CA1302958C - Refuse packer safety system - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A packer assembly for a refuse vehicle incorporates a safety system preventing operator access to the loading opening only during the critical part of the packing cycle, i.e. during that part of the cycle wherein the packer blade moves close to the sill followed by subsequent compression of the garbage. The system is arranged such that a safety gate or door, as the case may be, moves across the loading opening during the initial 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 critical portion of the cycle is interrupted only if the loading opening is not substantially fully obstructed before commencement of the critical portion of the cycle.

Description

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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 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.

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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:

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.

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(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.

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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~

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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~

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.

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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.

Claims (15)

1. A safety system for use on a refuse vehicle having a packer body and a packer assembly including laterally spaced apart side walls, a hopper having a bottom and a sill extending between said side walls and defining the lower edge of an opening through which refuse is loaded into said hopper, a movable pack head above the hopper bottom and extending between said side walls, and means supporting and moving said pack head through a packing cycle having the following parts wherein:
(1) the pack head is located in an upper position above any refuse which has been loaded into the hopper;
(2) the pack head is lowered to locate a lower portion of the pack head in position to compress refuse;
(3) the pack head is moved so as to crush and compress refuse in the hopper during which the pack head lower portion passes close to said sill creating a pinch point;
(4) the pack head is returned to said upper position during which movement the compressed refuse is forced into the packer body and further refuse can be loaded into said hopper by an operator;
said safety system comprising:
a safety gate adapted to be mounted for movement between a closed position preventing access to said opening and an open position permitting refuse to be placed in said hopper via said opening, means for moving said gate between said aforementioned positions, and control means adapted to be associated with said means for moving said gate and with said means supporting and moving said pack head and responsive to the locations and positions of said pack head and said gate and adapted to function such that in use:

(a) said gate is moved to said closed position substantially during said parts (1) and (2) of the packing cycle and is opened substantially during part (4) of the packing cycle; and (b) the packing cycle is interrupted before part (3) of the cycle in the event the safety gate fails to reach the closed position so that the danger of an operator being caught in the pinch point is alleviated.

2. The safety system of claim 1 wherein said control means is further arranged such that said packing cycle is interrupted generally after parts (1) and (2) and generally before part (3) in the event the safety gate fails to reach the closed position.

3. The safety system of claim 1 or 2 wherein said control means includes a switch for sensing the relative positions of an upper and the lower portion of the pack head, said switch being operatively associated with said means for moving said gate whereby to move said gate between said open and said closed positions in sequence with the packing cycle.

4. The safety system of claim 1 or 2 wherein said control means includes a switch for sensing the relative positions of an upper and the lower portion of the pack head, said switch being operatively associated with said means for moving said gate whereby to move said gate between said open and said closed positions in sequence with the packing cycle, and means for locking out an actuator control means in the packer assembly for effecting part (3) of said cycle except when said gate is in said closed position, said means for locking out including a lockout switch for sensing said gate in closed position whereby to deactivate said locking out means and to enable said actuator control means to effect part (3) of the cycle.

5. A safety system for use on a refuse vehicle having a packer body and a packer assembly including laterally spaced apart side walls, a hopper having a bottom and a sill extending between said side walls and defining the lower edge of an opening through which refuse is loaded into said hopper, a movable packing head above the hopper bottom and extending between said side walls, and means supporting and moving said packing head through a packing cycle wherein the pack head is located during initial portions of the cycle in an upper position above any refuse loaded by an operator into the hopper and lowered to locate a lower portion of the pack head in position to compress refuse; the pack head then being moved in an intermediate portion of the cycle so as to crush and compress refuse in the hopper during which the pack head lower portion passes close to said sill creating a pinch point; and the pack head being returned during a latter portion of the cycle to said upper position during which movement the compressed refuse is forced into the packer body;
said safety system comprising:
a safety gate adapted to be mounted for movement between a closed position preventing access to said opening and an open position permitting refuse to be placed in said hopper via said opening, means for moving said gate between said aforementioned positions, and control means adapted to be associated with said means for moving said gate and with said means supporting and moving said pack head and responsive to the locations and positions of said pack head and of said gate and adapted to control the movement of the gate and to influence the packing cycle such that in use:
(a) said gate is moved to said closed position substantially during said initial portions of the packing cycle and is opened substantially during said latter portion of the packing cycle; and (b) the packing cycle is interrupted between said initial portions and said intermediate portion of the cycle in the event the safety gate fails to reach the closed position so that the danger of an operator being caught in the pinch point or injured by debris during crushing is alleviated.

6. The safety system of claim 5 wherein said control means includes a switch responsive to movement of at least said lower portion of the pack head, said switch being operatively associated with said means for moving said gate whereby to move said gate between said open and said closed positions in time with the packing cycle.

7. The safety system of claim 5 wherein said control means includes a switch responsive to movement of at least said lower portion of the pack head, said switch being operatively associated with said means for moving said gate whereby to move said gate between said open and said closed positions in time with the packing cycle; means for locking out an actuator control means in the packer assembly for effecting said intermediate portion of the cycle except when said gate is in said closed position including a lockout switch for sensing said gate in said closed position whereby to deactivate said locking out means and to enable said actuator control means to effect said intermediate portion of the cycle.

8. The safety system according to claim 5 in combination with a refuse vehicle having a packer body and packer assembly as recited in claim 5.

9. A safety system for use in a refuse packer having a pack head and means supporting and moving said pack head through a multi-portion packing cycle, one portion of said cycle involving compaction and crushing of the refuse in the course of which one portion injury to an operator may occur; said safety system comprising:

a safety means adapted to be mounted for movement between a closed position preventing access to said packing head and an open position permitting access thereto, means for moving said safety means between said aforementioned positions, and control means responsive to the locations and positions of said pack head and of said safety means such that:
(a) said safety means is moved to said closed position substantially during portions of the packing cycle preceding said one portion of the cycle and 'is opened substantially during a portion of the packing cycle succeeding said one portion of the cycle; and (b) the packing cycle is interrupted generally between said preceding portions of the cycle and said one portion of the cycle in the event the safety means fails to reach the closed position so that the danger of an operator being injured is alleviated.

10. The safety system of claim 9 wherein the control means includes a switch responsive to movement of at least a portion of the pack head in the course of the packing cycle, said switch being operatively associated with said means for moving said safety means whereby to move said safety means between said open and said closed position in accordance with the packing cycle.

11. The safety system of claim 10 wherein the refuse packer includes actuator control means for effecting one portion of the cycle, said safety system also including means for locking out said actuator control means except when said safety means is in said closed position and including a lockout switch for sensing said safety means in said closed position whereby to release said locking out means and enable said actuator control means to effect said one portion of the cycle.

12. A packer assembly for use on a refuse vehicle having a packer body, the packer assembly including laterally spaced apart side walls, a hopper having a bottom and a sill extending between said side walls and defining the lower edge of an opening through which refuse is loaded into said hopper, a movable pack head above the hopper bottom and extending between said side walls, and means supporting and moving said pack head through a packing cycle having the following parts wherein:
(1) the pack head is located in an upper position above any refuse which has been loaded into the hopper;
(2) the pack head is lowered to locate a lower portion of the pack head in position to compress refuse;
(3) the pack head is moved so as to crush and compress refuse in the hopper during which the pack head lower portion passes close to said sill creating a pinch point;
(4) the pack head is returned to said upper position during which movement the compressed refuse is forced into the packer body and further refuse can be loaded into said hopper by an operator;
said packer assembly having a safety system comprising:
a safety gate mounted for movement between a closed position preventing access to said opening and an open position permitting refuse to be placed in said hopper via said opening, means for moving said gate between said aforementioned positions, and control means responsive to the locations and positions of said pack head and said gate with the control means adapted to operate such that:

(a) said gate is moved to said closed position substantially during said parts (1) and (2) of the packing cycle and is opened substantially during part (4) of the packing cycle; and (b) the packing cycle is interrupted just after part (2) of the cycle in the event the safety gate fails to reach the closed position so that the danger of an operator being caught in the pinch point is alleviated.

13. The packer assembly of claim 12 wherein said control system is further arranged such that pack cycle is interrupted generally after said parts (1) and (2) and generally before part (3) in the event the safety gate fails to reach the closed position.

14. The packer assembly of claim 13 wherein the control system further includes a switch for sensing the relative positions of an upper and the lower portion of the pack head, said switch being operatively associated with said means for moving said gate whereby to move said gate between said open and said closed positions in sequence with the packing cycle.

15. The packer assembly of claim 13 wherein the control system further includes a switch for sensing the relative positions of an upper and the lower portion of the pack head, said switch being operatively associated with said means for moving said gate whereby to move said gate between said open and said closed positions in sequence with the packing cycle, and actuator control means for effecting part (3) of said cycle, and means for locking out said actuator control means except when said gate is in said closed position including a lockout switch for sensing said gate in the closed position whereby to deactivate said locking out means and to enable said actuator control means to effect part (3) of the cycle.