Patent application title: APPARATUS AND METHOD FOR OVERHEAD CABLE TOWED SPORTS
Christian Von Lerchenfeld (Hindelang, DE)
IPC8 Class: AB61B1100FI
Class name: Traction cable ski tow
Publication date: 2012-12-27
Patent application number: 20120325106
An elevated loop of cable or other flexible traction member extends
suspended above a surface over which a sport participant is to be towed.
The loop includes upper and lower legs which run between a pair of
pulleys which are mounted for rotation in substantially vertical planes
atop respective ones of a pair of mutually separated support structures.
At least one of the pulleys is coupled to a reversible, variable speed
drive. A carrier is coupled to one leg of the loop and in response to
rotation of the drive, unit travels along according to a reversible
variable speed velocity profile.
1. A towed sports apparatus for towing a sports participant over a
surface, said apparatus, comprising: a first support structure and a
second support structure, said first support structure and said second
support structure being mutually separated from one another by at least a
portion of the surface over which the participant is to be towed; a first
pulley supportably mounted to said first support structure, said first
pulley being mounted for rotation in a first substantially vertical plane
about a first substantially horizontal rotational axis; a second pulley
supportably mounted to said second support structure, said second pulley
being mounted for rotation in a second substantially vertical plane about
a second substantially horizontal rotational axis; a flexible traction
member driveably coupled said first pulley and said second pulley to form
an elongated loop having upper leg and a lower leg, said upper leg
extending between an upper portion of said first pulley and an upper
portion of said second pulley and said lower leg being suspended between
said first support structure and said second support structure, at least
a portion of said upper leg and said lower leg passing overhead of said
portion of said surface; a drive coupled to said loop by way of at least
one of said first pulley and said second pulley, for selectively driving
said elongated loop in either a first rotational direction or a second
rotational direction and effecting said rotation of said first pulley
about said first substantially horizontal rotational axis and effecting
said rotation of said second pulley about said second substantially
horizontal rotational axis; a carrier mounted to said elongated loop with
for travel along at least a portion of said elongated loop, said carrier
travelling in a first linear direction in response to said driving of
said elongated loop in said first rotational direction and travelling in
a second linear direction in response to said driving of said elongated
loop in said second rotational direction, and a tow line having an upper
end coupled to said carrier and a lower end for towing the participant.
2. An apparatus according to claim 1, wherein at least one of said first support structure and said second support structure comprises a tower having a pair of legs which form an A-frame tower.
3. An apparatus according to claim 2, wherein said A-frame tower comprises at least one brace member connected between said legs.
4. An apparatus according to claim 2, wherein at least one of said legs comprises a pair of side rails which are connected to one another by way of a plurality of mutually spaced rungs to form a ladder.
5. An apparatus according to claim 2, further comprising at least one guy line coupled between said tower and an anchor location for stabilizing said tower.
6. An apparatus according to claim 1, wherein said drive comprises a motor.
7. An apparatus according to claim 4, wherein said drive further comprises a gearbox operably interposed between said motor and said first pulley.
8. An apparatus according to claim 4, wherein said drive further comprises a clutch operably interposed between said motor and said first pulley.
9. An apparatus according to claim 1, wherein said first substantially vertical plane and said second substantially vertical plane are substantially co-planar with one another.
10. An apparatus according to claim 1, wherein said first substantially vertical plane is a plane which deviates from vertical by no more than about fifteen degrees.
11. An apparatus according to claim 1, wherein said first substantially vertical plane is a plane which deviates from vertical by more than about five degrees.
12. An apparatus according to claim 1, wherein said second substantially vertical plane is a plane which deviates from vertical by more than about fifteen degrees.
13. An apparatus according to claim 1, wherein said second substantially vertical plane is a plane which deviates from vertical by more than about five degrees.
14. An apparatus according to claim 1, wherein said first substantially vertical plane and said second substantially vertical plane are tilted relative to one by more than about fifteen degrees.
15. An apparatus according to claim 1, wherein said first substantially vertical plane and said second substantially vertical plane are not tilted relative to one another by more than about five degrees.
16. A method for towing a sport participant over a surface, said method comprising the steps of: forming a flexible traction member into a loop extending drivably between a first pulley and a second pulley, said first pulley being mounted for rotation in a first substantially vertical plane, said second pulley being mounted for rotation in a second substantially vertical plane, at least a portion of said loop extending above said surface; coupling a tow line to said loop; rotatably driving at least one of said first pulley and said second pulley to cause said loop to rotate; and towing said participant over said surface by way of said tow line.
17. The method of claim 16 further comprising the step of controlling said rotatable driving according to a velocity profile which includes at least one increase and at least one decrease in rotational speed.
18. The method of claim 17 wherein said velocity profile further includes at least one reversal of direction of said rotatable driving of said loop.
19. The method of claim 18 wherein each said reversal of direction is preceded by a dwell interval during which a speed of rotation of said loop is maintained below a limit.
CROSS-REFERENCE TO RELATED APPLICATIONS
 This application claims priority under 35 U.S.C. §119(e) to commonly owned co-pending U.S. Provisional Application Ser. No. 61/241,824 filed Sep. 11, 2009 for all commonly disclosed subject matter.
STATEMENT REGARDING FEDERALLY SPONSORED-RESEARCH OR DEVELOPMENT
 Not Applicable.
INCORPORATION BY REFERENCE
 U.S. Provisional Application Ser. No. 61/241,824 is expressly incorporated herein by reference in its entirety to form part of the present disclosure.
FIELD OF THE INVENTION
 The invention relates to the field of overhead cable towed sports, namely, competitive or recreational sports of the type in which a participant is towed over a surface by way of a tow line which depends from a movably driven overhead cable. More particularly, the present invention relates to an apparatus and method for propelling snow skiers, snow boarders, riders of tubes or other inflatables, water skiers, wake boarders, knee boarders, ice skaters or other participants in towed sports and recreations, back and forth one or more times over a surface of land and/or water via a tow line, one end of which is coupled to a movable carrier mounted on an elevated, reversibly drivable, loop of cable which extends between a pair of mutually-spaced, substantially vertically oriented pulleys.
BACKGROUND OF THE INVENTION
 As contrasted with overhead cable towed sports, which utilize a powered overhead cable to provide towed propulsion of a participant during execution of sport itself, various cable powered conveyances for transporting participants to a location from whence they may disembark the conveyance to pursue a sport in the course of which they are propelled other than by a cable have been known in the prior art. For example, snow skiers and snow boarders are propelled downhill by gravity though it has long been known in the prior art to use power driven mechanical devices to transport them uphill. Various conveyances which utilize one or more power driven cables have been used for transporting snow skiers and snow boarders back up a slope to a location from which they may disembark and glide freely downhill propelled only by gravity. A simple form of such a transportation device, commonly referred to as a "rope tow", includes an endless rope which engages a drive pulley which is coupled to a motive power source such as an electric motor or combustion engine. A skier grasps the moving rope to be hauled uphill, gliding on their skies then releases the rope upon reaching an upslope location from which they wish to begin their downhill run.
 U.S. Pat. No. 4,047,487 to Wyss describes a towing mechanism for a ski lift of the type wherein an upright snow skier may be propelled uphill with skies remaining in contact with the snow cover by grasping and leaning on a towing bar which is coupled to a linearly traveling overhead hauling cable by way of a tow rope extending retractably from a mechanism which is connected to the hauling cable by way of a suspension. Since the skier is able to lean against the low bar, this type of ski lift is somewhat less tiring and easier to use than a basic rope tow. Even easier to use, and less physically demanding of the skier, are ski lifts of the type generally referred to as "chair lifts". For example, U.S. Pat. No. 2,582,201 to Huntington describes a ski lift in which skiers ride uphill while seated in a chair suspended from an overhead cable. With such a device, the skis of the skier typically remain suspended in the air until the skier disembarks the lift.
 While riding a ski lift such as any of the types described above might be regarded as "recreational" or even "sporting" in some sense, the true sport or recreation pursued by their users, namely, downhill skiing, begins only after the ride on the ski lift has ended. The conventional ski lift is merely a mode of transporting snow skiers uphill using a cable to a location from which they can ski downward. As contrasted with the use of a cable to merely transport a person to a location from which they could pursue a sport or recreation, German inventor Bruno Rixen pioneered the first true cable towed sport in the early 1960's, namely, cable waterskiing.
 U.S. Pat. Nos. 3,743,278 and 3,838,647, both to Rixen, disclose an apparatus for towing a water skier under motive power provided by a pair of mutually-spaced, parallel overhead cables arranged to define a closed loop circuit suspended above the surface of a body of water. As disclosed for example in Rixen '647 and represented in prior art FIGS. 1 and 2 hereof, a pair of endless cables 302 and 303, are driven to move continuously in one direction 352 at a constant speed around a continuous closed circuit 390 whose corner boundaries are established by pairs of pulleys. Although a triangular shaped closed circuit could be established using only three (3) pulley pairs, in the example of FIG. 1, four (4) pulley pairs 305, 306, 307 and 308 are used to form a generally quadrilateral shaped closed circuit. The two (2) pulleys making up pulley pair 305 serve as drive pulleys and the other pulley pairs serve as guide pulleys which, as shown in FIG. 2, are each mounted on a mast 310 stayed by guy wires 314 in order support cables 302 and 303 such that they are positioned elevated well above the surface 312A of a waterway 312. As illustrated in FIG. 2 with respect to guide pulley pair 308 which is typical, each guide pulley pair 306, 307 and 308 consists of a pair of horizontally oriented pulleys 308A and 308B of equal diameter mounted for rotation in a horizontal plane on a common, vertically oriented, shaft 308C, with upper pulley 308A being located directly above, and running generally parallel to, lower pulley 308B to support upper cable 302 directly above lower cable 303.
 The drive pulley pair 305 consists of an upper drive pulley and a lower drive pulley which are mounted for rotation about a common vertical axis in parallel horizontal planes. The upper drive pulley and the lower drive pulley are both mounted to coaxial vertically-oriented stub shafts of a conventional automotive differential which is drivably coupled, by way of a belt or a chain 345, to a prime mover, such as an engine 348 mounted on a horizontally extending frame member 338 which also supports the drive pulley pair 305 and is itself supported by a mast 339 which supports the drive pulley pair 305 at a elevated location above the water surface 312.
 Attached securely to the parallel upper and lower cables 302, 303 are one or more mutually spaced traction devices 301 which travel continuously with cables 302 and 303 in direction 352, around the closed loop circuit passing around the rear outside portions of each of pulley pairs 305, 306, 307, 308 as they do so. Each traction device 301 includes a releasable clamp 400, which permits the selective attachment and detachment of the end of a tow lie 355 whose opposite end is coupled, by way of a bridle formed by loop members 377, 388 to the ends of a handle bar 366, which may be grasped by a person "P" to be towed wearing water skis "S" or riding a wake board (not shown). A launching area 354, which may be located on the bank 311 of waterway 312 is spaced a distance laterally from the cables 302, 303 and positioned such that the tow line 355 can be maintained in a taut condition to accelerate a skier leaving the launching area 354 relatively smoothly from a standstill and increasing in speed until reaching the constant speed of the traction device 301 and cables 302, 303.
 Although prior art cable tow ski systems similar to those which have just been described with reference to FIGS. 1 and 2 have been relatively successful, they also suffer from a number of significant drawbacks and limitations. Because they require the upper and lower cables 302, 303 to be routed to form a continuous closed loop circuit whose corner boundaries are established by the locations of the horizontal pulley pairs, including not only drive pulley pair 305, but also at least two or more guide pulley pairs, a relatively large area of usable water surface is required in order to implement such a system. Moreover, such systems require a minimum of six (6) or more individual pulleys, a mast tower or other support structure to support each one of at least three pulley pairs and two drive cables of sufficient length to define the closed circuit. Accordingly, closed circuit cable tow systems require a large capital investment not only for a suitably large site but also to manufacture, install and maintain. Among the significant maintenance issues which are acute in such prior art systems are those associated with stretch and wear of the drive cables and the pulleys. Cable stretch is typically expressed in units of length per unit of overall length of the cable. That is, under a given sufficient tension, a cable of longer overall length will tend to increase its total length more than an otherwise identical cable which is shorter. Likewise, increases and decreases of cable length due to thermal expansion and contraction resulting from ambient temperature variations and heat generated by friction are more pronounced in the longer cables which closed circuit cable tow systems tend to require.
 In closed circuit cable tow systems of the type described above, the cables 302 and 303 are fitted with connectors necessary for securing the traction devices 301 to those cables. Those portions of the cable fitted with such connectors tend to create nonuniformities in the manner in which they pass over the pulleys as compared to the areas of the cable between the connectors. Since each of those connectors passes over multiple horizontal pulleys in the course or every orbit of every traction device 301 around the closed circuit, unless great care is taken, such non uniformities can give rise to accelerated wear and repeated impact forces and vibration which could tend to cause parts to loosen or other undesired effects.
 Because the pulleys in the pulley pairs 305, 306, 307, and 308 of the prior art systems described above rotate in horizontal planes, about vertical axes, a disproportionately large share of the mechanical load on each pulley due to the weight of the drive cables 302 and 303 is carried on one side of the vertical axis of rotation of each pulley. This uneven loading concentrates the effects of friction, heating and wear on the relatively thin, and thus potentially structurally vulnerable, lower walls of the peripheral grooved portions of the pulleys and on the lower sides of the drive cables themselves. It can also be appreciated that in the event one or both cables 302 and 303 were to fall as a result of cable failure, pulley failure and/or excessive stretch or thermal expansion of the cables, a serious safety hazard to skiers, bystanders and/or operators of the system could result. The uneven loading which results from the pulleys being mounted for rotation about vertical axes also generates undesirable lateral loads on the shafts and bearings which support the pulleys and tends to cause increased friction, accelerated mechanical wear, reduced operating energy efficiency, decreased component life and increased maintenance and operating expenses.
 Another significant limitation of the cable tow ski systems of Rixen '278 and '647 is that the drive cables 302, 303 run at a constant speed and in order to launch skiers from a standstill without excessive jerking of the tow line 355, the length of the tow line, and the distance and relative angle between the cable and the location from which skiers are launched are dependant upon the speed of the cables and not amenable to easy variation. As a consequence, such systems are difficult to adapt to participants of varying skill levels and provide a ride experience which can quickly become monotonous and uninteresting.
 In view of the foregoing, it is an object of the invention to provide a towed sports apparatus and method which is less costly to implement, operate and maintain than those of the prior art.
 It is a further object of the invention to provide a towed sports apparatus and method which can provide a participant with a continuous ride of indefinite desired duration yet can be implemented on either large or relatively small tracts of land and/or water.
 It is a further object of the invention to provide a towed sports apparatus and method capable of providing an interesting and readily changeable ride experience appropriate to participants whose skill levels may range from beginner to world class competitor.
 It is a further object of the invention to provide a towed sports apparatus and method capable of providing a ride experience which may consist of, or include, either: a one way ride across a surface beginning from a standstill at one side with the rider ending stopped at the opposite side or an intermediate location; a two-way back and forth ride across a surface, with the rider both beginning and ending the ride from a stop on one side; and/or a continuous, multiple back and forth ride, of indefinite desired duration, which may begin and/or end at an arbitrary location on or between the two sides.
 It is a further object of the invention of provide a towed sports apparatus which may be constructed as either a substantially permanent installation or one which is portable and capable of being erected quickly and simply at a given site then dismantled with comparable ease for transport and erection at a different site.
SUMMARY OF THE INVENTION
 Rather than the prior art approach of using three or more pairs of pulleys rotating in horizontal planes to define the corners of a continuous, closed circuit having two cables driven in the same rotational direction at constant speed, a preferred embodiment of the apparatus of the invention contemplates use of a directionally reversibly drivable loop of a flexible traction member, such as a cable, suspended overhead between a pair of pulleys which rotate in substantially vertical planes about substantially horizontal axes. Each of the pulleys is supported above the elevation of riding surface by a respective one of a pair of mutually spaced support structures. One of the support structures carries a motor driven, substantially vertically oriented drive pulley and the other support structure carries a non-driven, substantially vertically oriented deflection pulley. Preferably, the two pulleys are aligned such that their respective substantially vertical planes of rotation are co-planar, or at least substantially co-planer. Also, the respective substantially horizontal rotational axes of the two pulleys are preferably substantially parallel with one another and substantially co-planar with one another. The loop of cable has an upper leg and a lower leg. The upper and lower legs of the loop run generally parallel to one another in the region between the two pulleys and move in generally opposite linear directions, regardless of whether the loop is driven in a clockwise or counterclockwise rotational direction. With the two pulleys being substantially vertically oriented and aligned with one another such that the upper leg and the lower leg of the will also lie in a common, substantially vertical plane under quiescent conditions when the loop is still and not being subjected to external forces such as wind or tension transmitted by way of the tow line. A movable carrier is mechanically coupled between the upper leg and the lower leg of the loop. In a preferred embodiment the carrier is affixed to the lower leg and has rollers which allow it to move linearly along the upper leg. A tow line depends from a lower portion of the carrier assembly and is attached to a handle which is graspable by the sport participant.
 As the drive pulley is driven in one rotational direction by a drive which preferably includes a variable speed motor under the control of a motor controller, rotation of the loop in a first rotational direction causes the carrier assembly to be driven along the loop in a first linear direction headed generally away from the first support structure and toward the second support structure. On the other hand, when the drive pulley is driven in a second, opposite, rotational direction, the carrier assembly is driven oppositely along the loop, in a second linear direction which is opposite the first linear direction that is, a direction headed generally away from the second support structure and toward the first support structure. The participant is towed according to a vector, a component of which is oriented in either the first or second linear directions, depending on the direction of linear travel of the carrier assembly but it is to be appreciated that the participant is not limited to moving in a linear motion but can execute turns, jumps, or other complex maneuvers along the way, according to their desire and ability. It is also to be appreciated that the participant need not be limited to a one-way ride or to a single back and forth ride.
 Although the invention offers the flexibility to provide one-way rides, and/or two-way, single back and forth rides, as may be desired, it also allows a participant to ride continuously back and forth, being towed by reciprocating movement of the carrier back and forth multiple times, along or between virtually any desired portion(s) of the loop to provide a continuous ride of indefinite duration. Moreover, such rides may begin and end at respective start and end locations which can be located substantially arbitrarily, at any safe location within reach of the tow line. Moreover, none of the modes of operation just described are restricted to a constant speed or to an increase in speed only at the start of a ride.
 According to a preferred embodiment of the apparatus and method of the invention, the drive which drives the drive pulley is a drive is both reversible and speed variable. Thus, the loop and the carrier assembly can be driven at a velocity which can be set or changed as desired to assume substantially any desired magnitude within a range of speeds and/or execute reversals of direction of the carrier at any point during a ride. Such velocity control can optionally be carried out on pre-programmed basis, such as by causing the motor controller to execute a series of instructions which may either be stored in a local memory device or downloaded from a computer network or portable machine readable storage media. According to one preferred embodiment, a participant is towed according to a velocity profile which ramps up, that is, increases in speed, at least once, and ramps down, that is, decreases in speed, at least once between each reversal of 0000direction of the carrier.
 According to a further aspect of certain preferred embodiments of the apparatus and method of the invention, between reversals of linear direction, the carrier stops, or at least substantially slows, and either remains completely stopped or substantially slowed, or at least does not resume movement at more than a particular speed, for a certain dwell interval between reversals of direction of the carrier. This allows the participant to execute, or at least partially execute, a turn before the carrier itself begins its reverse travel thereby avoiding undue tension on the tow line which could otherwise cause the participant to be injured or lose their grip.
 According to yet a further aspect of the invention, in normal operation, neither the carrier itself, nor any connector or other member attaching the carrier to the traction member, passes over any portion of either of the substantially vertical pulleys. The drive is preferably controlled to prevent the carrier from coming into contact with either of the vertical pulleys in normal operation and is most preferably controlled so as to maintain at least a minimum clearance distance between the carrier and each of the substantially vertical pulleys at all times during normal operation.
 According to another aspect of the invention, a mechanical guard is physically interposed between the carrier and each of the substantially vertical pulleys to act as a barrier to prevent the carrier from coming into contact with either of the substantially vertical pulleys in the event of a malfunction or failure which might for any reason cause the carrier not to stop short prior to encountering the mechanical guard.
 According to yet a further aspect of the invention, the instantaneous speed and/or direction of the carrier can be controlled remotely under the control of an operator or some other person, by means of a wired or wireless remote control unit. In the case of a wireless remote control, even the participant themselves can exercise such control over their own ride while the ride is in progress. Such control can be carried out on a substantially real-time basis, or subject to a set or variable delay occurring between a change in a control input and the resulting response to that change being reflected in the actual velocity of the carrier in order to allow the rider some time to anticipate the change.
 These and other objects and advantages of the present invention will be made clear to a person of ordinary skill in the art upon review of the following detailed description of preferred embodiments taken in conjunction with the appended drawings in which like reference numerals are used to indicate like items.
BRIEF DESCRIPTION OF THE DRAWINGS
 FIG. 1 is a top plan view illustrating a power driven cable water ski tow apparatus according to the prior art;
 FIG. 2 is a side elevational view taken along line 2-2 of FIG. 1, further illustrating the prior art power driven cable water ski tow apparatus of FIG. 1;
 FIG. 3 is a perspective view of a preferred embodiment of the apparatus of the invention shown in use towing a participant, in this case by way of example, a wake boarder;
 FIG. 4 is a side elevational view of the embodiment of FIG. 3;
 FIG. 5 is a view taken along line 5-5 of FIG. 3;
 FIG. 5A is a side elevational view along line 5A-5A of FIG. 6.
 FIG. 6 is top plan view of the embodiment of FIG. 3;
 FIG. 7 is a view taken along line 7-7 of FIG. 3;
 FIG. 8 is perspective view illustrating further details of the drive of the embodiment of FIG. 3;
 FIG. 9 is perspective view illustrating further details of the mounting of the deflection pulley of the embodiment of FIG. 3;
 FIG. 10 is perspective view illustrating further details of the carrier of the embodiment of FIG. 3;
 FIG. 11 is graph of speed versus time illustrating examples of various velocity profiles which can be carried out according to certain aspects of the method of the invention;
 FIG. 12 is a side elevational view illustrating an alternative form of carrier.
 FIG. 13 is a perspective view further illustrating the alternative carrier shown in FIG. 12.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
 A preferred embodiment of a cable tow apparatus 10 for use in overhead cable towed sports is schematically illustrated in FIG. 3. Apparatus 10 includes a first support structure 12 and a second support structure 14 which are mutually spaced from one another across at least a portion of a surface 16 over which a sport participant 120 is to be towed by way of a tow line 26. By way of non-limiting example, surface 16 is illustrated in FIG. 3 as being a portion of a stream or river that is bounded on opposite sides by land "L" but it is to be understood that, depending upon the particular towed sport to be carried out, surface 16 may consist of, or include, any combination or subcombination of liquid freshwater or salt water, ice, snow, grass, concrete, asphalt, dry lakebed, salt flats, dirt, mud, turf, artificial turf or other natural or artificial surface(s). Again depending on the particular sport involved, surface 16 may optionally include or be provided with, or one or more structures (not shown) which might serve for example as obstacles, boundary markers, or platforms for performing stunts or maneuvers. Such optional structures might include for example, slalom poles, buoys, goal lines, distance markers, boundary markers, ramps and/or jumps (not shown).
 For cable towed water skiing and cable towed wake boarding applications, support structures 12, 14 are tall enough to support a loop 44 of a flexible traction member 40, such as a steel cable, synthetic cable or a drive belt, such that a minimum clearance of approximately twenty feet (20 ft.) is maintained between the traction member 40 and the surface 16 when apparatus is installed on a given site. The first support structure 12 and the second support structure 14 are preferably formed of steel and each include a pair of legs 79. Each leg 79 is made up of a pair of mutually spaced side rails 75, 76 that extend generally parallel to one another and are connected to one another by a plurality evenly mutually spaced rungs 85 which extend between, and are oriented transversely of, the side rails 75, 76. The opposite ends of each of the rungs 85 are welded, or otherwise suitably joined, to each side rail 75, 76 so that in addition to serving as a structural supporting member, each leg 79 forms a ladder that can be climbed by workers as an aid in the course of erecting and installing the apparatus 10. The legs 79 are also useful following installation of apparatus 10 as they can be climbed by personnel for purposes such as adjusting, maintaining and making periodic inspections of apparatus 10.
 As illustrated in FIG. 3 as well as in FIGS. 5 and 7 first support structure 12 and second support structure 14 are erected such that their respective pairs of legs 79 are relatively widely spaced from one another at their lower ends. Legs 79 angle toward one another and are mechanically coupled to one another at or near their upper ends such that support structure 12 takes the form of an A-frame tower 82 and support structure 14 takes the form of an elevated A-frame tower 83. By way of non-limiting example, in the case of A-frame towers 82, 83 having legs 79 approximately twenty one feet (21 ft.) in length, the lower ends of the legs 79 of each tower would typically be spaced about ten feet (10 ft.) apart.
 Optionally but preferably, A-frame towers 83, 85 each include at least one brace member 84 extending between its legs 79 to maintain a the angle between the legs 79 substantially fixed when apparatus 10 is installed. To enhance the portability and compact storage of support structures 12, 14 when not in use, brace members 84 are preferably secured to legs 79 removably, such as by use of removable bolts and nuts, preferably the type of nuts which include plastic inserts to resist inadvertent loosening. Alternatively, as illustrated in FIG. 5, a central portion of brace member 84 may optionally provided with an articulable joint 86 which can be latched open when apparatus 10 is in use or unlatched to allow brace member 84 to fold so that both legs 79 can be drawn close to one another for even more compact transportation and storage.
 Although support structures 12, 14 could alternatively be constructed as free-standing structures mounted removably or permanently upon foundations designed appropriately for local soil conditions, the support structures 12, 14 of the preferred embodiment may rest directly on top of the ground, either on dry land or partially submerged, as local soil conditions and topography will permit. Support structures 12, 14 are preferably anchored in place by one or more guy lines 61, 62, which may suitably comprise steel cables. Guy lines 61, 62 are preferably connected at or near the tops of the respective support structures 14, 12 at two locations via a wire rope harness 68, 69 using shackles 70 as shown. Each guy line 61, 62 is then connected to an anchor 63, 64 on the ground. In the Figs. anchors 63, 64 are illustrated schematically as stakes driven into the ground. While stakes may be suitable for certain applications, it is to be understood that local soil conditions may require use of any of various other forms of anchors which will be familiar to those skilled in the art, such as anchors consisting of buried plates and/or masses of reinforced concrete. The guy lines 61, 62 are preferably positioned rearwardly and sidewardly of support structures 12, 14 to help effectively resist static and dynamic forces such as those due to wind and those exerted on support structures 12, 14 by way of traction member 40. Guy lines 61, 62 thus serve to further stabilize the support structures 12, 14 and secure them in place in an upright orientation and without excessive sway or other undesired movement.
 The lower terminal end of each leg 79 of each support structure 12, 14 may optionally be fitted with a base 88 from whose underside extends one or more pointed, generally downwardly directed ground lugs or cleats 87. The bases 88 provide increased bearing surface area over which the downward forces exerted by support structures 12, 14 can be distributed to the underlying substrates on which they are installed to provide additional stability and to help prevent excessive sinking or tilting of the support structures 12, 14. The lugs or cleats 87 may suitably be welded to the underside of base 88 and dig into the underlying earth or other substrate as further aid in preventing undesired movement of the support structures 12, 14 by providing them additional support, stability and ground bearing. As can be seen in FIGS. 5 and 7, the bases 88 are preferably mounted so as to be capable of pivoting in two directions in order to better facilitate the stable installation of structures 12, 14 on terrain or other substrate which may be somewhat uneven.
 As shown in FIGS. 3 and 8, motive power for towing a sports participant 120 is provided by a drive 19 which includes an electric motor 20 which is mounted to a mounting bracket 18 affixed to the tops of the legs 79 of the first support structure 12. Electric motor 20 is preferably a reversible, variable-speed A.C. or D.C. motor which is disconnectably electrically coupled to a suitable electrical power source (not shown). Motor 20 is driveably mechanically coupled a substantially vertically oriented drive pulley 22 by way of a gearbox 23. Drive pulley 22 is mounted for rotation about a rotational axis 37 between a pair of mutually spaced vertical plates 48. The bottom edges of plates 48 are welded to bracket 18 while their upper ends are secured by a cap plate 90. Optionally, a clutch 24 may be interposed between pulley 22 and gearbox 23. For additional safety, clutch 24 may be of a type which disengages when a predetermined torque limit is exceeded, and/or when the electrical current drawn by motor 20 exceeds a predetermined limit, such as in the event traction member 40 and/or pulley 22 become jammed.
 As shown in FIGS. 3 and 9, a substantially vertically oriented deflection pulley 30 is freely rotatably mounted atop the second support structure 14. A length 36 of traction member 40 runs over the two pulleys 22, 30 and forms a loop 44 having an upper leg 50 and a lower leg 52 which span the two support structures 12, 14 and extend overhead of surface 16 in the region between pulleys 22 and 30.
 Preferably, the two pulleys 22, 30 are mutually aligned with one another such that their respective substantially vertical planes of rotation 97, 98 are co-planar, or are at least substantially co-planer. Also, the respective substantially horizontal rotational axes 37, 38 of the two pulleys 22, 30 are preferably substantially parallel with one another and substantially co-planar with one another. Pulleys 22, 30 are both preferably oriented in substantially vertical planes and rotate about respective substantially horizontal rotational axes 37, 38 so that upper leg 50 and lower leg 52 of traction member 40 lie in a common plane with one another that is substantially vertical. Most preferably, pulleys 22, 30 both rotate in a common vertical plane and rotational axes 37, 38 lie in a common plane and are both horizontal, or at least substantially horizontal, so that upper leg 50 of loop lies directly vertically above lower leg 52 at all points along their span under windless quiescent conditions when no participant is being towed. Pulleys 22 and 30 both preferably rotate in a vertical plane but can, if desired be tilted slightly provided neither tilts more than about fifteen degrees (15°) below vertical and the relative angle between the planes of rotation of the two pulleys 22, 30 does not exceed about fifteen degrees (15°) and preferably does not exceed about five degrees (5°). Most preferably however, pulleys 22, 30 are always aligned with one another so the relative angle between their respective planes of rotation 97, 98 is always zero or at least substantially zero.
 Apparatus 10 further includes a carrier 55, which, in the type shown in FIG. 3 and illustrated in detail in FIG. 10, has an elongated body 54 whose length is somewhat greater than the normal spacing distance which separates the upper leg 50 and lower leg 52 of traction member 40. The lower portion of the body 54 is coupled, by way of a first freely rotatable joint 66, to a cross bar 65 whose opposed ends each carry a coupling 58. The couplings 58 securely affix the crossbar 65 immovably to each free end of the lower leg 52 of the traction member 40. The lower end of the body 54 of carrier 55 terminates in a second freely rotatable joint 58 which includes a coupling 67 to which the upper end of a tow line 26 is securely affixed.
 As FIG. 10 shows, the upper end of the body 54 of carrier 55 carries a pair of freely rotatable rollers 56, 57 between which is routed the upper leg 50 of the traction member 40. The uppermost one of the two rollers, roller 56, includes a groove 76 which cooperates with the lower roller 57 to keep upper leg 50 inside the groove 71 while allowing rollers 56, 57 to roll freely along upper leg 50. Rollers 56, 57 allow carrier 55 to be pulled freely along upper leg 50 at the same speed and direction as the lower leg 52 to which the carrier 55 is fixedly coupled. Rollers 56, 57 further assure that the upper end of the carrier 55 does not fall away from the upper leg 50, but can at all times move linearly relative to the upper leg 50. A tow line 26 the lower end of which may be fitted with a handle 28 is connected to the lower end of carrier 55 to tow sport participant 120 using the apparatus 10 as the carrier 55 is driven by tension on the lower leg 52 of traction member 40 produced in response to rotation of drive pulley 40 by drive 19.
 FIGS. 12 and 13 illustrate an alternative carrier 55' which may be used in lieu of the carrier 55 described above. Carrier 55' has a body 121 which is comprised of a pair of mutually spaced, generally triangular plates 122, 123. A grooved roller 124 is freely rotatably mounted on a shaft 125 extending between the plates 122, 123 near their corners. A pair of rollers 126, 127 roll freely against roller 124 allowing the carrier 55' to roll above the upper leg 50 of traction member 40. Each of the two lower corners of body 121 carry a generally cylindrical bumper 129. Each bumper 129 is preferably formed of a relatively hard synthetic rubber material and includes a passage 130 through which a respective one of the end portions of the lower leg 52 of traction member 40 is received as shown. At a location intermediate the two bumpers 129, a bolt 133 having an unthreaded shank 134 passes through both plates 122 and 123 and is secured by a nut 135. A pair of oppositely directed wedge clamps 137, 138 are freely pivotably mounted on shank 134. The end portions of the lower leg 52 are firmly secured to carrier 55' by wedge clamps 137. Attachment of a tow line 26 to alternate carrier 55' is facilitated by an attachment ring 145 which, in order to reduce the risk of twisting and kinking of the tow line 26, is coupled by way of a swivel 147 to a U-bolt 148 which is suspended on shank 134.
 The apparatus 10 is driven by electric motor 20, which is controlled by a motor controller 124 housed in control panel 98. If desired, the motor controller 124 can be pre-programmed or can be operated manually by one person who can simply push a start and stop button 97 and adjust a speed control adjuster 99 on the control panel 98. This control panel 98 is preferably located on or near a starting location, where participants 120 take their turn being towed. Any suitable speed profile for carrier 55 or 55' such as for example one as illustrated in FIG. 11, can be pre-programmed into the motor controller 24 in the control panel 98. Alternatively, a person, even the participant themselves, can control the instantaneous speed and direction of the carrier 55 by controlling motor 20 through a wired or wireless remote control unit 100 which can be a handheld unit 100 which communicates with motor controller 24 by way of a wired or wireless communication link 102 such as a radio frequency or microwave communication link.
 As an option which may be particularly desirable when a remote control unit 100 is used to control the velocity of carrier 55 or 55', controller 124 may be programmed to provide a set or variable delay between a change a control input and the resulting actual change in the speed and/or direction of carrier 55 or 55'.
 To reduce the risk of carrier 55 or 55' and or the tow line 26 from becoming jammed or wrapped around drive pulley 22 and/or deflection pulley 30, mechanical guards 42 are preferably mounted in front of each pulley 22, 30 to provide a physical barrier interposed between each pulley 22, 30 and carrier 55 or 55' as shown in FIGS. 8 and 9.
 In a first mode of operation, the carrier 55 or 55' slows to a substantially complete stop allowing the participant to disembark after taking a one way ride. In response to the powered rotation of drive pulley 22 and the resulting tension on lower leg 52, rollers 124, 126 and 127 allow alternative carrier 55' to be pulled freely along upper leg 50 at the same speed and in the same direction as lower leg 52. The participant 120 may start from a standstill at an arbitrary location within reach of towline 26. Motor controller 124 energizes drive 19 to cause motor 20 to begin rotating in a first rotational direction at a speed which increases at a rate which may be varied as desired. Motor 20 causes drive pulley 22 to rotate, which in turn drives the carrier 55 or 55' in a first direction along loop 55, pulling the participant 120 behind at a corresponding speed and direction. If desired, controller 124 may cause the speed of the carrier 55 or 55' to increase or decrease one or more times in each instance at any desired rate, before decreasing as the participant approaches an arbitrary stopping point or turning point.
 In a second mode of operation of apparatus 10, a ride may begin as in the first mode of operation described above but instead of stopping after a one way ride, the controller 124 causes carrier 55 or 55' to slow or stop for a dwell interval sufficient to allow the participant 120 to execute a turn, then the controller 124 begins driving the drive pulley 22 and thus the carrier 55 or 55' in the opposite direction, accelerating at a desired rate, to pull the participant 120 in the opposite direction, back toward the starting location. After executing any desired intermediate changes in speed, carrier 55 or 55' is then decelerated to allow the participant to quit the ride at or near the location from which the ride started.
 In a third illustrative mode of operation, apparatus 10 may be towed back and forth, reversing directing two or more times, each reversal being preceded by a dwell interval during which the carrier 55 or 55' either remains completely stopped, or does not exceed a maximum limit before the dwell interval ends. Reversals of direction of the carrier 55 or 55' can take place at locations corresponding to the maximum desired extreme limits of its travel or can take place at any arbitrary locations between those limits. Likewise, changes in speed and/or acceleration of carrier 55 or 55' can be carried out in any safe manner at any location intermediate the extremes of travel of the carrier 55, 55'. Thus, a continuous non-stop ride of virtually arbitrary duration may be enjoyed by the participant 120.
 The participant 120 is towed back and forth between two support structures 12, 14 via the overhead running cable 40. For wakeboarding, the participant 120 holds the tow line 26 by way of a handle 28, which may be similar to the ropes used by water-skiers behind a boat. The tow line 26 is connected to carrier 55 or 55' that is attached to the lower leg 52 of the loop 44 formed by traction member 40. As the cable 40 is towed by carrier 55 back and forth over at least a portion of the surface 16 between the two support structures 12, 14. The participant 120 can ski, wakeboard, kneeboard, ride an inner tube or other inflatable device, wake skate, or the like. As the participant 120 approaches one of the support structures 12, 14, the carrier 55 or 55' stops or at least slows for an interval and thereafter reverses direction, so the participant 120 can make a turn and go back in the opposite direction. The traction member 40 and thus carrier 55 or 55' travel in one direction and then slow or pause for a dwell interval, illustrated as intervals I1, I2 and I3 in FIG. 11, allowing the participant 120 time to make a sweeping turn as they keep tension on the tow line 26, and return in the other direction. It is to be noted that dwell intervals I1, I2 and I3 etc. can be of either fixed or variable duration and may, if desired be varied during the course of a ride.
 While the invention has been described with reference to a preferred embodiment, it should be understood by those skilled in the art that various changes may be made and equivalents substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
Patent applications by Christian Von Lerchenfeld, Hindelang DE
Patent applications in class Ski tow
Patent applications in all subclasses Ski tow