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This application relies for priority on U.S. Provisional Patent Application Ser. No. 60/416,534, filed on Oct. 8, 2002, the contents of which are incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to snow grooming vehicles that use winches to assist in climbing steep inclines. The invention is also directed to level winding systems for winch assemblies. 
   2. Description of Related Art 
   Tracked vehicles used in rugged terrain often employ winch assemblies to assist in maneuvering steep inclines. Snow grooming vehicles, for example, are sometimes equipped with winches that have cables that attach to fixed points on the incline to allow the vehicle to be anchored to the fixed point while sweeping up or down the slope. The cable anchor prevents the vehicle from turning over or sliding down the slope, which could occur on very steep inclines. 
   A winch-equipped vehicle typically carries a cable that extends outwardly through a rotatable boom. The boom is an elongated metal arm that guides the cable through a series of pulleys. Depending on the direction of intended travel, the boom is rotated to extend forwardly over the cab or to extend rearwardly away from the cab. The cable is typically carried on a drum, preferably a grooved drum, that is driven to control outlay and intake of the cable. A guide, preferably a level winder, is provided at the base of the boom to assist in aligning the cable as it is fed to and from the drum to prevent twisting of the cable. 
   Most prior art winches use vertical guides and worm gears that follow a linear path parallel to the drum&#39;s axis of rotation to align the cable with the drum grooves. As the load on the cable in such a system can be up to 10,000 lbs., the guide assembly must be constructed to accommodate such forces. These assemblies require a large degree of maintenance to prevent the guides and gears from rusting and breaking. However, constant lubrication is necessary. Additionally, these guide assemblies consume a large amount of space, which leaves limited space for the pulleys and rollers associated with the cable system. As a result, the diameter of the pulleys and rollers are often smaller than the minimum recommended cable bending radius. Bending cable about a radius less than the recommended bending radius shortens the life and reliability of the cable. 
   Some prior art systems use capstan systems to address the problems associated with the prior art guide assemblies described above.  FIG. 5  illustrates a capstan system  100  that utilizes a linear guide system  110 . The torque applied to the guide system  110  is reduced by winding cable  120  around a capstan  130 . As a result, the force at the exit of the capstan  130  is a fraction, 1,000 lbs. for example, of the force in a conventional guide system. The cable  120  is guided from the capstan  130  through a sliding component  140  to a drum  150 . However, the capstan  130  itself occupies a great deal of space and is complex, due in large part to the motors required for driving the capstan. Further, maintenance for a capstan is complicated as changing a cable requires a large investment of labor. Moreover, the sliding component  140  must be constantly lubricated. 
   Thus, there is a need for a less complex and more compact guide assembly associated with such a winch, especially a level winder assembly. 
   SUMMARY OF THE INVENTION 
   An aspect of embodiments of the invention is to provide a winch assembly that has a relatively compact and simple design. 
   Another aspect of embodiments of the invention is to provide a winch assembly suitable for use on a snow grooming vehicle and further to provide a snow grooming vehicle equipped with such a winch. 
   A further aspect of embodiments of the invention is to provide a winch that is relatively easy to operate, may allow an operator to observe operation, and may extend the useful life of the wound cable. 
   Among other things, the invention is directed to a winch assembly that includes a drum, a driver, and a level winder. The drum carries a length of cable. The driver is coupled to the drum and rotates the drum to wind and unwind the cable. The level winder is disposed adjacent to the drum to guide the cable with respect to the drum, and is supported to move in an arc shaped path. 
   The invention is also directed to a winch assembly that includes a drum, a driver, and a level winder. The drum carries a length of cable. The driver is coupled to the drum and rotates the drum about a generally horizontal axis to wind and unwind the cable. The level winder is disposed adjacent to the drum to guide the cable with respect to the drum. The level winder is also supported to pivot about a generally vertical axis. 
   The invention is also directed to vehicle that includes a frame, an engine that is supported by the frame, a drive mechanism that is operatively connected to the engine, and a winch assembly that is supported by the frame. The winch assembly includes a drum that carries a length of cable. A driver is coupled to the drum for rotating the drum to wind and unwind the cable. A level winder is disposed adjacent to the drum to guide the cable with respect to the drum. The level winder is supported to move in an arc shaped path. 
   These and other aspects of embodiments of the invention will become apparent when taken in conjunction with the following detailed description and drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Features of the invention are shown in the drawings, which form part of this original disclosure, in which: 
       FIG. 1  is a partial view of a tracked vehicle having a winch assembly in accordance with embodiments of the invention; 
       FIG. 2  is an enlarged side view of the level winder illustrated as a part of the tracked vehicle shown in  FIG. 1 ; 
       FIG. 3  is a top schematic view of the level winder of  FIG. 2 ; 
       FIG. 4  is a side perspective view of the level winder of  FIG. 2 ; and 
       FIG. 5  is a view of a prior art capstan cable winding system. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   This invention is described for use on a tracked vehicle, particularly a snow grooming vehicle, for purposes of illustration only. However, the winch and level winder in accordance with embodiments of this invention may be used in any cable winding system. Further, the winch may be used on any type of vehicle, especially vehicles driven by rotatable tracks that may be driven over rugged terrain, such as steep inclines on mountains or ravines. 
   Throughout this description, reference is made to vertical and horizontal axes. It is understood that these axes are intended to refer to a vehicle position in which the vehicle is supported on a substantially horizontal surface. 
     FIG. 1  illustrates a vehicle  10  of the present invention. The vehicle  10  includes a frame  12 , an engine  14  supported by the frame  12 , a drive mechanism  16  operatively connected to the engine  14 , a winch assembly  24  supported by the frame  12 , and a boom  18  supported by the frame  12 . A cab  15  for having an operator and vehicle control elements is also supported by the frame  12 . In the illustrated embodiment, the engine  14  is not illustrated, but its location is indicated on the frame  12 . As would be appreciated by those skilled in the art, the engine  14  need not be positioned in the area indicated. Instead, the engine  14  may be located on the vehicle  10  in any alternative, suitable location. 
   The frame  12  can be fabricated from materials well known in the art, including but not limited to steel. Fabrication techniques well known in the art can be used to form and assemble the frame  12 . 
   The engine  14  can be any engine typically used in such vehicles. The size of the engine  14  will depend on the size and specific demands of the vehicle  10 . Preferably, the engine  14  is an internal combustion engine that can generate a high horse power. 
   The drive mechanism  16  is operatively connected to the engine  14  so as to move the vehicle  10  across a surface. The drive mechanism  16  allows for the vehicle  10  to move across land, ice, or water. The drive mechanism  16  may comprise an endless track, as illustrated by  FIG. 1 , wheels, or any component that will allow the vehicle  10  to travel. 
   The winch assembly  24  is supported on a winch frame  19  that is coupled to the frame  12 . The winch assembly  24  includes a drum  26  that carries a length of cable  28 , a driver  30  coupled to the drum  26  for rotating the drum  26  to wind and unwind the cable  28 , and a level winder  32  disposed at a base portion of the boom  18  and adjacent to the drum  26  to guide the cable  28  with respect to the drum  26 . 
   It is contemplated that the driver  30  is a hydraulic motor that is operatively connected to the engine  14  via a suitable hydraulic system. Of course, as would be appreciated by those skilled in the art, the driver  30  may be mechanically driven by the engine. Alternatively, the driver  30  my be an electrically-driven motor. It should be understood that the driver  30  may be of any type suited for this purpose without departing from the scope and spirit of the invention. 
   The boom  18  has a guide system that guides the cable  28  outward from (or inward to) the vehicle  10 . The guide system includes a series of pulleys  20 , a series of rollers  22 , or any combination of pulleys  20  and rollers  22 . The pulleys  20  are disposed on the boom  18 , and the cable  28  is fed around the pulleys  20 . The rollers  22  are disposed on the boom  18 , and the cable  28  is fed over the rollers  22 . The boom  18  is preferably formed of metal and may comprise a pair of parallel beams with the guide system supported therebetween. Alternatively, the boom  18  may be formed of a series of rigid members fixed together as an integral cantilever support. It is noted that the boom  18  may have any other suitable construction without departing from the invention. 
   As seen in  FIG. 1 , the boom  18  is supported for movement on a support platform  21  that is supported by the vehicle frame  12 , at least in part, via the winch frame  19 . Preferably, the boom  18  is supported for rotatable movement with respect to the platform  21  on the winch frame  19 . With this arrangement, the boom  18  can be oriented at various directions with respect to the drive mechanism  16  to accommodate different directions of travel. The direction of the boom  18  may be controlled by the operator or may be preset. Alternatively, other mounting structures may be implemented that allow for directional adjustment. It is also possible to use a fixed boom depending on the intended use of the vehicle  10 . 
   The cable  28  is typically metal, such as steel, but may be any material suitable for the intended purpose of the invention. Any known cable  28  capable of withstanding a large load is suitable. The diameter of the cable  28  and type of material are chosen to ensure that the load requirements of the vehicle  10  may be tolerated. 
   The drum  26  is mounted on the winch frame  19  such that it rotates about a longitudinal axis. The longitudinal axis is generally horizontal (when the vehicle  10  is supported on a horizontal surface). The drum  26  is sized to ensure that the appropriate amount of cable  28  can be completely wound onto the drum  26 . The cable  28  is wound across an outer circumferential surface of the drum  26 . The outer circumferential surface of the drum  26  may be smooth or grooved. In the preferred embodiment, the drum  26  is grooved, as illustrated in FIG.  3 . 
   Grooves with the appropriate radius may be formed in the circumferential surface of the drum  26  so that when the cable  28  wraps around the drum, the cable  28  lies in what is essentially one continuous groove. The grooves may be added to the drum  26  by standard fabrication techniques, including but not limited to machining. Spaced grooves around the circumference of the drum  26  allow the cable  28  to be retained in the grooves during winding and unwinding. The grooves provide a tighter, neater, and more compact wind as compared to drums with a smooth surface. This provides for smoother operation and may enhance the life of the cable  28 . 
   The driver  30  is coupled to the drum  26  and rotates the drum  26 . The drum  26  rotates in one direction to wind the cable  28  and in the opposite direction to unwind the cable  28 . As mentioned above, the driver  30  may be an electric or hydraulic motor, for example. The driver  30  may be operatively connected to the vehicle engine  14  and/or electrical system or may be an independent component. The driver  30  preferably is sized to handle the load created by the drum  26  and the cable  28 . 
   The level winder  32  is disposed adjacent to the drum  26  to guide the cable  28  from the boom  18  with respect to the drum  26 . The level winder  32  is supported to move in an arc shaped path and is preferably supported to pivot about a generally vertical axis. The arc shaped path is largely defined by the pivoting of the level winder  32  about the generally vertical axis. 
   As illustrated in FIG.  2  and  FIG. 3 , the level winder  32  includes a rotatable support  34 , a cable support frame  36  that is connected to the rotatable support  34 , and a pair of rotatable pulleys  38  carried by the cable support frame  36 . The cable support frame  36  pivots with the rotatable support  34 . By this, the pair of pulleys  38  pivot with respect to the drum  26 . 
   The rotatable support  34  is mounted on the winch frame  19 . The rotatable support  34  is preferably operatively connected to a pair of rotatable support bearings  58 . The rotatable support bearings  58  are fixedly attached to the winch frame  19 . The rotatable support bearings  58  are connected to opposite ends of the rotatable support  34  so that the rotatable support  34  can freely rotate about a generally vertical axis, while being fixed in the other two directions. The rotatable support  34  is substantially the shape of a hollow cylinder with at least one slot  35  along the longitudinal length of the cylinder. Of course, any suitable support assembly may be used to allow the level winder  32  to pivot with respect to the drum  26 . 
   The winch assembly  24  further includes a rotatable pulley  60  that is disposed adjacent to the rotatable support  34  such that an outer edge of the rotatable pulley  60  lies within the slot  35  of the rotatable support  34 . The rotatable pulley  60  is disposed between two substantially parallel support plates  37 . The support plates  37  are fixedly attached to the rotatable support  34  such that the support plates  37  rotate with the rotatable support  34  about a generally vertical axis. The rotatable pulley  60  is mounted to the support plates  37  such that the rotatable pulley  60  can freely rotate about its generally horizontal axis. The rotatable pulley  60  directs the cable  28  from the boom  18  to the level winder  32 . The rotatable pulley  60  has a radius greater than or equal to the minimum recommended bending radius of the cable  28 . 
   The level winder  32  further includes at least one actuator  40  that is coupled to the rotatable support  34 . In the preferred embodiment, one upper bracket  39  is mounted to each support plate  37 , preferably above the axis of the rotatable pulley  60 . One end of the actuator  40  is pivotally attached to the upper bracket  39 . The opposite end of the actuator  40  is pivotally attached to the winch frame  19 , as seen in  FIG. 1 , and is in communication with a proximity switch  56 . Preferably, the actuator  40  is a hydraulic or pneumatic cylinder. Upon activation, the actuator  40  extends or retracts to push or pull the support plates  37 , which in turn rotates the rotatable pulley  60 , the rotatable support  34 , and the cable support frame  36 . As will be discussed below, this causes the pair of pulleys  38  to pivot with respect to the drum  26  to maintain the cable  28  in a predetermined position relative to the drum  26 . The desired predetermined position relative to the drum  26  is generally perpendicular, in this case. 
   Referring to  FIGS. 2-4 , the cable support frame  36  includes an upper plate  41  and a lower plate  43  that are substantially parallel to one another. The cable support frame  36  has a longitudinal centerline CL that extends in a direction from the rotatable support  34  towards the drum  26 . Each support plate  37  further includes a pair of lower brackets  45  that are fixedly attached to the support plate  37  below the axis of the rotatable pulley  60 . The lower brackets  45  in each pair are spaced such that the cable support frame  36  can be disposed therebetween. A pair of level winder ball bearings  62  are disposed within the cable support frame  36  on opposite sides of the longitudinal centerline CL. The level winder ball bearings  62  are mounted and oriented in such a way as to create a generally horizontal axis. The level winder ball bearings  62  allow the cable support frame  36  to rotate within a fixed range about a generally horizontal axis. 
   A biasing mechanism  42  is coupled between the cable support frame  36  and the top of the support plates  37 , preferably at the upper brackets  39 . The biasing mechanism  42  maintains the cable support frame  36  in a predetermined position relative to the rotatable support  34 . The predetermined position relative to the rotatable support  34  is generally perpendicular. The biasing mechanism  42  can include a spring that retains the cable support frame  36  in a relatively horizontal position. Of course, any biasing mechanism can be used, including a resilient cable or hydraulic or pneumatic cylinder. By this construction, the cable support frame  36  can move slightly up or down with respect to the surface of the drum  26  to accommodate the thickness of the cable  28  wound on the drum  26 . 
   At the opposite end of the cable support frame  36 , the pair of pulleys  38  are disposed between the upper plate  41  and the lower plate  43  on opposite sides of the longitudinal centerline CL of the cable support frame  36 . The pair of pulleys  38  are connected to the cable support frame  36  with pulley bearings  47 . The pulleys  38  are generally oriented in the same plane and are spaced so that the cable  28  can pass between them. The centers of the pulleys  38  are aligned on an axis that is generally perpendicular to the longitudinal centerline CL of the cable support frame  36 . 
   The level winder  32  further includes a feeding mechanism  44  that is pivotally supported by the cable support frame  36 . The feeding mechanism  44  controls the tension and direction of the cable  28  as the cable  28  is fed from the pulleys  38  to the drum  26 . An embodiment of the feeding mechanism  44  is illustrated in detail in FIG.  4 . The feeding mechanism  44  includes a pivot arm  55 , a pair of guiding rollers  46 , and a pair of tensioning rollers  49 . 
   In the preferred embodiment, the pivot arm  55  is disposed above the upper support plate  41  of the cable support frame  36  such that the pivot arm  55  and the cable support frame  36  extend in substantially parallel planes to one another. The pivot arm  55  is pivotally connected to the cable support frame  36  with a bearing  59  and a fastener  61  at a position along the longitudinal centerline CL of the cable support frame  36 . The pivot arm  55  has a first end and a second end. The first end of the pivot arm  55  extends beyond the cable support frame  36  in the direction towards the drum  26 . 
   The guiding rollers  46  are attached between a pair of roller support brackets  53  with bearings and fasteners. The roller support brackets  53  are fixedly attached to the first end of the pivot arm  55  and extend generally downward in such a manner that they do not interfere with the pair of pulleys  38 . The guiding rollers  46  are generally aligned in a vertical plane and are spaced and shaped such that the cable  28  can fit snugly between them. 
   The pair of tensioning rollers  49  are disposed at one end of a pair of cantilever brackets  51 . The cantilever brackets  51  each have a first end and a second end. The first ends of the cantilever brackets  51  are pivotally connected to the first end of the pivot arm  55  with bushings and fasteners. The second ends of the cantilever brackets  51  extend away from the pivot arm  55  and cable support frame  36  towards the drum  26 . The tensioning rollers  49  are connected to the second ends of the cantilever brackets  51  with bearings and fasteners. Preferably, the tensioning rollers  49  and the guiding rollers  46  are oriented such that their axes of rotation are perpendicular to one another. For example, in the preferred embodiment, the guiding rollers  46  rotate about generally horizontal axes and the tensioning rollers  49  rotate about generally vertical axes (when the vehicle  10  is supported on a horizontal surface). Alternatively, the guiding rollers  46  may rotate about generally vertical axes and the tensioning rollers  49  may rotate about generally horizontal axes (when the vehicle  10  is supported on a horizontal surface). 
   The feeding mechanism  44  further includes a pressure controller  48 . The pressure controller  48  is coupled to the tensioning rollers  49  to control the pressure between the tensioning rollers  49  to control feeding of the cable  28 . Preferably, the pressure controller  48  includes a hydraulic cylinder. Alternatively, the pressure controller  48  may include a pneumatic cylinder or any other resilient device. In the preferred embodiment, the pressure controller  48  includes a pair of hydraulic cylinders, as illustrated in FIG.  4 . 
   The feeding mechanism  44  further includes a sensitivity controller  50 . The sensitivity controller  50  is coupled to the tensioning rollers  49  to adjust the distance between the tensioning rollers  49 . Preferably, the sensitivity controller  50  includes a first plate  64  mounted to one of the cantilever brackets  51  and a second plate  66  mounted to the other cantilever bracket  51 . A third plate  68  is disposed in between the cantilever brackets  51  and is fixedly attached to the pivot arm  55 . The sensitivity controller  50  further includes a pair of adjustment screws  52 . The adjustment screws  52  are used to set a gap between the first plate  64  and the third plate  66  and a gap between the second plate  68  and the third plate  66 . 
   As the adjustment screws  52  are tightened, the cantilever brackets  51  are pushed away from each other, thereby increasing the gap between the tensioning rollers  49 , which decreases the sensitivity to changes in the position of the cable  28 . Conversely, as the adjustment screws  52  are loosened, the cantilever brackets  51  will by drawn towards each other due to the pressure exerted by the pressure controller  48 . This in turn will decrease the gap between the tensioning rollers  49 , which increases the sensitivity to changes in the position of the cable  28 . 
   The feeding mechanism  44  further includes a position actuator  54  that is operatively coupled to the proximity switch  56  that activates the actuator  40  to pivot the level winder  32 . A first end of the position actuator  54  is pivotally connected to the pivot arm  55 . A second end of the position actuator  54  is pivotally connected to the proximity switch  56 . When the feeding mechanism  44  pivots beyond a certain predetermined position, the position actuator  54  signals the proximity switch  56 . The proximity switch  56  activates movement of the level winder  32  along the arc shaped path by signaling the actuator  40 . Any known type of proximity switch or position detector may be used. 
   In operation, the cable  28  starts in a fully wound position on the drum  26 . The cable  28  is fed from the drum  26  through the level winder  32 , through the rotatable support  34 , through the guide system within the boom  18 , and out one end of the boom  18 . The cable  28  is secured to a predetermined anchor point located on the terrain and the vehicle  10  moves away from the anchor point via the drive mechanism  16 . In order for the vehicle  10  to move away from the anchor point, the cable  28  must be lengthened or “played out” from the drum  26 . The driver  30  rotates the drum  26  such that the cable  28  unwinds from the drum  26 , thereby allowing the cable  28  to lengthen. 
   As the cable unwinds from the drum  26 , it releases from the drum at a release point  57 . The release point  57  moves parallel to the longitudinal axis of the drum  26  as the drum  26  rotates. The level winder  32  pivots in an arc such that the feeding mechanism  44  is substantially aligned with the release point  57 . This ensures that the cable  28  is generally perpendicular to the drum  26  at the release point  57  so that the cable does not twist or kink. 
   After the cable  28  releases from the drum  26 , the cable  28  passes in between the pair of tensioning rollers  49 . As the location of the release point  57  changes, the cable  28  exerts a greater pressure against one of the tensioning rollers  49 . When the resulting pressure on the pressure controller  48  exceeds a predetermined value, the pivot arm  55  pivots just enough to keep the cable  28  perpendicular to the drum  26 . When the pivot arm  55  reaches a maximum pivot point, the position actuator  54  activates the proximity switch  56 . The proximity switch  56  then signals the actuator  40 . The actuator  40  rotates the level winder  32  along an arc shaped path in the direction that the cable  28  is extending toward the drum  26 . As the level winder  32  rotates, the pivot arm  55  is drawn by the cable  28  to rotate independently to ensure the cable  28  remains perpendicular to the drum  26 . These adjustments by the feeding mechanism  44  are constantly repeated while the winch assembly  24  is in operation. 
   After the cable  28  passes through the tensioning rollers  49 , the cable  28  passes in between the guiding rollers  46 . The guiding rollers  46  ensure that the cable  28  is properly lined up to pass in between the pair of pulleys  38 , regardless of the amount of tension in the cable  28 . Once the cable  28  passes the pair of pulleys  38 , it travels through the cable support frame  36  and onto the rotatable pulley  60 . The rotatable pulley  60  feeds the cable  28  though the rotatable support  34  to the pulleys  20  and rollers  22  located in the guide system in the boom  18 . 
   To drive the vehicle  10  in a reverse direction towards the anchor point, the rotation of the drum  26  must be reversed by the driver  30  so that any slack in the cable  28  can be tightened. In other words, the cable  28  must be rewound onto the drum  26 . Further, the vehicle  10  may need the power of the winch assembly  24  help pull the vehicle  10  back towards the anchor point. The level winder  32  operates in the same manner as was described above, only the cable  28  moves in the opposite direction and the pulleys  20 ,  60 ,  38  and rollers  22 ,  46 ,  49  rotate in the opposite direction. 
   Due to the relatively compact design of the level winder  32 , the operator of the vehicle  10  can watch the winding process to ensure that the cable  28  is being properly unwound and wound, because the level winder  32  does not obstruct the view of the drum  26 . 
   It will be understood that the invention encompasses various modifications and alterations to the precise operating systems. For example, although the system is described for use in a heavy duty cable winding assembly, other windable materials may be used in the device, and the device may be adapted for use in smaller manufacturing environments.

Summary:
A level winder is provided for winding cable in a winch system. The winch is suitable for use on a tracked vehicle, such as a snow grooming vehicle, to assist the vehicle in maneuvering on steep inclines. The level winder uses a pivoting pulley assembly to feed cable onto and off of a drum.