Abstract:
An articulated work machine, such as a wheel loader, includes many regularly serviced hydraulic points, such as a hydraulic fluid filter, a case drain filter, a transmission fluid filter and brake accumulators that are grouped and mounted in a common service center subassembly, which may be preassembled and then later attached to the work machine chassis when the machine is being built. Likewise, an electrical service center subassembly might include a battery box, relays and an emergency shutoff switch that can be preassembled and attached to the machine chassis as a unit at the time that the work machine is being built. The respective hydraulic and electrical service centers are attached to the work machine chassis underneath cab access steps on opposite sides of the machine. This strategy allows for a potential reduction in cost during the work machine manufacture, and also better facilitates servicing of the hydraulic and/or electrical service points at an easily accessible and common location(s).

Description:
TECHNICAL FIELD  
       [0001]     The present disclosure relates generally to servicing systems associated with a work machine, and more particularly to grouping hydraulic and/or electrical servicing points at an easily accessible common service center on a work machine, such as a wheel loader.  
       BACKGROUND  
       [0002]     Work machines often include many electrical and hydraulic systems that require periodic servicing and/or monitoring. For instance, a typical work machine might include implement hydraulic systems that include pumps and hydraulic cylinders for operating the implements associated with the work machine. The implement hydraulic system would typically include a case drain filter for catching debris leaving the pump, and a hydraulic fluid filter for continuously trapping dirt, dust and other particulate matter that finds its way into the hydraulic system. An internal combustion engine which powers the work machine would typically include a lube oil system having lube oil that passes through a filter. A transmission would typically include circulated transmission fluid that passes through a filter. Hydraulically actuated service brakes may include gas accumulators that might require periodic inspection and recharging with gas if the pressure is low. In addition, some work machines include an electrohydraulic parking brake system with a parking brake valve that may require periodic inspection. Finally, these hydraulic fluid systems may require a means of draining and refilling on a periodic basis. These hydraulic fluid systems define a plurality of service points where inspection and maintenance processes are performed by a technician. In prior art work machines, these service points are distributed throughout the machine and may be difficult to identify and access, requiring an excess amount of time to perform the inspection and maintenance processes.  
         [0003]     The electrical system may, on the other hand, include a variety of relays and possibly a main shut down switch. Switches to raise and lower a hood and any waste or other guards may also be required. A jump start receptacle may also be included. In addition, the electrical system typically will include a battery that should be readily accessible, and may require servicing and/or periodic replacement. Thus, the electrical system also defines a plurality of service points where inspection and maintenance processes are performed by a technician. In prior art work machines, these service points are distributed throughout the machine and may be difficult to identify and access, requiring an excess amount of time to perform the inspection and maintenance processes.  
         [0004]     Those skilled in the art will also appreciate that servicing the various service points of the hydraulic and electrical systems of a work machine can sometimes be inconvenient when the machine is hot. For instance, some of the service points in prior art work machines may be located near relatively high temperature items, such as the engine. A technician may have to wait until the engine cools before accessing these service points.  
         [0005]     The present disclosure is directed to one or more of the problems set forth above.  
       SUMMARY OF THE DISCLOSURE  
       [0006]     In one aspect, a work machine includes a front portion that is joined to a back portion via an articulation joint. The front portion includes a front frame, a pair of front wheels and a moveable bucket. The back portion includes a back frame, a pair of back wheels, an engine and a step leading to a cab. A system comprises one of a plurality of hydraulic components and a plurality of electrical components. The system includes a plurality of service points. A plurality of the service points are grouped at a common service center underneath the step.  
         [0007]     In another aspect, the common service center is a hydraulic service center that includes a service center box with a chassis mount and at least one door. A plurality of hydraulic service points are attached inside the box, and the hydraulic service points include a hydraulic fluid filter, a case drain filter, a transmission fluid filter and at least one brake accumulator.  
         [0008]     In still another aspect, a method of assembling a work machine includes attaching a hydraulic service center underneath a step of a back portion of a work machine body, which includes a front portion joined to the back portion via an articulation joint. A plurality of hydraulic fluid system hoses are attached to at least one hydraulic filter mounted inside the hydraulic service center. At least one brake line hose is attached to at least one brake accumulator mounted inside the hydraulic service center. In addition, at least one transmission fluid hose is attached to a transmission filter mounted inside the hydraulic service center. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a right side diagrammatic view of a work machine showing a hydraulic service center;  
         [0010]      FIG. 2  is an isometric close up view of the opened hydraulic service center mounted on the work machine of  FIG. 1 ;  
         [0011]      FIG. 3  is a different isometric diagrammatic view of the hydraulic service center of  FIG. 2 ;  
         [0012]      FIG. 4  is an isometric exterior view of the hydraulic service center of  FIG. 2 ;  
         [0013]      FIG. 5  is a partial left side diagrammatic view of the work machine of  FIG. 1  showing an electrical service center;  
         [0014]      FIG. 6  is a partial interior isometric view of a relay box which may form part of the electrical service center of  FIG. 5 ;  
         [0015]      FIG. 7  is an exterior view of the relay box of  FIG. 6 ; and  
         [0016]      FIG. 8  is an isometric view of the electrical service center of  FIG. 5 . 
     
    
     DETAILED DESCRIPTION  
       [0017]     Referring to  FIGS. 1 and 5 , a work machine  10  is illustrated as an articulated wheel loader with a chassis that includes a front portion  12  joined to a back portion  14  via an articulation joint  16 . Articulation joint  16  allows front frame  20  to pivot about a vertical axis with respect to back frame  25 . Steering of work machine  10  may be accomplished with appropriate actuators via articulation joint  16  in a conventional manner. The front portion  12  includes a front frame  20 , a pair of front wheels  21  and a moveable bucket  22 . The back portion  14  includes a back frame  25 , a pair of back wheels  26 , an operator station  27  and an engine  28 . Access to the operator station  27  or cab can be gained from either the right hand side shown via ladder  30 , step  32  and door  33 , or via a left hand side ( FIG. 5 ) via another ladder  130 ,  131 , a step  132  and a left side door (not shown). The operator ascends to the operator station  27  on the right side by climbing up the ladder  30  and standing on step  32 . Door  33  can then be opened and the operator steps into the operator station  27 . Ascending on the left side can be done in a similar fashion. On the right hand side of work machine  10 , underneath step  32  is mounted a hydraulic service center  40  that is more thoroughly described infra. Likewise, work machine  10  may include an electrical service center  140  mounted on the opposite side of work machine  10  underneath a step  132  adjacent the ladder  130  on the left hand side.  
         [0018]     Work machine  10  includes hydraulic and electrical systems that support various aspects of the machine. These systems are mounted on, or carried by, front frame  20  and/or back frame  25  in a conventional manner. For instance, the hydraulic system may include, but is not limited to, pumps, hoses, filters, valves, fittings, accumulators, heads, sensors, gauges, and any other known hydraulic system components. Likewise, the electrical system may include, but is not limited to, wires, a jump start receptacle, batteries, lights, gauges, hood and other guard actuation switches, sensors, actuators, motors, generators, relays, fuses, processors, memory and any other known electrical system components. The hydraulic system may include one or more separate fluid circuits, such as one or more wheel brake actuator circuits, one or more hydraulic implement actuator circuits, a transmission fluid circuit, one or more lubrication fluid circuits, and any other fluid circuits known in the work machine art. Likewise, the electrical system may include a plurality of separate circuits, such as one or more associated with electrical power, various sensor circuits, command and control circuits and any other electrical circuits known in the work machine art. The hydraulic and electrical systems define several service points where inspection and maintenance operations may need to be performed by a service technician.  
         [0019]     Referring now to  FIGS. 2, 3  and  4 , various service points grouped together in hydraulic service center  40  can be seen. Hydraulic service center  40  may be based upon any suitable structure such as an open frame, a frame with panels attached to create an enclosed, or partially enclosed box, or a formed sheet metal box frame  38  as illustrated.  FIG. 4  shows an exterior view of the hydraulic service center  40  as it might appear as a subassembly before being installed on a work machine. In the illustrated embodiment, the frame  38  of hydraulic service center  40  has a generally open back side that faces the work machine chassis and allows the various hydraulic fluid hoses to enter the hydraulic service center from a chassis side of the machine. Frame  38  includes mounts  80 ,  81 ,  82 ,  83  and  84  that facilitate attachment to the work machine  10 . Different work machines in a product line, such as a product line of different sized wheel loaders, might include similar mounting points to accommodate mounts  80 ,  81 ,  82 ,  83  and  84 , and whatever hydraulic servicing points that suit a particular model.  
         [0020]     The frame  38  of hydraulic service center  40  includes a small diagnostic tap door  45  that is mounted on a hinge  46 , and may include either a latch or a lock point. Frame  38  also includes a service main door  48  that may be mounted on a set of hinges  47 , and may be kept in a closed position via some suitable means, such as via bolts  49  that mate to flanges  68  or a latch or a lock ( FIG. 2 ). A ladder  30  ( FIG. 1 ) can be attached to the service main door  48  of hydraulic service center  40  ( FIG. 4 ) via ladder mounts  90 . The various internal service points of hydraulic service center  40  can be preassembled, and brought to the work machine assembly line as a subassembly. Furthermore, a substantially identical hydraulic service center shell can be used across a product line and include mounting features suitable for the servicing points that differ to some extent from one work machine to another in a product line. For instance, a line of wheel loaders might include identically shaped and sized hydraulic service centers with some identical internal features, and some that may differ from one work machine model to another. Different applications may include an identical hydraulic fluid filter head, but may have attached different hydraulic fluid filters. In other instances, a completely different filter head or other point could use the same or different mounting features in the hydraulic service center  40 .  
         [0021]     The hydraulic service center  40  may also include first and second brake accumulators  52  and  53  that are supported by appropriate brackets  43  and  44 . Those skilled in the art will appreciate the brake accumulator  52  and  53  provide a means of storing pressure energy for use by the braking system via a movable piston and pressurized gas. The accumulators include a valve for adjusting the gas pressure. A transmission filter head  55  may be connected to transmission fluid hoses  62  in a conventional manner and mounted under a platform stiffener  41 . A transmission filter  54  may also be pre-assembled to filter head  55 . Although not necessary, frame  38  might also include an access opening  39  so that transmission filter  54  may be easily removed and changed without opening the main service door  48 . Those skilled in the art will appreciate that transmission fluid is continuously circulated through transmission filter  54 , which removes dirt, dust and other particulate matter from the transmission fluid. Thus, transmission filter  54  needs to be periodically replaced based upon the operating environment of the work machine, its duty cycle and other factors known in the art. Likewise, brake accumulators  53  and  52  are connected to brake line hoses  60  and  61 , respectively in a conventional manner. In addition, a hydraulic fluid filter head  70  and case drain filter head  71  may be connected to other hydraulic fluid hoses in a conventional manner, and may be mounted to any inside surface of frame  38 . Those skilled in the art will appreciate that the case drain filter  51  captures debris leaving the hydraulic pump (not shown) and must be periodically serviced to maintain the hydraulic system in good working order. In addition, a separate hydraulic filter  50  is utilized to capture dust, dirt and other particulate matter that may find its way into the hydraulic system due to the operating environment and/or duty cycle of the work machine. Those skilled in the art will appreciate that this filter should also be periodically replaced to maintain the hydraulic system in good working order. In the illustrated embodiment, filter heads  70  and  71  are mounted on an underside of the top surface of frame  38 . These hoses enter in through the opened side of the frame  38  of the hydraulic service center  40  adjacent the work machine frame  25 . The service center sub-assembly  40  may or may not arrive at a work machine assembly line with case drain filter  51 , hydraulic filter  50  or transmission filter  54  attached to their respective filter heads  71 ,  70  or  55 .  
         [0022]     The hydraulic service center might also include an ecology drain  56  that facilitates evacuation and refilling of certain hydraulic fluid circuits. In addition, a hydraulic parking brake valve  66  may also be mounted inside or outside, as shown, of the frame  38  of the hydraulic service center  40 . A separate hydraulic fluid hose line (not shown) would fluidly connect the parking brake valve  66  to the appropriate parking brake cylinder(s) on the work machine. The hydraulic service center also may include a diagnostic pressure tap group mount  64  adjacent the small diagnostic tap door  45 . In particular, a panel  42  is mounted on diagnostic pressure tap group mount  64  so that one face of the panel  42  is adjacent the small diagnostic tap door  45 . Before mounting that panel  42 , a plurality of diagnostic pressure taps  58  may be attached to the opposite side of panel  42 . Customer optional attachment diagnostic pressure taps  59 , which are shown as unused in this embodiment, may also be available. In addition, this panel might include one or more grease zerks  73  that allow various aspects of the work machine  10  to be lubricated from hydraulic service center  40 . Other attachment hydraulic components might also be mounted on frame  38  of service center  40 , including but not limited to a quick coupler shut-off valve, and an axle oil cooling valve. Those skilled in the art will recognize that a hydraulic service center according to the present disclosure may include any combination of servicing points known in the art. As used in this application, a servicing point means a feature that is expected to need periodic replacement and/or inspection (e.g. fluids, filters, batteries, fuses, etc.), allows access to diagnose the status of a feature (e.g. diagnostic pressure taps), reset features (e.g., switches), and other conventional features such as a jump start receptacles and the like; however not a feature that could break but is not expected to require regular and periodic access or maintenance for the intended proper operation of the work machine.  
         [0023]     Referring now to  FIGS. 5 through 8 , work machine  10  may also include an electrical service center  140  mounted on back frame  25  underneath step  132 , on a side opposite from that of the hydraulic service center  40 . Step  132  is adjacent a left side cab access door (not shown). The left hand side of work machine  10  may also include an optional tool box  141  mounted underneath electrical service center  140 . Tool box  141  may include an access door  142  between rungs of ladders  130  and  131 . The electrical service center  140  may include a battery box  144 , a relay box  145  and a main shut down switch  150 . Those skilled in the art will appreciate that other electrical service features might also be included depending upon the needs of a particular work machine. For instance, the electrical service center  140  might also include other servicing features such as a hood switch, a waste guard belly switch (if used), a main disconnect, and possibly even jump start receptacles for jump starting the work machine engine starter. In addition, fuses, if any, might also be located in the electrical service center  140  without departing from the scope of the present disclosure.  
         [0024]     Like the hydraulic service center  40  described earlier, electrical service center  140  may be preassembled as shown in  FIG. 8  to include a battery box  144 , within which is mounted a battery (not shown) and a relay box  145  that is attached to battery box  144  via appropriate fasteners  149 . The battery may be accessed via a battery access panel  148 , which may be attached to battery box  144  in any suitable manner, such as via bolts  161 . Like the hydraulic service center  40 , electrical service center  140  includes a frame  138 , and mounts  180 ,  181 ,  182 ,  183  and  184  that allow it to be mounted underneath step  132  in a manner similar to that previously described with respect to the hydraulic service center.  FIGS. 6 and 7  show the relay box  145  that includes a relay access door  143  mounted on a hinge  146  and includes a latching mechanism such as a lock  147 . This allows the relay reset buttons to be readily accessed through the lockable door  143 . An emergency shut off switch  150  is also incorporated into the relay box  145 . The emergency shut off switch  150  is located in an easy to reach location for someone on the ground next to the machine, or for an operator dismounting the machine via ladder  30 . The emergency shut off switch  150  turns off electrical power to the engine, but maintains electrical power to other systems. A main shut off switch can also be incorporated and provides a means for disconnecting the battery from all electrical circuits of the work machine. A main shut off switch prevents unauthorized use of the machine and is also generally used to keep the battery fresh when the machine is not being used. Having the main shut off switch located inside the electrical service center  40  which can be locked helps restrict access thereto to only authorized persons.  
       INDUSTRIAL APPLICABILITY  
       [0025]     When manufacturing a work machine, the various filter heads and other hydraulic servicing points must often be individually mounted to the machine chassis as the assembly of the work machine proceeds along an assembly line. Thereafter, filters must be attached to the respective heads. This can be rather expensive and slows the progress of the work machine assembly. The present disclosure addresses this issue by allowing much of the servicing points associated with the hydraulic and/or electrical service centers to be preassembled in respective hydraulic and electrical service centers  40 ,  140  and brought to the work machine assembly line as pre-assembled units.  
         [0026]     Before the preassembled service centers  40  and  140  are brought to the machine  10 , the panel  42  may have a plurality of diagnostic taps  58 ,  59  and grease zerks  73  attached thereto. As the hydraulic service center  40  is brought adjacent to back frame  25 , the panel  42  with the various diagnostic tap hoses and grease zerk hoses may be loosely inserted and positioned inside of the service center  40 . In addition, the various hydraulic hoses and brake line hoses are inserted through the opening of the hydraulic service center  40 , and may be allowed to remain loose until the hydraulic service center is mounted to the work machine  10 . The hydraulic service center  40  can then be mounted to the back frame  25  of the work machine  10  via the mounts  80 ,  82 , and  84 . The hydraulic service center  40  may also be mounted to the step  32  at  81  and  83 . Next, the various hydraulic hoses may be attached to in respective hydraulic components. For instance, the brake line hoses  60  and  61  are attached to brake accumulators  53  and  52 , respectively in a conventional manner. The appropriate hydraulic fluid hoses are connected to the hydraulic filter head  70  and case drain filter  71 , and the appropriate transmission fluid filter hoses are fluidly connected to transmission filter head  55 . Finally, other fluid connections, such as the hydraulic fluid brake hose, may be connected to brake valve  66 , and the appropriate fluid hoses connected to eco-drain  56 . Panel  42 , with taps  58 ,  59  and zerks  73  already attached, can be mounted to group mount  64  after the frame  38  of service center  40  has been attached to frame  25 .  
         [0027]     This construction is similar for the electrical service center except that it is mounted on the opposite side of the work machine via its mounts  180  and  181 . Step  132  may be attached at mounts  182 ,  183 , and  184 . However, instead of fluid hoses being brought into the opening in the electrical service center, electrical wires are brought into the same and may be attached to the already mounted battery relays and shut off switch within the electrical service center after the electrical service center  140  is mounted to work machine  10 . The various hoses and wires may also be connected in whole, or in part, before the respective service centers  40 ,  140  are mounted on the back frame  25 . Other hydraulic and/or electrical servicing points could be included in the service centers  40 ,  140  without departing from the intended scope of the present disclosure. For instance, the hydraulic service center  40  might also include a quick coupler shut off valve, or possibly even an axle oil cooling valve group.  
         [0028]     The central location for the respective hydraulic and electrical service centers can save time at the factory during assembly of the work machine, and in the field by making the various servicing points easy to locate. Also, diagnostics can be improved by making the various pressure diagnostic pressure taps located centrally to connect to pressure gauges to diagnose a problem in the field. For instance, pressure taps  58 ,  59  and grease zerks  73  can be easily accessed by opening the small pressure tap access door  45 . On the other hand, electrical relays can be reset at the electrical service center  140  by accessing the same through relay access door  143  on the opposite side of the machine.  
         [0029]     The location of the hydraulic and electrical service centers  40 ,  140  on the work machine  10  as described herein is advantageous for several reasons. First, the service centers  40 ,  140  are located within reach of a technician standing on the ground. The places all of the service points included therein in an easy to access position so that the technician does not need to lay on the ground, crouch down on the ground, or climb on the machine to reach them. Second, the service points are located away from some of the hot components and moving components on work machine  10  such as the engine, exhaust systems, and bucket. Third, the service centers  40 ,  140  are located on the side of the machine underneath the steps which lead to the cab doors. In this position, the tires, rear bumper and counterweight, bucket, and linkage of the work machine will not impede the technician&#39;s access to the service centers  40 ,  140 . The service centers  40 ,  140  are also close to the cab so that a technician or operator can access the service centers quickly after dismounting from the cab, or can quickly climb into the cab after performing service center maintenance.  
         [0030]     In addition, the structure of the present disclosure facilitates less chance of oil/grease spills during servicing. For instance, a drip pan can be placed inside or below the hydraulic service center  40  to catch any dripping fluids. In another aspect, the servicing decal descriptions may be mounted on the respective insides of the main service panel door and the diagnostic tap door so that a technician can easily reference and confirm the locations of various servicing points, while at the same time the decals are protected from the elements during normal machine operation.  
         [0031]     It should be understood that the above description is intended for illustrative purposes only, and is not intended to limit the scope of the present disclosure in any way. Thus, those skilled in the art will appreciate that other aspects, objects, and advantages of the disclosure can be obtained from a study of the drawings, the disclosure and the appended claims.