Note: Descriptions are shown in the official language in which they were submitted.
PC'T/CA94100090
~~,' WO 94!19106 ~... ~. e~
f
Title: CRUSHING APPARATUS
' This invention relates to crushing apparatus, of the type that is suitable
for crushing
metal cans, plastic bottles, and the like.
it is becoming increasingly common that householders are prepared to separate
out
certain items of garbage which are suitable for recycling. Each householder
has a
special receptacle, separate from the other garbage, in which the recyclable
items are
placed. It is part of the recycling truck operative's task to place the
recyclable items
in a separate compartment on the recycling truck.
One of the problems with such items as cans, bottles, and containe9rs is that
an
un-crushed heap of the items occupies a large volume of space without much
weight.
it is desirable that the items be crushed prior to being placed in the truck.
A
recycling trunk has capacity enough to carry the weight of the garbage: the
limitation
gerteraily is one of volume. The compaction of garbage of course is a weN-
known
measure, and most trucks~inclu~ie compacting means whereby ordinary garbage is
placed straight into the compactor. Conventionally, each individual item of
garbage is
carried at its un-compacted volume only for a short distance.
The same principle of reducing the volume of the item as soon as the item is
placed
on the truck applies equally to the recyclable items. However, the crushing
process
required is somewhat different from the procass far ordinary garbage. In
ordinary
compaction, the individual items are fed into a large hopper, and the items
are
crushed together by a heavy ram. This has the effect of locking many of the
items
together. As many as fifty percent of the items can be inseparable after
compaction
in a nom=t~rpe compactor.
One of the key aspects that goes towards making recycling an economical
proposition is that each individual recyclable item must be readily separable
from ail
the other recyclable items. Therefore, it is required of the manner in which
the items
are crushed that the manner of crushing does not cause the items to become
locked
together in a way that would make it subsequently difficult to separate the
items. By
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PCTlCA94/00090 'o
'WO 94/19106
2
contrast, where the garbage is simply to be placed in a landfill, it does not
matter that
items cannot be separated.
It is not too much to say that whether recycling of household containers can
proceed
as an economical industrial activity depends on whether the items can be
crushed
without being compacted, is without being locked together, or. the recycling
truck.
The inventian is aimed at providing an apparatus which is effective to crush
metal
cans and plastic bottles without compacting them together, and which is small
enough to frt conveniently on a recycling truck, and which can be powered by
power
sources available on the recycling truck.
Another factor which affects the acceptability of recycling as an industrial
process is
whether the items are individually safe and easy to handle. If the crushing
apparatus
r~sults in the metal items being torn, the cost of taking precautions against
the
resulting protruding sharp edges can be too much. The invention is aimed at
providing an apparatus which does not tear the metal items as it crushes them.
The householder collects the plastic and metal containers for recycling into
the
special container (termed the "blue box" in many jurisdictions) provided for
recyclable
items: Upon collection, the recycling truck operative tosses the contents of
the blue
box into a hopper of the crushing apparatus. The invention is aimed at
providing an
apparatus which can receive and process all the items tossed in from the blue
box,
including the occasional un-crushable item that has got into the box by
mistake.
As mentioned, it is a fact that the ram type of compactor, if such were used
on
recyclable items, would tend to make the individual recyclable items; lock
together.
The invention is based on a rotary crusher mechanism, which has been found to
be
much less prone than the ram type to causing the items to lock together. The
following is proposed as an explanation for this difference.
In a ram type compactor, it may be observed that the items are not crushed
evenly. .
When a heap of items is placed in the crushing chambEr, and crushed, the metal
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F~r ~. ~ e~..! ~ ~ ~~ PCT/CA94I00090
W~ 94119106 ,
3
cans naturally tend to collapse at first in the centre, while the more rigid
ends of the
can, supported by the end watts and flanges ofi the can, retain their shape
for much
longer. If, therefore, can A lies with one ofi its ends against the centre of
can B, the
end wall of can A drives easily into the soft centre ofi can B, which
collapses the
centre of can B. As the centre of can B collapses, the end walls of can B are
naturally drawn together, and in fact the converging end walls of can B are
drawn
together over the end wail of can A. The end walls of can B therefore curl
over onto
the end wall ofi can A. Once this cutting over has started, there is nothing
in the
action of a ram type compactor to break cans A and B free from each other, and
in
fact the locking together, once started, becomes more consolidated as crushing
is
completed.
This locking together of the items happens much less frequently in the
apparatus as
described herein. When a rotor, as opposed to a ram, is performing the
crushing,
the Items are in constant motion upon being drawn into the nip or pinch of the
crushing apparatus, and therefore the items tend to shake or pull themselves
apart
and align themselves individually within the apparatus. Also, in the described
apparatus the~rotor is equipped with blades or splines, which concentrates the
crushing action at the tips thereof, and allows the portions of the item not
directly
under the tips to buckle and fold into the spaces between the splines.
Therefore, the
buckling and folding portions tend not to buckle and fold into adjacent items,
and
thus items do not lock together.
Metal and plastic containers are often placed in the blue box with a screw cap
or
other stopper in place. Pressure can therefore build up in the container when
crushing is attempted, which can make crushing difficult. ft is not that the
pressure
required to crush a sealed container is too high for the apparatus, but rather
that it is
more difficult for the crushing rotor to dent the walls of a sealed container
enough to
gain a purchase - once the purchase is obtained, the sealed container is
crushed as
' easily as an unsealed container. The crushing rotor preferably is equipped
with
. pointed spikes for the purpose of piercing sealed plastic bottles, and thus
relieving
pressure build-up inside the container during crushing. ,
WO 94/19106 ~ ~ ~ ~ ~ '~ PCT/CA94100090
4
Metal containers also may be present in the blue box with the cap on, and the
spikes
should be robust enough to pierce not only plastic containers but also metal
containers, it may be noted that spikes on the rotor will tend to drive the
material
inwards, and so the puncturing of the metal does not give rise to a protruding
dangerous sharp edge.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
By way of further explanation of the invention, an exemplary embodiment of the
invention will now be described with reference to the accompanying drawings,
in
which:
Fig 1 is a cross-sectional side elevation of a crusher apparatus which
embodies the
invention, shown with a crammer of the apparatus in a retracted position;
Fig 2 is the same view as Fig 1, but with the crammer in an extended position;
v iY
Fig 3 is the same view as Fig i, the crammer being omitted;
v ~g 4 is a side elevation corresponding to Fig 1;
Fig 5 is a pictorial view of the crusher of Fig 1, shown with a hopper of the
apparatus
r~mo~Qd;
Fig 6 is another pictorial view of the crusher of Fig 1.
Fig 7 is a view of ~ crush-roller of another crusher apparatus;
Fig 7a is a diagammatic end elevation of the roller of Fig 7 in operation;
Fig B is a view of a crammer component of another crusher apparatus;
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PCT/CA94I00090
WO 94Ix9106
Fig 9 is a diagram of a crusher unit mounted in a truck, crushed items of
garbage
being stored in a receptacle within the truck.
The apparatuses shown in the accompanying drawings and described below are
examples which embody the invention. It should be noted that the scope of the
invention is defined by the accompanying claims, and not necessarily by
specific
features of exemplary embodiments.
The apparatus includes a crush rotor 10, which comprises a central cylindrical
shaft
12, t~ which are attached a total of nine blades or splines. Three of these
splines 14
are radially short, and carry pointed spikes 16 which protrude radially from
the spline
14. The other six splines 18 are rather longer radially, whereby the tips of
the spikes
16 are at about the same radius as the ends of the splines 18.
The shaft 12 is mounted in bearings 20 in a fixed frame 21, and is driven for
rotation
through a reduction chain drive 23, by a motor 25. The motor 25 is a hydraulic
motor
=~ powered by the hydraulic pressure that is conveniently available on most
recycling
trucks. an other trunks, and on stationary installations, other power sources
may be
more appropriate. The rotor 10 is sat to rotate at a speed of about 50 rpm.
The rotor 10 is set to rotate clockwise in Fig 1. A hopper 26 receives items
to be
crushed, and directs the items onto the top of the rotor, which, drives the
items to the
right.
Also mounted in the frame 21 is a crush plate 27. The crush plate 27 is
curved, and
is mounted with the concavity of its cu:vature facing the crush rotor 10. The
crush
plate 27 is maunted for arcuate movement about a pivot 29. Strong springs 30
urge
the lower end 32 of the crush plate towards the crush rotor 10. Stops (not
shown)
prevent the plate 27 from actually touching the rotor.
The crush rotor 10 and crush plate 27 are so arranged with respect to each
other as
to create an open mouth 34 between the top end 36.pf the plate 27 and the
rotor. As
may be seen from the drawings, the distance of separation. between the crush
plate
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PCTlCA94/00090
WO 94/19106
.,
s
and the crush rotor then diminishes, tapering to a minimum distance of
separation at
the lower end 32 of the plate.
Items entering the open mouth 34 are therefore drawn into a gradually
narrowing .
pinch-throat 38 between the crush rotor 10 and the curved crush plate 27. The
spring 30 is strong enough that the plate 27 does not, in normal operation of
the
apparatus, move away from the rotor 10, except when an item enters the throat
38
that cannot be crushed. Thus the spring 30 serves as a safety relief, to
prevent
damage to the apparatus.
In fact, it may be arranged that the spring 30 is depressed during normal
operation,
and that a multiple-rate spring be fitted, whereby different degrees of
crushing are
imparted at different force levels.
A crammer 40 is mounted in bearings in the frame 21 for arcuate reciprocating
motion with respect to the crush rotor 10 and to the open mouth 34. The
crammer
40 is driven as an accessory from the drive 23 to the crush rotor. The crammer
40
moves in what can be described as a pecking motion, whereby items present in
the
open mouth 34, waiting to be crushed, are crammed into the mouth 34 by a beak
43
of the crammer.
The crammer 40 moves from an retracted position as shown in Fg 1, to ate
extended
position as shown in Fg 2. When the crammer is open (Fig.1) the crammer is far
enough away from the rotor 10 to permit a cylindrical item 45 of diameter
about 18
cm to reside between the rotor 10 and the crammer. In this position, it will
be noted
that when the beak 43 arcs to the left, and contacts the item 45, the beak
makes
contact above the axis or centre of the item 45. Thus, when the beak 43 arcs
to the
left, the item 45 is trapped.
In the particular apparatus as shown, if the ft3m 45 ware larger in diameter
than
about 18 am, the beak would effectively be pushing upwards against the item,
in
which case the item probably would never be crammed into the mouth 34.
Therefore, the apparatus as described is not suitable for items larger than
about 18
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PCTICA94I00090
WO 94/I9106
7
cm, ie it is not suitable for items of which the diameter is too large for the
item to
adopt the position of item 4.5 in Fig 1. ~nce the item 45 reaches the position
shown
' 1 in Fig 1, although it might bounce and bobble around in the mouth 34 for a
few
moments, the item will inevitably eventually be crammed into the mouth, and be
' drawn into the nip or pinch-throat between the rotor and the plate.
f~f course, a larger size of apparatus could be built, which would accommodate
larger
items. However, it is recognised that an apparatus that is limited to
containers no
larger.than 18 cm is perfectly adequate for the general run of household
recyclable
items, and it is recognised also that an apparatus constructed as described, .
and of a
size to accommodate 18 cm containers, is very well sized for installation on,
and
operation on, the general run of recycling trucks.
It may be noted that other designs of crushing apparatus which have the
capacity to
accommodate items of 18 cm diameter, are generally much larger than the
apparatus
as described herein. It is an aim of the invention to provide an apparatus
which
accommodates large items for crushing, wherein the apparatus itself is compact
.:
enough for installation on a recycling truck,
Without the crammer 40, the diameter of item that would enter the mouth 34 of
its
own accord would be conside~~abiy smaller; in fact, without the crammer, the
largest
cylindrical item that cauld be accommodated would be 13 or 14 cm in diameter,
as
shown at 4'? in ~g 3. That is to say, without the crammer 40 items larger than
14
cm in diameter would not enter the mouth 34.
Items smaller than 13 or 1 ~. cm of course will easily enter the mouth, and
pass into
the pinch throat of the apparatus, with little trouble. if the item has one
dimension
greater than 13 or 14 cm - if the item is a plastic bottle of 12 cm diameter
and a
height of 22 cm, for example -- the item will bounce around until it happens
to tumble
' with its 12 cm diameter aligned parallel with the axis of the rotor, which
may take a
few seconds; and then the item will be drawn into the pinch-throat of the
apparatus.
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WfJ 94119106 PCT'ICA94100090 '
8
The curved crush plate 27 is furnished near its upper end 36 with a mat of
rubber 49.
The rubber 49 serves to increase the friction between the crush plate and an
item
entering the open mouth 34. This friction serves to improve the efficiency
with which
the items are grabbed at the mouth 34, allowing the item to be forced into the
pinch-throat of the apparatus. The nabber mat 49 also serves to deaden some of
the
noise that can arise from the crushing apparatus.
The splines 14,18 are aligned parallel to the axis of the rotor 90, and are
welded
firmly to the heavy shaft 12. Ths splines themselves are of heavy gauge bar,
whereby the splines and the shaft are extremely robust, and highly capable of
crushing the metal and plastic containers encountered in recyclable household
items.
The shaft 12 is 12 cm in diameter, and the tips 50 of the long splines 18 form
an
overall diameter of 24 cm. There are nine splines in total, the splines thus
being
pitched 4~ degrees apart around the shaft 12. The tips 5n of the splines 18
thus lie
with an open space between adjacent tips of about 7 cm.
The pointed spikes 16 are screwed into the short splines 14, and the tips of
the
.:øau
spikes lie on the same 24 crri~~diameter. 1'he spikes are robust enough to
pierce
metal of plastic containers falling into the apparatus, puncturing the item,
and
. ~ preventing air pressure from building up inside the item.
it should be noted that the dimensions of the splines, are such that the items
are
crushed between the tips 50 of the splines and the crush plate 27. During
crushing,
the items in fact do not, a~ a rule, penetrate deep enough between the splines
to
contact the cylindrical shaft 12. It is the tips of the splines that do the
crushing, not
the shaft 12. The tips of the splines concentrate the crushing action over a
small
area.
The fact that the items do not touch the shaft 12 is often an advantage. The
splines
are deep enough that the open spaces 52 between the splines allow each
individual
item to fold and buckle substantially into the spaces 52 without interfering
with
neighbouring items. This freedom of each item to distort in its own way helps
to
keep the items separate.
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'r WO 94/19106 ~ ~ ~ ~ '' ~ ~ PCT/C~94J00090
9
If the items were crushed with a flat rotor, or with a rotor which, though
splined, had
' splines so short that the items could make substantial contact with the
shaft between
the splines, then there would be nowhere into which the buckling and folding
material
' could freely buckle and distort. As a result, the items would tend to
overlap and
become compacted together. ~y contrast, the radialiy deep splines in the
apparatus
as described provide spaces 52 between the splines of sufficient depth to
allow the
progressively buckling material to distort without interlocking other pieces.
in the apparatus as described, it almost never happens that two items become
so
interlocked and compacted together that they do not simply fall apart upon
emerging
from the apparatus. (It should be stated that an exception to this general
rule occurs
when a large can and a small can happen to fall into the apparatus with the
small
can wholly inside the large can. in that case, the two cans, upon emerging,
often are
compacted inextricably.) It does however happen from time to time that an item
becomes enwrapped around one of the splines 18, and especially around the
spikes
16. The item then tends to remain on the crush rotor 10, being dragged around
with
the rotor.
To strip such enwrapped items from the rotor, two strippers 54 are provided.
These
comprise rods, welded to the frame 21, which protrude into gaps 56 in the
splines.
The strippers reach almost to the surtace of the shaft 12. Any item which
becomes
enwrapped in such a manner that a portion of the item overhangs into the gap
56,
will be swept away by the stripper from the spline or spike on which it is
enwrapped.
As a res~it, in the apparatus as described it is unusual for any item to
remain
snagged on the rotor for more than two or three revolutions.
When considering the mechanism or process by which items enter into the mouth
34,
it may be noted that a compromise arises between the width of the mouth, and
the
angle of nip or pinch at the mouth. (This angle of pinch at the mouth 34 of
course is
on the curve, as will be understood from the drawings. Tangents 58 may be
drawn
to the overall diameter of the rotor and to the curved plate. These define the
angle of
pinch 60.) The designer could easily make the mouth ~4 larger in width, if he
did not
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PCTICA94100090
W~ 94119106
2~.~3~~
care about increasing the angle of pinch: however, the items will only enter
and
continue through the pinch throat if the pinch angle 60 is small. For the item
not only
to enter the mouth, but to be drawn through the mouth and into the pinch
throat 38
of the apparatus, the pinch angle 60 must be small: if the pinch angle 60 is
too steep,
the item will simply bounce around at the mouth 34, and will not be drawn in.
Thus,
if the designer wishes to make the apparatus accept larger items, it is not
enough for
the designer simply to make the mouth 34 larger; he must take care also to
keep the
pinch angle 60 small. The pinch angle should be no more than about 20 degrees,
and preferably should be about 15 degrees.
Without the crammer 40, the only way in which the pinch angle 60 can be kept
small,
when increasing the width of the mouth, is to increase the diameter of the
rotar, and
to increase the dimensions of the rest of the components of the apparatus, in
proportion. The crammer 40 allows larger items to be accommodated without the
need to increase the size of the rest of the components of the apparatus, and
in
particular without the need to increase the width of the mouth.
It cr~ay be noted that the action of the crammer is, to some extent, similar
to that of a
_,
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reciprocating compactor is that the items are compacted inseparably together,
which
is unacceptable. In the crammer, however, the beak 43 of the crammer does not
crush the items against the rotor. in fact, the beak of the crammer never'
gets closer
(distance 63, Fg 1 ) than about 5 cm, typically, to the tips of the splines on
the rotor.
As a result, the crammer does not compact the items; the crammer merely
performs
a preliminary distortion of the larger items, until the item has a dimension
short
enough to allow the item to enter the mouth of the apparatus,
When the crammer 40 is in its extended position (Fg 2j the crammer to a large
degree blocks access to the mouth 34, and by so doing momentarily breaks the
gravity fed stream of material entering the mouth. The resulting metered
feeding of
the items helps to prevent overfeeding and hence overloading the apparatus.
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WO 94/19106 .
11
At the time the crammer is carrying out its preliminary distortion of the
item, the item
is being bounced and shaken by the action of the moving splines, which again
helps
to ensure that individual items do not become compacted together.
The rubber mat 49 serves to allow the splines to gain a purchase on the items.
If the
rubber were not present, there would be i'ittle friction at the top end ~6 of
the crush
plate, whereby it would be possible for the item to slide with respect to the
surface of
the crush plate.
In the lower portion of the crush plate, it is of course required that the
item being
crushed must slide over the surface of the crush plate, and therefore a low
friction is
beneficial in the lower portion of the crush plate. But near the top of the
crush plate
the situation is different: before the item has actually been drawn into the
mouth, the
item tends not to slide but rather the roiling action from the rotor drives
the item into
rotation.
Thus in Fig 1, the rotor 10 is rotating clockwise, which drives the item to
rotate
anti-clockwise. The item is therefore moving upwards at its point of contact
with the
'~r crush plate 27. Once its position in the pinch throat is established, the
item then
exhibits little tendency to rotate, and slides bodily down the crush plate:
before
entering the mouth of the pinch throat, the item does tend to rotate, whereby,
at its
point of contact with the crush plate, the item is moving upwards relative to
the crush
plate. Thus, while the item is residing at the entrance to the pinch throat,
but has not
yet been grabbed into the pinch throat, the item is not moving bodily at ail,
but is
simply rotating.
As mentioned, insofar as the item is rotating anti-clockwise (in Fg 3) the
right side of
the item, ie the side of the item in contact with the crush-plate, is moving
upwards.
This upwards movement of the item relative to the crush plate can be resisted,
it has
been found, by the addition of the rubber mat, which increases the coefficient
of
friction between the item and the crush plate in the critical zone. With the
extra
friction due to the rubber, the upwards movement of the item relative to the
rubber, ie
relative to the crush plate, is resisted. The friction resists the rotation of
the item.
The item is therefore less able to simply rotate in the entrance to the mouth,
and is
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W~ 94119106 PCTlCA94100090
12
therefore less able to escape being grabbed and drawn into the mouth and into
the
pinch-throat.
It is the larger items, of course, that have the problem of being reluctant to
enter the
mouth. The presence of the rubber enables the tips of the splines to gain a
purchase
on the large diameter items; once the item has been drawn info the mouth, the
pinch
of the apparatus takes over, and crushing proceeds.
once the item has passed the mouth, the item is trapped, and now it is
preferred that
the item should slide with as little friction as possible over the surface of
the crush
plate; that is why the rubber mat should be present only in the zone near the
mouth,
and not over the whole surtace of the crush plate.
The smaller items pass straight into the mouth 34 of the pinch throat, without
being
driven into rotation at the mouth. It is observed that the smaller items that
emerge,
crushed, from the apparatus have indentations only on one side (ie
indentations from
the tips of the splines), whereas the larger items have indentations on both
sides, and
,,.
at many different orientations, indicating that the larger items suffered
several
"snatches" at the mouth before being finally grabbed.
The position of the crush plate pivot 29 is important. if the pivot were too
high, ie
close to the top end 3C of the crush plate, the arc of the crush plate might
cause the
crush plate to undergo a self-servo action: in such a case, an excessive crush
force
would cause the crush piste to move upwards into the rotor, instead of
downwards
against the spring 30. Given the looation of the lower end 32, ie the point at
which
the items exit from the pinch throat, of the plate 2T, the pivot should be no
more than
v, ' . ' about 1 t00 degrees of arc of the crush plate' away from the lower
end; in order to
avoid any possibility of the self-servo effect.
The apparatus as described is aimed at overcoming a special compromise: that
is to
say, the apparatus has to be small enough to be accommodated on a recycling
truck, and yet the apparatus has to be able to process (nearly) all the items
put out
for recycling by the householder. The apparatus is intended to be used to
crush the
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13
kinds and sizes of metal and plastic containers normally found in household
garbage.
The householder places the cans and plastic bottles in a special container for
' recycle-able items (the "blue box"). The apparatus as described is mounted
on the
recycling collection truck, and the aim is that the apparatus will receive all
the said
containers, and will crush these items prior to the items being fed into the
appropriate
transportation compartment on the truck. The truck operative must be required
to
spend as little time as possible in sorting out the items for size or type:
preferably the
apparatus should accept all sizes.
The largest plastic bottles likely to be found in the blue box of recyclable
household
garbage are the rectangular 4 litre containers used typically for wind-shield
washer
fluid or the like. These have overall dimensions around 18 x 11 x .?0 cm. The
largest
metal containers likely to be found in the blue box are the rectangular
containers
used typically for 4 titres of cooking oil, syrup, or the like. These have
overall
dimensions of around 11 x 16 x 26 cm. The largest circular (ie cylindrical)
container
normally encountered in the blue box is the metal container typically used to
contain
4 litres of coffee or the like, which is about 18 cm diam x 20 cm long. The
metal
cans may be either of steel or aluminum.
The apparatus as described is aimed at crushing these sizes of items, and of
course
smaller sized items, without interlocking the items together, and without
tearing metal
and producing sharp edges. To accommodate these sizes in an apparatus which
itself fits within a small space envelope, the overall diameter of the crush
rotor is 20
cm, and the pinch throat width at the mouth 34 is 10 cm.
Fg 7 shows a modified form of crushing toiler 70. The roller is fabricated by
welding
end-plates 72 to a shaft 74 and a drum 76. Splines 78 and spikes 80 are
secured to
the drum 76.
The splines 78 are considerably shorter than the splines 18 in the earlier
drawings.
Also, the drum 76 is of a larger diameter than the shaft 12. As a result, the
items to
be crushed can be expected to tend to bottom against the drum much more than
they would tend to bottom against the shaft 12.
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WCD 94!19106 PCT/CA94/00090
it might be expected that items that had passed through the rotier ~0 would be
more
crushed, and more evenly crushed, and in fact there is same small gain in
degree of
crushing with Fig 7. However, in most cases, the earlier arrangement, using
the long
splines, is preferred, because of the increased "grab-ability" that arises
from, and is a
consequence of, the long splines. Preferably, the items should not ubottom"
against
the cylindrical surface between the splines.
in fact, insofar as a trade-off has to be made, it is usually preferable to
sacrifice a little
crushing in order to ensure that substantially any and all items entering the
hopper
are quickly grabbed intsa the pinch-throat, and forced between the roller and
the crush
plate.
Fig 7a is a diagram illustrating the spacing of the splines and s;rsikes 78
and 8~. It
has been found that the items to'be crushed are grabbed and forced into the
pinch-
throat more effici~ntiy if the extremity of the forward movement of the beak
of the
crammer is timed to occur at a gap between the passing splines on the roller.
In
fact; it was found that splines should be absent from some orientations of the
roller
(as may be understood fram Fig 7a) in order to permit the beak to force an
item
between the splines, thus enabling the item to be grabbed. The timing of the
movement of the crammer in relation to the spacing of the splines is thus
,seen to be
of importance in maximising the efficiency of grabbing.
It may be noted that it will ~be most obstructive to the operation of the
garbage
collection truck if the operator has to stap to clear an item that refuses to
be grabbed.
The system preferably should be such that there is nat a single instance of an
item
remaining ungrabbed during the whole collection shift. The emphasis is that no-
exceptions grab-ability is more important than absolute crushing power.
ll
Of course, some items will be too large to be grabbed. There is a requirement
on
householders not to place items above a certain size in the re-cycling boxes;
just as
there is a requirement not to place un-crushable items, such as telephone
directories,
in the boxes.
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Some, items are unsuitable for passing through the crusher apparatus, being
items
that have been wrongfully categorised as recycle-able by the householder. It
depends on the particular case as to what should be done about such items -
whether it is better to let the items pass through the crusher and be manually
separated later, or to allow the item to stall the crusher, whereby the item
is cleared
immediately but at the expense of stopping and interrupting the collection
process.
in fact, it has be~n faund that a telephone directory will sometimes pass
through the
crusher without stalling the drive. Same items that are placed occasionally in
garbage categorised for recycling will inevitably stall the drive: items such
as cast-
iron saucepans, planks of wood, hair-dryers, and the like. The apparatus copes
with
glass bottles in that the glass is simply broken. Aerosol cans are punctured
and
crushed, even though the puncturing of an aerosol might sometimes be
explosive.
Cans and bottles with liquid still inside, such as cans of paint, are crushed
as if the
liquid were not present: the liquid of course then spills and flows into the
bottom of
the apparatus.
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Even large items can be grabbed if enough purchase can be gained to force the
item
past the condition shown in Fg 7. Some items, though nominally too large, are
soft
enough that even though the item may be of a large diameter the item can~ be
di$torted by tha action of the crammer to what appears to the crusher machine
to be
a small enough diameter that the item can be seized.
~g 8 shows a mod~ication that may be made to the crammer in order to enable
grabbing to be performed with even more efficiency. The spikes 83 set into the
' upper surface of the crammer 85 provide enough extra purchase on the large,
and
especially soft, items.
Fg 9 shows a crusher unit 87 installed in a garbage collection truck. The unit
87 is
placed low enough on the side of the truck that the operator can easily tip
the items
to be crushed into the hopper 89. After being crushed, the items emerge into
the
chute 90; through which the items travel upwards into the receptacle 92. it
may be
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16
noted that no elevator or conveyor belt or the like is required in order to
force the
crushed items into the receptacle 92: the action of the cr usher unit in
forcing the
items through and out is sufficient to ford the items upwards into the
receptacle.
Thus, the entry hopper 89 of the crusher unit 87 may be positioned lower than
the
receptacle 92. Even when the receptacle is almost full, the operatoc still can
tip the
items onto the hopper at the low level. The chassis of the truck is shown
diagrammatically at 94: as will be understood, the crusher unit may be
positioned
lower than the top of the chassis.
Where the crusher unit is installed such that the unit ants to "pump" the
crushed items
up into a receptacle, it will be preferred to take steps to prevent the just-
crushed
items from passing around the crusher roller again. The strippers 96 are
shaped so
as to within the chute 90 to some extent, so that an item, once it has become
detached from the roller, will hardly ever be drawn back into the roller due
to random
bouncing motion.
It is a relatively easy matter for the operator to tip items into the hopper,
provided the
hopper is not above waist height. There should preferably be no requirement
that the
operator should have to climb steps or otherwise raise the items above waist-
height
a.
(ie waist-height when he is standing on the ground beside the truck) since
that would
greatly reduce the efficiency with which he can handle large quantities of
items shift
after shift. The design of the apparatus as described atiaws the hopper to be
placed,
on the truck; at or below waist-height. It may be noted that some conventional
designs of truck-installed garbage processing equipment do require the
operator to
climb steps, as the shift progresses, to place garbage on top of a
progressively rising
pile thereof.
In a real installation, safety precautions must of course be taken to ensure
the
operator cannot tae injured by the crusher.
It is a consequence of the manner in which a garbage collection truck is
operated
that a time period of at least several seconds occurs between the occasions
when the
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17
operator tips successive loads of recycle-able items into the hopper, as he
moves
from collection point to collection point. In the normal manner of use, there
is no
' requirement that the crusher should be able to process a large quantity of
items
received all at once, and it is no disadvantage if the items in the hopper
take a few
seconds to clear, since those few seconds will inevitably be available.
The unit as described is especially suitable for use actually on the garbage
collection
truck, since the operation of the unit fits the timing and manner of operation
of the
truck so well. The unit may be driven by means of a hydraulic pump, which is
readily
added as a belt-driven accessory to the kind of engine that is normally fitted
to a
garbage truck.
