Abstract:
A portable ski rope tow system, which is capable of ascending various pitched slopes. The system only needs to be anchored into snow for operation. The system consists of a main drive mechanism, a continuous loop tow rope, rope support posts that include adjustable rope guide sheave wheels, an end post that includes a rope return pulley utilizing a cable puller/come-a-long for tow rope tensioning. The system is equipped with a pull cord safety device, which runs the length of the system. A towrope clamp attached to a climbing harness is needed by the skier/snowboarder to eliminate hand fatigue and mainly to be able to pass through rope guide sheave wheels. Most of the structural components of the system are lightweight, made of aluminum to provide easier mobility, set up and take down.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of Provisional application 61/447,234 filed Feb. 28, 2011 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to ski rope tow system and particularly to portable ski rope tow systems, which are capable of ascending various pitched slopes. 
     2. Description of the Prior Art 
     Today, ski facilities uses two main systems for moving skiers to the top of a ski run. The first is the chair lift and the second is the towline. Towlines have been in use longer than chair lifts as they are much easier to install. At traditional ski areas, these lifts are usually permanently installed. That means setting poles or supports in the ground at specific places and installing all of the necessary equipment needed to operate them. 
     Alternatively, temporary towlines may be installed at locations. These towlines usually have a two posts and a line, on pulleys, strung between them. The problem with is system is that there is no way to extend the line to more than one post as there is no simple way for the tow bar from pass from post to post. The tow bar is attached to the towline and is held by the skier on the way up the slope. Another problem with these temporary towlines is that they cannot be installed on uneven terrain. The problem here is with uneven terrain. The towline may contact the ground unless the posts are unreasonably close together. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The instant invention solves these problems. It is a portable ski rope tow system, which is capable of any length. It is also easily able to ascend various pitched slopes. The system only needs to be anchored into snow for operation. The system consists of a main drive mechanism, a continuous loop tow rope, rope support posts that include adjustable rope guide sheave wheels, and an end post that includes a rope return pulley utilizing a cable puller/come-a-long for tow rope tensioning. The system is equipped with a pull cord safety device, which runs the length of the system. A unique towrope clamp that is removably attached to a climbing harness is used by the skier/snowboarder to move up the slope. The unique design allows the clamp to pass over the rope guide sheave wheels, which enables the system to use multiple posts for long runs and to deal with any terrain issues that might be encountered. The unique clamp also eliminates hand fatigue for the users. Most of the structural components of the system are lightweight aluminum to provide easier mobility, set up and take down. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of the system. 
         FIG. 2  is side view of the main drive system. 
         FIG. 3  is a front view of the main drive system. 
         FIG. 4  is a top view of the main drive system 
         FIG. 5  is a front view of a rope support post that includes adjustable rope guide sheave wheels. 
         FIG. 6  is a side view of a rope support post that includes adjustable rope guide sheave wheels. 
         FIG. 7  is a side view of the end post that mounts the towrope return pulley and cable puller/come-a-long. 
         FIG. 8  is a front view of the end post that mounts the towrope return pulley and cable puller/come-a-long. 
         FIG. 9  is a top view of a towrope clamp shown in the closed position. 
         FIG. 10  is a side view of a towrope clamp shown in the closed position. 
         FIG. 11  is a side view of a towrope clamp shown in the partially open position. 
         FIG. 12  is a side view of the towrope-coiling reel system, which mounts to main drive system. 
         FIG. 13  is a side view of the coiling shaft. 
         FIG. 14  is a top view of the reel bracket. 
         FIG. 15  is a front view of the safety gate for the pull cord safety device. 
         FIG. 16  is a side view of the top safety gate for the pull cord safety device. 
         FIG. 17  is a top view of the top safety gate for the pull cord safety device. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to  FIG. 1 , a side view of the system  1  is shown. The system has a number of components. First, there is a main drive unit  2  that consists of an aluminum mainframe  10 , which supports a gas powered, air-cooled, vertical drive shaft engine  11 . The engine is supplied from a gas tank,  11   a , which is mounted in the bottom of the frame  10 . Of course, any similar type of engine or motor can be used. Gas is preferred as a fuel because the invention is preferably used in remote areas as a temporary ski tow in areas in which electricity is not normally available. A centrifugal clutch  12  is attached to the drive shaft of the engine  11  (see  FIG. 2 ). A sprocket  13 , which allows load free starting from the clutch, runs a chain  14 . The chain  14  is attached to a keyed hub sprocket  15 , which runs a keyed drive shaft  16  (see  FIG. 2 ). The drive shaft  16  has top and bottom flange block bearings  17 . The bearings and drive shaft are mounted on plates  18  with slotted holes to adjust chain tension, the chain tension is held with tension bolts/blocks, which hold bearings with fitted blocks  19  along with a tensioning arm  19   a . The drive shaft  16  is held in place by set screws on the bearing and also by collars  12   a  added on the topside of the top bearing and the underside of the bottom bearing (see  FIG. 2 ). A bull wheel/rim  20  runs a towrope  21 . The rim  20  is attached to the drive shaft  16  with a keyed hub. The rim/rim  20  works as a capstan pulley with the towrope  21  wrapped once around it to provide bite on the rope. 
     Attached to the mainframe  10  are cylindrical pockets  22  that hold anchoring posts  23  for the main drive system  2 . Here, mainframe  10 , which supports a gas powered, air-cooled, vertical drive shaft engine  11 . Of course, any similar type of engine or motor can be used. A centrifugal clutch  12  is attached to the drive shaft  16  of the engine  11  (see  FIG. 2 ). A sprocket  13 , which allows load free starting from the clutch, runs a chain  14 . The chain  14  is attached to a keyed hub sprocket  15 , which attaches to the keyed drive shaft  16  (see  FIG. 2 ). The drive shaft  16  has top and bottom flange block bearings  17 . The bearings and drive shaft are mounted on plates  18  with slotted holes to adjust chain tension, the chain tension is held with tension bolts/block which hold bearings with fitted blocks  19 . The drive shaft  16  is held in place by set screws on the bearing and also by collars  12   a  added on the topside of the top bearing and the underside of the bottom bearing (see  FIG. 2 ). A rim/rim  20  runs a towrope  21 . The rim  20  is attached to the drive shaft  16  with a keyed hub. The rim/rim  20  works as a capstan pulley with the towrope  21  wrapped once around it to provide bite on the rope. 
     Also attached to the mainframe  10  is pull-cord kill switch  24  that ties to the engines main kill switch  24   a , as discussed below. 
     The towrope  21  runs outward from the main drive system  2  to run up a slope. To support the rope, a number of support posts  25  are placed at points along the slope. As discussed below, the support posts have sheaves to allow the rope to run both up and down the slope as the tow system is operated. At the top of the slope and end post  26  is installed. The end post is guyed with a rope  26   a  to a stake  26   b  to ensure the end post remains stable. A pulley  27  is attached to the end post by means of a cable puller/come along  28  that ensures proper tension on the rope  21  is maintained. Note that the pulley  27  has a guy line  27   a  and a stake  27   b , which are used to ensure that the pulley  27  remains in a vertical orientation during operation. 
     In the preferred embodiment, the total length of the towline can vary from 300 to 2,400 feet. To accomplish this the number of posts  25  varies. The distance between posts is called a “pitch” and for the 2,400 foot length requires at least 7 posts, spread approximately 300 feet apart. The minimum system uses two posts spaced about 300 feet apart. One unique feature of this system is that it can operate on uneven terrain. The requirement for operation is that the rope  21  is held above the surface of the snow. Thus, conditions may require additional posts to provide a smooth operation over the entire length of the tow. 
       FIG. 1  also shows a safety gate  29  that has a line  29   a  that runs down to the pull-cord kill switch  24 . This is a safety device that shuts down the motor is a user cannot disengage from the rope. If that happens, the user will hit the gate, which will pull the line, and shut down the engine. One advantage of the safety line is that a user can grab the line at any time during the run and pull it to shut down the engine in an emergency. 
     More specific details of the system are discussed below. 
       FIGS. 2 ,  3  and  4  are side, front and top views of the main drive system, respectively. Here, details of the drive system are shown in better detail. The mainframe  10 , the vertical drive shaft engine  11 , the centrifugal clutch  12 , the drive shaft  16  of the engine  11 , the sprocket  13 , the chain  14 , the keyed hub sprocket  15 , the top and bottom flange block bearings  17 , the plates  18 , the fitted blocks  19 , the collars  12   a , the pockets  22 , and the rim/rim  20  are all shown. 
       FIGS. 3 and 4  also show the connection for the kill switch  24  that attaches to the pull cord  29   a . This switch is mounted on the front of the frame and is wired to the main engine kill switch  24   a  by wires  24   b . In this way, the engine is shut down, as described above. 
       FIGS. 5 and 6  are a side view and a front view of the rope support posts  25 . These figures show details of the support posts  25 . The posts are planted into the snow along the route of the towline. The posts  25  have stability plates  30  installed on the side and face of the post  25  as shown. The stability plates are connected with clevis pins  31  for fast and easy attachment. The towrope runs uphill passing over the uphill sheave  32 . The rope can ride over the top or bottom of the sheave wheel depending on incline, to ensure proper tensioning of towrope. The downhill sheave  33  is spaced differently than the uphill sheave  32 . The uphill sheave  32  is held away from the post by a bracket  34  to keep the user away from the posts. If the towrope comes out of the sheave wheel, it can be easily placed back into the wheel. 
     Each post also has an eye bolt  35  installed, through which the safety pull cord  29   a  passes on its way to the safety gate at the top of the towline run. 
       FIGS. 7 and 8  are a side view and a front view of the end post  26  that terminates the towrope and holds the return pulley  27  and cable puller/come-a-long  28 . The end post  26  has a larger stability plate  36  to provide support for the towrope tension in the direction of the towrope, and a smaller plate  37  for lateral support. The end post has an eyebolt  38 , which is used for mounting the cable puller/come-a-long  28  as shown in  FIG. 1 . As noted, the towrope return pulley  27  is attached to the cable puller  27 . As shown in  FIG. 1 , the end post  26  is further supported on both sides with ropes  26   a  tied to stakes  26   b  for extra support. 
       FIG. 9  is a top view of a towrope clamp  40  shown in the closed position. This clamp is the key to enabling multiple pitches over several pulleys. Without this clamp, users could not safely go past the pulleys on successive posts. The clamp has two side members  41  and a central pivoting arm  42  that pivots on a pin  43 . The clamp has a second pin  44 , to which a rope  45  is attached. The user attaches the rope to a climbing harness using a carabineer (not shown). As shown in  FIGS. 9 ,  10  and  11 , the clamp  40  fits over the towrope  21  (see  FIG. 9 ). To attach the clamp to the towrope, the user drops the center arm (see  FIG. 11 ), and slips it over the rope  21   b . The user then lifts the center arm up to the position shown in  FIG. 10 . The user then holds the clamp such that the center arm remains horizontal ( FIG. 10 ). In this way, the towrope is held firmly by the clamp. As the towrope moves, the user rides up the slope with the rope. When the user arrives at a pulley sheave, the clamp simply rides over the top (or under the bottom) of the sheave and the user continues on the way up the mountain. At the top of the run, the user simply releases the clamp and the clamp is removed from the towrope. In the event of a problem, and the user cannot remove the clamp, the user will reach the safety gate, which will shutdown the engine as discussed below. At any time during the run, if a user experiences a problem, the user can pull the safety line  29   a  to shutdown the engine as well. 
       FIG. 10  is a side view of a towrope clamp shown in the closed position. In this view, the central pivoting arm  42  is shown in hidden lines. Note that the top end of the arm is shown below the side members  41 . The pinned end of the central pivoting arm  42  extends downward as shown and the side members  41  are curved upwards, to form a small opening into which the towrope is placed (see  FIG. 9 ). As noted above, the user holds the central pivoting arm  42  between the side members  41  to retain the towrope in the clamp. When the device is in operation, the towrope pulls the clamp and thus the rider along the run. 
       FIG. 11  is a side view of a towrope clamp shown in the partially open position. As noted above, to attach or remove the clamp  40  from the towrope, the user releases the central pivoting arm  42 , which then drops downward as shown in the figure. 
       FIG. 12  is a side view of the towrope-coiling reel. The reel  50  fits over the top of the drive shaft  16 . The reel is used to deploy the towrope  21  when entire system is being set up and to the coil the towrope  21  after use. The reel is used as follows: to deploy the rope, the end post &amp; pulley are set. A smaller diameter rope (not shown) (e.g., ⅛ inch, with which it is easier to make the initial ascent is taken to the top of the run. The smaller rope is run from the base frame after being tied to an end of the towrope that is spooled on the reel. The smaller rope is then run through the pulley and then to an empty spool mounted to the bracket. Once the engine is engaged, it will do the work of pulling the towrope. Other rope support posts may be used to prevent rope damage. To coil the towrope, the towrope is secured to the reel on top of the shaft. As the engine runs, the rope is coiled on the reel until is completely removed from the run. 
       FIG. 13  is a side view of the coiling shaft  51 . This shaft is secured to the drive shaft using the reel bracket  52  (see  FIG. 14 ). 
       FIG. 14  is a top view of the reel bracket  52 . As shown, the bracket has a center hole  53  that holds the shaft  51 , and two smaller mounting holes  54 . 
       FIGS. 15 ,  16  and  17  show details of the safety gate  29 .  FIG. 15  is a side view showing the gate  60 , which is attached to a side plate  61 , which is part of a support post  62  by a hinge  63 . Referring now to  FIGS. 16 and 17 , the safety line  29   a  passes through an eye  64  that is attached to the post  62 . It then attaches to the gate  60 . If a skier is stuck on the towrope and is unable to remove the clamp, the user will contact the gate. This action pushes the gate back, which pulls the safety line  29 . This causes the engine to shut down and stop the towrope. 
     The present disclosure should not be construed in any limited sense other than that limited by the scope of the claims having regard to the teachings herein and the prior art being apparent with the preferred form of the invention disclosed herein and which reveals details of structure of a preferred form necessary for a better understanding of the invention and may be subject to change by skilled persons within the scope of the invention without departing from the concept thereof.