Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Tractor Mounted Rolled Sheet Dispenser
with Axially Adjustable Edge Means
This invention is concerned with dispensers, and
relates in particular to tractor-drawn dispensers
suitable for use with rolls of sheet material such as
that GCL sheeting used in the lining or capping of tips,
reservoirs, contaminated land and the like.
The disposal of rubbish (trash, garbage), and other
waste materials, is a problem that has concerned mankind
for centuries, and that worsens with each year as
populations and the shear amount of waste increase. It
has long been the practice to transport all rubbish to,
and dump it at, some central site, and at the present
time there are, adjacent most large towns, such dumps -
or "tips" - specially designated for this purpose.
In earlier years a tip was merely an open area of
ground onto which waste could be deposited, or at the
very most a natural depression that could be filled up
with the refuse. Later, though, much use was made of
artificial pits such as result from the excavation of
sand, gravel, clay, and other natural raw materials,
while these days it is often necessary to construct a
pit specifically for the purpose. And as dumps evolve,
so the rules and regulations governing their use become
more strict and more complex, in an effort to prevent
their causing more problems than they solve.
Specifically, it has become a regulatory requirement
that every refuse pit be so constructed that none of its
contents - and none of any materials that might arise
from its.contents - can in any way affect the ambient
conditions. In particular, every pit must be so lined
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that nothing can seep down, into the underlying ground,
and so pollute the surroundings __. and especially the
local water table and supply. Moreover, once the pit is
full, and before earth can be laid on top and the whole
landscaped, it is necessary to seal off the top as well.
A modern pit, which can vary in size from
25,000sq.m (2.5 hectares, or about 6.25 acre) for a
small pit up to 80,000sq.m (8ha, or about 20 acre) and
beyond for a larger one - the latter are usually made up
of a number of smaller pits, or "cells" - must be
constructed to a set of very tight rules, and so far as
leakage or seepage are concerned these relate to how the
pit is lined. Without going into too much detail, an
earth pit must first have a compacted surface on top of
which is a compacted sand layer with a flat and smooth
surface (with no projections or indentations more than
an inch - 25mm - high or deep). Then, on top of the
sand, there must be laid an impervious lining layer -
such as that known as a geosynthetic clay liner, or GCL.
Such a liner is, in essence, a sandwich of bentonite
clay between two layers of heavy-duty synthetic resin
fabric (which may be either in film or in woven form).
Typical examples of such liners are those made by
Colloid Environmental Technologies Co (CETCO), of
Illinois, USA and available under the Registered
Trademarks BENTOMAT and CLAYMAX, which cost around f-3
per square metre. They come in rolls each of which is a
ribbon-like sheet of material (known, when deployed, as
a "panel") from 3.5-5m (12-16.5ft) wide, from 40-45m
(135-150ft) long, and about 100-110mm (0.4-0.45in)
thick, and weighs, depending on the material, anywhere
from 1000-1450kg (about 2,200-3,2001b, or about a ton to
a ton and a half). These are laid directly onto the
ground formation surface with an overlap - normally of
around 15-22.5mm (6-9in), but in any case as required by
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the local Authorities. Ignoring the overlap, it can be
seen that the cost in materials alone of lining a large
pit will be of the order of a quarter of a million
pounds, with another quarter of a million for
subsequently capping it - sealing it off once it's full!
Getting the overlap right so that it is large enough to
form a satisfactory seal but not so large as to waste
significant amounts of material can save quite a lot of
money.
The laying is commonly accomplished bythe simple
but effective means of threading the roll onto a support
rod, attaching the rod by chains at each end to a rigid
beam, mounting the beam (again with chains) to the
bucket of a JCB - or a tracked 360 excavator, which is
preferred if the ground is not to be churned up - and
then carrying the roll along, letting the sheet liner
pay out. Unfortunately this method, though
uncomplicated, is not especially accurate. Under windy
conditions the unrolling liner can billow back and
forth. Additionally, the chains that support the roll
on the beam, and the beam on the bucket, allow the roll
to swing from side to side, and it is all too easy to
lay the liner such that the overlap is either too large
or too small (so that there may even be a gap).
Moreover, unless the roll is somehow braked, it can
easily spin off excess material to form a heap. The
present invention seeks to solve these problems by
providing a novel form of dispenser apparatus that can
be "rigidly" attached to a tractor's (conventional)
three-point mounting - a single, upper, pivot mounting
that can be raised or lowered by the tractor's normal
hydraulic system so as similarly to raise or lower
whatever the mounting is carrying, and a pair of
laterally-separated lower "floating" rigid link arms
pivotally attached at their inboard ends to the tractor
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for slight sideways movement - and that can, optionally,
be associated with "steering" means by which the roll
can be shifted laterally from side to side so as to
enable some small adjustment of the liner's laying
position, and thus of the overlap between the sheet
presently being laid and one previously laid.
More specifically, the invention proposes a long
beam, or framework of beams, having roughly centrally
thereof a three-point mounting by which it can be
attached behind a tractor clear of the ground, the beam
having normally-disposed end plates between which there
may be borne a support rod carrying a roll of liner
material. In the preferred case the beam is associated
with positioning control means that can be used to
adjust the lateral angle of the lower three-point
mounting linkages, and so move the roll to either side
to modify where the liner is laid.
In one aspect, therefore, this invention provides a
tractor-mountable dispenser for a roll of material such
as a geosynthetic clay liner, the dispenser comprising
an elongate beam, or framework of beams, having roughly
centrally thereof a three-point mounting by which it can
be attached to the tractor so as to extend laterally
therebehind, the beam carrying at either end a plate
having rod-mounting means such that there may in use be
borne between the end plates a support rod carrying the
roll of material.
It is particularly preferred if the beam be
associated with positioning control means that in
operation can be used to effect adjustment of the
lateral angle of the lower linkages of the three-point
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mounting, and thus move the roll to one side or the
other to modify where, in use, the liner is laid.
Although for the most part herein the invention is
discussed in relation to the lining or capping of a tip
for rubbish, refuse and the like, it may in fact also be
of use in the lining of other container-like holes in
the ground. For example, modern water reservoirs need
to be lined to stop their contents leaking away, and the
dispenser of the invention can be used to lay such a
lining. Again, in some countries it may be desirable to
store crude oil in giant pits, or perhaps to place
surface storage tanks in safety pits to contain any
leakage, and obviously it is extremely important to
ensure that the pits are sufficiently well lined and/or
capped to prevent oil seeping into the surroundings.
The invention provides a tractor-mountable
dispenser. The tractor employed to carry the dispenser
may be of any type - a suitably-shod conventional
agricultural tractor or loading shovel, for example, or
a tracked crawler of some sort - provided, of course,
that it has a suitable three-point mounting. As noted
above, a conventional such three-point mounting
comprises a single, upper, pivot mounting with an
adjustable-length link and a pair of laterally-separated
lower rigid link arms pivotally attached at their
inboard ends to the tractor both for vertical movement
and for slight sideways movement, which lower arms can
be raised or lowered by the tractor's normal hydraulic
system so as to raise or lower whatever the mounting is
carrying. It is normal for the sideways movement to be
restricted by a chain on the outside of each lower arm;
as is discussed further hereinafter, in the employment
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of the preferred forms of the dispenser of the invention
these chains are removed, one of them being replaced by
a hydraulic ram that can be used to drive the arm, and
thus the dispenser, from side to side.
Bearing in mind the regulations regarding the
smoothness of a tip's underlying surface, one important
point about the tractor to note here is that it must be
equipped with tyres, or other ground-contacting drive
and support means (such as tracks), that do not leave
significant marks or indentations in the ground
formation surface of the tip. For the most part
standard low flotation tyres as are commonly used on
tractors on soft, boggy ground, and preferably with a
tread not more than about 5mm (0.25in) deep, are
perfectly satisfactory.
The invention's dispenser is for dispensing a roll
of material such as a geosynthetic clay liner (GCL), or
whatever is appropriate to the particular task at hand,
and naturally, the roll may be of any suitable size. In
the case of GCLs, those BENTOMAT and CLAYMAX materials
mentioned hereinbefore are typical examples.
The dispenser of the invention is an elongate beam,
or beam framework, having a three-point mounting and
carrying at either end a plate such that there may be
borne between the end plates a support rod carrying a
roll of material
Although the dispenser could have only a single
beam - it is quite possible to provide such a beam made
of square-section mild steel tube, say, and strong
enough to carry the roll and rigid enough to allow
satisfactory distribution therefrom - it is much more
convenient to construct the dispenser as a framework of
beams, and typically as part of a "box" framework
wherein the end plates form two opposed (side) faces of
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the box and the top surface of the box is defined by a
pair of spaced parallel beams suitably elongated to
provide the length appropriate for the chosen roll and
perhaps with one or more bracing cross strut. For use
with a roll 4m long and 0.5m diameter (about 13.5ft
by 1.75ft) long such a framework might be 4.2m long and
0.75m wide and deep (about 14ft by 2.5ft by 2.5ft). The
individual beams making up the framework are
conveniently square-section mild steel tube around
100x100mm and 10mm thick (about 4x4in, 0.5in thick),
suitable welded to the end plates, which are themselves
10mm (0.5in) mild steel plate.
Hereinafter, and unless the context clearly
indicates otherwise, the term "beam" is used both to
mean a single beam and to mean the beam part of a
framework.
Because rolls come in different widths, depending
on their precise purpose and cost, it is desirable to
arrange for the width of the dispenser - the length of
the beam - to be adjustable so that it can more easily
and efficiently cater for the several different rolls.
To this end the beam - or each individual beam making up
the length of the framework - is "telescopic", it
comprising a hollow, tubular main beam having slidably
mounted therewithin at each end small (short) end beam
portions that can be moved in or out of the main beam,
and then fixed in place, so as to alter the overall
length of the whole beam. If the outer, main beam has
at each end a sequence of holes extending along the
beam, and each end beam portion has at its inboard end
(the end that fits within the main beam) a single
matching hole, then each end beam portion once
positioned can conveniently be fixed in place by a
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securing pin inserted through the relevant aligned
holes.
The dispenser of the invention is tractor-
mountable, and on the beam there is a three-point
mounting - one upper mounting and two spaced lower
mountings positioned symmetrically either side of the
upper one - by which it can be attached to the tractor
so as to extend laterally therebehind. In itself there
is nothing particularly special about this mounting, which
is such as might be found on any agricultural implement,
and so it need no further comment here. However, in
order to enable the beam to be lifted well clear of the
ground for when it is to be loaded with a fresh roll,
and for carrying the roll to the place where it is to be
laid, it may be desirable to have the bottom mountings
are relatively low - that is, somewhat lower than would
usually be the case for an agricultural implement to be
mounted on a tractor this way.
The three-point mounting is conveniently roughly
central of the beam in its length direction, so that the
roll it carries is similarly central of the tractor. it
might, though, be desirable to offset the mounting, and
thus the roll, to one side or another, so the expression
"roughly central" can be interpreted quite widely. For
example, the mounting might be 30cm (a foot or so) to
one side.
The beam in the invention's dispenser has at either
end a plate having rod-mounting means such that a
support rod carrying the roll of material may be borne
between the end plates. In the case where the beam is
telescopic then the plate is carried on the relevant
smaller end beam partion. The plate - although the term
"plate" might imply a solid object, and in fact the
plate preferably is a solid plate, it could itself be in
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the form of a framework - is disposed generally normal
to the beam (the exact angle is not especially relevant)
and is. of such a size and shape, and so positioned
relative to the beam, that, with the roll on its support
rod in place between the end plates, the roll is clear
of the beam, and free to rotate on or with its rod as
the material is dispensed therefrom.
The end plates have rod-mounting means such that
the roll's support rod may be carried thereby. The rod
mounting means might be a socket suitably positioned on
the inside of the plate, and in which socket the very
end of the rod is seatable, or it might be an aperture
through the plate through which the rod is threaded,
slightly projecting out at either end (this aperture
could be associated with bearing means, allowing the rod
to turn within the aperture while the roll material is
being dispensed, or it could simply be a hole; if the
rod sticks in the hole then the roll, being loosely
mounted on the rod, will rotate around the rod). Most
preferably, however, it is a deep, inverted, U-shaped
notch in the bottom edge of the plate into which the rod
can be slotted without the need for any threading
action, and preferably the notch is associated with
displaceable retaining means so that the rod, once in
place, can be prevented from falling out.until it is to
be removed. A possible retaining means is a small
apertured plate that slides over the rod ends and is
then pinned or otherwise detachably attached to the main
plate (such a plate could include any bearings necessary
to allow the rod to rotate when so mounted). However, a
much preferred retaining means is a detente (or catch),
conveniently a hook-like detente spring-biassed shut but
manually openable, to retain the rod within the notch.
Using such a detente, in operation the dispenser is
raised, the roll on its support rod is moved underneath
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to where the rod is aligned with the notches in the
plates, and then the dispenser is lowered onto the rod,
so that each rod end slips past the detente and into the
notch, whereupon the detente springs back to hold the
rod in place. To release the rod (when the roll is used
up, say), the detente is simply pulled back, and the rod
falls out.
It is preferable if such a hook-like detente be
configured as a lever device, the free end of the lever
being connected via suitable means - wires and pulleys,
say, or pull/push rods, or even a hydraulic ram and
appropriate controls - to a master control operable
manually by the tractor driver.
As noted hereinbefore, it is a particularly
preferred feature of the invention that the beam be
associated with positioning control means that can in
operation be used to effect adjustment of the lateral
angle of the lower linkages of the tractor's three-point
mounting, and thus to move the roll to one side or the
other to modify where, in use, the liner is laid.
First, there is needed a driver device for effecting
this movement, and conveniently such a device is a
hydraulic ram taking the place of one of the movement-
restriction chains usually employed with the arms, which
ram is powered by the tractor's hydraulic system. Then
there is needed a control arrangement - and preferably
such an arrangement as can be utilised by an Operator
walking along just behind and to one side of the
dispenser, and gauging by eye the accuracy with which
the roll material is being laid. Advantageously, then,
this control arrangement is a conventional lever-
operated hydraulic switch operatively connected to the
ram and mounted at the rear and side of the beam - and
one on each side is obviously desirable, so that the
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Operator may be at whichever side is where there is
being formed the overlapping seam of the liner being
laid on that previously laid.
Conveniently, the dispenser of the invention is
associated with some metering means whereby there may be
determined what length of material has been dispensed
from the roll, and thus how much is left. Such a meter
can be driven directly from the rotation of the roll,
much like a car or bicycle odometer is driven by
rotation of the wheels or drive chain.
As so far described the invention is a dispenser
for a single roll of material. There is no reason,
however, why the dispenser should not handle two, or
more, rolls at once, each roll being similarly mounted
between the end plates. Indeed, for some purposes a
two-roll dispenser might be ideal - for example, there
might be distributed as the bottom layer (from one roll)
a liner that is physically very strong but not
necessarily impenetrable by water (or some other
liquid), and this could, effectively simultaneously, be
itself covered (from the second roll) by a layer of a
less robust but totally liquid-blocking material - or,
of course, vice versa.
As noted above, it is important, when laying a
liner in a tip, reservoir or the like, not to mark the
smooth surface of the underlying ground formation, and
any undesirable marking can be avoided, or at least
mitigated, by using a tracked vehicle or low flotation
tyres (preferably without tread). However, if despite
this the surface is marked, it may be possible to smooth
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it out immediately prior to laying the liner by the
simple expedient of mounting just behind the tractor, or
on the dispenser but just ahead of the roll being laid,
a roller that will take out or level any indentations.
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An embodiment of the invention is now described,
though by way of illustration only, with reference to
the accompanying diagrammatic Drawings in which:
Ficrure 1 shows a view of a cell - a hole to be
filled - of a rubbish tip being lined in
the known manner using a loading shovel;
Firnxre 2 shows a perspective view of a 360
excavator equipped to lay a liner in
accordance with known techniques;
Figure 3 shows a perspective view of a tractor
equipped to lay a liner using a
dispenser in accordance with the
invention;
Fiqure 4 shows a perspective view of one end of a
dispenser of the invention, and similar
to that shown in Figure 3;
Figure 5 shows a top plan view of the dispenser
shown in Figure 4;
Figure 6 shows a top plan view of the whole of
the dispenser of Figure 4, attached to a
tractor; and
Figure 7 shows an end/side view of the dispenser
of Figure 4.
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Figure 1 shows a view of a cell of a rubbish tip
pit (generally 11) being lined in the known manner with
the use of a loading shovel to carry the roll of lining
material. It is not to scale - in reality the cell is
much larger, and the loading shovel much smaller, but it
serves to illustrate how the liner is laid in strips
(as 12) pulled out from a roll (13) mounted on the front
of a loading shovel (14: the loading shovel is moving
backwards, in the direction of arrow A, paying out the
strip as it goes, with the driver manoeuvring as he
proceeds in order to keep the strip straight and
correctly overlapping the previously-laid adjacent
strip).
Figure 2 shows a perspective view of an excavator
(of the type referred to as a 360) equipped to lay a
liner in accordance with known techniques. The
excavator (generally 21) carries on its arm a
conventional hydraulically-actuated bucket (22) from an
eye on the mounting for which dangle chains (23) holding
up a girder-like beam (24) to the ends of which are
similarly attached (by chains and rings 25) a supporting
rod (26) which is threaded through, and thus supports, a
roll (27) of liner which is in operation dispensed out
as the excavator travels along.
Figure 3 shows a perspective view of a conventional
tractor having a rear-mounted three-point implement
mounting system and equipped to lay a liner using a
dispenser in accordance with the invention. Fitted with
balloon, or low flotation, tyres (31) the tractor
(generally 32) carries on its rear mounting a framework
dispenser (generally 33) of the invention. The
framework has two square-section main beams (34)
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extending laterally across the full width of the
tractor 32 (and tyres 31) and beyond, and at each end of
the beams is a normally-disposed end plate (35) to which
the beams 34 are welded. Centrally of each
end plate 35, but nearer the bottom (as viewed) edge
thereof, is an inverted U-shaped slot (not shown in this
Figure) through which passes the rod 26 supporting a
roll 27 of liner. The rod 26 is retained in the slot by
an apertured end capping plate (36) which is affixed by
nuts/bolts (37) to the end plate 35 and through the
aperture of which passes the rod 26.
The framework of beams 34 is cross-braced by
struts (38), and has three-point mounting struts (39)
forming the mounting points by which it is attached to
the tractors three-point mounting system.
Figure 4 shows a perspective view of one end of a
dispenser of the invention, and similar to but not the
same as that shown in Figure 3. Other views of this are
shown in Figures 5, 6 and 7.
In Figure 4 can clearly be seen the use of hollow
square-section telescopic beams - two fore and aft main
beams (41) each ending at each end (though only one end
is shown in Figures 4 and 5) in a smaller beam
portion (42) mounted slidably within the main beam 41.
The end plate (43) is welded to the "free" ends of the
smaller beam portions 42, and its position relative to
the main beams 41 - and thus to the similar end plate
(not shown) welded at the "free" end of the small beam
portions other end of the main beams 41 (not shown) -
may be adjusted by sliding the smaller beam portions in,
or out (as appropriate) and then locking them in place
with the hand pins (44) passing through mating holes (as
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45, 46) in the main beam 41 and in the small beam
portions 42.
As in the Figure 3 embodiment, here too the roll 27
is supported on a rod 27 that is slotted into an
inverted U-shaped slot (47) in the bottom edge of each
end plate 43. However, instead of an apertured capping
plate 36 (as in Figure 3), there is a hook-shaped
pivoted detente (48: best seen in Figure 7) that is
biassed closed by a spring (51: not shown in Figure 4)
to retain the rod 27 in place in the slot 47. The
detente 48 can be drawn back, to release the rod 26, by
a system of wires (71) and pulleys (shown, in part, only
in Figure 7).
A top plan view of the whole of the dispenser of
Figure 4, attached to a tractor, is shown in Figure 6,
while Figure 7 shows a view of an end/side - the left
side, as seen in Figure 6 - of the dispenser.
From Figure 6 can be seen the three-point
linkage (61: one upper, two lower rigid connections) to
the tractor's three-point mounting, together with a
hydraulic ram (62) mounted between the tractor and one
of the link arms 61 and operated by a control stick (63)
mounted to the rear and inboard of the right-hand (as
viewed) end plate 43. This enables an Operator walking
along behind and to the right of the dispenser to
"steer" the dispenser, so as to adjust the overlap (64)
of the liner (65) being laid on top of the
previously-laid liner (66). If the ram pushes out, the
dispenser is moved slightly to the right (as viewed); if
it pulls in, the adjusting movement is to the left_
