the
brake disc 62, the T-section girder 12 has fixed thereon
a L-shaped brake support 77 carrying a pin-like fulcrum
70, about which is rotatably mounted a brake lever 69
supporting the movable brake plate 68. This brake
lever 69 is constantly pre-tensioned by a pressure-
applying spring 72 with a force which is adjustable by
means of a tensioning device 73 in such a way that the
movable brake plate 68 clamps the brake disc 62 between
it and the fixed brake plate 67 with an adequate braking
force.
As shown in Figure 2, a control device 79 in the
form of a brake lever is arranged close to one of the two
handles 16, and it is possible by means of the said member 79
to release the brake 60 as required by means of a Bowden
cable 75. As shown in Figure 3, the sheath of the cable 75
is connected to the brake support 77 and the internal
cable thereof is connected to the bottom end of the brake
lever 69.
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The tongs of conventional type,as shown in Figures 1
and 2, have two clamping jaws 80 on the bottom end of two
intersecting arms 82, which are rotatably mounted at their
point of intersection on a common pivot 84.
Figures 4 and 5 represent a particularly preferred
alternative construction of the tongs, in which the two
clamping jaws 80 are fixed on the bottom ends of two inter-
secting arms 82 of the tongs. By contrast with the tongs
of known type, the two arms 82 do not have a common pivot
at the point of intersection. In acutal fact, each arm 82
is mounted to be rotatable about its own pivot 86 and 88,
respectively. The pivots 86, 88 extend parallel to one
another at opposite ends of a pair of connecting rods 90.
The upper ends of the arms 82 are connected to the cantilever
arm 20 by means of pivotally arranged links 83 so that -
the arms 82 of the tongs and thus the clamping jaws 80
rotate about the pivots 86, 88 when the cantilever arm 20
is raised. As a result, the clamping jaws 80, because of
their small spacing from the pivots 86 and 88, travel a
relatively small distance in the direction towards the
elements to be laid. On account of the correspondingly
large lever transmission, relatively large clamping forces
become operative. The two pivots 86, 88 are positioned
at a distance from one another which is prescribed by the
- dimensions of theelements to be laid. Apart from the
pivots 86 and 88, the connecting rods 90 do not have any
other mounting or fixing means.
The clamping jaws can be shaped to correspond to the
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contour of the elements to be laid and can be provided, at
least in certain positions, with resilient coverings 85.
The clamping force can also be transmitted through possibly
adjustable pressure-applying rollers 81 or the like.
In operation, the transporting and laying device
is advanced by an operator up to a stack of slabs, and then,
by tilting the apparatus forwards about the axis of wheels
14, the tongs are moved towards the uppermost slab of the
stack of elements to be laid. When the apparatus is tilted
back, the clamping jaws of the tongs 30 grip the slab and,
since these jaws are self-locking, the slab is lifted.
The operator now moves the apparatus with the slab to the
laying site, releases the brake 60 by means of the control
member 79, so that the weight of the slab depending from
the beam 20 is able to overcome the force of the compression
spring 41 and the beam 20 moves downwardly at a speed which
possibly is adjustable by means of a hydraulic throttling
device. Just before the slab has reached the ground,
the operator once again allows the brake 60 to engage. He
now so aligns the complete device that the slab hanging
on the tongs 30 is exactly located above the position at
which it is to be fitted. He then once again releases the
brake until the slab makes contact with the ground. After
once again engaging the brake, the operator briefly tilts
the apparatus in a forward direction, so that the tongs 30
are released. A new working cycle can then commence.
The tongs 30 are shown at Figures 4 and 5 as holding
a composite slab 94 consisting of interlocked stone blocks.
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