Abstract:
A portable log skidder is disclosed, having a base frame with an axle and a pair of wheels at the rear end and a trailer coupler at its front end. A winch with a motive or power source and a cable-winding drum is mounted on the base frame near its front end. A fixed pulley is mounted on the base frame near its rear end. Three support columns for a tripod-like support frame are provided above the base frame. A plurality of accessory attachment fittings are disposed around the support columns. A movable pulley is connected to one of the accessory attachment points. A log bunk is located at the rear of the base frame, to which a log chute is attached. A stabilizer is provided that articulates with the log chute. A cable wound on the drum of the winch has a free end engaging the fixed pulley, the moveable pulley and, finally, a log to be hauled aboard the portable log skidder.

Description:
BACKGROUND OF RELEVANT PRIOR ART 
   The present invention relates to a portable log skidder, specifically to a trailer capable of being towed by an all-terrain vehicle and of hoisting on board logs and cut timber. 
   In the timber industry, large trees are cut down and de-limbed. The bare logs are then removed from the forest using various mechanized systems. These systems are large and expensive and require a long period of use to recoup the owner&#39;s investment. 
   Many private or individual landowners have wooded plots from which they occasionally or periodically desire to remove trees or fallen timber. They may desire to remove trees to improve the overall health of the forest by selective thinning, or to use the remove timber for firewood or to have cut for small lots of sawn lumber. 
   Cut trees or timber of a useful size are typically too large for an unassisted individual to haul out of the forest. This difficulty is often compounded because the forest is located on a hillside. Woodlot owners typically must use a vehicle, such as a four-wheel drive all-terrain vehicle (“ATV”) to access and remove the fallen or cut timber. 
   However, using an ATV to simply pull a log out of a forest is difficult. When pulling a timber by a cable attached to an ATV, the front end of the log can dig into the ground or catch on rock outcroppings, boulders or undergrowth. When a dragged log catches in such a manner, it can overturn the towing ATV, causing great risk of injury to the driver, or it can cause significant damage to the frame of the ATV. 
   To avoid some of these dangers in dragging or otherwise removing a fallen timber or log from a forest, various types of “skidders” are used to raise the front end of a log up and partially onto the skidder, leaving only the trailing end of the log to drag along the ground. This provides less chance of catching on outcroppings or digging into the soil. 
   A number of examples of skidders are provided in the prior art. 
   U.S. Pat. No. 6,231,030, issued to Smith, discloses a log skidding trailer with a winch and a single fixed, rigid, near vertical hoist supporting a winch operating a lift cable running through a snatch block at the top end of the hoist. 
   U.S. Pat. No. 6,155,771, issued to Montz, discloses a simple hoist with boom at its top which can be attached to the end of a pickup truck bed. 
   U.S. Pat. No. 5,876,174, issued to Arsenault, discloses an improvement on traditional, horse-drawn log transporters, having a simple cantilever frame that may attach to an all-terrain vehicle. It must be positioned over the log, which is then attached to the trailer while its center beam is articulated upwards and raised up by a cantilever action to it by pulling the front end of the center beam down. 
   U.S. Pat. No. 5,061,150, issued to Rentscheler, discloses a single-handed skidding apparatus comprising a pair of grappling hooks. No cable is provided, and the apparatus must be positioned directly over the log which is to be transported. 
   U.S. Pat. No. 5,010,933, issued to Doyle, teaches of a skidding vehicle with a winch and a hoist which articulates with the vehicle frame to raise and lower a hoist pulley. A complicated system of springs is used to articulate the hoist. 
   SUMMARY OF THE INVENTION 
   The present invention is a log skidder capable of being towed by a one-man all-terrain vehicle and skidding a single log from a woodlot or forest, even under conditions of rugged terrain. The invention comprises a base frame parallel to the ground surface, with a trailer coupler at its front end wheels place on the underside of the base frame near its rear end section rotationally engaging the base frame by means of an axle or the like. A winch with a drum or spool capable of winding on a length of cable is located on the base frame near its front end. A fixed pulley is mounted near the rear end of the base frame, aligned with the drum of the winch. An elongated log bunk is mounted transversely on the end of the base frame. Three support columns for a tripod support on the base frame. Two of the support columns attach by bottom ends to either end of the log bunk. A cross member spans the top ends of the support columns. A third, center support column attaches by its bottom end to the base frame forward of the winch and attaches by its top end to the center of the cross member. 
   A plurality of accessory attachment fittings are provided along the bottom side of the center support column, as well as along the bottom side of the cross member. One or more movable pulleys may be attached to these accessory attachment fittings. By placing the movable pulley at different accessory attachment fittings, the angle at which a hauling cable attaches with a log will vary. By placing the movable pulley at a lower position, the tension from the cable is exerted on the trailer lower to its center of gravity, thereby increasing the stability of the trailer and permitting greater force on the cable for pulling a log without destabilizing or tipping the log skidder. By placing the movable pulley at a higher position, the cable will meet with a log at a greater angle to the ground, tending more to lift the front end of the log off the ground. This is especially more useful when the log has been pulled to the log skidder and is to be brought on board it. 
   To aid in bringing a log on board the log skidder, the rear end of the log skidder has a log bunk, a log chute and a stabilizer. The log chute is a guide plate which directs the front end of a log up and towards the center of the log bunk. The log bunk is not straight, but instead is curved or bent generally upward from its center, with its medial point disposed lowest to the base frame. The stabilizer, attached to the log chute, restrains the log skidder from sliding backwards while hauling in a log. 
   These and other objectives and advantages of the invention will become apparent from the description which follows. In the description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be protected. These embodiments will be described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the scope of the invention. In the accompanying drawings, like reference characters designate the same or similar parts throughout the several views. 
   The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is best defined by the appended claims. 

   
     DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an isometric view of the portable log skidder, viewed from the above rear left view. 
       FIG. 2  is an isometric view of the portable log skidder, viewed from the above front right view. 
       FIG. 3  is an elevation view of the portable log skidder, viewed from the left view 
       FIG. 4  is an elevational view of the rear components of the portable log skidder, viewed from the rear. 
       FIG. 5  is an isometric view of the winch assembly. 
       FIG. 6  is an isometric view of the fixed pulley assembly. 
       FIG. 7  is an isometric view of the movable pulley. 
       FIG. 8  is an elevational view of the portable log skidder, shown in operation. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The following discussion describes in detail one or more embodiments of the invention. The discussion should not be construed, however, as limiting the invention to those particular embodiments, and practitioners skilled in the art will recognize numerous other embodiments as well. The complete scope of the invention is defined in the claims appended hereto. 
   As illustrated in  FIGS. 1 and 2 , a portable log skidder  10  comprises, in part, of a base frame  12 . The base frame  12  provides a structural platform or foundation upon which the other components of the portable log skidder  10  are assembled. The base frame  12  is an assembly of elongated structural components and members commonly found in the art. These structural members are typically elongated metal tubes and may have one or more of various cross-sectional shapes, including circular or rectilinear. The structural members are joined by commonly known methods, such as welding or bolted fasteners. 
   The base frame  12  has a front end and a rear end. The front end is that end at which would connect to or couple with a vehicle, such as an All-Terrain Vehicle, or “ATV”, for towing the portable log skidder  10 , while the rear end is located at the end opposite from the front end and is the end at which logs  64  or timber which are to be transported are brought onto the portable log skidder  10 . For the purpose of description, an imaginary longitudinal axis is considered traversing the length of the portable log skidder  10  from the front end to the rear end, while a transverse axis is considered traversing the width of the portable log skidder  10  perpendicular to the longitudinal axis. A vertical axis is considered, for the purpose of description, extending in the vertical plane perpendicular to the longitudinal and transverse axis. In normal use of the invention, the longitudinal and transverse axes are parallel to the ground surface, and the vertical axis is orthogonal to the ground surface. 
   As used herein, the terms “longitudinal” or “longitudinally” refer to a direction parallel or collinear with the longitudinal axis. The terms, “transverse” or “transversely” refer to a direction parallel or collinear to the transverse axis. The terms, “vertical” or “vertically” refer to a direction parallel or collinear with the vertical axis. 
   As used herein, the term, “frontal plane” refers to that plane that divides the invention into front and rear sections and is orthogonal to the longitudinal axis. The transverse and vertical axes lie within the transverse plane. 
   The term, “horizontal plane” refers to a plane that divides the invention into upper and lower sections, and is orthogonal to the vertical axis. The longitudinal and transverse axes lie within or are parallel to the horizontal plane. 
   The term, “medial plane” refers to a plane that divides the invention into left and right sections, and is orthogonal to the transverse axis. The longitudinal and vertical axes lie within or are parallel to the medial plane. 
   One preferred design of the base frame  12  has a central support beam  14  traversing longitudinally the length of the portable log skidder  10 , and two additional side support beams  16  traversing longitudinally on either side of the central support beam  14 , for at least a part of the overall length of the base frame  12  to provide additional support where needed, and additional bracing assembled transversely between the central support beam  14  and the side support beam  16 . 
   In an alternate embodiment, the base frame  12 , may comprise a truss (not shown) assembled from a plurality of struts or structural members, rather than one or more longitudinal support beams  14 ,  16 . 
   Mounted on or substantially near the longitudinal centerline of the base frame  12 , near or proximal to its front end, is a winch  18 . As better shown in  FIG. 5 , a winch  18  typically has a motive force  20 , such as a motor or engine, for providing rotation and torque on an axial shaft  22  one end of which protrudes from the motive force  20 , and a generally cylindrical drum  24  mounted on the protruding end of the axial shaft  22 . The motive force  20  may be a 12-volt, direct current electric motor, capable of receiving D.C. electric power from an ATV or other vehicle towing the portable log skidder  10 . In another embodiment, the motive force  20  is a gasoline engine, which allows the portable log skidder  10  to be decoupled from and operate independently from a towing vehicle. In another embodiment, the motive force  20  is supplied by the towing vehicle engine through a PTO linkage. 
   The winch  18  is mounted with its axial shaft  22  aligned transversely to the base frame  12  and with the longitudinal center of the drum  24  substantially aligned with the longitudinal centerline of the base frame  12 . 
   The drum  24  on the winch  18  has a length of cable  26 , rope or the like wound around its circumference. The cable  26  has a free end which can be spooled out as described below to attach to and haul in a fallen timber or log  64 . A clutch (not shown) is commonly provided to allow the drum  24  to turn freely to allow spooling out of the cable  26 , but to engage for rotating the drum  24  in the opposite direction to haul in the cable  26  under load of a log  64 . Speed controls are typically provided as well to control the rate at which the cable is retrieved and rewound on to the drum  24 . 
   A fixed pulley  28 , better shown in  FIG. 6 , is disposed on the base frame  12 , proximate to its rear end. The fixed pulley  28  typically has a pulley axle  30  about which the pulley rotates freely. The pulley  30  axle is mounted in a fixed frame  32  which is secured to the base frame  12  by means commonly available in the art. The pulley axle  30  is aligned transversely on the base frame at substantially the same vertical distance above the base frame  12  as the winch axial shaft  22 . The longitudinal center of the fixed pulley  28  is aligned with the longitudinal center of the drum  24 . 
   The free end of the cable  26  which is spooled from the drum  24  will first pass around the fixed pulley  28 , passing around the fixed pulley  28  from bottom to top and continue on to a movable pulley, described below. A cable  26  operating on the fixed pulley  28  must engage and disengage the pulley rim substantially radial to the fixed pulley  28 , or the cable  26  may “jump off” or dislodging from the rim of the fixed pulley  28 . Because the length of the drum  24  is greater than that of the fixed pulley  28 , the cable  26  will not necessarily engage the fixed pulley  28  at a precise radial alignment, but may engage it at a slight angle to the fixed pulley&#39;s  28  radius. In such an angular engagement, the cable  26  may catch on the rim of the fixed pulley  28  and be dislodged out of the rim of the fixed pulley  28 . To prevent this, the fixed frame  32  has a pair of vertical rollers  36  disposed forward of the fixed pulley  28  and aligned with the lower half of the fixed pulley  28 . The vertical rollers  36  accept the cable  26  at lateral angles from the fixed pulley  28  radius, and guide it radially onto the pulley rim. 
   On the opposing side of the fixed pulley  28  is a pair of cable guides  38  to maintain the cable  26  on the fixed pulley  28  rim as the cable  26  disengages from the fixed pulley  28  and proceeds to a movable pulley  34 . The movable pulley  34 , as shown in  FIG. 7 , may be disposed laterally offset from the centerline of the base frame  12 , resulting in an angle between the fixed pulley  28  and the cable  26  as it exits the fixed pulley  28  and traverses to the movable pulley  34 . The cable  26  guides maintain a radial alignment of the cable  26  as it disengages the pulley rim, preventing the cable  26  from dislodging from the rim. 
   At the rear end section of the base frame  26 , better shown in  FIG. 4 , is disposed a rear frame assembly  40 . A log bunk  42  is located at the bottom of the rear frame assembly. The log bunk  42  is a generally horizontal, elongated member attached at its middle transversely to the base frame  12 . The log bunk  42  is preferably not straight, but rather either angled or curved upward, the center of the log bunk  42  positioned lowest to the base frame  12 . Two elongated rear support columns  44  further comprise the rear frame assembly  40 . Each rear support column  44  attaches by its lower end to either end of the log bunk  42 . The log bunk and two rear support columns  44  are typically fabricated from tubular structural members. A cross member  46  further comprises the rear frame assembly  40 . The cross member  46  is preferably fabricated from plate or angle members, but may use structural tubing or other structural shapes as well. Either end of the cross member  46  attaches to the upper ends of the two rear support columns  44 . Together the log bunk  42 , the two rear support columns  44  and the cross member  46  are co-planar and form a closed frame. 
   Turning to  FIG. 3 , the rear frame assembly attaches to the rear end section of the base frame  12 . The plane of the rear frame assembly  40  is parallel to the transverse axis but is not parallel to the transverse plane. The plane of the rear frame assembly  40  is pitched forward and downward toward the horizontal plane from the transverse plane by, preferably, about 10°. 
   The log skidder  10  further comprises an elongated center support column  48 . The center support column  48  has a lower end section which attaches to the forward end section of the base frame  12 , forward of the winch  18 . The upper end section of the center support column  48  attaches to the center of the cross member. The center support column  48  is preferably curved or arcuate but preferably lies within the medial plane containing the center support beam. 
   Disposed on the interior side of the center support column  48  are one or more accessory attachment fittings  50 . They are typically, but not necessarily, spaced at substantially equal intervals on the length of the center support column  48 . These accessory attachment fittings  50  provide a means for attaching or securing a variety of accessories, such as movable pulleys  34 , pulley blocks, or “come-alongs” to the center support column. These accessory attachment fittings  50  may be simple loops, lugs, rings, hooks, hangers or the like onto which an accessory can be hung, attached or secured. One or more accessory attachment fittings  50  are also provided along the bottom or lower edge of the cross member  46 . 
   The various accessories which can be attached to the log skidder  10  may include movable pulleys  34 , pulley blocks, sheeves, or like devices capable of routing a cable, line, rope, etc. in a different direction. The accessory is attached to an accessory attachment fitting  50 . The cable  26  emanating from the fixed pulley  28  is routed around the rim of the movable pulley  34  from the front and around the top. The cable  26  then proceeds from the movable pulley  34  through the interior opening of the rear frame assembly  40  and onward behind the log skidder  10  to a log  64  or timber which is to be hauled aboard the log skidder  10 . 
   To facilitate hauling a log  64  on board the log skidder  10 , a log chute  52  is disposed at the rear end section of the log skidder  10 . As best shown in  FIG. 3 , the log chute  52  is a plate having a straight chute rear edge and a forward edge curving or bending upward towards its transverse ends. The straight chute lower edge is parallel to the transverse axis. The chute forward edge shape is congruent to that of the log bunk, and attaches thereto. The longitudinal centerline of the log chute  52  is tilted downward and rearward at an angle of approximately 15°. 
   A stabilizer  58  having a straight stabilizer upper edge  60  articulates with the chute rear edge  54 . The stabilizer  58  is a plate which has a stabilizer lower edge  62  that may rest on the ground or have elongated stabilizer extensions  66  from the stabilizer lower edge  62  to rest on the ground. The stabilizer extensions  66  which may extend from the stabilizer lower edge  62  either longitudinally or at a transverse angle outward from the longitudinal centerline of the stabilizer  58 . The stabilizer lower edge  62 , along with the stabilizer extensions  66 , if present, rests on and braces into the ground surface to anchor the log skidder  10  and resist rearward motion when a log  64  is hauled to an on board the log skidder  10 . When not in use, the stabilizer  58  may be articulated upward around the stabilizer upper edge  60  and secured in the elevated position with a chain or the like. This will prevent the stabilizer lower edge  62  from dragging on the ground. 
   In use, as shown in  FIG. 8 , the log skidder  10  is towed to a site at which cut timber or logs  64  are present which are desired to be removed from the site. The log skidder  10  is designed to be towed by an all-terrain vehicle, which provides the best ability to access difficult, sloped terrain for small haulage projects. 
   The log skidder  10  is positioned with its rear end directed towards the logs  64  or cut timber which are desired to be hauled. The stabilizer  58  is lowered to plant the stabilizer lower edge  62  and the stabilizer extensions  66 , if any, into the ground. Then, a movable pulley  34  is positioned on one of the accessory attachment fittings  50 . The fittings  50  selected will depend on the distance and direction to the log  64  and the type of terrain across which the log  64  must be pulled. For logs  64  that are a greater distance away or will be hauled across relatively smooth terrain, the movable pulley  34  will normally be attached to an accessory attachment fitting  50  forward and lower on the center support column  48 . As the log  64  approaches the log skidder  10 , or is blocked or entangled in undergrowth or rocks, the movable pulley  34  can be moved to an accessory attachment fitting  50  higher and more rearward on the center support column  48 . This will raise up the front end of a log  64 , causing it to clear an obstacle or to be lifted onto the log chute  52  and over the log bunk  42 . Once the front end of a log has cleared the log bunk  42 , the movable pulley  34  can be repositioned to a more forward accessory attachment fitting  50  to haul a greater portion of the log  64  on the log bunk  42 . The log  64  can then be secured to the portable log skidder  10  with come-alongs attached to other accessory attachment fittings  50 . 
   While various embodiments of the invention have been described above, it should be understood that they have been presented by way of example, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail may be made therein without departing from the spirit, and scope and application of the invention. This is especially true in light of technology and terms within the relevant art that may be later developed. Thus, the present invention should not be limited by any of the above-described exemplary embodiments, but should only be defined in accordance with the appended claims and their equivalents.