Patent Publication Number: US-2017362030-A1

Title: Articulated front loader arm mechanism for use with a conventional refuse collection extended cab chassis

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a non-provisional application claiming priority to provisional Patent Application Ser. No. 62/352,326 filed Jun. 20, 2016, the entire disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND OF INVENTION 
     The present invention relates generally to front loader arm mechanisms associated with refuse collection vehicles and, more particularly, to a novel articulated front loader arm structure for use with a conventional refuse collection vehicle having a conventional cab chassis wherein a programmed logic controller (PLC) monitors and controls the movement of the front loader articulated arm structure and communicates with various cylinders and sensors to control the extension/retraction of such cylinders during movement through both its container dump cycle and its container return cycle. The articulated arm structure further allows the present front loader arm mechanism to be stored on top of the vehicle under the current legal height restriction of 13 feet, 6 inches. 
     Various types of refuse collection vehicles are well known in the industry. Such refuse collection vehicles typically include a refuse collection vehicle body positioned on a vehicle chassis where the vehicle chassis includes a cab or operator compartment for housing the vehicle operator, a frame structure for holding the refuse collection vehicle body including an appropriate number of wheels for carrying the designated load, and an engine for powering the vehicle and the hydraulic and/or pneumatic systems associated therewith. 
     Depending upon the particular task at hand, that is, whether the refuse collection vehicle is being used for residential or commercial purposes, the vehicle body will typically include a storage compartment and a mechanism for emptying the refuse material collected within the storage compartment. The storage compartment typically includes a somewhat rectangular straight body design and a rear access door for allowing egress of the stored refuse or waste material from the storage compartment. The rear access door is typically a pivotally mounted tailgate associated with the rear portion of the storage compartment. Typically, the tailgate is activated by a pair of hydraulic lift cylinders to open and close the tailgate. The refuse material can be egressed from the storage compartment through conventional ejection systems. Where a refuse container or dumpster is to be emptied into the storage compartment, the refuse collection vehicle will likewise include a front loader arm mechanism for engaging, elevating and dumping the refuse container or dumpster into the storage compartment of the vehicle. 
     Whenever the known prior art front loader arm mechanism is utilized on a refuse collection vehicle, the conventional cab chassis arrangement is not utilized because the overall structure of the known front loader arm mechanism cannot fully extend over the conventional cab arrangement. Instead, a modified cab arrangement such as the cab over engine (COE) or a low cab over engine (LCOE) cab arrangement is utilized. This modified cab arrangement accommodates the known front loader arm structure as will be hereinafter explained. 
       FIG. 1  illustrates a typical prior art refuse collection vehicle  10  having a COE cab compartment  12 , the vehicle  10  being equipped with the known prior art front loader arm mechanism  14  for engaging a refuse container or dumpster and lifting the refuse container over the cab compartment  12  to a dumping position. The vehicle  10  also includes a storage compartment  16  in which refuse is dumped and collected. Typically, the front loader arm mechanism  14  is a one piece design which is pivotally attached to the vehicle frame structure on each opposite side of cab compartment  12  at respective pivot arm assemblies  18 . Movement of the front loader arm mechanism  14  between its lowered position as illustrated in  FIG. 1  and its raised or dump position (not shown) is controlled by a corresponding pair of arm lift cylinders  20 , one cylinder  20  being located on each respective side of the vehicle  10  between the storage compartment  16  and the cab compartment  12 . A forklift assembly  22  is pivotally attached to the terminal end portion of the front loader arm mechanism  14  at respective pivot assemblies  24 , which movement is controlled by a respective pair of fork cylinders  26 . 
     As illustrated in  FIG. 1 , the front loader arm mechanism  14  is shown in its lowered position preparatory to engaging a refuse container or dumpster, but the fork assembly  22  is shown in its collapsed position. Obviously, prior to engaging a typical refuse container, fork assembly  22  would be lowered to approximately a horizontal position relative to the ground and the fork assembly  22  would be positioned to engage corresponding engagement means associated with the container or dumpster for allowing the fork assembly  22  to hold the refuse container in a stable position during the dumping cycle. Once the refuse container is attached to the fork assembly  22 , transfer of the refuse material contained within the dumpster to the storage compartment  16  is accomplished by retracting the arm lift cylinders  20  which allows the front loader arm mechanism  14  to start moving upward to its dumping position over the storage compartment  16  as best indicated by the location of reference numeral  28  in  FIG. 1 . Because of the structure of the front loader arm mechanism  14 , a modified cab structure (COE or LCOE) must be utilized as the arm structure  14  is not of sufficient length to extend over a conventional cab chassis arrangement as will be hereinafter further explained. 
     In addition, the prior art front loader arm mechanism  14  is typically stowed for road travel either in the position as illustrated in  FIG. 1 , or in a slightly elevated position wherein the fork assembly  22  rides in the vicinity of the upper portion of cab  12 . Due to the current legal height restriction for refuse collection vehicles of 13 feet, 6 inches, the prior art front loader arm mechanisms such as the mechanism  14  illustrated in  FIG. 1  cannot be rotated to its dump position  28  above the storage compartment  16  for road travel as the fork assembly  22  will ride or extend above the legal height limit of 13 feet 6 inches. As a result, the prior art front loader arm mechanism  14  cannot be stowed for road travel on top of the vehicle  10 . 
     It is therefore desirable to have a front loader arm mechanism capable of extending over a conventional refuse collection cab chassis, and which is capable of being stored on top of the collection vehicle over the storage compartment during road travel and still meet the current legal height restriction of 13 feet, 6 inches. 
     The present invention seeks to overcome the shortcomings and disadvantages associated with the known prior art front loader arm mechanisms by articulating the front loader arm structure and controlling its movement through the use of a pair of arm lift cylinders, a pair of arm hinge cylinders, and a programmed logic controller (PLC) or other controller mechanism which will control the lift and hinge cylinders and the articulated movement of the present front loader and mechanism through both its dump cycle and its return cycle while, at the same time, allowing the present front loader arm mechanism to extend over a conventional cab chassis. 
     In addition, the present invention also allows the present front loader arm mechanism to be stowed above the vehicle over the storage compartment at a height which is under the legal height restriction of 13 feet 6 inches. Still further, the fork assembly associated with the present front loader arm mechanism includes a position sensor which likewise communicates with the PLC to store the angular position of the front arm relative to the fork assembly when the dumpster is engaged, so that when the dumpster is returned to a ground surface after dumping, the dumpster can be returned to that stored angular position and thus be substantially level on the surface from which it was lifted. 
     SUMMARY OF INVENTION 
     The present invention overcomes many of the shortcomings and limitations associated with the known prior art front loader arm mechanisms discussed above and teaches the construction and operation of an articulated front loader arm structure which is specifically adaptable for use with a conventional refuse collection vehicle extended cab compartment. 
     In one aspect of the present invention, the present articulated front loader arm mechanism includes a pair of front arm sections pivotally attached to a pair of rear arm sections having a pair of arm hinge cylinders positioned and located therebetween for allowing the front arm sections to move in relationship to the rear arm sections. A forklift assembly is likewise pivotally attached adjacent the terminal end portion of the front arm sections and its movement relative to the front arm sections is controlled by a pair of fork cylinders. The forklift assembly includes a pair of forklift arms which can be positioned and maneuvered to engage a refuse container or dumpster so that the refuse material contained within the dumpster can be transferred to a storage compartment associated with the refuse collection vehicle via operation of the present articulated front loader arm mechanism. 
     In this regard, the present articulated front loader arm mechanism is movable between a first position where a dumpster engaged with the forklift assembly is resting on a support surface at or near ground level, and a second position where the dumpster is located over the storage compartment of the vehicle in a dump position. Movement of the present arm mechanism between its first and second positions will be hereinafter referred to as the container dump cycle and movement of the present arm mechanism from its second position back to its first position will be hereinafter referred to as the container return cycle. 
     Movement of the present articulated front loader arm mechanism is controlled by a pair of arm lift cylinders, a pair of arm hinge cylinders, and a pair of fork cylinders. Each of the cylinders communicate with a programmed logic controller (PLC) or other system controller or processor means which monitors and controls the extension and retraction of the arm lift, arm hinge, and forklift cylinders relative to each other as the present front loader arm mechanism moves during both its container dump cycle and its container return cycle. The PLC or system controller monitors the position of the cylinders during movement of the front loader arm mechanism through the use of sensors associated with such cylinders so as to ensure that the front arm sections, the forklift assembly and any refuse container or dumpster engaged therewith will not hit or otherwise make contact with the hood area or the cab compartment associated with the refuse vehicle during its cycle movements. 
     The PLC farther monitors the angular position of the forklift arms relative to the terminal end portion of the front arm sections through the use of an additional position sensor associated with the forklift assembly. The position sensor measures the angular position of the forklift arms relative to the terminal end portion of the front arm sections upon engaging the dumpster, and it stores that angular position in its memory until the stored angular position is again used at the initiation of the dumpster&#39;s return cycle, as further explained below. 
     The container dump cycle starts with the present articulated front loader arm mechanism being positioned by the vehicle operator using a joystick or other mechanism such that the forklift arms are at a height for engaging the engagement means associated with a typical refuse container or dumpster. When a refuse container is engaged with the forklift arms, the arm lift cylinders are near full extension, the arm hinge cylinders are at full extension, and the forklift cylinders are extended so that the forklift arms are in position to engage the refuse container. Once a refuse container is engaged with the forklift assembly, the position sensor associated with the forklift assembly measures the angular position of the forklift arms relative to the terminal end portion of the front arm sections and sends a signal to the PLC including that angular orientation for subsequent use. 
     The operator will then activate the PLC through a control panel, joystick and/or other control mechanism in the cab compartment to start the container dump cycle. When activated, the PLC will start to retract the arm lift cylinders, allowing the front loader arm mechanism to start its movement upward towards its dump position. When the arm lift cylinders reach a pre-determined location which coincides with the refuse container being lifted to a pre-determined position such as just over the hood area of the vehicle, the PLC will signal the arm hinge cylinders to start their retraction. This ensures that the front arm sections and the refuse container will not hit or otherwise make contact with the hood area of the vehicle. At a predetermined location programmed into the PLC, the PLC will send a signal to the forklift cylinders to further extend so as to keep the refuse container or dumpster somewhat level with the ground during this portion of its movement towards the dump position. 
     During the container dump cycle, as the arm hinge cylinders retract, the PLC will continuously monitor the location of the arm hinge cylinders relative to the location of the arm lift cylinders to ensure that the position of the respective cylinders are within a pre-determined range programed within the PLC. This is necessary to ensure that the front arm sections, the forklift assembly and the refuse container or dumpster engaged therewith will clear the cab compartment and any cab shield positioned above the cab compartment during movement of the present articulated front loader arm mechanism during the remainder portion of its travel to its dump position. If, for example, the arm hinge cylinders are not within the pre-determined range programmed into the PLC, the PLC will either slow down the retraction of the arm hinge cylinders or slow down the retraction of the arm lift cylinders as needed so as to keep movement of the respective front and rear arm sections within a pre-determined range to again ensure that no portion of the arm structure or the dumpster will contact any portion of the refuse vehicle. 
     When the arm lift cylinders and the arm hinge cylinders reach full retraction, the refuse container will be located above the refuse vehicle and over the storage compartment and, at this point, the PLC will send a signal to the forklift cylinders to retract the forklift cylinders thereby rotating the refuse container or dumpster to dump the contents of the refuse container into the storage compartment. After the refuse container is emptied, the PLC will again send a signal to the forklift cylinders to extend the forklift cylinders to again partially rotate the refuse container or dumpster away from its dump positions, and it will also send a signal to slightly extend the arm hinge cylinders while leaving the arm lift cylinders retracted. This allows the front arm section to have sufficient clearance between itself and the top of the refuse vehicle before the container return cycle is initiated. The forklift cylinders will initially extend such that the angular orientation between the forklift arms and the terminal end portion of the front arm sections will be the same as the angular position stored in the PLC that was measured when the dump cycle was initiated. That way, when the dumpster is returned to its ground surface upon completion of the dumpster return cycle, it will be substantially level with that ground surface. 
     After the arm hinge cylinders reach a pre-determined location during its extension after the dump cycle has been completed, the PLC will send a signal to the arm hinge cylinders to continue to extend while likewise sending a signal to the arm lift cylinders to begin their extension. This will now start movement of the present articulated front loader arm mechanism on its return cycle. Like the dump cycle, the PLC will monitor the location of the arm lift cylinders and the arm hinge cylinders relative to each other during its return cycle to again ensure that the correct relationship between the cylinders is maintained throughout the entire return cycle. This similarly ensures that the refuse container, forklift assembly and/or the front arm sections of the present arm mechanism will not contact any portion of the vehicle during its return cycle. The arm hinge cylinders will reach full extension when the container is generally over the hood area of the vehicle, and the arm lift cylinders will be still extending. The arm lift cylinders will continue to extend until the container is on the ground. 
     Because of the articulation between the front and rear arm sections of the present front loader arm mechanism, the present mechanism can be fabricated to extend over a conventional refuse collection cab chassis. In addition, because of this same articulation, the front arm sections as well as the forklift assembly can be positioned and oriented for road travel on top of the refuse vehicle and over the storage area at a height which is under the current legal height restriction of 13 feet, 6 inches for refuse collection vehicles. The pivoting of the front arm sections relative to the rear and sections allows for storage of the present front loader arm mechanism on top of the refuse vehicle during road travel, a stowed or travel position not obtainable with the known prior art front loader arm mechanisms. In addition, movement and control of the front and rear arm sections relative to each other as well as movement of the forklift assembly via a programmable logic controller or other system controller ensures that the front arm sections, the forklift assembly and/or a refuse container or dumpster attached to the forklift assembly will always clear the hood area and cab compartment of the vehicle during both its container dump cycle and its container return cycle. 
     Additional features of the present invention will be described and will become apparent to those skilled in the art during the course of the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       For a better understanding of the present invention, reference may be made to the accompanying drawings. 
         FIG. 1  is a side elevational view of a typical refuse collection vehicle having an COE cab compartment and being equipped with a typical known prior art front loader arm structure. 
         FIG. 2  is a perspective view of a typical refuse collection vehicle utilizing the present articulated front loader arm mechanism constructed in accordance with the teachings of the present invention. 
         FIG. 3  is a side elevational view of the refuse collection vehicle of  FIG. 2  showing the present articulated front loader arm mechanism engaged with a refuse container at the beginning of its dump cycle. 
         FIG. 4  is a schematic diagram of one embodiment showing the operation of the PLC, position sensor, control panel and joystick for controlling and monitoring the movement of the lift, hinge and forklift cylinders and the present articulated front arm mechanism. 
         FIG. 5A  is a partial side elevational view showing a first embodiment of the present position sensor associated with the terminal end portion of at least one front arm section and the forklift arms. 
         FIG. 5B  is a partial side elevational view showing a second embodiment of the present position sensor associated with the terminal end portion of at least one front arm section and the forklift arms. 
         FIG. 6  is a partial side elevational view of  FIG. 3  showing the present articulated front loader arm mechanism moving through a portion of the dump cycle. 
         FIG. 7  is a partial side elevational view of  FIG. 3  showing the present articulated front loader arm mechanism moving through a further portion of the dump cycle. 
         FIG. 8  is a partial side elevational view of  FIG. 3  showing the present articulated front loader arm mechanism at its dump position. 
         FIG. 9  is a partial side elevational view of  FIG. 3  showing the present articulated front loader arm mechanism at the beginning of its return cycle. 
         FIG. 10  is a partial side elevational view of  FIG. 3  showing the present articulated front loader arm mechanism moving through a portion of its return cycle. 
         FIG. 11  is a partial side elevational view of  FIG. 3  showing the present articulated front loader arm mechanism moving through a further portion of its return cycle. 
         FIG. 12  is a partial side elevational view similar to  FIG. 3  showing the present articulated front loader arm mechanism at its returned ground level position. 
         FIG. 13  is a side elevational view similar to  FIG. 3  showing the present articulated front loader arm mechanism in its stowed road travel position. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 2  illustrates a refuse collection vehicle  30  having a chassis including a conventional operator or cab compartment  32  and a storage compartment  34  in which refuse is dumped and collected during the refuse collection process described below. The storage compartment  34 , which is substantially similar to storage compartment  16  described above, is generally rectangular in shape, though in alternative embodiments the storage compartment  34  could take on a different shape. The refuse collection vehicle  30  includes on its front portion the present articulated front loader arm mechanism  36 . The construction and operation of the articulated front loader arm mechanism  36  allows the present mechanism to extend over a conventional refuse collection cab compartment such as cab compartment  32 , rather than a COE, an LCOE or other modified cab compartment. In addition, the articulated front loader arm mechanism  36  can be positioned and oriented for road travel on top of the refuse vehicle  30  and over the storage compartment  34  at a height under the current legal height restriction of 13 feet, 6 inches for refuse collection vehicles as will be hereinafter further explained. 
       FIG. 3  illustrates the refuse collection vehicle  30  and the present articulated front loader arm mechanism  36  from a side elevational view, thus showing only one side of the collection vehicle  30  and one side of the articulated front loader arm mechanism  36 . Because of their symmetrical construction, the opposite side of collection vehicle  30  and the opposite side of the articulated front loader arm mechanism  36  not illustrated in  FIG. 3  are substantially similar to the sides shown in  FIG. 3 .  FIG. 2  illustrates this symmetry. 
     The front loader arm mechanism  36  includes a pair of front arm sections  38  positioned and located on either side of vehicle  30 . The front arm sections  38  are pivotally attached to a pair of rear arm sections  40  via a pair of first pivot arm assemblies  42 . The pivot arm assemblies  42  pivotally attach the arm sections  38  and  40  to one another and also allow for the angular rotation of arm sections  38 ,  40  relative to one another. A pair of arm hinge cylinders  44  positioned and located between the front arm sections  38  and the rear arm sections  40  allow the front arm sections  38  to angularly move relative to the rear arm sections  40  when the front loader mechanism  36  is in operation as will be described below. The arm hinge cylinders  44  may be hydraulically or pneumatically operated as well known and understood in the art. 
     The rear arm sections  40  are pivotally attached to the storage compartment  34  or to any other portion of the refuse collection vehicle  30  via a pair of second pivot arm assemblies  46 . The rear arm sections  40  are further attached to a pair of arm lift cylinders  52 . One end portion of the respective arm lift cylinders are attached to the refuse collection vehicle  30  at a first fixed point  48  and their opposite end portions are attached to the rear arm sections  40  at a second fixed point  50 . The arm lift cylinders  52  operate to allow rear arm sections  40  to rotate toward the rear of the vehicle  30  during operation of the loader mechanism  36 . Like the arm hinge cylinders  44 , the arm lift cylinders  52  may be hydraulically or pneumatically operated as well known and understood in the art. 
     A forklift assembly  54  is likewise pivotally attached to the terminal end portion of the front arm sections  38  via a pair of third pivot arm assemblies  56 . The forklift assembly  54  includes a pair of forklift arms  60  which can be positioned and maneuvered to engage a refuse container or dumpster  62  (as shown in  FIGS. 3 and 6-12 ) so that refuse material contained within the dumpster  62  can be transferred to the storage compartment  34  associated with the refuse collection vehicle  30  via operation of the present articulated front loader arm mechanism  36 . Movement of the forklift assembly  54  and its forklift arms  60  relative to the front arm sections  38  is controlled by a pair of forklift cylinders  64 . The forklift cylinders  64  each have one end portion attached to a respective front arm section  38  and each have their opposite end portions attached to a respective flange  58  associated with the respective third pivot arm assemblies  56 . Like cylinders  44  and  52 , the fork cylinders  64  may also be either hydraulically or pneumatically operated. 
     In this regard, the present articulated front loader arm mechanism  36  is movable between a first position where a dumpster such as dumpster  62  engaged with the forklift assembly  54  via engagement means  66  on the dumpster  62  is resting on a support surface  68  at or near ground level, such as shown in  FIG. 3 , and a second position where the dumpster  62  is located over the storage compartment  34  of the vehicle  30  in a dump position, such as shown in  FIG. 8 . Movement of present arm mechanism  36  between its first and second positions is hereinafter referred to as the container dump cycle, and movement of the arm mechanism  36  from its second position back to its first position is hereinafter referred to as the container return cycle. 
     The schematic diagram of  FIG. 4  illustrates the interaction and communication between the arm lift cylinders  52 , the arm hinge cylinders  44 , the forklift cylinders  64  and a programmed logic controller (PLC)  70  which measures, monitors, and controls the extension and/or retraction of the arm lift cylinders  52 , the arm hinge cylinders  44 , and forklift cylinders  64  as the present front loader arm mechanism  36  moves during both its container dump cycle and its container return cycle, The PLC  70  may be of the type commonly known or understood in the art, and thus should act as a digital computer used for automation. As an alternative to the PLC  70 , any system controller or processor means which is able to monitor or control the extension and retraction of the cylinders  52 ,  44 ,  64  relative to each other may be used. 
     The PLC  70  or other system controller monitors and/or adjusts the position of the arm lift cylinders  52 , the arm hinge cylinders  44 , and forklift cylinders  64  during movement of the front loader arm mechanism  36  via its communication with an arm lift sensor  72 , an arm hinge sensor  74 , and a forklift sensor  76  as well as communication with the respective cylinders. The sensors  72 ,  74 , and  76  may be of any type suitable for measuring the relative extension and retraction positions of the arm lift cylinders  52 , the arm hinge cylinder  44  and the forklift cylinders  64  as well as the relative positions of the arm sections  40 ,  38  and/or the forklift assembly  54 . The communication between the PLC  70  and the sensors  72 ,  74 , and  76  via conductive paths  90 ,  92  and  94  and communication between the PLC  70  and the respective cylinders  52 ,  44  and  64  via conductive paths  91 ,  93  and  95  may be either of wired or wireless communication. The PLC  70  may be physically located in a number of different locations on the vehicle  30 , such as in the cab compartment  32 , where a user can operate the PLC  70 . The sensors  72 ,  74 ,  76  are illustrated as associated with the cylinders  52 ,  44 ,  64  in  FIG. 4 , but in other embodiments, the sensors  72 ,  74 ,  76  may be built into the cylinders  52 ,  44 ,  64  or otherwise associated with the cylinders  52 ,  44 ,  64 . 
     The sensors  72 ,  74 ,  76  ensure that the cylinders  52 ,  44 ,  64  do not retract and/or extend too quickly and thus cause uncontrolled and potentially dangerous movements of any of the rear arm sections  40 , front arm sections  38 , or the forklift assembly  54 . The sensors  72 ,  74 ,  76  also measure the relative positions of the rear arm sections  40 , front arm sections  38 , and/or forklift assembly  54 , and using a predetermined algorithm, the PLC  70  continuously monitors the cylinders  52 ,  44 ,  64  to ensure that the front arm sections  38  and the forklift assembly  54  and any refuse container or dumpster such as dumpster  62  engaged therewith do not hit or otherwise make contact with the hood area or the cab chassis  32  associated with the refuse vehicle  30  during its cycle movements. 
     The PLC  70  is also used to initiate and otherwise operate the arm mechanism  36  and its cylinders  52 ,  44 ,  64  during its dump cycle and its return cycle. PLC  70  may be operated to initiate the dump cycle, return cycle, or the operation of any of cylinders  52 ,  44 ,  64  by way of a user interface such as a control panel  78 , a joystick  80  and/or other control mechanism compatible with the operation of the arm mechanism  36  as described herein (the schematic diagram of  FIG. 4  illustrates this relationship). The control panel  78 , joystick  80  and/or other control mechanism used to control the PLC  70  and the arm mechanism  36  are operatively connected to the PLC  70  via conductive paths  96  and/or  98  and are of a type known or foreseeable in the art able to be in electrical and/or data communication with the PLC  70 . The control panel  78 , joystick  80  and/or other control mechanism are preferably located in the cab chassis compartment where an operator is seated when operating the front loader and mechanism  36 . The PLC  70 , through user interfaces  78 ,  80  or other mechanisms, controls the respective cylinders  52 ,  44  and  64  via conductive paths  91 ,  93 ,  95  or some other known mechanism. 
     The PLC  70  also monitors and measures the angular position of the forklift arms  60  relative to the terminal end portion of at least one front arm section  38  through the use of a position sensor  82  associated with the forklift assembly  54  as shown in  FIG. 5A . The position sensor  82  is illustrated in  FIG. 5A  as a rotary sensor  82 . An alternative position sensor  84  is also illustrated in  FIG. 5B  as a linear sensor  84 . Either of the position sensors  82  or  84  are in communication with the PLC  70  via conductive path  100  and either sensor may be any type so long as it is able to monitor and measure the angular position of the forklift arms  60  relative to the terminal end portion of at least one front arm section  38 . Position sensors  82  or  84  and their relative functions during the operation of the articulated arm mechanism  36  are discussed in detail when further describing the operation of the articulated arm mechanism  36  below. 
       FIG. 3  illustrates a side elevational view of the loader arm mechanism  36  at the start of its container dump cycle. The container dump cycle starts with the present articulated front loader arm mechanism  36  being maneuvered and positioned by the vehicle operator using the control panel  78 , the joystick  80 , or some other interface mechanism to operate the PLC  70  such that the forklift arms  60  are at a height for engaging the engagement means  66  associated with a typical refuse container such as dumpster  62 . 
     When the dumpster  62  is engaged with the forklift arms  60  via engagement means  66  in a manner known, the arm lift cylinders  52  are at or near full extension, the arm hinge cylinders  44  are at or near full extension, and the forklift cylinders  64  are extended so that the forklift arms  60  are engaged with the dumpster  62 . After the dumpster  62  is engaged with the forklift assembly  54 , the position sensor  82  or  84  (illustrated in  FIGS. 5A and 5B ) associated with the forklift assembly  54  measures the angular position of the forklift arms  60  relative to the terminal end portion of the front arm sections  38  and sends a signal to the PLC  70  via conductive path  100  including that angular position measurement, which the PLC  70  stores in a memory (not illustrated). The angular orientation measurement of the forklift arms  60  relative to the terminal end portion of the front arm sections  38  will again be used after the dumpster  62  has been dumped and the front loader arm mechanism  36  is maneuvered to start its return cycle. 
     When activated, the PLC  70  will first send a signal via conductive path  91  to retract the arm lift cylinders  52 . The retracting of arm lift cylinders  52  allows front loader arm mechanism  36  with dumpster  62  attached thereto to initiate its movement upward towards its dump position. The dumpster  62  having begun its upward ascent is illustrated in  FIG. 6 , where arm lift cylinders  52  are shown in a partially retracted position. In this position, the arm lift cylinders  52  have reached a pre-determined location which coincides with the dumpster  62  being lifted to a pre-determined position such as just over the hood area of the vehicle  30 . This pre-determined location which is read and measured by sensors  72 ,  74 ,  76  is sent to the PLC  70  via conductive paths  90 ,  92  and  94  which then will signal via conductive paths  93  the arm hinge cylinders  44  to start their retraction. The arm lift cylinders  52  beginning their retraction prior to the arm hinge cylinders  44  ensures that the front arm sections  38  and the refuse container  62  do not hit or otherwise make contact with the hood area of the vehicle  30  thus potentially damaging vehicle  30 . 
     At the same time, when the refuse container  60  is at a position such as just over the hood area of the vehicle  30  or a different position and location pre-programmed into the PLC  70 , the PLC  70  will send a signal via conductive path  95  to the forklift cylinders  64  to extend a pre-determined amount so as to keep the refuse container  62  somewhat level with the ground during this portion of its movement towards the dump position. If the forklift cylinders  64  did not extend as set forth above, the refuse container  62  would be angled inwardly toward the vehicle  30  to the point of risking dumping refuse prematurely onto the cab compartment or other parts of the vehicle  30  during its ascent to the dump position rather than in the storage compartment  34 . This not only could defeat the purpose of the entire dump cycle, but it also could pose a danger to the operator within cab compartment  32  or cause damage to the vehicle  30 . 
     Continuously throughout the duration of the container dump cycle, as the arm lift cylinders  52  and arm hinge cylinders  44  are retracted, the PLC  70  will monitor the location of the arm hinge cylinders  44  relative to the location of the arm lift cylinders  52  via conductive paths  90  and  92  to ensure that the respective positions of the cylinders are within a pre-determined range programed within the PLC and to further ensure that the cylinders are not retracting too quickly. If cylinders  52 ,  44  are moving too quickly or too slowly relative to one another, the dumping cycle could take place prematurely prior to reaching the storage compartment  34 . This continuous monitoring is also necessary to ensure that the front arm sections  38 , the forklift assembly  56 , and the refuse container  62  engaged therewith will likewise clear the cab chassis  32  and any cab shield (not illustrated) positioned above the cab chassis during movement of the present articulated front loader arm mechanism  36  during the remainder portion of its travel toward the dump position as best illustrated in  FIG. 7 .  FIG. 7  is a partial side elevational view showing the present arm mechanism  36  and attached dumpster  62  clear of the cab compartment  32  and moving through a further portion of the dump cycle. 
     In order to avoid the aforementioned undesirable scenarios, if the arm hinge cylinders  44  are not retracting within the pre-determined range programmed into the PLC  70  during the dump cycle, the PLC  70  will either slow down the retraction of the arm hinge cylinders  44  or slow down the retraction of the arm lift cylinders  52  as needed. That way the respective front and rear arm sections  38 ,  40  remain within a pre-determined range so that no portion of the front loader arm mechanism  36  or the dumpster  62  will contact and/or damage any portion of the refuse vehicle  30 . It is the articulation between the front and rear arm sections  38 ,  40  of the present front loader arm mechanism  36  that allows the present mechanism  36  to be fabricated such that it is able to extend over a conventional refuse collection cab chassis such as cab chassis  32 . 
     After some time of retracting, the arm lift cylinders  52  and the arm hinge cylinders  44  reach full retraction, and the refuse container  62  is located above the refuse vehicle  30  and over the storage compartment  34 , as shown in  FIG. 8 . It is at this moment that the PLC  70  sends a signal to the forklift cylinders  64  via conductive path  95  to retract the forklift cylinders  64  thereby rotating the dumpster  62  toward the rear of the vehicle. The contents of the refuse container or dumpster  62  are then dumped into the storage compartment  34  as illustrated in  FIG. 8 . 
     After the refuse container is emptied, the PLC  70  will again send a signal to the forklift cylinders  64  to extend the forklift cylinders  64  to initiate the rotation of the refuse container  62  away from its dump position. The PLC  70  will also simultaneously send a signal to the arm hinge cylinders  44  via conductive path  93  to begin extending, while leaving the arm lift cylinders  52  retracted. This allows the front arm section  38  to clear itself away from the top of the refuse vehicle  30  before the container return cycle is initiated, as shown in  FIG. 9 . 
     Next, the PLC  70  further instructs the forklift cylinders  64  via conductive path  95  to extend to the same angular position between the forklift arms  60  and the terminal end portion of the front arm sections  38  measured by the position sensor  82  or  84  previously stored in the PLC at the initiation of the dump cycle. The forklift arms  60  having returned to the stored angular position relative to the front arm sections  38  shown at the start of the dump cycle in  FIG. 3  is again shown in  FIG. 9 . In this angular position, the dumpster  62  will be substantially parallel to the ground surface when the dumpster  62  is returned to its starting position as illustrated in  FIG. 12 . Depending on how the PLC  70  is programmed, the forklift cylinders  64  may extend such that the forklift arms  60  are completely returned to the stored angular position relative to the front arm section  38  before the arm hinge cylinders  44  extend rather than the arm hinge cylinders  44  extending at the same time as the forklift cylinders  64 . 
     After the arm hinge cylinders  44  reach a pre-determined location which is stored in the PLC  70  during extension after the dump cycle has been completed, the PLC  70  will signal the arm hinge cylinders  44  via conductive path  93  to continue to extend while likewise signaling the arm lift cylinders  52  via conductive path  91  to initiate their extension. These signals from the PLC  70  initiate the return cycle of the front loader arm mechanism  36 .  FIG. 10  is a partial side elevational view showing the present arm mechanism  36  moving through a portion of its return cycle. 
     As with the dump cycle, the PLC  70  continuously monitors the location of the arm lift cylinders  52  and the arm hinge cylinders  44  relative to one other during its return cycle. This continuous monitoring allows the PLC  70  to again ensure that the correct relationship between the cylinders  52 ,  44  is maintained throughout the entire return cycle. If necessary, the PLC  70  can instruct one or both of the cylinders  52 ,  44  to extend at an increased or decreased rate in order to prevent the dumpster  62 , forklift assembly  54  and/or the front arm sections  38  of the present arm mechanism  36  from contacting and/or causing damage to any portion of the vehicle  30  including its cab compartment  32  during the return cycle. 
     Preferably, the arm hinge cylinders  44  will reach full extension when the refuse container  62  is generally over the hood area of the vehicle  30 , prior to the arm lift cylinders  52  reaching their full extension. The arm hinge cylinders  44  having reached full extension prior to the arm lift cylinders  52  having reached full extension is shown in  FIG. 11 . 
       FIG. 12  shows completion of the return cycle, with the arm lift cylinders  52  continuing to extend until the refuse container  62  is on the ground. At this moment the vehicle  30  is able to reverse away from the dumpster  62  such that the forklift arms  60  disengage the dumpster  62  and its engagement means  66 . The PLC  70  may then signal the arm lift cylinders  52 , arm hinge cylinders  44 , and forklift cylinders  64  via conductive paths  91 ,  93  and  95  to all retract at a preprogrammed rate to a pre-determined position after the return cycle has been completed. One such position can be a road travel position located on top of the refuse vehicle and over the storage area  34  as best illustrated in  FIG. 13 . The cylinders  52 ,  44 , and  64  retract at a rate which prevents the front arm sections  38  and/or forklift assembly  56  from making contact and/or damaging the hood or cab compartment  32  of vehicle  30 . Thus, the arm lift cylinders  52  preferably retract first such that the front arm sections  38  and forklift assembly  56  are lifted upwardly away from the cab chassis  32 . Movement of the front loader arm mechanism  36  to its road travel position can also be accomplished by activating the dump cycle with no dumpster engaged, with the front loader arm mechanism  36 . 
     Once the articulated front loader arm mechanism  36  is in its fully stowed position, the vehicle  30  is prepared for road travel.  FIG. 13  illustrates the articulated front loader arm mechanism  36  in its fully stowed position. In the fully stowed position, all cylinders  52 ,  44 , and  64  are fully retracted, and the rear arm sections  40  are positioned and located at the side of the storage compartment  34 , and below the top edge portion of the storage compartment  34 . In the stowed position, the front arm sections  38  and forklift assembly  56  are positioned and located just above the storage compartment  34 . The front arm sections  38  as well as the forklift assembly  54  are stowed on top of the refuse vehicle  30  and over the storage compartment  34  at a height which is under the current legal height restriction of 13 feet 6 inches for refuse collection vehicles such as vehicle  30 . 
     It is because of the articulation between the front and rear arm sections  38  and  40  the present arm mechanism  36  can both extend over a conventional cab chassis and retract to a storage position on top of the vehicle for road travel and still stay below the current legal height restriction of 13 feet 6 inches for refuse collection vehicles. It is the arm hinge cylinders  44  that allow for the novel articulation of the arm mechanism  36  as explained above. 
     From the foregoing, it will be seen that the various embodiments of the present invention are well adapted to attain all the objectives and advantages hereinabove set forth together with still other advantages which are obvious and which are inherent to the present structures. Since many possible embodiments of the present invention may be made without departing from the spirit and scope of the present invention, it is to be understood that all disclosures herein set forth or illustrated in the accompanying drawings are to be interpreted as illustrative only and not limiting. The various constructions described above and illustrated in the drawings are presented by way of example only and are not intended to limit the concepts, principles and scope of the present invention. 
     Thus, there has been shown and described several embodiments of a novel articulated front loader arm mechanism. As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that other modifications and applications, or equivalents thereof, will occur to those skilled in the art. The terms “having” and “including” and similar terms as used in the foregoing specification are used in the sense of “optional” or “may include” and not as “required.” 
     Many changes, modifications, variations and other uses and applications of the present constructions will, however, become apparent to those skilled in the art after considering the specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow.