US3779171A

US3779171A - Portable ski lift drive mechanism

Info

Publication number: US3779171A
Application number: US00220263A
Authority: US
Inventors: J Littlehorn
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-01-24
Filing date: 1972-01-24
Publication date: 1973-12-18
Anticipated expiration: 1990-12-18

Abstract

A portable ski lift including a sled-mounted power drive mechanism and a return pulley mechanism between which extends a continuous-loop tow rope. The power unit drives the rope to pull a skier uphill. The tow rope is driven by a rope drive mechanism which includes two or more drive sheaves fixed on the drive shaft for powered rotation by the engine. A corresponding number of rope drive pulleys are journaled for rotation about an axis parallel to the axis of rotation of the drive shaft and are drivingly connected with the sheaves by drive belts. A rope idler wheel is positioned intermediate the pulleys and sheaves. The tow rope enters the drive mechanism and passes sequentially over the pulleys and idler wheel, then exits from the drive mechanism through a positive rope feed wheel arrangement. The tow rope is gripped between each rope drive pulley and the associated drive belt extending between the pulley and the sheaves. Additional guide rollers may be provided to direct the tow rope in and out of the drive mechanism.

Description

United States Patent Littlehorn, Jr.

[ Dec. 18, 1973 1 1 PORTABLE SKI LIFT DRIVE MECHANISM [76] Inventor: John J. Littlehorn, Jr., 4530 S.

Broadway, Englewood, Colo. 801 10 [22] Filed: Jan. 24, 1972 [21] Appl. No.: 220,263

[52] US. Cl. 104/173, 74/219 R, 198/130 [51] Int. B6lb 7/06 [58] Field of Search 104/173, 183, 178, 1 104/197, 229, 237, 173 ST; 74/219 R; 198/130 [56] References Cited UNITED STATES PATENTS 2,608,935 9/1952 Moore et a1 104/173 ST 3,486,606 12/1969 Demon et a1 74/219 3,376,829 5/1968 Hancock 104/173 ST 3,473,486 lO/l969 Harmon 104/173 ST Primary ExaminerGerald M. Forlenza Assistant Examiner-Richard A. Bertsch Attorney-Ralph F. Crandell [5 7] ABSTRACT A portable ski lift including a sled-mounted power drive mechanism and a return pulley mechanism between which extends a continuous-loop tow rope. The power unit drives the rope to pull a skier uphill. The tow rope is driven by a rope drive mechanism which includes two or more drive sheaves fixed on the drive shaft for powered rotation by the engine. A corresponding number of rope drive pulleys are journaled for rotation about an axis parallel to the axis of rotation of the drive shaft and are drivingly connected with the sheaves by drive belts. A rope idler wheel is positioned intermediate the pulleys and sheaves. The tow rope enters the drive mechanism and passes sequentially over the pulleys and idler wheel, then exits from the drive mechanism through a positive rope feed wheel arrangement. The tow rope is gripped between each rope drive pulley and the associated drive belt extending between the pulley and the sheaves. Additional guide rollers may be provided to direct the tow rope in and out of the drive mechanism.

8 Claims, 6 Drawing Figures PATENTED DEC 19 I975 3.779.171 SHEET 20? 2 PORTABLE SKI LIFT DRIVE MECHANISM BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a portable ski lift apparatus of the rope or cable tow type, and more particularly to a new and improved mechanism for driving the tow rope.

2. Description of the Prior Art Portable rope tow mechanisms which include a small, lightweight engine-driven power unit adapted to be placed either at the top or the bottom of a ski slope, together with a pulley unit which may be secured at the opposite end of the slope and a continuous loop rope extending between the power unit and the pulley are known in the art. Such units are adapted to be erected and maintained at a low cost for use in towing or pull ing skiers up a slope at areas selected by the skier. U. S. Pat. No. 2,608,935 issued Sept. 2, 1952 to W. L. Moore et al. for Ski-Tow Apparatus discloses a mobile ski tow apparatus for driving a rope or cable. The apparatus includes a tract chassis so that it may be power driven to any selected position. U. S. Pat. No. 3,166,021 issued Jan. 19, 1965 to D. M. Schippers for Ski-Lift discloses a portable rope tow apparatus together with a rope gripping mechanism and a safety device. U. S. Pat. No. 3,368,498 issued Feb. 13, 1968 to C. Doveri for Disassemblable and Transportable Ski- Tow discloses a rope tow apparatus which can be knocked down and packed into readily transportable packages. Each of the portable ski tow devices disclosed in the prior art patents utilizes a rope drive mechanism which includes a rope drive pulley connected directly to the engine through a clutch or gear reducer, and an idler or counterpulley to provide for two or more passes of the tow rope about the main drive pulley.

It is also known to fix a guide rope or cable at the top and bottom of a ski slope for guiding a power sled mechanism. See U. S. Pat. No. 3,473,486 issued Oct. 21, 1969 to J. V. Harmon for Method and Apparatus For Towing Skiers and the Like. The skier holds onto the power sled and is pulled to the top of the ski slope.

Another portable mechanism which has been utilized involves a power sled with a take-up reel and a tow rope fixed at the top of the ski slope. U. S. Pat. No. 3,307,494 issued Mar. 7, 1967 to E. Samitz for Draw Implement, Particularly A Ski Lift Device, For Transportation Of Individuals."

A major problem involved in the construction and use of small, portable lightweight rope tow ski lift devices resides in the drive mechanism for the tow rope. The drive mechanism must prevent the rope from slipping and, at the same time, must not cause undue wear on the rope when a load is placed on it, such as when a skier holds the rope and is being towed to the top of the ski slope. It is also desirable to provide a rope drive mechanism which is equally useful at both the top and the bottom of the ski slope, as in many instances it is more convenient for the user to locate the power unit at the bottom of the ski slope rather than at the top. When the mechanism is placed at the bottom of the slope, provision must be made for preventing the slack in the tow rope between a skier being towed and the drive mechanism from fouling the drive mechanism or causing the rope to slip out of the drive mechanism. This latter problem can be a serious one as it is often difficult for an individual to place sufficient tension on the tow rope, particularly when a long rope is being used, to prevent slack in the tow between the downhill drive mechanism and the skier being towed.

OBJECTS OF THE INVENTION The principal object of the present invention is to provide, in combination with a lightweight portable rope or cable ski tow device, an improved tow rope drive mechanism. More particularly, it is an object of the invention to provide a rope drive mechanism for a portable ski tow device which affords a positive, continuous drive and grips the rope tightly without cutting, biting into or otherwise damaging it.

Another object of the present invention is to provide a ski tow apparatus of the foregoing character which includes a positive feedout mechanism for the tow rope so that the apparatus may be utilized at the bottom of a ski slope without danger of fouling or slipping of the drive mechanism as the result of slack created between the mechanism and a skier being towed uphill.

A further object of the invention is to provide a portable ski tow rope drive mechanism of the above character which reduces wear on the rope, and is capable of passing splices or lumps in the rope without affecting the drive operation.

Still a further object of the invention is to provide a rope drive mechanism of the foregoing type which is simple and rugged in construction, and trouble-free in operation. More particularly, it is an object to provide a rope drive mechanism of the foregoing type into which the rope can be readily fed or threaded even under cold, snowy or adverse conditions.

Other objects and advantages of the present invention will become apparent from the following description thereof.

SUMMARY OF THE INVENTION The foregoing objects are accomplished by the rope drive mechanism for a portable ski tow embodying the present invention. The portable ski tow is formed by a rope drive mechanism positioned at one end of the slope, a return pulley mechanism positioned at the opposite end of the ski slope and a continuous loop tow rope extending between the two mechanisms. The power mechanism drives the rope and effectively pulls uphill a skier who holds onto the rope while the unit is in operation. Because of the heavy load on the rope when a skier is being pulled uphill, the drive mechanism embodied in this invention affords a strong, positive driving engagement with the tow rope. To this end, the rope drive mechanism includes a main drive shaft driven by an internal combustion engine forming a part of the power unit. On the main drive shaft there is secured a pair of drive sheaves. Positioned adjacent and parallel to the drive sheaves are a pair of drive pulleys, in one-to-one correspondence with the sheaves, and connected to the drive sheaves by drive belts. A rope idler wheel is positioned between the sheaves and pulleys. The tow rope enters the mechanism and passes around one of the pulleys, to which it is gripped by the pulley drive belt. The tow rope then continues around the idler wheel and thence around the other pulley and then out of the drive mechanism. In both instances, the tow rope is tightly gripped between the drive pulley and its associated belt. In this manner, the tow rope is positively and tightly gripped and driven by the power mechanism without slipping and without damage to the rope. Additional sheaves, pulleys and belts may be used to further increase the pulley strength of the drive mechanism.

In order to positively feed the tow rope out of the drive mechanism, and thereby enable the user to place the drive mechanism at the bottom of a ski slope rather than at the top, feed wheels are provided for engaging the rope as it exits from the drive mechanism and positively feed the same outwardly from the mechanism where it may be gripped by a skier. Because the tension on the rope created by the pull of the skier may cause slack in the rope between the skier and the drive mechanism, the positive feed wheels prevent the rope slack from causing the rope to slip or tangle in the drive mechanism. Any slack will accumulate on the ground in front of the mechanism and will gradually be taken up as the tension on the rope is decreased.

Additional guide wheels and rollers may be provided for directing the tow rope into and out of both the drive mechanism and the housing enclosing the drive apparatus.

DESCRIPTION OF THE DRAWINGS FIG. 1.

FIG. 5 is a front end elevation view of the rope tow device shown in FIG. 1.

FIG. 6 is a perspective view, with portions cut away, of a pulley unit adapted to be used at the opposite end of the ski slope from the portable rope tow unit shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Large fixed location ski tows such as rope tows, chair lifts and the like are conventionally large permanent installations located in a given place at a selected ski run location. These large installations are commercial operations and it is impractical for an individual skier to purchase and install such a lift on a private ski run or as a temporary installation. Portable ski lifts have been devised which are generally rope tows intended primarily for use on smaller slopes, private property or in isolated areas accessible only to those using skis, snowshoes or snowmobiles. Such portable rope tow devices provide a lightweight transportable mechanism which can be quickly installed alongside a ski slope and used by one or two skiers at a time. These mechanisms enable skiers to enjoy skiing at areas other than commercial ski resorts.

A portable rope ski tow must be light enough to be pulled either by a man on skis or snowshoes, or by a snowmobile, to the place where it is to be located. The tow includes a drive mechanism and a return pulley with the tow rope being positioned around the drive mechanism at one end of the slope and around a pulley unit at the other end of the slope. The drive mechanism and rope is usually of a strength sufficient to pull one or two skiers at a time, but it is important that the drive mechanism be simple and of a character which tightly grips the rope during the lifting operation. Safety mechanisms may also be provided to stop the tow in the event a skier becomes caught in the tow rope or fails to let go at the top of the slope.

The portable ski lift device embodying the present invention is a small, compact, lightweight, easily transportable rope tow device. To this end, the ski lift includes a power unit indicated generally at 7 which includes an internal combustion engine and drive mechanism, a return pulley unit indicated generally at 8 adapted to be positioned at the opposite end of the ski slope from the power unit 7, and a continuous loop tow rope 9 extending between the power unit 7 and the return pulley mechanism 8. The present invention is directed particularly to the rope drive mechanism forming a part of the power unit 7.

Referring to the drawings, the power unit 7 is pro vided with a base 10 in the form of a skid or sled adapted to facilitate movement of the unit over the snow. As mentioned in the prior art, the base may also embody a power-driven track mechanism, although it is a simple matter to utilize a sled-type base adapted to be hitched onto a snowmobile.

For driving the rope drive mechanism, a small internal combustion engine I1 is mounted on the sled base. This engine may be one of a wide variety of gasolinedriven internal combustion engines and will be of a size determined according to the length of tow rope, the steepness of the slope and the number of skiers to be pulled at one time. A generally rectangular frame 12 formed of welded tubular members is mounted on the base 10 adjacent the engine 11 and forms the supporting superstructure for the rope drive mechanism indicated generally at 14. A housing (not shown) may be formed of sheet metal or plastic to enclose the sledmounted drive mechanism. This housing will have appropriate openings to receive the motor drive shaft and tow rope and is preferably designed to present an attractive appearance to the unit. The sled base will also desirably include a tow bar 15 adapted for use in pulling the mechanism behind a snowmobile or a skier, as well as for tying and holding the apparatus in position either at the top or the bottom of a ski slope. Appropriate anchor members (not shown) may be utilized to hold the apparatus in place, or it may be tied to a convenient tree or rock.

The return pulley mechanism 8 is positioned at the opposite end of the ski slope from the drive unit and is likewise secured in place to a convenient tree, rock, etc. or is held in position by appropriate snow anchors. While various types of return pulley arrangements may be utilized, the particular structure shown in the drawings comprises a return pulley 18 mounted on a vertical shaft 19 which is secured to a rigid sled-like base 20. A housing 21 encloses the pulley and shaft and appropriate rope guides 22 are provided for guiding the tow rope into and out of the return pulley mechanism and around the pulley l8. For both towing the pulley unit as well as for securing it in place, a tie-down and tow bar 241 is mounted on the base 20. Various rope tightening mechanisms (not shown) may be associated with the return pulley structure for tensioning the tow rope when the drive mechanism and return pulley units have been located in place.

The tow rope driven by the rope drive mechanism extends over the length of the ski slope and is in the form of a continuous loop of rope providing an uphill pulling section 16a and a downhill return section 16b. When the drive mechanism is located at the bottom of a slope, the portion of the uphill 16a between a skier being pulled uphill and the upper pulley unit, as well as the downhill section 16b between the pulley and the rope drive mechanism is under tension. The portion of the uphill section 16a between the rope drive mechanism and the skier will not be under tension and, in some instances, considerable slack may develop in this portion of the rope. Alternatively, when the drive unit is located at the top of the hill, the uphill and downhill rope sections will be reversed and the portion of the rope section 16b between the skier and the drive unit is under tension, while the balance of the tow rope may include some slack. The rope is preferably of high strength woven nylon, and various means are known for splicing the ends of the rope together to form a continuous loop once the rope has been placed through the drive mechanism and around the return pulley.

In accordance with the present invention, the drive unit 7 includes a new and improved drive mechanism 14 for driving the tow rope and thereby pulling a skier uphill. Essentially, the tow rope is driven by a combination pulley or sheave and belt mechanism in which the drive belts both drive the rope pulley as well as securely grip the rope during the driving operation. The tow rope is positively fed out of the drive mechanism by means of a rope feed device operating in conjunction with the pulley and belt drive mechanism. While the rope drive pulleys may technically more properly be defined as sheaves, they have been characterized herein as pulleys for convenience in the description and to distinguish them from the drive sheaves.

Power from the internal combustion engine 11 is supplied to a main drive shaft journaled by appropriate bearings in a bearing housing 26 on a shaft support post 28 secured to the frame 12. In the mechanism shown in the drawings, this power supply comprises a main drive pulley 29 secured to one end of the drive shaft 25 and driven by a belt or chain 30 drivingly engaged with a clutch 31 on the drive shaft 32 of the engine 11. The clutch 31 may be of the centrifugal type, or any other suitable clutch mechanism may be utilized. Also, for some applications, it may be desirable to provide a brake in the main drive system. The speed of the drive shaft 25 will be determined by a throttle arrangement on the engine carburetor. The engine is preferably adapted to operate at either an idle or at the optimum speed, with the speed of the tow rope being determined by the sizes and ratios of the various pulleys and sheaves.

Fdr driving the tow rope, there .is provided two or more rope drive pulleys 40, 41 journaled for rotation on a rope drive pulley shaft 42. The pulley shaft 42 is mounted on an upstanding pulley support post 44 fixed on the frame 12. Adjacent the rope drive pulleys 40, 41 and rotatably mounted on the frame 12 is an idler pulley 45. Where more than two rope drive pulleys are utilized, a number of idler pulleys are provided totaling in number one less than the number of rope drive pulleys. The main drive shaft 25 has secured thereon a plurality of drive sheaves 35, 36 corresponding in number to the drive pulleys 41, 42.

For driving the drive pulleys and simultaneously gripping the tow rope for powering the same to lift a skier up the hill, a plurality of

drive belts

38, 39 are provided engaged between each of the drive sheaves 35, 36 and the

corresponding drive pulley

40, 41. The tow rope 9 passes into the drive mechanism, as shown in FIG. 2, and around a first one of the drive pulleys 40, from the bottom thereof and out from the top. From the first drive pulley, the rope passes over the idler pulley 44, and then around the second drive pulley 41. If additional drive pulleys are utilized the rope passes serially over a corresponding idler and thence over each successive drive pulley. The rope is gripped in the channel of each drive pulley between the pulley and the corresponding drive belt (FIG. 4). The

belt

38, 39 squeezes the rope 9 tightly in the pulley groove over a substantial circumferential length of each

pulley

40, 41.

For guiding the input section 1617 of the rope 9 into the drive mechanism, a guide wheel 46 is journaled for free rotation on the main drive shaft 25. Guide bars 47 are also provided in the frame 12 for directing the rope into and out of the drive mechanism.

When a skier holds onto the uphill section 16a of the rope, the rope may stretch and slack form between the skier and the drive mechanism. For positively feeding the output section 16a of the tow rope 9 out of the mechanism in order to prevent any slack from tangling in the mechanism, the rope 16a is gripped between a rubber or friction drive wheel 49 secured to the drive shaft 25 and a rope guide Wheel 50 journaled on the shaft support post 28. The rubber-tired or covered wheel 49 secured to the shaft 25 pulls the rope 9 out of the drive mechanism and thereby prevents the possibility of any slack in the rope section 16a from becoming tangled in the drive mechanism or causing the tow rope to slip out from between the

pulleys

40, 41 and

drive belts

38, 39. Additionally, a guide ring 51 is mounted on the support post 28 and guides the output section of the rope into the rubber wheel positive output feed mechanism.

Various modifications may be made in the drive belt and pulley arrangement. For example, the belts may include integrally molded teeth which mesh with corresponding teeth in the pulley groove, with the teeth centrally notched to receive and grip the tow rope. The pulley groove may be lined with a friction coating, or an inner friction strap may be placed in each pulley groove. Under some conditions it may also be desirable to use belts with integral teeth or lugs to further assist in gripping the tow rope.

While a certain illustrative embodiment of the present invention has been shown in the drawings and described above in considerable detail, it should be understood that there is no intention to limit the invention to the specific form disclosed. On the contrary, the intention is to cover all modifications, alternative constructions, equivalents and uses falling within the spirit and scope of the invention as expressed in the appended claims.

I claim as my invention:

1. In a portable ski tow machine including a base, a frame structure mounted on said base, a power source mounted on said base, and a continuous loop tow rope driven by said power source for pulling a skier up a slope, a tow rope drive mechanism comprising, in combination:

a. a main drive shaft journaled for rotation on the frame and drivingly coupled with the power source;

b. a pair of drive sheaves fixed on said drive shaft for powered rotation by the power source;

c. a pair of rope drive pulleys journaled for rotation on the frame about an axis parallel to the axis of rotation of said main drive shaft and in one-to-one correspondence with said sheaves;

d. a drive belt drivingly engaged between each corresponding pulley and sheave;

e. and a rope idler wheel intermediate said pairs of pulleys and sheaves and journaled on said frame for rotation about an axis parallel to the axis of said pulleys and sheaves;

f. said continuous loop tow rope entering the drive mechanism and passing sequentially over one of said pulleys, thence over said idler wheel, thence over the other pulley and thence exiting from the drive mechanism; and

g. said tow rope being gripped between each rope drive pulley and the drive belt associated therewith over a substantial circumferential length of each of said pulleys, whereby said rope is gripped by said belt and powered by said pulleys and belts in response to the rotation of said sheaves and belts by said power source.

2. A portable ski tow machine as defined in claim 1 further including rope guide means for guiding said tow rope to pass into and out of said rope drive mechanism in alignment with said pulleys and belts.

3. A portable ski tow machine as defined in claim 1 further including feed-out wheels for engaging the tow rope and positively feeding said rope out of the drive mechanism.

4. A portable ski tow for driving a continuous loop tow rope extending between a power driven rope drive mechanism and a fixed pulley, wherein the improvement comprises: a rope drive mechanism comprising a power driven sheave, a rope drive pulley and a drive belt extending between said sheave and said pulley with the tow rope trained around said pulley between said pulley and said drive belt whereby said belt and said drive pulley frictionally engage said tow rope to drive the same for pulling a skier up a slope.

5. A portable rope ski tow mechanism comprising a power unit, a pulley unit, and a continuous rope loop extending between said power unit and said pulley unit and powered by said power unit for pulling a skier up a slope, said power unit including a rope drive mechanism comprising a main drive shaft having a pair of drive sheaves secured thereon, a pair of rope drive pulleys adjacent said sheaves and drivingly coupled in oneto-one correspondence therewith by a pair of drive belts, and a rope idler wheel intermediate said pairs of pulleys and sheaves, said continuous loop tow rope entering the drive mechanism and passing sequentially over said pulleys and rope idler wheel, said tow rope being gripped between each rope drive pulley and the drive belt associated therewith over a substantial circumferential length of each of said pulleys whereby said rope is gripped between said belts and pulleys and powered thereby in response to the rotation of said sheaves.

6. A portable ski tow machine as defined in claim 5 further including feed-out wheels for engaging the tow rope and positively feeding said rope out of the drive mechanism.

7. A portable ski tow machine as defined in claim 6 wherein at least one of said feed-out wheels includes resilient tow rope gripping means for frictionally holding said rope against the associated wheel with said one wheel being secured in power driven relation on the main drive shaft.

8. A portable ski tow machine as defined in claim 5 including rope guide means for guiding the tow rope into and out of the drive pulleys and belts.

Claims

1. In a portable ski tow machine including a base, a frame structure mounted on said base, a power source mounted on said base, and a continuous loop tow rope driven by said power source for pulling a skier up a slope, a tow rope drive mechanism comprising, in combination: a. a main drive shaft journaled for rotation on the frame and drivingly coupled with the power source; b. a pair of drive sheaves fixed on said drive shaft for powered rotation by the power source; c. a pair of rope drive pulleys journaled for rotation on the frame about an axis parallel to the axis of rotation of said main drive shaft and in one-to-one correspondence with said sheaves; d. a drive belt drivingly engaged between each corresponding pulley and sheave; e. and a rope idler wheel intermediate said pairs of pulleys and sheaves and journaled on said frame for rotation about an axis parallel to the axis of said pulleys and sheaves; f. said continuous loop tow rope entering the drive mechanism and passing sequentially over one of said pulleys, thence over said idler wheel, thence over the other pulley and thence exiting from the drive mechanism; and g. said tow rope being gripped between each rope drive pulley and the drive belt associated therewith over a substantial circumferential length of each of said pulleys, whereby said rope is gripped by said belt and powered by said pulleys and belts in response to the rotation of said sheaves and belts by said power source.

5. A portable rope ski tow mechanism comprising a power unit, a pulley unit, and a continuous rope loop extending between said power unit and said pulley unit and powered by said power unit for pulling a skier up a slope, said power unit including a rope drive mechanism comprising a main drive shaft having a pair of drive sheaves secured thereon, a pair of rope drive pulleys adjacent said sheaves and drivingly coupled in one-to-one correspondence therewith by a pair of drive belts, and a rope idler wheel intermediate said pairs of pulleys and sheaves, said continuous loop tow rope entering the drive mechanism and passing sequentially over said pulleys and rope idler wheel, said tow rope being gripped between each rope drive pulley and the drive belt associated therewith over a substantial circumferential length of each of said pulleys whereby said rope is gripped between said belts and pulleys and powered thereby in response to the rotation of said sheaves.