Load compacting and ejecting mechanism for a refuse truck
BACKGROUND OF THE INVENTION 
     One of the common types of refuse collecting vehicles comprises an open, elongated rectangular body into which refuse is dumped near its front end, either by operators who actually empty refuse cans through a side door or by powered mechanisms which may raise large refuse containers and dump their contents into such a body. Many of these bodies are equipped with transversely extending ejector plates and have openable tailgates at the rear ends of the bodies. Such an ejector plate usually is actuated by an hydraulic cylinder which first moves the plate and the refuse rearwardly, to compact it against the tailgate, thus to reduce the space occupied, for example, by large cardboard cartons. After the tailgate is opened, the ejector plate is moved all the way to the rear of the body to eject a load of refuse from the body at a location such as a city dump. 
     When large volumes of refuse are dumped into a truck of this type the ejector plate usually is cycled, first to move the refuse backwardly to compact it somewhat and, when the resistance to further movement of the ejector plate backwards reaches a certain level, the controls are reversed to pull the ejector plate to the front of the body for the reception of additional refuse. 
     Because the resistance to compaction is a function of the area of the ejector plate acting against the entire mass of refuse in the vehicle body, it is the object of the instant invention to apply the same hydraulic force to a small portion of the ejector plate to extend such a &#34;compaction plate&#34; into the refuse to achieve further compaction. 
     It is therefore the principal object of the instant invention to provide an ejector plate mechanism which consists of a main, transversely extending ejector plate that is powered by a main hydraulic cylinder which acts between a forward part of the vehicle body and the ejector plate structure to move the ejector plate rearwardly for pushing the refuse to the rear of the truck and partially compacting it against the closed tailgate, the mechanism also including a compaction plate which is extended rearwardly relative to the main ejector plate when the resistance to further rearward movement of the ejector plate reaches a predetermined level. 
     It is yet another object of the instant invention to provide a transversely extending ejector plate powered by a hydraulic cylinder and including a compaction plate which is generally centrally located in the ejector plate and forms a part of the refuse contacting face of the ejector plate and which is pivotally mounted at its upper end to the ejector plate; the main cylinder being connected directly to the compaction plate and one or more secondary cylinders being connected between the ejector plate structure and the compaction plate; the hydraulic circuitry including a pressure relief valve which controls the flow of fluid to the secondary cylinders so that the compaction plate can be moved rearwardly relative to the main ejector plate when the resistance to the movement of the ejector plate reaches a predetermined level. 
     Other and more specific objects and advantages will become apparent from the specification which follows and from the drawings to be described below. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view in elevation of a front loading type of refuse truck equipped with an ejector plate mechanism embodying the invention, parts being broken away to show parts of the mechanism; 
     FIG. 2 is a vertical sectional view taken along the line 2--2 of FIG. 1 and shown on an enlarged scale; 
     FIG. 3 is a fragmentary, vertical sectional view taken along the line 3--3 of FIG. 2, and shown on a further enlarged scale, illustrating in detail a mechanism embodying the invention; 
     FIG. 4 is a fragmentary, vertical sectional view taken along the line 4--4 of FIG. 3 and shown on the same scale as FIG. 2; and 
     FIG. 5 is a schematic hydraulic circuit illustrating how hydraulic fluid under pressure is made available to actuate a main ejection cylinder means and to provide for the movement of secondary hydraulic cylinder means when desired. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
     A refuse truck generally indicated with the reference number 10 has an elongated, hollow rectangular body 11, the body being provided with an openable tailgate 12 and being mounted upon the chassis of the truck 10. The truck 10 is illustrated as having a front loading mechanism 13 adapted to engage, to raise, to invert and to dump refuse from large refuse containers 14. When the mechanism 13 is actuated a refuse container 14 is raised over the top of the body 11 and dumped through an opening 11a (FIG. 3) in the top of the body 11, located near the front of the body 11. The particular loading mechanism is well known in the art and does not, in itself, constitute a part of the instant invention. 
     A truck of this type is equipped with a main ejector plate 15 which extends transversely across the interior of the body 11 and is guided for movement back and forth in the body 11 by slides 16 (FIG. 2) which travel in ways 17 mounted in the side walls of the body 11. The ejector plate 15 is actuated by a main hydraulic cylinder means 18, in this case a multiple-stage, telescoping cylinder, which is illustrated as being connected between the upper front corner of the body 11 and the structure of the ejector plate 15, but may be connected to the body at a lower level, if desired. 
     In FIG. 3 the telescoping cylinder means 18 is illustrated as being pivotally connected by its rod 19 to a pair of ears 20 that are mounted on a heavy front wall 21 of the truck body 11. The base, or cylinder end, of the cylinder means 18 is pivotally connected to a cross rod 22 (FIG. 4) which, in turn, extends through a series of vertically extending, parallel heavy gusset plates 23. The gusset plates 23 are welded or otherwise rigidly connected to a rectangular face 24 of a compaction plate 25. 
     The compaction plate 25 also has vertical reinforcing plates 26, side plates 27 and thrust pin support plates 28, all of the plates 26-28, inclusive, extending vertically and parallel to each other and forming the structure for the support of the face 24 of the compaction plate 25, itself. The entire compaction plate 25 is pivotally mounted in the structure of the ejector plate 15 for angular movement from the position shown in solid lines in FIG. 3 to the rear position shown in broken lines in FIG. 3. The compaction plate 25 is mounted for this pivotal movement on a heavy cross bar 29 which extends through sleeves 30 at the upper edge of the compaction plate 25 and shorter border sleeves 31 mounted in the structure of the ejector plate 15 near its upper end. 
     Two second hydraulic cylinder means 32 are mounted within the structure of the ejector plate 15, their base ends 33 being pivotally carried by thrust pins 34 which extend through the side plates 27 and the inwardly spaced, parallel support plates 28. Rods 35 of the second cylinder means 32 are yolked to a cross rod 36 which extends horizontally across the compaction plate 25 through the reinforcing plates 26 and the side plates 27. 
     FIG. 5 is a simplified hydraulic circuit showing the main hydraulic cylinder 18 partially extended as if the ejector plate 15 and the compaction plate 25 has been moved rearwardly against a load of refuse in the body 11, compacting that refuse to a degree such that the resistance to further movement of the ejector plate 15 has reached a predetermined level. 
     The main cylinder 18 is connected by hydraulic lines 37 and 38 to a reversing valve 39. The valve 39, in turn, is connected by a line 40 to a pump 41 and the pump 41 has an intake line 42 from a reservoir of sump 43. The valve 39 is also connected by an overflow line 44 to the sump 43. When the valve 39 is so set as to feed hydraulic fluid from the pump 41 to the base end of the cylinder 18, the cylinder is extended to move the ejector plate 15 and the compaction plate 25 rearwardly in the truck body 11. During this &#34;normal&#34; operation, the rods 35 of the second cylinders 32 are in their retracted positions holding the face of the compaction plate 25 in its normal position as a part of the refuse contacing face of the ejector plate 15. 
     The base ends of the cylinders 32 are connected by a hydraulic line 45 to the rod ends of the cylinders 32 through a pair of one-way valves 46 and 47 which are located in the line 45, being mounted parallel to each other. The first one-way valve 46 is so designed as to provide for the flow of hydraulic fluid from the base ends of the cylinders 32 to their rod ends with an overflow line 48 branching from the lines 45 and leading to a second sump 49. The second one-way valve 47 is so designed as to prevent the flow of hydraulic fluid from the rod ends of the cylinders 32 to their base ends during &#34;normal&#34; operation, when the main cylinder 18 is extended merely to move refuse from the front of the body 11 toward its rear or, after the body has been completely loaded, and the tailgate 12 has been opened, to move the ejector plate all the way to the rear of the body 11 for ejecting the refuse load therefrom. 
     However, when a situation is encountered, as is illustrated in FIG. 5, i.e., when the ejector plate 15 has been moved rearwardly against a mass of refuse in the body 11 in order to compact that refuse, and the resistance to further movement of the ejector plate 15 rearwardly against the refuse reaches a predetermined level, pressure in the base end of the cylinder 18 rises by reason of this resistance. When the pressure in the base end of the cylinder 18 reaches a predetermined level, this pressure is transferred by a pressure line 50 that is connected to the pressure responsive valve 47, which causes that valve to open. This provides for flow of hydraulic fluid from the rod ends of the cylinders 32 through the line 45 to their base ends. The main cylinder 18 can then continue to extend, thrusting the compaction plate 25 angularly rearwardly relative to the ejector plate 15 in order to further compact the refuse. 
     After this extension of the compaction plate 25 has been completed, the operator reverses the valve 39 feeding the hydraulic fluid under pressure to the rod end of the main cylinder 18 to retract that cylinder and, first, to move the compaction plate 25 back into its &#34;normal&#34; position as a continuation of the refuse compacting face of the ejector plate 15. The initial portion of this retraction movement causes fluid to flow from the base ends of the cylinders 32 through the valve 46 to their rod ends, with the excess fluid flowing down the over flow line 48 to the sump 49. Continued retraction of cylinder 18 pulls the ejector plate 15 to the front of the body 11.