Abstract:
A portable tow device ( 20 ) for selective attachment to a tow line ( 24 ) having a length includes a handle ( 32 ). The tow device also includes a locking member ( 28 ) rotatably attached to the handle. The locking member includes first and second bearing members ( 28   a ) and ( 28   b ) and an elongate slot ( 42 ). The tow device further includes a lever arm ( 30 ) attached to the locking member for selectively rotating the locking member between a locked position, wherein the tow line is clamped between the first and second bearing members for propelling a person along a surface at a rate substantially equal to the rate of the tow line, and an unlocked position, wherein the tow line passes freely through the tow device.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to portable ski lift devices and, more particularly, to a portable hand-held rope tow device. 
     BACKGROUND OF THE INVENTION 
     Back country or out of bounds skiing, such as telemarking, is a growing aspect of outdoor activities. In certain areas, back country skiers may have set up a well-known rope tow that includes an endless rope strung between two pulleys and extending along the slope of a hill. Typically, one of the pulleys is connected to a motor, wherein the motor drives the rope between the two pulleys. In operation, a skier approaches the lower end of the rope tow located near the bottom of the hill and physically grabs onto the rope, thereby propelling the skier up the hill. Although such an arrangement is effective at propelling a skier along the slope of a hill, it is not without its problems. 
     First, because the skier must grab onto the moving rope with either their bare or gloved hand, the friction associated with grabbing a moving rope oftentimes results in premature wear of the glove or burns to the hands. Additionally, because the skier is forced to hold onto the rope with their hand to propel themselves up the hillside, the entire drag load associated with being propelled by the tow rope is carried by the skier&#39;s hands. As a result, the skier&#39;s hands are often prematurely fatigued. Also, because the rope used in most common rope tows is large in diameter, it is not easily transportable. Further, when the skier grabs onto the rope, there is a sudden jerking motion. This is undesirable because such a motion may cause the skier to fall. Finally, permanently attaching a well-known T-bar to the tow rope to propel a skier up the hillside is often impractical in the back country location due to the remoteness of the location and because such an apparatus requires large structure. 
     Thus, there exists a need for a relatively simple portable rope tow device for back country skiers. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, a portable rope tow device for selective attachment to a tow line having a length is provided. The portable tow device includes a handle and a locking member attached to the handle. The locking member is selectively actuatable between a locked position, wherein a portion of the tow device is clamped to the tow line for propelling a person along a surface, and an unlocked position, wherein the tow line passes freely through the tow device. 
     In accordance with other aspects of this invention, the portable tow device also includes a lever arm attached to the locking member to selectively rotate the locking member between the locked and unlocked positions. The locking member includes first and second bearing members and an elongate slot. 
     In accordance with additional aspects of this invention, the elongate direction of the slot extends substantially parallel with the length of the tow line when the tow device is in the unlocked position. The elongate direction of the slot extends substantially normal to the length of the tow line when the tow device is in the locked position. 
     In accordance with still other aspects of this invention, the first and second bearing members are elongate cylinders and are held in spaced parallel disposition on opposite sides of the elongate slot, such that the elongate direction of each bearing member is substantially normal to the elongate direction of the slot. The first bearing member rotates about the second bearing member to clamp the tow line between the first and second bearing members when the tow device is actuated into the locked position. 
     In accordance with still yet other aspects of this invention, the portable tow device further includes a coupling member having a first end removably fastened to the handle and a second end selectively attachable to the person to assist in propelling the person along the surface. 
     A portable tow device formed in accordance with the present invention has several advantages over such devices used in the past. First, because the device is portable, it may be easily stored within a backpack carried by a skier. Further, such a device provides for a convenient method of clamping onto a tow line, thereby minimizing damage to either the gloved hand or bare hand of the skier due to frictional contact with the tow line. Additionally, such a device is adaptable by slowing increasing friction to minimize the jerking motion associated with most common tow ropes. Therefore, a portable tow device formed in accordance with the present invention is safer, more convenient and simpler to use than those currently available. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing aspects and many of the attendant advantages of this invention will become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is an environmental view of a portable rope tow device formed in accordance with the present invention as it would be used to propel a skier (shown in phantom) along a hillside; 
     FIG. 2 is a perspective view of a portable rope tow device formed in accordance with the present invention; 
     FIG. 3 is a side view of a portable rope tow device formed in accordance with the present invention shown in the unlocked position; 
     FIG. 4 is a cross-sectional side view of a portable rope tow device formed in accordance with the present invention shown in the locked position; 
     FIG. 5 is a perspective view of an alternate embodiment of a portable rope tow device formed in accordance with the present invention showing a clamping member exploded away from one end of the portable rope tow device; and 
     FIG. 6 is a perspective view of a second alternate embodiment of a portable rope tow device formed in accordance with the present invention showing a buckle and tab fastener attached to one end of the tow device. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1 and 2 illustrate a preferred embodiment of a portable tow device  20  constructed in accordance with the present invention. The tow device  20  is shown as it would be used to propel a skier  22  (shown in phantom) along a surface in the direction indicated by the arrow  23  by selectively fastening the tow device  20  to a tow rope  24 . The tow rope  24  is well-known in the art and is commonly configured as an endless rope strung between two pulleys (not shown). Typically, one pulley is located at a lower portion of a hillside, while the second pulley is located at some predetermined location and elevation up the hillside. At least one of the pulleys is connected to a well-known motor (not shown) to drive the pulleys and, therefore, the tow rope  24 . 
     As may be best seen by referring to FIG. 2, the tow device  20  includes a body  26 , a locking mechanism  28  and a lever arm  30 . The body  26  includes a handle  32  suitably injection-molded from a thermoplastic and an attachment member  34 . The U-shaped attachment member  34  is suitably formed from a high-strength, lightweight material, such as aluminum, and is rigidly attached to one end of the handle  32  by a well-known fastener  36 , such as a bolt threadably received within the handle  32 . The attachment member  34  is fastened to the handle  32 , such that the open end of the attachment member  34  extends outwardly away from the handle  32 . 
     The locking mechanism  28  is suitably formed from a high-strength lightweight material, such as aluminum. The locking mechanism  28  includes first and second cylindrical bearing members  38   a  and  38   b  held in space parallel disposition by a plurality of side rings  40   a - 40   c.  The first side ring  40   a  is substantially oval in configuration and has one end of the first and second bearing members  38   a  and  38   b  integrally formed or welded substantially near its center. Both the first and second bearing members  38   a  and  38   b  extend outwardly from the first side ring  40   a  in a parallel manner, such that the elongate direction of each bearing member  38   a  and  38   b  is substantially normal to a plane extending laterally through the width of the first side ring  40   a.  The other end of each bearing member  30   a  and  30   b  has D-shaped second and third side rings  40   b  and  40   c  integrally formed therewith. 
     The second and third side rings  30   b  and  30   c  are integrally formed with or welded to the bearing members  38   a  and  38   b,  such that the spines of the second and third side rings  40   b  and  40   c  oppose each other. As configured, an elongate slot  42  is defined between the spines of the second and third side rings  40   b  and  40   c.  Further, the first and second bearing members  38   a  and  38   b  extend laterally between the side rings  40   a - 40   c,  such that the elongate direction of each bearing member  38   a  and  38   b  is substantially normal to the elongate direction of the slot  42 . 
     Still referring to FIG. 2, the lever arm  30  will now be described in greater detail. The lever arm  30  is substantially L-shaped in configuration, such that the base defines a gripping portion  31  extending substantially normal to one end of the lever arm  30 . The other end of the lever arm  30  is suitably bent to permit rotation of the lever arm  30  during actuation of the tow device  20  between a locked and unlocked position without interfering with the handle  32 , as is described in greater detail below. 
     The lever arm  30  is rotatably attached to the free end of the attachment member  34  by a pin  44  extending through the free end of the attachment arm  30 . The pin  44  also extends coaxially through the elongate direction of the second bearing member  38   b  to rotatably attach the locking mechanism  28  between the arms of the attachment portion  34 . Thus, as assembled, the locking mechanism is pinned between the arms of the attachment portion  34 , such that the first bearing member  38   a  rotates about the second bearing member  38   b  when the tow device  20  is actuated between the locked and unlocked positions, as is described in greater detail below. 
     Operation of the portable tow device  20  may be best understood by referring to FIGS. 3 and 4. In the unlocked position (FIG.  3 ), the handle  32  of the tow device  20  is held in one hand of the skier, while the gripping portion  31  of the lever arm  30  is held in the other hand of the skier. The lever arm  30  is positioned towards the rearward end of the device  20 , such that the first and second bearing members  38   a  and  38   b  are substantially aligned in the vertical direction. Also, in the unlocked position, the elongate direction of the slot  42  is substantially parallel with the length of the tow rope  24 . As a result, the tow rope  24  may be received between the vertically aligned first and second bearing members  38   a  and  38   b  by the skier aligning the slot  42  with the length of the tow rope  24 . The skier then positions the tow device  20  such that the tow rope  24  is received within the locking mechanism  28  and is located substantially midway between the sides of the locking mechanism  28 . The tow device  20  is actuated into the locked position by rotating the lever arm  30  one complete revolution in either a clockwise or counterclockwise direction about the pin  44 . 
     Referring to FIG. 4, as the locking mechanism  28  is rotated into the locked position, the first bearing member  38   a  rotates at least one complete revolution about the second bearing member  38   b  and the pin  44  to clamp the tow rope  24  between the first and second bearing members  38   a  and  38   b.  For discussion purposes, the lever arm  30  is illustrated as rotating about the pin  44  in a clockwise direction and, therefore, rotational directions and motion of various components are described accordingly. However, as noted above, the lever arm  30  may be rotated in either direction about the pin  44 . Further, it is preferred that the lever arm  30  be rotated in a counterclockwise direction about the pin  44 . Therefore, directional descriptions are for illustrative purposes only and the invention is not intended to be so limited. 
     During the actuation between the unlocked and locked positions, the first bearing member  38   a  lifts upwardly against the lower surface of the tow rope  24 , thereby causing the upper surface of the tow rope  24  to engage the second bearing member  38   b.  During continued rotation of the locking mechanism  28  into the locked position, the first bearing member  38   a  continues to rotate about the second bearing member  38   b  until the tow rope  24  is securely clamped between the first and second bearing members  38   a  and  38   b,  thereby locking the tow device  20  to the tow rope  24 . In this position, the tow rope  24  is doubled over onto itself to lock the tow rope  24  into place. As a result, the load associated with being towed is applied primarily to the tow device  20 , instead of the lever arm  30  and, therefore, results in a more comfortable towing experience for the skier. 
     To actuate the tow device  20  from the locked to unlocked position, the lever arm  30  is rotated in a direction opposite from that described above for the locked position, thereby releasing the tow rope  24  from between the first and second bearing members  38   a  and  38   b.  The lever arm  30  is rotated until the elongate direction of the slot  42  is once again substantially parallel with the length of the tow rope  24 , thereby permitting the skier to withdraw the tow device  20  from the tow rope  24 . 
     Referring now to FIG. 5, an alternate embodiment of a tow device  120  constructed in accordance with the present invention will now be described in greater detail. The tow device  120  is identical in both design and operation as described above for the preferred embodiment with the following exception. The tow device  120  includes a coupling member that may be selectively fastened to the tow device  120 . In this alternate embodiment, the coupling member is a T-bar  150  suitably formed from a well-known thermoplastic, such as PVC tubing. One end of the T-bar  150  includes an externally threaded portion  152  sized to be received within an internally threaded portion (not shown) located in the end of the handle  132  opposite the attachment member  134 . The other end of the T-bar  150  includes first and second tubular members  154   a  and  154   b  slidably received within a T-joint  156 . The tubular members  154   a  and  154   b  are sized to be received snugly against the hamstrings of a skier&#39;s legs to assist in propelling the skier along the hillside, thereby relieving at least a portion of the drag load on the skier&#39;s hands associated with being propelled by the tow rope  124 . 
     In operation, the T-bar  150  is assembled by sliding the tubular portions  154   a  and  154   b  into the T-joint  156  and then threading the T-bar within the corresponding threaded portion of the tow device  120 , thereby securing the T-bar to the tow device  120 . Then, the tow device  120  is attached to the tow rope  124  as described above. The T-bar  150  is placed between the skier&#39;s legs, such that the tubular portions  154   a  and  154   b  are received against the hamstrings of the skier. Thus, the skier holds the tow device  120  in the locked position, while the T-bar  150  pulls the skier along with the tow rope  124 . Although a T-bar  150  is preferred as the coupling member, other coupling members, such as a clamp device or assembly of belts, are also within the scope of the present invention. 
     Referring now to FIG. 6, a second alternate embodiment of a tow device  220  constructed in accordance with the present invention will now be described in greater detail. The tow device  220  is identical in both design and operation as described above for the preferred embodiment with the following exception. The tow device  220  includes a coupling member  270  that may be reversibly fastened to the tow device  220 . In this alternate embodiment, the coupling member  270  includes a buckle portion  272  and a tab fastener  274 . One end of the buckle portion  272  includes an externally threaded portion  276  sized to be received within an internally threaded portion (not shown) located in the free end of the handle  232 . The other end of the buckle portion  272  includes a well-known automobile seat belt buckle  278 . The buckle  278  includes a release handle  280  hingedly attached thereto to selectively release the corresponding tab fasteners  274 . The tab fastener  274  is adapted to be attached to the skier by a number of attachments, such as a strap fastened to a well-known waist pack. 
     In operation, a skier attaches the buckle portion  272  to the tow device  220  by screwing the buckle portion  272  into the handle  232 . Then, the skier would attach the tow device  220  to the tow rope  224  as described above. The buckle portion  272  is coupled to the tab fastener  274  by sliding the tab fastener  274  into the buckle portion  272 . To release the tab fastener  274  from the buckle portion  272 , the skier pulls the release handle  280 , thereby releasing the tab fastener  272  from within the buckle portion  272 . Thus, when the tab fastener  274  is received within the buckle portion  272 , the skier is pulled along a surface by the tow device  220  without subjecting the skier&#39;s hand to fatigue due to the loads associated with being towed by the tow device. 
     The previously described versions of the present invention provide several advantages over tow devices currently available in the art. First, because the device is portable, it may be easily stored within a backpack carried by a skier. Second, such a device provides for a convenient method of clamping onto a tow line, thereby minimizing damage to either the gloved hand or bare hand of the skier due to frictional contact with the tow line. Also, if the skier should fall, the skier would let go of handle, and the pulling pressure of the tow rope will pull the device into a nonlocked position and, therefore, is safer. Therefore, a portable tow device formed in accordance with the present invention is safer, more convenient and simpler to use than those currently available. 
     While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.