Note: Descriptions are shown in the official language in which they were submitted.
13~)Z9~
REFUSE PACKER SAFETY SYSThM
BACKGROUND OF THE INVENTION
This invention relates to refuse packers such as
are commonly used on rear loading refuse vehicles and, in
particular, to a safety system for use in conjunction
therewith thereby to alleviate or reduce the risk of
operator injury.
Rear loading refuse vehicles are very well
known. Such vehicles usually have an open rectangular
body with a rear end closed by a refuse packer assembly.
The packer assembly usually has a hopper-like bottom, a
rear opening through which refuse is dumped into the
hopper, and a packer blade which is actuated to move
through a cycle within the packer for scooping the refuse
out of the hopper and forcing it forwardly into the body
of the vehicle. The packer blade actuating mechanism
usually is hydraulic and it is capable of exerting a
substantial amount of force in order to compact the refuse
against the forward wall of the hopper bottom and to force
it into the body of the vehicle thereby to compact it so
as to enable the loading of a substantial amount of refuse
into a vehicle of given size.
The bottom edge of the rear loading opening in
such packers usually comprises a sturdy horizontally
extending sill which forms a ledge against which
containers can be laid when they are being emptied. The
sill must be low enough so that the operator can readily
lift the refuse can sufficiently as to enable it to be
emptied into the hopper.
3~ During operation of the packer, the packer blade
must move downwardly across the loading opening, passing
closely adjacent the sill before entering the rear part of
the hopper. Movement of the blade past the sill
represents a substantial danger to an operator. Often
times a piece of refuse will become caught in the opening
~3~
in such a way that the operator will attempt to dislodge
it after the packer blade has been activated. If the
operator's hand or arm is still extending into the hopper
when the packer blade moves downwardly across the loading
opening and past the sill, serious injury to the operator
can occur,and in the past, complete severance of a hand or
forearm has occurred under the circumstances noted above.
Various types of safety gates and doors for
closing off the loading opening during operation have been
provided. In one form of safety gate, such gate was
activated at the very start of the cycle, i.e. as soon as
the refuse was tossed in, the gate was lowered downwardly
and the packing cycle would not commence until the gate
was fully down and in contact with a suitable limit
switch. The difficulty with this arrangement was that it
took up too much time. The operator had to deposit the
refuse, wait for the safety gate to close, and then wait
through the complete packing cycle until such time as the
gate could again be opened thereby allowing more refuse to
be tossed in. This almost doubled the usual operating
time and was found to be completely unacceptable.
SUM~RY OF THE INVENTION
The present invention provides a safety system
for a refuse vehicle packer assembly, which system acts to
prevent operator access to the loading opening during
the critical part of the packing cycle, i.e. during that
part of the cycle wherein the packer blade is moving close
to the sill followed by subsequent compression of the
refuse.
The present invention takes advantage of the fact
that while the packing cycle is divided into four distinct
motions of the pack head, the only dangerous portion of
the cycle insofar as operators or bystanders is concerned,
is the portion wherein the pack head moves through the
pinch point, i.e. the point where the edge of the pack
head moves close to the sill, and also wherein objects
~3t3;~8
-- 3 --
such as broken glass may be propelled out of the hopper
due to the compression forces involved.
The packing cycles of typical refuse packers of
the type under consideration are generally divided into
four distinct portions. In the first portion of the cycle
the upper part of the pack head is in a raised position
with the lower part of the pack head in a position above
the refuse which was tossed into the hopper during a
fourth part of the cycle. The second portion involves the
lowering of the upper part of the pack head to position
the lower part of the pack head such as to enable crushing
of the refuse during the third portion of the cycle. The
third portion of the cycle inv~lves a downward (usually
sweeping) movement of the lower portion of the pack head
which crushes the refuse in the hopper. The fourth
portion of the cycle involves return of the complete pacX
head to its upper position, during the course of which
movement the compressed refuse is forced into the packer
body while at the same time more refuse is put into the
hopper by the operator.
As indicated above, the third portion of the
cycle is the dangerous part. This is when any breakables
are subjected to enough pressure to crush them and pieces
of these things can be propelled outwardly from the packer
hopper. Furthermore, the lower part of the pack head
passes close to the sill of the packer hopper creating the
dangerous pinch point referred to above.
In accordance with the invention, the system is
arranged, in order to save operating time, such that a
safety gate or door, as the case may be, moves across the
loading opening during the first and second portions of
the pack cycle. This saves time since these operations
are occurring at the same time as the loading opening is
being closed off. The crucial third portion of the cycle
is interrupted only if the loading opening is not
substantially fully obstructed before commencement of the
third portion of the cycle.
~3~
-- 4 --
In the preferred form of the invention there is
provided a vertically slidable gate which slides down
during the first and second portions of the pack cycle,
releasing a lock-out on a hydraulic valve,and allowing the
third portion of the cycle to be safely used to crush the
refuse. In the event that the gate does not come all of
the way down, a limit switch controlling the lock-out is
not triggered, and the hydraulic valve associated with the
third portion of the cycle will not operate.
A preferred embodiment of the invention
incorporates a switch which senses the relative positions
of the upper and lower portions of the pack head thereby
to make the movement (e.g. lowering and raising) of the
gate automatic and in time with the sequence of the
packing cycle. The gate itself controls the lock-out,
which is only released when the gate is in its fully
closed position overlying the loading opening. By virtue
of these controls an automatically actuated safety gate
arrangement is provided. Since the movement of the safety
gate is interlocked with the pack cycle so that it is
fully closed only during the dangerous third portion of
the cycle, a very substantial amount of time is saved as
compared with prior art arrangements.
The system, with minor modifications, can be
adapted to a wide variety of refuse vehicles, particularly
rear loading refuse vehicles. In fact, the safety system
to be described hereinafter is particularly suitable for
use in ~he modification of existing equipment although, of
course, it can be made an integral part of new equipment
being manufactured.
Further features and advantages of the invention
will become apparent from the following description of a
preferred embodiment of same witn reference being had to
the accompanying drawings.
BRIEF DESCRIPTION OF THE VIEWS OF DRAWINGS
Fig. 1 is a rear perspective view of a rear
loading refuse vehicle incorporating a safety system in
accordance with the present invention:
-- 5 --
Fig. 2 is a side elevation view of a rear loading
refuse vehicle incorporating the principles of the present
nventlon:
Fig. 3 is a side elevation view of a typical
refuse packing assembly incorporating tne safety system of
the present invention:
Figs. 4, 5, 6 and 7 are diagrammatic views
showing the relative positions of the packing assembly
during the four stages of the packing cycle and
illustrating the relative positions of the pack head, the
safety gate and certain control components associated
therewith:
Figs. 8 and 9 are plan and side elevation views
respectively of a typical hydraulic valve equipped with a
lock-out wedge and actuator:
Figs. 10 and 11 are diagrammatic views of the
pneumatic and electrical control systems for the safety
system, respectively, and
Figs. 12 and 13 are diagrammatic views of the
safety gate operating switch and the manner in which it is
associated with the upper and lower pack head portions.
DETAILED DESCRIPTIO~ OF THE PREFERRED EMBODIME~T
-
Referring to the drawings, a refuse vehicle 10 is
shown including a packer assembly 12 mounted to the rear
of the packer body 14 and being pivotally connected to the
packer body by lugs (not shown) at the upper rear corner
of the packer body. Suitable hydraulic cylinders (not
shown) are provided enabling the packer assembly 12 to be
swung upwardly out of the way when it is desired to open
the packer body 14 for the ejection of refuse therefrom.
The packer assembly has a hopper 16 extending
between its side walls 18~ Hopper 16 is formed by a
rearward curved sheet 20 extending downwardly and
forwardly from a sill 22 which defines the lower edge of a
loading opening indicated by reference 24. Hopper bottom
16 also includes a forwardly extending portion 26 leading
upwardly from the rearward sheet 20 and blending into an
apron 28 at the floor of the packer body 14 when the
packer assembly is in its lowered closed position.
A pack head 29 includes a packer blade 30
extending transversely across the packer assembly 12
between and close to the side walls 18. Packer blade 30
typically has a reinforced lower edge 32, and a curved
frontal face 34. The upper end of blade 30 is carried by
the upper portion of the pack head 29, namely, a pair of
slide blocks 36 which travel in a pair of inclined
parallel guide tracks 38, the latter being located in or
on the side walls 18. The blade 30 is pivotally connected
to the slide blocks 36 by trunnions 40 which extend from
the upper corners of the packer blade 30. The slide
blocks 36 are reciprocated along the guide tracks 38 by a
pair of hydraulic pack cylinders 42 mounted adjacent the
upper ends of tracks 38 in alignment with the latter.
Extension and retraction of the rods of cylinders 42
causes the slide blocks 36 to move downwardly and upwardly
along the tracks 38.
A second pair of hydraulic cylinders 44, often
termed the sweep cylinders, are located in the pack
assembly. The upper ends of cylinders 44 are pivotally
mounted at 46 by pivot pins and the lower ends of the
cylinder rods 48 are pivotally attached to the back of the
packer blade by pivot pins (not shown). Extension and
retraction of the rods 48 pivots the packer blade around
its upper end trunnions 40 both to move the lower edge of
the blade backwardly over refuse accumulated in the hopper
16 and to move it forwardly through the hopper to remove
refuse from the hopper and to pack it in the packer body
14.
A suitable fall back shield (not shown) is
commonly employed to prevent refuse packed in body 14 from
falling back over the upper end of packer blade 30.
The above-noted pack head 29 may be thought of as
comprising two separate portions, i.e. an upper portion
29A and a lower portion 29B. The upper portion 29A
comprises the slide blocks 36 and any other components
fixed thereto such as the lugs or ears to which the
hydraulic pack cylinders 42 are secured. The lower
portion 29B comprises the packing blade 30 and any other
components fixed thereto, e.g. trunnions 40. As the pack
head is moved through its cycle, the relative angle,
measured in a vertical plane, between the lower and upper
pack head portions 29A and 29B varies as will be described
in further detail hereafter.
By properly cycling the application of power to
the two sets of cylinders 42 and 44 the pack head 29 is
moved through a closed path, four part, four position
cycle, reference being had to Figures 4-7. The cycle has
the following parts:
(1) At the start of the cycle, the pack head
upper portion 29A is in an upwardly raised position and
the pack head lower portion 29B is also moved into an
elevated position well above the hopper 16 by virtue of
the retraction of sweep cylinders 44 and above any refuse
that has been placed in the hopper through the loading
opening 24 during part (4) of the cycle. The pack
cylinders 42 and sweep cylinders 44 are both in retracted
positions at the end of part (1).
(2) In-the second part of the cycle, the pack
cylinders 42 extend thus ~oving pack head upper portion
29A downwardly. The sweep cylinders 44 remain retracted.
The pack head lower portion 29B (blade 30 etc.) occupies a
generally hori~ontal position just above the refuse in the
hopper ~6.
(3) In the thi~ part of the cycle, the sweep
cylinders extend thus pivoting the pack head lower portion
29B around so that the edge of packer blade 30 passes
close to the sill 22 (creating the dangerous pinch point
noted above) and thence crushing the refuse against the
hopper bottom, during which crushing action there is the
danger of broken pieces being ejected from the loading
opening 24.
~3~
-- 8 --
(4) In the fourth stage of the cycle, with the
sweep cylinders 44 still extended, the pack cylinders 42
retract causing the upper portion 29A of the pack head to
move upwardly while the lower portion 29B of the pack head
pivots around still further thereby to move the compressed
debris into the packer body. The operator places refuse
into hopper 16 through opening 24 generally at the same
time. At the end of part (4) the pack cylinders 42 are
fully retracted.
The various mechanisms described above are all
well known in the art as are also the hydraulic control
circuits for actuating the hydraulic cylinders in the
correct sequence. A description of the hydraulic control
circuits for the purposes described above is not
considered necessary here as such circuits are well known
to those skilled in the art and have been commercially
available for many years from a number of manufacturers.
In order to protect operators and bystanders from
the haæards noted above, the packer assembly 12 is
provided with a rear safety gate 50 which is mounted to a
frame 52 at the rear of the packer assembly. Frame 52
includes vertical guide rods 54 at the opposing sides of
the gate and along which the gate 50 slides vertically
upwardly and downwardly by virtue of tubular guides 56
welded to opposing ends of the gate and surrounding the
respective guide rods 54. In the lower position of the
gate 50, the loading opening 24 is fully obstructed, so
that operators and bystanders cannot gain access to the
hopper and the pack head therein. In the raised position
of the gate, the operator has full access to the loading
opening 24 for pla~ement of refuse in the hopper. In
order to raise and lower the gate 50, the latter is
provided with an air cylinder 58, the upper end of which
is secured to the top horizontal member 60 of the frame 52
and the ram of which cylinder is connected to the
lowermidpoint of the gate at 62. Application of
compressed air to the cylinder 58 lifts the gate
13~ 9~
g
upwardly. Release of air from the cylinder allows the
gate 50 to drop downwardly into the closed position.
With reference now to Figs. 8-13, the means for
ensuring tnat the gate 50 is moved to the closed position
during parts (1) and (2) of the cycle and held closed for
the critical part (3) of the cycle will now be described.
In Figs. 8 and 9 there is shown a lockout wedge
assembly for use with the hydraulic control valve 70.
~ Valve 70 is a multi-port valve such as a Husco B80L 702
hydraulic control valve, com~only used on an E.Z. Pack
C-200-D refuse packer. The valve includes a valve plunger
72 connected to an actuating link 74. When valve plunger
72 is moved inwardly of the valve body, hydraulic fluid
flow~ from a hydraulic pump (not shown) into the sweep
cylinders 44 thereby to extend same to produce part (3) of
the cycle. In order to block this action in the event the
gate 50 does not come all the way down, a wedge lockout
assembly 76 is provided. This assembly is mounted via
bracket 78 to the body of the valve 70. The bracket 78
supports an air cylinder 80,(e.g. a Bimba Model 092D), to
the ram 82 of which is connected an elongated wedge 84
which moves to and fro in a guide track 86 fixed to
bracket 78. A coil compression spring 88 surrounds the
ram 82 and urges-the wedge 84 outwardly away from air
cylinder 80. The above-noted valve actuating link 74 is
provided with a lateral arm 90 located in the path of
travel of the wedge 84. Hence, when the wedge is fully
retracted, as when air pressure is supplied to cylinder
80, there is no contact between the arm 90 and the
inclined edge of the wedge 84 and the link 74 and valve
plunger 72 can move inwardly to actuate the sweep
cylinders to e~fect part (3) of the cycle. However, in
the event that the air pressure is released from the
cylinder 80, the spring 88 urges the wedge 84 into
3~ engagement with the arm 90 on the actuating link thus
making it impossible to deprecs the valve plunger and
initiate part (3) of the cycle.
-I ~Qd~ "",~k
~3i~
-- 10 --
Referring to Figs. 10 and 11, the refuse vehicle
will have a compressed air reservoir 92 (usually provided
for the truck air brake system). A line 94 from this
reservoir is connected to a standard 12 volt air/electric
solenoid valve 95 which controls the admission and
exhausting of air from the lockout wedge air cylinder 80
described above. Line 94 continues on to a control valve
96 which controls the admission and exhaust of air from
the gate air c~linder 58. The gate control valve 96 is a
~-~ 10 commercially available air toggle valve such as a Berg*
Model 1559 tsee Figs. 12 and 13). Control valve 96 is
effectively interconnected between the upper and lower
portions 29A and B of the pack head. The valve 96 is shown
mounted to the pack head upper portion 29A (e.g. adjacent
the lower end of a slide block 36). The toggle arm 98 of
the valve is connected to a coil tension operating spring
100, the other end of the latter being connected to pack
head lower portion 29B. The Berg toggle valve is modified
so that it is biased in the released (gate down)
position. The pull of the spring 100, due to changes in
the relative positions of the upper and lower portions of
the pack head 29, overcomes that bias force (about 6
pounds force is needed) to raise the safety gate 50.
Hence, as the uertical angle R between portions 29A and
29B changes, the control valve toggle arm 98 moves to and
fro as a result of which the air cylinder 58 is activated
to open or close the safety gate 50 as will be described
in more detail hereafter.
Returning now to Fig. 11, current from battery
100 (e.g. the truck battery) through side loading light
102 provides power to the positive side of the
air/elec~ric solenoid valve 95. The negative or ground
side of this solenoid is connected to ground through a
lockout switcn 104. (The switch 104 is located on the
frame 52 at the lower end of the travel path of the gate
50).When switch 104 is closed by a pin on the gate 50,
current flows through the coil of the solenoid valve 95,
T~qc~é~
13~
allowing air from reservoir 92 to enter air cylinder 80
and withdraw the wedge thus enabling valve plunger 72 to
move inwardly and permitting the sweep cylinders to extend
and the critical part (3) of the cycle to proceed.
It can be seen from the above that the systems
illustrated in Figs. 10 and 11 work together to provide
power to move the safety gate 50 and to retract the
lockout wedge ~4. Since the gate air control valve 96
senses the relative angular positions of the upper and
lower portions 29A and B of the pack head, and since the
switch 104 is closed to cause retraction of the lockout
wedge 84 only when the safety gate 50 is in the fully
lowered position, it can be seen that an integrated system
is provided which lowers the safety gate 50 at the correct
time and allows the critical third part of the cycle to
take place only if the safety gate is fully closed. The
system described is very simple and can easily be adapted
to almost any commercially available form of packer
hydraulic actuator system. Small changes may be needed in
the manner in which the lockout wedge 84 is arranged and
mounted depending on the exact configuration of the packer
main hydraulic circuit control valve and the linkages and
valve plunger arrangement associated therewith. However,
it is believed that the necessary minor modifications
needed will be readily apparent to those skilled in the
art having regard to the foregoing description.
The operation of the system described will be
evident from the description given above. However, for
purposes of completeness, reference is again had to
Figures 4-7 which illustrate parts (1) through (4) of the
packing cycle.
With reference to Figure 4, the gate 50 is in the
up position at the beginning of part (1) of the cycle and
the gate or lo~kout control switch 104 is in the open
position. This means that the lockout wedge 84 is in the
advanced position preventing actuation of the sweep
cylinders 44 in the manner described previously. The
13VZ~3~
- 12
relative angular position between the upper and lower
parts 29A and B of the pack head is such that the gate
control valve 96 is activated so as to release air from
the gate cylinder 58 thus allowing the gate 50 to descend.
In part (2) of the cycle as illustrated in Figure
5, the gate control valve 96 allows the gate 50 to
continue to fall during the second part of the cycle. The
gate or lockout switch 104 closes when the gate 50 reaches
the bottom of its path of travel thus energizing the air/
electric solenoid 95 and allowing compressed air into the
air cylinder 80 thus retracting the lockout wedge 84.
In part (3) of the cycle, the lockout wedge 84
remains retracted while the gate 50 is down. If, for some
reason, the gate 50 is lifted upwardly, the gate (lockOut)
switch 104 is opened and the lockout wedge is advanced
thereby to prevent further actuation of the hydraulic
sweep cylinders 44. The previously described gate control
valve 96 senses the angular relation between the upper and
lower portions of the pack head thus starting the safety
gate 50 upwardly at the end of the third cycle.
In part (4) of the cycle, as illustrated in
Figure 7, the gate or lockout switch 104 opens as soon as
the safety gate 50 starts up. ~ence, the air/electric
solenoid 95 is de-energized thus allowing the pressurized
air in air cylinder 80 to escape whereupon spring 88
causes the lockout wedge 84 to extend. The gate control
valve 96, responding to the angular relation between the
upper and lower portions of the pack head, holds the
safety gate 50 upwardly until the packing cycle is
restarted. It should be noted here that the lockout wedge
84 does not prevent reverse movement of the sweep
cylinders 44, i.e. movement to the retracted position as
illustrated in Figure 4 because, to effect this movement,
outward movement of valve plunger 72 is effected and the
lockout wedge 84 does not restrict this outward movement
in any way.
13~
A preferred embodiment of the invention has been
described for purposes of illustration. Those skilled in
this art will realize that various modifications and
changes may be made while still remaining within the
spirit and scope of the invention.
