Railways – Traction – Cable
Patent
1986-04-28
1988-02-16
Reeves, Robert B.
Railways
Traction
Cable
104140, 1041732, 198716, 198733, B65G 1726, B65G 1738
Patent
active
047247720
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a device for towing loads and especially to a ski tow, that is a device for towing skiers gliding on their own skis, preferably uphill. However, the device can also be used in transporting people in chair lifts or in trolleys running on rails. The device is intended for installation between a predetermined starting point and a predetermined end point spaced by a substantial distance of at least several hundred meters and sometimes more than one thousand meters.
Known devices of this type for transporting people by towing in open country are based upon the use of a tension element in the form of a wire, a rope or the like, which transmits energy to the load towed. To prevent accidents occuring from a break of the wire a close control and extensive maintenance of the device are required.
From German printed accepted patent specification No. 24 34 817 there is also known a lift which is towed along two parallel guide pipes containing a sequence of pressure elements each having at either end an end face contacting the opposed end face of an adjacent element, thus allowing the elements to be advanced as a string along the guide pipe, said device also comprising a drive means engaging at least one pressure element of the string at any time and pushing the string along the guide pipe. Thereby, the difficulties associated with the inherent risk of a break of a wire, a chain, a rope or a similar tension element are avoided.
However, the lift according to the German specification can be used only for relatively short transport stretches, since the pressure elements will engage the inner walls of the guide pipe with considerable frictional force, whereby the propulsion energy imparted to the string of pressure elements by the drive means will be consumed as frictional energy when the device is loaded, leaving little or no energy for moving the payload. For this reason the use of a device according to the German specification in the towing of loads over long stretches such as required by ski tows is not possible.
The object of the invention is to improve the principle of using a sequence of pressure elements instead of a tension element by reducing the resistance of the string of elements to movement along a guide means to an extent allowing the use of this principle for rather long transport stretches, such as required in ski tows or ski lifts.
The device according to the invention comprises a guide means extending in a closed path and including a load towing section, a sequence of pressure elements each having at either end an end face contacting the opposed end face of an adjacent element, thus allowing the elements to be advanced as a string along the guide means, towing means engaging the string and towing the loads, and drive means engaging at least one pressure element of the string at any time and pushing the string along the guide means. The invention is characterized in that the size and shape of the end faces are such that at any possible angular position of two adjacent elements due to tolerances between the guide means and the elements and/or to curves in the load towing section of the closed path the point of contact between the contacting end faces lies to the side of a notional straight line extending through the centers of said two adjacent elements opposite from the point of intersection between the longitudinal notional axes of said two adjacent elements, whereby the string of pressure elements when subjected to a pushing force from the drive means will tend to form a stable, straight column, still being free to fold when required by curves in the guide means.
Preferably, the end faces are substantially plane, whereby said point of contact will be shifted to the edges of the contacting end faces as soon as the respective elements are not in alignment. These edges may be positioned on the radially outermost contour of the element, whereby a maximum stabilization of the column is obtained for a given radial dimension of the elements.
However, the end faces do not need to be ex
REFERENCES:
patent: 2975727 (1961-03-01), Kokoras
patent: 3411456 (1968-11-01), Stevens
patent: 3854410 (1974-12-01), Crowder
patent: 3910403 (1975-10-01), Morsbach et al.
patent: 3968861 (1976-07-01), Kernen
patent: 4354575 (1982-10-01), Andersson
patent: 4399904 (1983-08-01), Canziani
Bryan Roland T.
Reeves Robert B.
Werny Scott H.
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