Patent Publication Number: US-8109356-B2

Title: Auxiliary hydraulic flow control system for a small loader

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is related to and claims priority from U.S. Provisional Patent Application 60/974,519, which was filed on Sep. 24, 2007 and is entitled “Vehicle Including an Interlock System, Industrial Equipment Including an Interlock System, and a Method of Controlling an Auxiliary System”. 
     BACKGROUND 
     The present discussion is related to a vehicle, such as a walk behind loader, or industrial equipment having a drive system and an auxiliary system. The present discussion is more particularly related to a method of enabling an auxiliary system on the vehicle. 
     Vehicles such as loaders are useful for performing a variety of tasks in industrial, agricultural, commercial and other applications and environments. Loaders come in a variety of configurations and sizes, including, for example, walk-behind loaders, which are operable from the rear of the loader by an operator that can walk behind the loader. Such loaders can also include a platform on which an operator can ride. In such instances, an operator rides along with the loader instead of walking behind the loader. 
     Loaders often include hydraulic systems, which are coupled to an engine and provide power that can be utilized to perform a number of tasks, such as propelling the machine and providing power to perform loader functions, such as raising and lowering lift arms. In addition, some loaders provide hydraulic power sources that can be utilized by attachments, implements or accessories (collectively, for the purposes of this discussion, “implements”) that are coupled to the loader. The hydraulic power source provided for use by implements is generally known as an auxiliary power source. 
     SUMMARY 
     In one illustrative embodiment, a vehicle having an engine, a drive system operably coupled to the engine, and an auxiliary power system operably coupled to the engine for supplying a power source to an implement during an active state and refraining from supplying the power source to the implement during an inactive state. The drive system causes the vehicle to move relative to a support surface and includes a drive handle operable by an operator for providing a signal indicative of a desired direction of travel. 
     The auxiliary power system includes an auxiliary power enablement device, an auxiliary actuator, an operator actuable continuous actuation device, and a continuous enablement actuator. The auxiliary power enablement device is moveable between an actuated position and a de-actuated position. In the actuated position, the auxiliary power enablement device enables the power source to be supplied to the implement. In the de-actuated position, the auxiliary power enablement device prevents the auxiliary power from being supplied to the implement. 
     The auxiliary actuator is operably coupled to the auxiliary power enablement device and is capable of being manipulated by an operator between a first position and a second position. The first position corresponds to the de-actuated position of the auxiliary power enablement device and the second position corresponds to the actuated position of the auxiliary power enablement device. The operator actuable continuous actuation device is movable between an engaged position and a disengaged position. It provides an actuation signal indicative of the position of the operator actuable continuous actuation device. 
     The continuous enablement actuator is capable of engaging the power enablement device when the power enablement device is in the actuated position to prevent the power enablement device from moving to the de-actuated position while the continuous enablement actuator is engaging the power enablement device. The continuous enablement actuator is configured to engage the power enablement device when the actuation signal is indicative of one of the engaged position and the disengaged position and is configured to attempt to be disengaged from the power enablement device with the actuation signal is indicative of the other of the engaged position and the disengaged position. 
     In another embodiment, a method of providing a power source to an implement from a vehicle having an engine, a drive system operably coupled to the engine, and a power control system for providing the power source is discussed. The power control system includes a power enablement device moveable between an actuated position and a de-actuated position for selectively providing the power source to the implement. The method includes receiving an operator signal from a sensing mechanism indicative of the position of an operator actuable continuous actuation device and providing an enablement signal to a continuous enablement actuator. The operator actuable continuous actuation device has an engaged position and a disengaged position. The operator actuable continuous actuation device is biased toward the disengaged position. 
     Providing the enablement signal to a continuous enablement actuator includes providing a signal indicative of urging the continuous enablement actuator to attempt one of engaging the power enablement device and disengaging the power enablement device. Engaging the power enablement device with the continuous enablement actuator prevents the power enablement device from moving to the de-actuated position. Dis-engaging the continuous enablement actuator from the power enablement device allows the power enablement device to move to the de-actuated position. The signal indicative of engaging the power enablement device is provided when the operator signal received is indicative of one of the engaged position and the disengaged position, but not the other of the engaged position and the disengaged position. 
     In yet another embodiment a hydraulic system for a loader configured to provide hydraulic fluid to an implement attached to the loader is discussed. The hydraulic system includes a valve, an actuator, an enabling member and a continuous engagement member. The valve has a de-actuated position, which blocks hydraulic fluid from being supplied to the implement and actuated position, which allows hydraulic fluid to be supplied to the implement. The valve has a bias toward the de-actuated position. The actuator is operably coupled to the valve and is capable of being manipulated by an operator to overcome the bias and cause the valve to move from the de-actuated position to the actuated position. 
     The enabling member is moveable between an engaged position and a disengaged position and provides an enablement signal indicative of its position. The continuous engagement member is capable of engaging the valve when the valve is the actuated position to cause the valve to remain in the actuated position while the continuous engagement member is engaged with the valve. The continuous engagement member is configured to attempt to engage the valve when the enablement signal is indicative of one of the engaged position and the disengaged position and disengage from the valve when the enablement signal is indicative of the other of the engaged position and the disengaged position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view generally taken from a rear of a walk behind loader of the type where incorporation of the embodiments discussed herein can be useful. 
         FIG. 2  is another perspective view of the walk behind loader illustrated in  FIG. 1  generally taken from a front of the loader. 
         FIG. 3  is a side elevation view of the walk behind loader illustrated in  FIG. 1 . 
         FIG. 4  is a schematic illustration of a control panel located in a rearward portion of the loader of  FIG. 1  including devices capable of being manipulated by an operator to control various loader related functions according to one illustrative embodiment. 
         FIG. 5  is a perspective view of a drive handle for the walk behind loader that is illustratively located on the control panel of  FIG. 4 . 
         FIG. 6  is a rear elevation view of the drive handle of  FIG. 5  showing a continuous flow engagement device in an engaged position. 
         FIG. 6A  is a rear elevation view of the drive handle of  FIG. 5  showing the continuous flow engagement device in a disengaged position. 
         FIG. 7  is a schematic block diagram illustrating a power control system for controlling hydraulic functions on the loader of  FIG. 1  according to one illustrative embodiment. 
         FIG. 8A  is a schematic diagram of a control valve for use in the power control system of  FIG. 7  illustrating a spool valve in a neutral position so as to prevent the flow of a fluid through the valve. 
         FIG. 8B  is a schematic diagram of the control valve of  FIG. 8A  illustrating a spool valve in a first momentarily engaged position so as to allow the flow of a fluid through the valve. 
         FIG. 8C  is a schematic diagram of the control valve of  FIG. 8A  illustrating a spool valve in a second momentarily engaged position so as to allow the flow of a fluid through the valve in a direction opposite of that illustrated in  FIG. 8B . 
         FIG. 8D  is a schematic diagram of the control valve of  FIG. 8A  illustrating a spool valve in a continuously engaged position so as to allow the flow of a fluid through the valve in a direction opposite of that illustrated in  FIG. 8B . 
         FIG. 9  is a block diagram illustrating a control system for controlling a continuous engagement feature for providing continuous hydraulic flow through a valve in accordance with one illustrative embodiment. 
         FIG. 10  is a flowchart illustrating a method of providing continuous hydraulic flow to an implement according to one illustrative embodiment. 
         FIG. 11  is a flowchart illustrating a method of controlling an engagement signal to a starter for the loader of  FIG. 1  according to one illustrative embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The embodiments that are discussed herein are illustrative in nature and are not intended to limit the scope of any claimed subject matter. As such, their discussion does not limit the scope of claimed subject matter to any particular details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. 
     Also, it is to be understood that the terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
       FIGS. 1-3  illustrate a small self propelled, walk behind loader  10  of the type for which a continuous flow engagement system is advantageous. The loader is shown with a loader frame  100  and a pair of track drive systems  102  and  104  that are illustratively bolted onto the loader frame  100  on a first side  106  and a second side  108  of the loader frame  100 , respectively. The loader  10  can include a ride-on platform not shown in any of  FIGS. 1-3 , but as shown in, for example, U.S. Patent Application Publication No. 2004/0145134 A1, published on Jul. 29, 2004, which is hereby incorporated by reference. The loader  10  shown in the figures and described herein is one example of a vehicle upon which the embodiments discussed herein can be incorporated. It should be appreciated that such the embodiments can alternatively be incorporated with other vehicles, such as those commonly employed in lawn and garden applications, to give one example, without departing from the scope of the discussion herein. In general, vehicles that incorporate the discussed embodiments are intended to include various self propelled arrangements. Furthermore, such vehicles may have tracks, rigid or steerable wheeled axles, as well as other drive and/or steering arrangements. In addition, such vehicles need not provide a means for carrying the operator. 
     The frame  100  of loader  10  illustratively includes a pair of vertically extending upright support structures  110 , disposed on the first side  106  and second side  108  near a distal end  112  of the loader  10 . The vertically extending upright support structures  110  support lift arms  114 , each of which are pivotally coupled at a distal end  112  thereof to one the upright support structures  110  at pivot points  118 . The lift arms  114  are illustratively coupled together via a crossmember  120 , which is positioned between, and attached to, the lift arms  114 . The lift arms  114  support an implement interface structure  122  that is pivotally attached to a proximal end  124  of each of the lift arms  114  at pivot points  126 . The implement interface structure  122  is capable of receiving any of a number of implements (not shown in  FIGS. 1-3 ), which can be used in conjunction with loader  10  to perform various tasks. 
     As discussed above, the lift arms  114  are pivotally coupled to the upright support structures  110  at pivot points  118 . In addition, an actuator  128  (only one of which is shown) is coupled to each of the upright support structures  110  and lift arms  114  at connection points  130  and  132 . In one illustrative embodiment, the actuators  128  are hydraulic cylinders, which are capable of being actuated so that they extend and retract to cause the lift arms  114  to rotate about the pivot points  118  in a generally arcuate path. Alternatively, the actuators  128 , lift arms  114 , and upright support structures  110  can be configured to cause the lift arms  114  to raise and lower in paths other than a generally arcuate path when the actuators  128  are actuated, such as, for example, a generally vertical path. 
     Similar to the connection between the lift arms  114  and the upright support structures  110 , the implement interface structure  122  is pivotally attached to the lift arms  114 . In addition, an actuator  134 , such as a hydraulic cylinder, is coupled to each of the crossmember  120  and the implement interface structure  122 . When the actuator  134  is actuated, the implement interface structure  122  is capable of pivoting about pivot points  126  in a generally arcuate path with respect to the lift arms  114 . While  FIG. 2  illustrates a single actuator  134 , it should be appreciated that multiple actuators may be incorporated to cause the implement interface structure  122  to pivot with respect to the lift arms  114 . 
     As discussed above, the implement interface structure  122  is capable of receiving and being coupled to a number of different types of implements. The cooperation of an implement with loader  10  allows an operator to manipulate the combination of the loader  10  and the implement to perform various tasks. As an example, one type of implement is a bucket (not shown in any of the Figures). A bucket is a relatively simple implement that can be utilized to dig and/or carry material. By manipulating the drive systems  102  and/or  104 , the lift arms  114  and the implement interface structure  122 , an operator can, for example, move the bucket to cause material to be loaded into the bucket, move the loader  10  to another location, and dump the material out of the bucket. 
     Some implements are more complex than the simple bucket described above. By “complex”, it is to be understood that such implements are capable of performing functions by converting a power source illustratively provided by the loader  10  to control a working device on the implement. To that end, loader  10  also illustratively includes an auxiliary hydraulics power system (not shown in  FIGS. 1-3 , but shown in  FIG. 7  as block  138  and discussed below in the text accompanying  FIG. 7 ), which provides a hydraulic power source capable of being accessed by an implement. The auxiliary hydraulics power system  138  includes port  136 , which illustratively include tubing, hoses, hydraulic fittings, or the combination thereof that are configured to be coupled to hydraulic components on an implement so that pressurized hydraulic fluid from the loader  10  is accessible by an implement. 
     One example of such a complex implement is a mower (not shown in any of the figures). A mower typically includes a blade that is rotatably coupled to a mower frame (i.e. a working device) along a generally vertical axis with respect to the mower frame and a device such as a hydraulic motor coupled to the blade. When hydraulic fluid from the auxiliary hydraulics power system  138  flows through the hydraulic motor, the motor is capable of rotating the blade about the axis. When properly positioned, the blade is capable of mowing grass or other similar vegetation. It should be appreciated that many other types of implements can be coupled to loader  10  and that the mower discussed herein is but one example. Other examples include, but are not limited to, augers and tillers. 
     The drive and loader functions as well as operation of a working device on any implement that may be attached to loader  10  are controllable by the operator. To that end, loader  10  also includes, as illustrated in  FIGS. 1 and 4 , a control panel  140  located near the distal end  112  of loader  10  between the upright support structures  110  so that it is accessible by an operator positioned in the proper operating position immediately behind the distal end  112  of the loader  10 . The control panel  140  includes a number of operator control devices that are capable of being manipulated by the operator to control the various machine functions. For example, a drive handle  142  is located in the control panel  140  and is capable of being manipulated to provide one or more signals indicative of whether the operator intends to have the loader  10  move in a particular direction and at a given rate. Signals from the drive handle  142  are provided to a drive control system (not shown in  FIGS. 1-4 , but discussed in more detail below), which controls movement of the drive systems  102  and  104 . 
     In addition, the control panel  140  includes a loader control input device  144 . The loader control input device  144  is configured to be manipulated by an operator to provide signals indicative of a desired control of the movement of the lift arms  114  and the implement interface structure  122 . In one illustrative embodiment, the loader control input device  144  is a two-axis joystick. Movement along one of the axes provides a signal indicative of desired movement of the lift arms  114 . Movement along the other of the axes provides a signal indicative of desired movement of the implement interface structure  122 . Signals from the loader control input device are provided to a loader control system (not shown in  FIGS. 1-4 , but discussed in more detail below) for controlling the actuators  128  and  134 . 
     The control panel  140  also illustratively includes an auxiliary function input device  146 . The auxiliary function input device  146  is, in one embodiment, a lever that is capable of being manipulated by an operator. The auxiliary function input device or lever  146  provides a signal indicative of a desired control of the auxiliary hydraulics power system  138  based on the position of the auxiliary function input device  146 . The signal provided by the auxiliary function input device  146  may be a hydraulic signal, an electric signal, a mechanical signal or any other type of signal capable of conveying the position of auxiliary function input device  146 . In one embodiment, the auxiliary function input device  146  is moveable along an axis and is biased toward a center position. When the auxiliary function input device  146  is positioned in the center position, a signal is provided that is indicative of a neutral condition. In a neutral condition, it is intended that the auxiliary hydraulics power system  138  provide no hydraulics fluid to any implement. 
     If the auxiliary function input device  146  is not in the center position, it is intended that hydraulic fluid is provided to any implement attached to the auxiliary hydraulics power system  138  in one of two directions. For example, if an operator applies a force to the auxiliary function input device  146  to move it in a first direction, the auxiliary function input device  146  provides a signal indicative of the operator&#39;s intention to provide hydraulic fluid to an implement in a first direction. Similarly, if an operator applies a force to the auxiliary function input device  146  to move it in a second direction, the auxiliary function input device  146  provides a signal indicative of the operator&#39;s intention to provide hydraulic fluid to an implement in a second direction. Because the lever  146  is biased to the center position, unless a force is applied to the lever  146 , the lever  148  is inclined to return to the center position without operator intervention. Thus, a signal indicative of a condition where no hydraulic fluid is enabled to flow to an implement is sent to the auxiliary hydraulics power system  138 . It should be appreciated that any acceptable force can be provided to bias the lever  148  in the center position including spring mechanisms integral to, or remote from, the auxiliary function input device  146 . As will be discussed in more detail below, however, it can be advantageous to allow for continuous hydraulic fluid flow to an implement without requiring that an operator continuously applying a force to manipulate lever  148 . 
     The control panel  140  also illustratively includes an operator actuable continuous flow engagement device  150  and an auxiliary hydraulic mode switch  152 . The continuous flow engagement device  150 , in illustrative embodiment, is an operator actuable continuous actuation device such as a lever that is pivotally attached to the drive handle  142 . As will be described in more detail below, the continuous flow engagement device  150  is biased in one position so that a force need be applied to the continuous flow engagement device  150  to cause the continuous flow engagement device  150  to pivot from an unactuated position into an actuated position. A sensing mechanism (not shown, but discussed in more detail below) is, in one embodiment, positioned in close proximity to the continuous flow engagement device  150  and is configured to provide a signal indicative of when continuous flow engagement device  150  is in an actuated or unactuated position. 
     The auxiliary hydraulic mode switch  152  is illustratively a two-position switch that an operator can manipulate to cause the loader  10  to control the function of the auxiliary hydraulics power system  138  in one of two modes, depending on the position of the switch. In some embodiments, the control panel  140  does not include an auxiliary hydraulic mode switch  152 , thereby eliminating one of the two modes of operation of the auxiliary hydraulics power system  138 . The operation of the auxiliary hydraulic mode switch  152  and the two possible modes of operation for the auxiliary hydraulics power system  138  will be discussed in more detail below. 
     The control panel  140  also illustratively includes a keyswitch  145 . The keyswitch  145 , in one illustrative embodiment, has at least three positions, including an off position, a run position, and a start position. In the off position, the engine ( 202  in  FIG. 7 ) is provided a signal or an absence of a signal, which is intended to turn off the engine. In the run position, the engine is provided a signal that is indicative of allowing the engine to run if it has been started. In the start position, a signal is provided that, if received by a starter ( 201  in  FIG. 7 ), causes the starter to engage the engine and cause engine to start running. Providing such a signal to the starter will be discussed in more detail below. 
     The drive handle  142  is illustrated in more detail in  FIGS. 5 ,  6  and  6 A, showing features of the continuous flow engagement device  150 . The continuous flow engagement device  150  is pivotally attached to the drive handle  142  at pivot  156  at a first end  158  of the continuous flow engagement device  150 . The continuous flow engagement device  150  has slots  160  on a second end  162  that are advantageously positioned to engage protrusions  164  on the drive handle  142 . The engagement between the protrusions  164  and the slots  160  effectively limit the rotational movement of the continuous flow engagement device  150  about pivot  156 . A spring  155  positioned between the continuous flow engagement device  150  and the drive handle  142  biases the lever away from the drive handle  142 . The continuous flow engagement device  150  and/or the drive handle  142  are advantageously formed, at least in part, from materials that provide cushioned feel for an operator when grasping the drive handle  142  and continuous flow engagement device  150 . 
     In one embodiment, a sensing mechanism (not shown) is positioned proximal to continuous flow engagement device  150  for sensing the position of the continuous flow engagement device  150  with respect to the drive handle  142 . The sensing mechanism is, in one embodiment, a switch or other suitable device capable of providing a signal indicative of the position of the continuous flow engagement device  150 . The signal may be provided via electrical wires, wireless signals, or any other type of signal to a control device. The sensing mechanism provides an output signal indicative of one of two distinct positions of continuous flow engagement device  150 , which, as discussed above, can be described as a disengaged position and an engaged position. Alternatively, the sensing mechanism may be sensitive to contact with, for example, an operator&#39;s hand. In such an embodiment, the continuous flow engagement device may simply be a handle that the operator can grab rather than one that requires an operator to manipulate the device from one position to another. In such embodiments, mere touch of the continuous flow engagement device causes the sensing mechanism to sense the engaged position. 
     In the disengaged position, the force from the spring  155  biases the continuous flow engagement device  150  away from the drive handle  142 , as is illustrated in  FIG. 6A . Unless a force is applied to the continuous flow engagement device  150 . In the engaged position, a force, such as may be applied by an operator&#39;s hand, is applied in a direction illustrated by arrow  154  to overcome the bias of the spring  155  and cause the continuous flow engagement device  150  to be rotated in close proximity to, if not in actual contact with, the drive handle  142 . The sensing mechanism is then configured to provide a signal indicative of the engaged position. Because the continuous flow engagement device  150  requires a constant force to be applied to the continuous flow engagement device  150  before the sensing mechanism provides the engaged signal, the continuous flow engagement device  150  effectively provides an indication of whether an operator is properly positioned in close proximity to the control panel  140 . How the signals provided by the sensing mechanism are processed to affect the functionality of the auxiliary hydraulics power system  138  will be discussed in more detail below. 
     As discussed above, loader  10  includes a hydraulic system that provides a power source and control of the auxiliary hydraulics power system  138 .  FIG. 7  is a block diagram that schematically illustrates such a power control system  200  for loader  10 , which includes hydraulic components that are part of auxiliary hydraulics power system  138 . Auxiliary hydraulics power system  138  is shown as a dashed line in  FIG. 7  for clarity purposes. It should be appreciated that some of the components included in hydraulics power system  138 , in some embodiments, provide capabilities for the loader  10  that are in addition to the capabilities as part of the hydraulic power system  138  and this is illustrated in  FIG. 7 . 
     The power control system  200  includes an engine  202  and a hydraulic pump system  204 , which is coupled to an output shaft of the engine  202 . The engine  202  provides power to the hydraulic pump system  204 , which in turn converts the input power received from the engine  202  into hydraulic power. A starter  201  provides a signal to the engine  202  to start the engine, based on inputs provided by a user, as will be discussed in more detail below. In one illustrative embodiment, the hydraulic pump system  204  includes one or more hydrostatic pumps that provide hydraulic power in the form of hydraulic fluid under pressure to a pair of hydraulic drive motors  206 , which are in turn coupled to track drive systems  102  and  104 . While the hydraulic pump system  204  is shown as a single block in  FIG. 7 , it should be appreciated that the hydraulic pump system  204  can include any number of hydraulic pumps. For example, separate hydrostatic pumps are advantageously implemented so as to be coupled to each of the hydraulic drive motors  206 . It should be further appreciated, of course, that other types of drive systems besides track drive systems can be incorporated into loader  10 , as described above. Furthermore, although each of the track drive systems  102  and  104  are shown as being coupled to a separate drive motor  206 , it should be appreciated that a single drive motor can, in some embodiments, be coupled to more than one drive system. For example, a single drive motor can be coupled to two-wheeled drive systems on the same side of a loader. Other drive arrangements are also contemplated. 
     The hydraulic pump system  204  also illustratively includes a hydraulic pump that provides an output to a hydraulic control valve  210 . Hydraulic control valve  210  illustratively provides hydraulic outputs to actuators  128 , actuator  134 , as well as a hydraulic output to port  136 , which is part of the auxiliary hydraulics power system  138 . The hydraulic control valve  210 , in one embodiment, is a collection of spool valves, each of which controls the flow of hydraulic fluid to their respective load, the load being one of the actuators  128 , actuator  134 , and an attached implement to the port  136 . It should be appreciated that while the hydraulic control valve  210  includes, in one embodiment, a single valve body with a plurality of spool valves located therein, alternatively, hydraulic control valve  210  can include a plurality of valve bodies with spool valve or other types of valve configurations that are configured to provide hydraulic fluid to the actuators listed above. In the illustrative embodiment, each of the spool valves has a neutral position, in which hydraulic fluid is not provided to its designated load. Manipulation of one of the spool valves from the neutral position will cause flow of hydraulic fluid in one of two directions. Operation of the hydraulic control valve  210 , particularly as it pertains to the control of hydraulic fluid to the port  136  of auxiliary hydraulics power system  138 , will be discussed in more detail below. 
     As discussed above, the control panel  140  includes a plurality of operator controls, which are configured to provide input signals indicative of a desired control of one or more of the output functions of the hydraulic pump system  204  and the control valve  210 . The signals are represented generally in  FIG. 7  by input signals  218 , which are shown as providing inputs to both the hydraulic pump system  204  and the control device  208 . These signals will be discussed in more detail below. It should be appreciated that the input signals  218  are provided directly, or indirectly (such as via sensing mechanisms located proximal to one or more of the input devices), from devices including the drive handle  142 , the auxiliary function input device  146 , the continuous flow engagement device  150 , and the auxiliary hydraulic mode switch  152  as well as other devices that may be incorporated into loader  10 . 
     As discussed above, the hydraulic control valve  210  is illustratively connected to port  136  so that, under certain conditions, hydraulic fluid is proved to port  136  and thus made available to an implement attached to port  136 .  FIGS. 8A-D  are diagrammatic illustrations of a cross-section of a spool valve  220 , which is part of the hydraulic control valve  210  and is provided to provide a pathway for hydraulic fluid to flow to an attached implement through port  136 . The spool valve  220  has a housing  222 , which is capable of receiving a spool  224 . The housing  222  has an inlet  226  to which the hydraulic pump system  204  is attached. The inlet  226  has a pair of ports  228  and  230 . Hydraulic fluid is illustratively provided from the hydraulic pump system  204  to the spool valve  220  through duct  232  to port  228  as shown by arrow  234 . Similarly, hydraulic fluid is returned from the spool valve  220  to the hydraulic pump system  204  via port  230  and through duct  236  as illustrated by arrow  238 . 
     The spool valve  220  has an outlet  240 , including ports  242  and  244 , through which hydraulic fluid can be directed to an external device. Spool valve  220  is shown as being coupled to an implement  246  via ducts  135  and  137  to port  136 , which includes coupling devices  139  and  141  to which the implement  246  is illustratively attached. For the purposes of this discussion, implement  246  can be any implement. One example, as discussed above, is a mower having a hydraulic motor that can be operated to rotate its blade. Of course, the implement  246  need not be a mower, but can be any of a number of different types of implements. It should be appreciated that a mower or other similar implements may have hydraulic circuitry that allows flow in only one direction through its motor. However, other implements, like a tiller, may allow flow in first and second directions such as is described in  FIGS. 8B and 8C . Depending upon the position of the spool  224  with respect to the housing  222 , the spool valve  220  either blocks the flow of hydraulic fluid or provides a path through the spool valve  220  to allow hydraulic fluid to travel to the implement  246  in one of two directions. 
     Spool  224  is engaged by a pair of springs  248  and  250 , each of which positioned adjacent an end of the spool  224 . When no outside force is applied to the spool the springs  248  and  250  are illustratively biased to urge the spool  224  to a neutral, or centered, position as is shown in  FIG. 8A . When the spool  224  is in the centered position, hydraulic fluid provided by the hydraulic pump system  204  is not permitted to flow through to the implement  246 . As is illustrated in  FIG. 8A , symbol  252 , which represents the blockage of hydraulic flow, is aligned with inlet  226  and outlet  240 . Linkage  254  is illustratively attached to the spool  224 . Although not shown in  FIGS. 8A-8C , the linkage  254 , in one embodiment, is operatively coupled to the auxiliary function input device  146  (shown in  FIG. 4 ) and provides one of the input signals  218  discussed above with respect to  FIG. 7 . Manipulation of the auxiliary function input device  146  by an operator transfers a signal, which, in one embodiment, is a mechanical force, through the linkage  254  and onto the spool  224  corresponding to the manipulation by an operator. The signal provided by the linkage  254  cause the spool  224  to be shifted away from the centered position that is shown in  FIG. 8A  by overcoming one of the springs  248  and  250 . 
     In  FIG. 8B , the linkage  254  applies a signal that causes the spool  224  to push against the spring  248 , thereby causing the spring  248  to compress and shift the spool  224  away from the neutral position illustrated in  FIG. 8A . This position, shown in  FIG. 8B , provides a path to allow hydraulic fluid to pass from the hydraulic pump system  204  through the outlet  240  at port  242  to the implement  246 . Likewise, hydraulic fluid is allowed to pass from the implement  246  through port  244  and back to the hydraulic pump system  204 . The direction of flow in this position is illustrated by symbol  256 , which also represents the position of the spool  224 . When the spool  224  is positioned as shown in  FIG. 8B , when hydraulic fluid is allowed to pass through the implement  246  in the direction illustrated by symbol  256 , the fluid flow to the implement  246  is provided in a first direction. 
     Conversely,  FIG. 8C  illustrates a condition where the linkage  254  applies a force that pulls the spool  224  against spring  250 . In such a case, the spool  224  provides a path for hydraulic fluid to flow out to the implement  246  through port  244  and back from the implement through port  242 . This is represented by symbol  258 , which also represents the position of the spool  224 . In such a case, hydraulic fluid is provided to the implement  246  in a direction opposing the direction shown in  FIG. 8B . When fluid flows in either direction, the spool  224  can allow for metered flow of the hydraulic fluid, or alternatively, can allow only full flow when the fluid flows or no flow at all. 
     The linkage  254  described above and illustrated in  FIGS. 8A-8C  implies a solid mechanical link that is coupled to both the spool  224  and the auxiliary function input device  146 . However, it should be appreciated that linkage  254  can be implemented in a variety of ways without departing from the spirit and scope of the discussion. For example, linkage  254  can be a push-pull cable. Alternatively still, linkage  254  can be an electrical or hydraulic signal supplied from the auxiliary function input device  146  that is coupled to the spool valve  220  that facilitates control of the position of the spool valve  220 . 
     From the discussion above, one skilled in the art will appreciate that manipulation of the auxiliary function input device  146  controls movement of the spool  224 , specifically away from the centered position illustrated in  FIG. 8A . When an operator ceases to manipulate the auxiliary function input device  146 , the spool  224  would, under normal circumstances, return to the centered position, thereby blocking the flow of hydraulic fluid to and from the implement  246 . There may be times, however, when it is advantageous to have continuous flow of hydraulic fluid through the implement  246  in either of the directions illustrated in  FIGS. 8B and 8C . For example, when using a mower, an operator may wish to have the mower blade turning continuously for an extended period of time. In such a case, it may be further advantageous for the spool  224  to remain in the desired position without requiring that an operator continuously manipulate the auxiliary function input device  146  when positioned immediately behind the distal end  112  of loader  10 . 
     The spool valve  220  includes a pair of actuators  260  and  262 , each of which is attached to the housing  220 . The actuators  260  and  262  are coupled to wedges  264  and  266 , respectively, as is illustrated in each of the  FIGS. 8A-8C . In addition, the spool  224  has a pair of engagement features  268  and  270  located in either end of the spool. In one embodiment, the engagement features  268  and  270  are tapered notches formed into the surface of the spool  224 . The engagement features  268  and  270  are capable of being engaged with the wedges  264  and  266  when the spool is positioned so that one of the wedges is aligned with one of the engagement features. 
       FIG. 8D  illustrates the spool valve  220  with its valve spool positioned such that the valve  220  is in a continuous flow condition according to one illustrative embodiment. The spool  224  is positioned so that it has compressed the spring  248 . In addition, wedge  264  extends into the engagement feature  268  in spool  224  to prevent the spool  224  from returning to the centered position until the wedge  264  is retracted out of the engagement feature  268 . When the wedge  264  is thus positioned, the hydraulic pump system  204  can provide continuous hydraulic flow through the hydraulic control valve  210  to an implement. In one illustrative embodiment, the wedge  264  is controlled by actuator  260 , which causes the wedge  260  to extend or retract, depending on a signal provided to it by the actuator  260 . Similarly, wedge  266  is controlled by an actuator  262  so that when it is desirable to have continuous flow in the opposing direction to that illustrated in  FIG. 8D , wedge  266  can be extended to engage engagement feature  270  in the spool  224  when the spool  224  is properly positioned. 
     The actuators  260  and  262 , in one illustrative embodiment, are electric actuators, such as solenoids, which receive electrical signals that control the position of their respective wedges. A first signal sent to the actuators  260  and  262  urges the actuators to retract their associated wedges. A second signal sent to of the actuators  260  and  262  urges the actuators to attempt to extend their associated wedges. 
     As is detailed in  FIG. 8D , the hydraulic control valve  210  can be placed in a condition where continuous hydraulic flow is provided to an implement.  FIG. 9  provides an illustration of the control device  208  according to one embodiment of the present discussion, which illustratively provides control of the positioning of spool  224  and the positioning of wedges  264  and  266 . The control device  208  receives inputs from an operator actuable continuous actuation device and provides one of the signals  218  to the spool valve  210 . An enablement input  280  provides a power source for the control device  208 . The control device  208  also receives inputs from a sensing mechanism  168 , which illustratively provides an indication of the position of the drive handle  142 , the keyswitch  145 , a neutral position sensor  147 , and the auxiliary hydraulic mode switch  152 . The neutral position sensor  147  in one illustrative embodiment, provides a signal indicative of whether the spool  224  is in the centered position and therefore blocking any flow of hydraulic fluid to the implement  246 . 
     The control device  208  provides an output signal  282  to the actuators  260  and  262  and an output signal  284  to the starter  201  based upon the status of the inputs received by the control device  208 . It should be appreciated that the control device  208 , while shown here as a single device, may actually be more than one device. For example, a separate control device from the one that provides the output signal  282  may be incorporated that provides output signal  284  to the starter  201 . 
     If the output signal  282  is an engagement signal, the actuators  260  and  262  will allow wedges  264  and  266  to attempt to engage engagement features  268  and  270 . In one embodiment, the wedges  264  and  266  will engage their respective engagement features  268  and  270 , only when the spool  224  is positioned to allow one of the wedges to engage, as is shown in  FIG. 8D . Otherwise, either or both of the wedges  264  and  266  will engage the spool  224  along a portion of the surface of the spool. If the spool  224  is not aligned so that either of the wedges  264  and  266  are capable of engaging one of their respective engagement features  268  and  270 , automatic continuous flow will not be provided. Thus, if the operator does not apply a force via the auxiliary function input device  146 , the springs in the spool valve will tend to urge the spool  224  to a neutral position as shown in  FIG. 8A . If, however the engagement signal is provided and the spool  224  is subsequently manipulated to position one of the engagement features  268  or  270  inline with its corresponding wedge, the wedge will be capable of engaging the spool  224  and allowing continuous hydraulic flow to an implement. Alternatively, if the output signal  282  is a disengagement signal, the actuators  260  and  262  will endeavor to position the wedges  264  and  266  so that they do not engage the engagement features even if one of the wedges is aligned with one of the engagement features. It is possible, in some embodiments, for an operator to apply sufficient force via the auxiliary function input device  146  to force one of the wedges that is engaging its engagement feature out of the engagement feature and thereby ending the continuous flow condition. If the engagement signal is still being applied, a subsequent realignment of one of the wedges with its respective engagement feature will allow the wedge to re-engage the engagement feature and thus provide a continuous flow condition once again. 
     In one embodiment, the actuators  260  and  262  are biased so that the disengagement signal is actually an absence of a signal. Thus, with no signal, the wedges  264  and  266  are positioned away from the spool  224  so that the wedges will not engage the engagement features  268  and  270 , even if one of the wedges are positioned inline with a corresponding wedge. For example, the wedges  264  and  266 , in one embodiment, are spring loaded so that they are drawn toward the actuators  260  and  262  and the application of a signal  282  causes the wedges to move away from the actuators  260  and  262  and toward the spool  224 . 
     Functional embodiments of the control device  208  will be discussed in more detail below. It should be appreciated, though, that the control device  208  can include various electrical and/or electronic components. For example, control device  208  can include logic devices, microcontrollers, microprocessors, relays, timers, output driving circuitry, and the like. Any suitable electrical or electronic, electromechanical, or mechanical system can be implemented. One suitable embodiment includes a plurality of relays that are controlled by signals provided by the sensing mechanism  168  and the auxiliary hydraulic mode switch  152  so that, under suitable conditions as described below, the power source provided by enablement input  280  is directed to the actuators  260  and  262 . 
       FIG. 10  illustrates a method  300  of providing continuous flow to an implement coupled to loader  10  according to one illustrative embodiment. As part of method  300 , the control device  208  receives signals indicative of the status of the continuous flow engagement device  150  and the auxiliary hydraulic mode switch  152 . This is illustrated in block  302 . At decision block  304 , if the signals received indicate that the continuous flow engagement device  150  is in an engaged position, the method moves to block  306 . At decision block  306 , the status of the signal indicative of the position of the auxiliary hydraulic mode switch  152  is examined. As discussed above, the auxiliary hydraulic mode switch  152  is illustratively a two-position switch. A first position indicates that the continuous flow feature of the auxiliary hydraulics of loader  10  is intended to be operated in a non-stationary position, that is, that the loader  10  is intended to be moved by either or both of the traction drive systems  102  and  104 . A second position indicates that the continuous flow feature of the auxiliary hydraulics of loader  10  is intended to be operated in a stationary position. If the signal from the auxiliary hydraulic mode switch  152  is indicative of the first of the two positions, the control device  208  provides an engagement signal  282  to the actuators  260  and  262 . This is illustrated at block  308 . If the signal from the auxiliary hydraulic mode switch  152  is indicative of the second of the two positions, the control device  208  provides a signal  282  indicative of disengagement to the actuators  260  and  262 . This is illustrated at block  308 . 
     Returning to block  304 , if is it determined that continuous flow engagement device  150  is in an disengaged position, the method moves to block  312  and the status of the signal indicative of the position of the auxiliary hydraulic mode switch  152  is examined. If the signal from the auxiliary hydraulic mode switch  152  is indicative of the first of the two positions, the control device  208  provides a signal  282  to the actuators  260  and  262  indicative of disengagement. This is illustrated at block  314 . If the signal from the auxiliary hydraulic mode switch  152  is indicative of the second of the two positions, the control device  208  provides a signal  282  indicative of engagement to the actuators  260  and  262 . This is illustrated at block  316 . Thus, the position of the auxiliary hydraulic mode switch  152  illustratively causes the control device  208  to change the response to the continuous flow engagement device  150 . 
       FIG. 11  illustrates a method  350  of controlling the starter  201  according to one illustrative embodiment. At block  352 , if the keyswitch  145  is in the start position, the status of the continuous flow engagement device  142  is considered. As discussed above, the status of the continuous flow engagement device is monitored by sensing mechanism  168  and in one embodiment, a signal from sensing mechanism  168  is indicative of the position of the continuous flow engagement device  142 . This is illustrated at block  354 . If the continuous flow engagement device  142  is in the disengaged position, the signal from the neutral position sensor  147  is considered. This is indicated at block  356 . If the signal from the neutral position sensor  147  indicates that the spool  224  is in a centered position, a signal to start the loader  10  is provided to the starter  201 . This is illustrated at block  358 . If, at block  352 , the keyswitch  145  is not in the start position, or if at block  354 , the continuous flow engagement device  142  is in the engaged position, or if at block  356 , the neutral position sensor  147  indicates that the spool  224  is not in a centered position, the starter is not sent a signal to start the engine  202 . This is illustrated at block  360 . As discussed above, in one embodiment control device  208  receives input signals from sensing mechanism  168 , the keyswitch  145 , and the neutral position sensor  147 . Control device  208 , in one embodiment, includes a plurality of relays that are controller by the sensing mechanism  168 , the keyswitch  145 , and the neutral position sensor  147  so that the power source provided by enablement input  280  is directed to the starter  201  under conditions described above and illustrated in  FIG. 11 . 
     The discussion above lays out important advantages. Methods and systems disclosed above provide for a continuous flow engagement system for vehicles such as walk behind loaders that provide the ability to continuously engage auxiliary hydraulic functions if an operator properly manipulates input devices on the control panel. Such systems and methods allow for differing modes of operation, based on the status of different devices. Although, specific embodiments are disclosed above, it should be understood that the embodiments are illustrative in nature. Other embodiments that are within the spirit and similar to those presented here will be apparent to those skilled in the art.