US3221667A - Rope tow - Google Patents

Description

R. D. WATT Dec. 7, 1965 ROPE TOW ROBERT D. WATT INVENTOR E ATTORNEYS Dec. 7, 1965 R. D. WATT 3,221,667

ROPE Tow Filed April 13, 1964 n 2 Sheets-Sheet 2 ROBERT D. WATT INVENTOR,

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ATTORNEYS United States Patent O 3,221,667 ROPE TOW Robert D. Watt, Seattle, Wash., assignor to Electro-Watt, Inc., Seattle, Wash., a corporation of Washington Filed Apr. 13, 1964, Ser. No. 359,293 9 Claims. (Cl. 104-173) This application relates to ski tows, and particularly that type of ski tow commonly known as a rope tow. Rope tows are characterized in that the skier grips a bare rope, riding his skis while pulled by such rope up a slope. The rope is endless, passing over a sheave or sheaves at each end limit of the run.

Rope tows as heretofore known have not been acceptable as approved equipment in many skiing areas from the fact that the ropes have been subject to twisting. This can be quite dangerous in that a users wrist strap, glove, or sleeve can become caught between strands of the twisting rope. The twisting is attributable A to the reaction of the lays of the rope as the rope bears against a sheave, or more especially a flange of the sheave,

in passing over the sheave. For its principal object the present invention aims to provide a rope tow having a perfected sheave assembly so constructed and arranged ,that twisting of the rope can be substantially obviated. With this and other objects and advantages in view which A teachings of the present invention.

FIG. 2 is a fragmentary horizontal sectional view q drawn to an enlarged scale on line 2--2 of FIG. l.

FIG. 3 is a fragmentary transverse vertical sectional I view on line 3-3 of FIG. 2; and

FIG. 4 is a fragmentary longitudinal vertical sectional view on line 4 4 of FIG. 3.

In said drawings, and rst having reference to FIG. 1, i

the numerals 10 and 11 denote mounting posts the former located at the down-hill end and the latter located at the up-hill end of a ski slope. An endless lpower-driven tow rope 12 extends between the two poles, being trained about sets of sheaves 4to provide a lower-level tow run and an upper-level return run. As here shown, the uphill set is comprised of two vertically spaced sheaves 13 and 14. The down-hill set is comprised of six sheaves 15, 16, 17, 18, 19 and 20. The sheave 18 is a live sheave driven from a power plant 21 sheltered by a house 22. Each of the other sheaves is free-running.

Generally considered, the several sheaves all occupy a common vertical plane, with the sheaves of the lowerlevel set so placed that the return run of the rope 12 rst passes under the sheave 15, and thence takes successive bights about the sheaves 16, 17, 18 and 19 before passing downwardly to and about the sheave 20. Sheave 16 is carried by a carriage 23 mounted upon a guide rod 24 for slide movement in a direction endwise to the ski slope, and is ten-sioned, so as to maintain the rope in a taut condition, by a weight 25.

For a purpose which will hereinafter appear, the down-hill sheave 20 and each of the two up- hill sheaves 13 and 14 receive their support from respective brackets, as 26, 27 and 28, which are attached to respective I- beams 30, 31 and 32. They are each so mounted that the plane in which the respective sheave lies can be canted within prescribed limits in either direction from center, and set at any selected point within the permitted range of this prescribed movement. The individual mounting is much the same for each of said three sheaves and a detailed 3,221,667 PatentediDec. 7, 1965 ice description of the sheave 13 will thus suice for the sheaves 14 and 20.

I-beam 31 lies perpendicular to the ground and is welded or otherwise rigidly secured to the post 11. Bracket 27 is or may be a fabricated structure and at the back provides vertically spaced claw-feet 33 arranged to be slipped onto the outer llange 34 of the I-beam. The exposed front face 35 of the bracket is vertically elongated and flat, and occupies a plane normal to the plane in which the two runs of the rope lie. Two threaded studs 36 and 37 are made rigid with the bracket and project forwardly beyond said face 35, one adjacent the upper end and the other adjacent the lower end thereof.

A swing-plate 40 seats upon the face 35, having at its upper end a pivot-hole 4-1 to t over the upper stud 36 .and at its lower end lan arcuate slot 42 developed about the drill-hole as a center and tting over the stud 37. Holding the swing-plate to the bracket are sets of jamnuts 43 and 44, with the former being applied to the stud 36 and bearing through a washer 47 upon a spacer 48, and the latter being applied to the stud 37 and bearing upon a cross-head 50. Set screws 51 and 52 threadably carried by lugs 53 and 54 located beyond the two ends of the slot bear upon diametrically opposite flats of the cross-head to permit said cross-head to be set at a selected adjusted position between limits prescribed by the slot.

Upstanding cheeks 55 project forwardly from the swing-plate `at opposite sides of the pivot-hole 41, and drilled through such cheeks on a coinciding transverse axis lying normal to the plates major axis and preferably placed so as to give little more than bare clearance relative to the spacer 48 are holes accommodating a crosspin 56. Pivoted from this cross-pin is a yoke having its arms 57 rigidly connected by a cross-bar 58. The sheave 13 is received between said arms of the yoke, being journaled upon a spindle 59 for free rotation about an axis paralleling that of the cross-pin 56.

The brackets for the two sheaves 20 and 13 are each slidably adjustable upon the related I-beam, being set in the desired position by means such as the indicated chains 60. Inner ends of these chains are hooked in eyes 61 which are provided at the upper and lower ends of the bracket. Outer ends of the chains engage suitable catches provided at the upper and lower ends of the I-beam. The purpose of this adjustment is to place the lower or tow run of the rope at a desired elevation above the snow level. Substantial changes in the snow level require compensating vertical adjustment of the brackets for the two lower sheaves. Should it be desired, the bracket for the upper sheave 14 can be welded in place in that this sheave does not require vertical adjustment.

An operator in adjusting the rope tow so as to obviate the objectionable twisting, first backs off both set screws from the cross-head of the upper sheave 14. This allows the swing-plate for such sheave to hunt, so to speak, as adjustment is being made to the two lower sheaves 20 and 13. It has been found that this hunting positions sheave 14 in its proper plane as an automatic consequence of the lower-level adjustment. When the latter adjustment has been completed, the set screws for the upper sheave are set against the cross-head.

The 'lower-level swing adjustment is perforce made by taking up on one or the other of the two set screws 51 and 52, responsively canting the plane of the concerned sheave in a direction such as to im-pose upon the rope, from the anges of the sheave, a pressure which will work counter to any twist which the rope exhibits. The twist, working back along the run of a rope from a sheave over which the rope is trained, can be in either a clockwise or a counter-clockwise direction depending upon which of a sheaves flanges imposes dominating pressure upon the lays of the rope. Trial and error allows an operator to ascertain the particular degree of cant, in one direction or the other from center, necessary to neutralize ange pressure.

It is believed that the invention will have been clearly understood from the foregoing detailed description of my now-preferred illustrated embodiment. Changes in the details of construction may be resorted to without departing from the spirit of the invention and it is accordingly my intention that no limitations be implied and that the hereto annexed claims be given the broadest interpretation to which the employed language fairly admits.

What I claim is:

1. In a rope tow, a set of sheaves including two pairs of guide sheaves one pair for the up-hill end and one pair for the down-hill end of a ski slope, individual mountings providing rotary journals for the two guide sheaves of each pair and placing the two sheaves one above another in longitudinal vertical planes which generally coincide, an endless power-driven tow rope of the twisted character trained over said set of sheaves and in its travel over the guide sheaves tracing a generally rectangular course rst working downwardly from the upper to the lower sheave of the down-hill pair, thence progressing on a lower-level tow run to the lower sheave of the up-hill pair, and then working upwardly to the upper sheave of said up-hill pair before making an upper-level return run, the mountings for at least the lower sheaves in said two pairs of guide sheaves being each carried for adjusting swivel motion about a respective horizontal axis located normal to the concerned journal axis, and means for setting said adjustable mountings at selected points within a permitted range of swivel motion.

2. A rope tow according to claim 1 in which the mounting for the upper sheave of said up-hill pair is also carried for adjusting swivel motion about a horizontal axis normal to the concerned journal axis.

3. A rope tow according to claim 1 in which the mountings for said lower guide sheaves are vertically movable, and have means for setting the same at selected points within a given range of permitted vertical movement.

4. A rope tow according to claim 3, standards being provided at the up-hill and down-hill ends of the ski slope, said standards each providing a vertical slide-way, `the adjustable Vmountings comprising brackets carried for slidemotion by the slide-ways.

5. A rope tow according to claim 1, standards being provided at the up-hill and down-hill ends of the ski slope, said standards each providing a vertical slide-way, the adjustable mountings comprising brackets carried for slide motion by the slide-ways and each having a stud rigid therewith and extending horizontally inwardly of the course in the approximate plane of the rope tow, a respective yoke for each sheave having the sheave journaled for rotation in the space between the arms of the yoke, and a respective plate to which each yoke is attached pivoted for swing motion to the stud of the concerned bracket, the means for setting said mounting comprising: a second stud rigid with the concerned bracket and located in offset paralleling relation to the pivot stud and Working in a slot provided in the swing-plate and developed on an arc having the pivot stud as its center, a cross-head fitting over said second stud, and opposing set screws carried by the swing-plate at opposite sides of the second stud and bearing against flats provided by the cross-head.

6. A rope tow according to claim 5 characterized in that the attachment of each yoke to its swing-plate places the rotary axis of the concerned sheave in close proximity to the horizontal plane in which the pivot-stud lies.

7. A rope tow according to claim 5, the attachment of each yoke to its swing-plate being a pivot attachment allowing vertical swing motion of the yoke about a horizontal axis located in close proximity to the pivot-stud.

8. A rope tow according to claim 5 in which the yokes position the concerned sheaves so that the plane which each sheave occupies contains the swing axis of the related swing-plate.

9. In a rope tow, a set of sheaves including two pairs of guide sheaves one pair for the up-hill end and one pair for the down-hill end of a ski slope, individual mountings providing rotary journals for the two guide sheaves of each pair and placing the two sheaves one above another in longitudinal vertical planes which generally coincide, an endless power-driven tow rope of the twisted character trained over said set of sheaves and in its travel over the guide sheaves tracing a generally rectangular course rst working downwardly from the upper to the lower sheave of the down-hill pair, thence progressing on a lower-level tow run to the lower sheave of the up-hill pair and then working upwardly to the upper sheave of said up-hill pair before making an upper-level return run, the mountings for at least the lower sheaves in said two pairs of guide sheaves being each carried for adjusting motion permitting the sheave to be placed so that the longitudinal vertical plane which it occupies lies either parallel with or canted in either lateral direction from the longitudinal vertical plane which the related upper sheave occupies, and means for setting said adjustable mountings at selected points within a permitted range of said adjusting motion.

No references cited.

MILTON BUCHLER, Primary Examiner.

Claims (1)

1. IN A ROPE TOW, A SET OF SHEAVES INCLUDING TWO PAIRS OF GUIDE SHEAVES ONE PAIR FOR THE UP-HILL AND ONE PAIR FOR THE DOWN-HILL END OF A SKI SLOPE, INDIVIDUALLY MOUNTINGS PROVIDING ROTARY JOURNALS FOR THE TWO GUIDE SHEAVES OF EACH PAIR AND PLACING THE TWO SHEAVES ONE ABOVE ANOTHER IN LONGITUDINAL VERTICAL PLANES WHICH GENERALLY CONCIDE, AN ENDLESS POWER-DRIVEN TOW ROPE OF THE TWISTED CHARACTER TRAINED OVER SAID SET OF SHEAVES AND IN ITS TRAVEL OVER THE GUIDE SHEAVES TRACING A GENERALLY RECTANGULAR COURSE FIRST WORKING DOWNWARDLY FROM THE UPPER TO THE LOWER SHEAVE OF THE DOWN-HILL PAIR, THENCE PROGRESSING ON A LOWER-LEVEL TOW RUN TO THE LOWER SHEAVE OF THE UP-HILL PAIR, AND THEN WORKING UPWARDLY TO THE UPPER SHEAVE OF SAID UP-HILL PAIR BEFORE MAKING AN UPPER-LEVEL RETURN RUN, THE MOUNTINGS FOR AT LEAST THE LOWER SHEAVES IN SAID TWO PAIRS OF GUIDE SHEAVES BEING EACH CARRIED FOR ADJUSTING SWIVEL MOTION ABOUT A RESPECTIVE HORIZONTAL AXIS LOCATED NORMAL TO THE CONCERNED JOURNAL AXIS, AND MEANS FOR SETTING SAID ADJUSTABLE MOUNTINGS AT SELECTED POINTS WITHIN A PERMITTED RANGE OF SWIVEL MOTION.

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