The present invention relates to a cable transportation system.

More specifically, the present invention relates to a cable transportation system of the type comprising a draw cable; at least one supporting cable; a transportation unit comprising a trolley supported by the supporting cable and connected to the draw cable by a clamp; and at least one fixed idler comprising a succession of rollers distributed along a first trajectory to support and guide the draw cable, and a fixed shoe for supporting and guiding the supporting cable along a second trajectory extending along the first trajectory; the first and second trajectory, when projected in a horizontal plane, respectively defining a first and second path having a first curved intermediate portion and a second curved intermediate portion respectively.

In known cable transportation systems, see for example GB-A-27,151, the supporting cable is located over the draw cable, and the clamp is fitted to an arm, which extends downwards from the trolley and is designed so that, when the trolley runs along the idler, the draw cable is detached from the idler rollers along a suspension portion, of which a central part is located at the clamp, and two straight lateral parts extend from the clamp towards the rollers.

In known cable transportation systems, the idler rollers are cylindrical, and each have a circumferential groove to guide the draw cable, and is fitted to a fixed carrier to rotate idly about a respective normally horizontal axis.

In known cable transportation systems of the above type - i.e. in which the idler rollers are distributed in space along a first trajectory, the horizontal projection of which extends along a first path having a first curved intermediate portion, and the shoe guides the supporting cable along a second trajectory, the horizontal projection of which extends along a second path having a second curved intermediate portion - the first and second path are normally parallel, i.e. are the same shape.

Such a solution has potential drawbacks, in that, as the trolley runs along the curved intermediate portion of the second path, the clamp runs along the curved intermediate portion of the first path, and each straight lateral part of the suspension portion of the draw cable is located along a chord connected to the curved intermediate portion of the first path by a given angle of other than 180°.

This invariably results in wear of both the idler rollers and the draw cable, and may even result in jamming and/or unseating of the draw cable.

It is an object of the present invention to provide a cable transportation system of the above type, designed to eliminate the aforementioned drawbacks.

According to the present invention, there is provided a cable transportation system comprising a draw cable; at least one supporting cable; a transportation unit comprising a trolley supported by the supporting cable and selectively connectable to the draw cable by a clamp; and at least one fixed idler comprising a succession of rollers distributed along a first trajectory to support and guide the draw cable, and a fixed shoe for supporting and guiding the supporting cable along a second trajectory extending along the first trajectory; the first and second trajectory, when projectect in a horizontal plane, respectively defining a first and second path having a first curved intermediate portion and a second curved intermediate portion respectively; wherein, along the idler and when the trolley is located, in use, along the idler, the draw cable comprises a suspension portion detached from the rollers, and of which a central part is located at the clamp, and two straight end parts extend from the clamp towards the rollers; the cable transportation system being characterized in that the first curved portion extending along an envelope curve of the horizontal projections of said straight end parts in the successive positions occupied by the straight end parts as the trolley moves, in use, along the second curved portion.

To assist detachment of the upstream end part of the suspension portion from the rollers, and reconnection of the downstream end part of the suspension portion to the rollers as the trolley runs along the second curved intermediate portion, the rollers along the first curved intermediate portion are preferably inclined rollers mounted to rotate about respective axes, which are inclined so that a top peripheral portion, engaged by the draw cable, of each inclined roller faces outwards with respect to the second curved intermediate portion.

Finally, each inclined roller preferably has an outer surface defined by two opposite truncated-cone-shaped surfaces defining a V-section annular groove.

A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:

• Figure 1 shows a schematic side view, with parts removed for clarity, of a preferred embodiment of the transportation system according to the present invention;
• Figure 2 shows a larger-scale view in perspective of a detail in Figure 1;
• Figure 3 shows a side view of the Figure 2 detail;
• Figure 4 shows a larger-scale detail of Figure 3;
• Figure 5 shows a plan view of the Figure 2 detail;
• Figure 6 shows a larger-scale section along line VI-VI in Figure 5;
• Figure 7 shows a larger-scale section along line VII-VII in Figure 4;
• Figure 8 shows a larger-scale section along line VIII-VIII in Figure 3;
• Figure 9 shows a larger-scale schematic, with parts removed for clarity, of a detail in Figure 8.

Number 1 in Figure 1 indicates as a whole a cable transportation system comprising a bottom station 2; a top station 3; two intermediate idlers 4 supported by respective pylons 5; two supporting cables 6 (only one shown in Figure 1); a draw cable 7; and a transportation unit 8 comprising a trolley 9, which is supported by supporting cables 6, and is drawn, in use, by draw cable 7, to which trolley 9 is connected by a clamp 10.

More specifically, supporting cables 6 are parallel, and draw cable 7 extends below supporting cables 6 and is so positioned that, along substantially the whole of cable transportation system 1 and at any point in its operation, connecting the corresponding points of supporting cables 6 and draw cable 7 gives a substantially isosceles triangle with a horizontal base at the top and a downward-facing apex defined by a point on draw cable 7.

As shown more clearly in Figures 2 and 4, trolley 9 comprises a longitudinal frame 11 with two cross members 12, each of which extends crosswise to supporting cables 6 and supports at each end a wheel assembly 13 comprising a rocker arm 14, which is connected to relative cross member 12 to oscillate about an axis 15 crosswise to supporting cables 6, and supports, at each end, an idle roller 16, the periphery of which rolls in contact with relative supporting cable 6. An L-shaped arm 17 projects downwards from frame 11, and the end portion of the arm is located below and connected to draw cable 7 by clamp 10, which is selectively releasable in known manner to release trolley 9 from draw cable 7.

A further arm 18 projects laterally from longitudinal frame 11, bends downwards and outwards of supporting cables 6, and supports in rocking manner a load forming part of transportation unit 8 and defined, in the example shown, by a car 19.

As shown in Figure 1, each idler 4 comprises a roller assembly 20 in turn comprising a succession of rollers 21, which are fitted idly to an elongated carrier 22 integral with relative pylon 5, and support and guide draw cable 7 in space through idler 4 and along a trajectory T1. Idler 4 also comprises an elongated shoe 23 integral with relative pylon 5, and which supports and guides supporting cables 6 along respective trajectories T2.

As shown more clearly in Figure 2, shoe 23 comprises two parallel, elongated lateral shoulders 24, each of which is vertical and bounded at the top by a transverse core supporting a respective rail 25, which has a longitudinal groove 26 extending along relative trajectory T2 and engaged by relative supporting cable 6. The two lateral shoulders 24 are connected to relative pylon 5 in known manner not shown, and are connected to each other by a number of transverse ribs 27. Each pair of adjacent ribs 27 defines, together with lateral shoulders 24, a window 28 engaged by a relative roller 21 of roller assembly 20. Each rib 27 is bounded at the bottom by a flat, substantially horizontal edge, and is bounded at the top by an upwardly-concave curved edge 29 having a central recess 30, which divides edge 29 into two sloping sides converging downwards towards recess 30, and the end portions of which, adjacent to recess 30, are fitted with respective converging pads 31 inclined as specified in detail below. The succession of recesses 30 defines a channel 32 extending substantially along trajectory T1, and from the bottom of which rollers 21 project partly upwards through relative windows 28.

As shown in Figure 3, when projected in a vertical plane, trajectories T1 and T2 (Fig. 2) define respective parallel, downwardly-concave, curved paths.

As shown in Figure 5, when projected in a horizontal plane, trajectories T1 and T2 define respective paths P1 and P2. More specifically, path P1 comprises a curved intermediate portion 33 interposed between a straight entry end portion 34 and a straight exit end portion 35; whereas paths P2 are parallel, and each comprise a curved intermediate portion 36 interposed between a straight entry end portion 37 parallel to end portion 34, and a straight exit end portion 38 parallel to end portion 35. Straight entry end portions 37 are generally symmetrical with respect to straight entry end portion 34; straight exit end portions 38 are generally symmetrical with respect to straight exit end portion 35; whereas curved intermediate portion 33 has a smaller curvature than curved intermediate portions 36, and gets gradually closer to the inner curved intermediate portion 36, eventually reaching a minimum distance from it at the centre of the inner curved intermediate portion 36.

This difference in the shape of curved intermediate portions 33 and 36 is due to the fact that, as trolley 9 runs along curved intermediate portions 36 of paths P2, its clamp 10 moves along a path parallel to curved intermediate portions 36 and, at the same time, lifts draw cable 7 off rollers 21 along a suspension portion 39 movable with trolley 9, and of which an intermediate part extends along clamp 10, and two end parts 40 extend along respective chords of the path travelled by clamp 10, and form angles of other than 180° with the portions of draw cable 7 adjacent to them. If the horizontal projections of end parts 40 for each position of trolley 9 along curved intermediate portions 36 are represented in a horizontal plane, this gives a so-called "envelope curve", the shape and position of which coincide with those of curved intermediate portion 33.

By arranging rollers 21 along a path P1 of the shape described above, the two end parts 40 are respectively detached from and reconnected to rollers 21, forming angles of substantially 180° with the respective adjacent portions of draw cable 7.

As shown more clearly in Figures 5 and 6, rollers 21 comprise cylindrical rollers 21a, which are arranged successively along straight portions 34 and 35 of path P1, each have an annular, substantially semicircular-section groove 41 engaged by draw cable 7, and are fitted to carrier 22 (Figure 1) to rotate idly about respective horizontal axes 42.

As shown more clearly in Figures 4, 5, 7 and 8, rollers 21 also comprise rollers 21b arranged successively along curved intermediate portion 33 of path P1, and fitted to carrier 22 (Figure 1) to rotate about respective axes 43 (Figures 7, 8), which are inclined to the horizontal by an angle of 5 to 45 degrees, so that a top peripheral portion, engaged by draw cable 7, of each roller 21b faces the outer curved intermediate portion 36, and has an outer surface (Figures 7, 8) defined by two opposite truncated-cone-shaped surfaces 44, 45 defining an annular, V-section groove 46. More specifically, at the highest point of truncated-cone-shaped surfaces 44 and 45, the relative generating lines are substantially parallel to and coplanar with the respective adjacent pads 31, and cooperate with pads 31 to completely close channel 32 at relative window 28.

As such, rollers 21b not only provide for guiding detachment and reconnection of end parts 40 from and to roller assemblies 20 along curved intermediate portion 33 of path P1, but also make jamming and/or unseating of draw cable 7 along curved intermediate portion 33 of path P1 substantially impossible.