Technical field

The present invention falls in general within the field relating to the movement of suspended vehicles; in particular, the invention relates to a roller unit for cable transport systems.

Prior art

As is known, in cable transport systems, the hauling cables are driven and continuously moved by means of pulleys located at the ends of a closed-loop path. Suspended vehicles are fastened to the cables by means of suitable gripping devices and are moved within said path. The cable is supported by a plurality of supporting towers distributed along the cable path. Crossbars extend projecting from the supporting towers and support in an oscillating manner the roller units so as to distribute homogeneously among several rollers the load transferred from the cable to the supporting towers.

The passage of the vehicles over the roller units may prove to be critical in the event of significant differential wear of the rollers of a same roller unit and this wear is difficult to compensate for by means of the conventional systems.

For a better understanding of the state of the art and the problems associated therewith a roller unit of the conventional type, as illustrated in Figures 3 to 6, will first be described. A conventional roller unit comprises a series of rocker arms 24 oscillating in a longitudinal vertical plane coinciding with the path of the cable along that section. Two respective rollers 20 which engage the same cable are mounted at the ends of each rocker arm. The rollers of a same rocker arm are mounted idly about two horizontal transverse and parallel axes of rotation A spaced from one another in the longitudinal direction of the cable. The rocker arm 24 is mounted in an oscillating manner about a transverse and horizontal axis of oscillation B arranged equally spaced between the axes of rotation of the rollers. Any dif- ferential wear of the two rollers results in a reconfiguration of the roller unit which will adapt to follow a slightly different trajectory of the cable.

Following accidental separation of a roller from the rocker arm, the cable is no longer correctly supported and the rocker arm impedes the movement of the vehicles. As shown in Figure 6, the loss of a roller results in rotation of the associated rocker arm about the axis of oscillation B; the rocker arm with the roller still attached thereto intercepts the trajectory of the vehicle gripping devices. In the case of conventional roller units, the loss of a roller requires immediate stoppage of the system and constitutes a danger for the structural integrity of the vehicles and the safety of the passengers, should the missing roller not be immediately noticed and the movement of the cable not be stopped in good time.

Moreover, the rollers of the roller unit are conventionally circumferentially coated with a homogeneous elastic material which is deformed by contact with the cable and the gripping devices. Since in a roller unit of the conventional type vehicles can oscillate transversely with angles greater than 10°, the yielding material must cover the entire axial dimension of the roller, so as to absorb the impact of the clamp on the roller due to swinging of the jaws (as can be seen in Figure 15B). However, this results in a large amount of energy being used by the haulage system to compensate for the elastic deformation affecting the whole strip of yielding material, to the detriment of the power consumption levels.

Summary of the invention

One object of the present invention is to overcome the drawbacks mentioned above by providing a roller unit which allows the envelope of the cable to be kept more or less unchanged, preventing collision between vehicle and interfering rocker arm following the loss of a roller.

In order to achieve this result, a dual load-bearing/hauling cable transport system is provided with roller units combined in the transverse direction so that the possible loss of a roller is counterbalanced by the action of the remaining rollers connected to each other. According to an embodiment of the invention, a roller unit comprising two or more pairs of idle rollers and a rocker arm is provided. The rollers of each pair are mutually facing, spaced from one another and idly mounted about an axis of rotation. Each of the two rollers of one pair engages a respective cable of a pair of load-bearing/hauling cables arranged side by side. The rocker arm frame rotatably supports the pairs of rollers and is pivotable about an associated horizontal and transverse axis of oscillation equally spaced from and parallel to the axes of rotation of the rollers. The rocker arm frame has two longitudinal sides opposite and transversely spaced from one another, the two rollers of each pair being arranged on a respective longitudinal side of the frame. At least one rigid connection element is integrally formed or rigidly mounted on the rocker arm frame. The rigid connection element extends transversely and rigidly connects the two opposite longitudinal sides of the rocker arm frame.

Owing to this configuration, any malfunction or loss of a roller will result in an overall readjustment of the loads along the frame and consequently a redistribution of the stresses acting on the remaining rollers.

Moreover, as will be understood more clearly from the continuation of the description, a roller unit configured according to the present invention is able to provide the vehicle with a total stability against lateral swinging. In this way it is possible to reduce the yielding coating with which the roller is lined since the need to absorb the impacts of the jaws on the roller is reduced. Consequently the elastically yielding volume affected by deformation is smaller and therefore the force needed to compensate for this deformation is also reduced.

The aforementioned and other objects and advantages are achieved, according to an aspect of the invention, by a roller unit having the features defined in Claim 1. Preferred embodiments of the invention are defined in the dependent claims. Brief description of the drawings

The functional and structural characteristics of a number of preferred embodiments of a roller unit according to the inverition will now be described. Reference is made to the accompanying drawings in which:

Figures 1 and 2 are front schematic views of a vehicle suspended from a pair of cables passing respectively above and below the rollers of a roller unit according to an embodiment of the invention;

Figure 3 is a side view of a roller unit of a dual cable system, according to the prior art;

Figure 4 is a plan view in the direction of the arrow IV of Figure 3;

Figure 5 is a front view in the direction of the arrow V of Figure 3;

Figure 6 is a schematic side view of a conventional roller assembly which is defective;

Figure 7 is a schematic perspective view of a roller unit, according to an embodiment of the invention;

Figures 8 and 9 are respectively a schematic side view and a schematic view from above of the roller unit according to Figure 7;

Figures 10 to 12 are perspective views of a roller assembly according to an embodiment of the present invention;

Figure 13 is a schematic side view of a roller assembly according to Figures 10 to 12 in a defective condition;

Figure 14 is a schematic side view of a roller assembly, according to a further embodiment of the invention;

Figure 15A is a schematic view of a support arm for a cable of a suspended vehicle, according to the prior art, shown in an oscillating condition with respect to the vertical;

Figure 15B is an enlarged view of the zone of contact between the cable and the roller shown in Figure 15 A;

Figure 16A is a schematic view of a pair of cables for a suspended vehicle, associated with a roller unit, according to an embodiment of the present invention; and

Figure 16B is an enlarged view of the zone of contact between the cable and the roller shown in Figure 16A. Detailed description

With reference initially to Figures 1 and 2, the reference number 9 denotes overall an intermediate supporting tower 9 for a pair of cables 10a, 10b of the load-bearing/hauling type. The supporting tower 9 comprises a pillar 12 with a fixed top crossbar 14 having, suspended from its two opposite ends, roller assemblies 32 for homogeneous redistribution of the load transmitted from the cables to the supporting tower. In a manner known per se, each cable 10a, 10b is guided along a closed-loop path by means of driving and transmission pulleys (not shown) situated at the ends of said path. Suspended vehicles 18 are fastened to the cables by means of mechanical gripping devices 1 1.

Said devices may be functionally associated with both automatic gripping systems and fixed gripping systems.

Figures 1 and 2 show two alternative operating configurations in which the cables may be located in relation to a series of rollers 20 mounted on the bottom of the roller units: in Figure 1 the cables pass over the rollers; in Figure 2 the cables pass underneath the rollers.

Figures 7 to 9 show a roller unit 16 according to an example of embodiment of the present invention. The roller unit 16 may be combined with other identical or similar units for composition of a roller assembly, as for example shown in Figures 10-12, so as to distribute in a uniform manner among the rollers the load transferred to the supporting towers from the two adjacent cables 10a, 10b (Figure 1 or 2) of the dual load-bearing/hauling cable transport system.

The roller unit 16 has two pairs of rollers 20a, 20b and 20c, 20d. The rollers 20a, 20b of the first pair of rollers are mutually facing, spaced from one another and idly mounted about a axis of rotation Al . The rollers 20c, 20d of the second pair of rollers 20c, 20d are also mutually facing, spaced from one another and idly mounted about an axis of rotation A2, parallel to and longitudinally spaced from the axis of rotation Al . Throughout the present description and in the claims, the terms and the expressions indicating positions and orientations such as "longitudinal", "transverse", "vertical" or "horizontal" are to be understood as being in relation to the axes of rotation A.

Each of the two rollers of a pair of rollers is intended to engage a respective load- bearing/hauling cable 10a or 10b.

The roller unit 16 comprises a rocker arm frame 24 which rotatably supports the rollers 20.

In a preferred embodiment, the rollers are mounted in the vicinity of the opposite longitudinal ends of the rocker arm frame 24.

The rocker arm frame has a rotatable support device 23 defining a horizontal and transverse axis of oscillation B spaced from and parallel to the axis of rotation Al and A2 of the rollers. In the example shown, the axis of oscillation B is arranged equally spaced between the axes of rotation of the rollers. This arrangement, which is preferred, is not to be regarded as limiting.

The rotatable support device 23 has the function of suspending the rocker arm frame 24 rotatably about the axis of oscillation and niay comprise a pair of bearings 23, for example sliding bearings which are spaced transversely from one other.

According to one embodiment, the bearings 23 may be mounted on two longitudinal walls or sides 25, 27 of the rocker arm frame which are opposite and transversely spaced from one another.

The two rollers of each pair of rollers are arranged on a respective longitudinal side 25, 27 of the rocker arm frame 24.

In the embodiment shown in Figures 7 to 9, the rollers 20 project transversely from the longitudinal sides 25, 27. The rocker arm frame 24 comprises one or more rigid connection elements 34-37 which are formed integrally with the rocker arm frame or are rigidly mounted thereon. The rigid connection elements 34-37 extend transversely between the two opposite longitudinal sides 25, 27 of the rocker arm frame 24 and connect them together rigidly.

According to a particularly compact embodiment (Figures 7 to 9) the rocker arm frame 24 comprises a metallic tubular element with a rectangular cross-section which has two opposite longitudinal sides 25, 27 from which the rollers 20 project transversely, and two horizontal walls 34, 35. The horizontal walls 34, 35 rigidly connect the longitudinal sides 25, 27. Each horizontal wall forms one of the rigid connection elements as defined above.

According to an alternative embodiment not shown, the rocker ami frame 24 may have a tubular shape with a circular or oval cross-section or shape of other geometrical figures, with closed or open profile. For example, the rocker arm frame may alternatively have the form of an overturned U, i.e. with a horizontal wall 34 which joins together the two longitudinal sides 25, 27.

According to other embodiments (not shown), a roller unit may comprise three or more pairs of rollers.

In the embodiment shown in Figures 7 to 9, two further rigid connection elements consist of two transverse tubular elements 36 which extend transversely between the two opposite longitudinal sides 25, 27 of the rocker arm frame 24 and rigidly connect them together. For example, the transverse tubular elements 36 may be welded to the two longitudinal sides 25, 27 of the rocker arm frame and/or fixed inside openings formed therein. The circular shape of the transverse tubular elements 36 shown here is not to be regarded as limiting.

According to alternative embodiments (not shown) the opposite longitudinal sides of a rocker arm frame 24 may be transversely connected together by means of other rigid connection elements such as ribs, bars, plates or grilles. The rigid connection elements 34-37 have the function of keeping unchanged the horizontal orientation of the axes of rotation of the rollers, even if one of the rollers 20 should accidentally become detached from or be displaced so as not to engage correctly one of the cables 10a, 10b. In such a case the rigid connection elements 34-37 help redistribute the loads over the rollers which remain correctly positioned.

According to other embodiments (not shown) the two opposite longitudinal sides of the rocker arm frame may be formed by two bars or longitudinal members which are connected together by a single rigid connection element in the form of a metal bar which joins together the two longitudinal sides or longitudinal members at respective intermediate joining points situated between their opposite ends. According to this variant the two longitudinal sides and the rigid connection bar together form an H-shaped rocker arm frame.

In another embodiment (not shown) two (or more) rigid connection elements in the form of parallel and longitudinally spaced transverse metallic bars may be provided, these joining together the two opposite longitudinal sides at respective pairs of joining points situated on opposite sides of the oscillation axis B.

In all the embodiments cited here, the rigid material forming the rocker arm frame 24 is preferably a metallic material or a composite material.

In the embodiments described hitherto, the rigid connection elements 34-37 are rigidly fastened directly to the two opposite longitudinal sides 25, 27 of the rocker arm frame 24.

Not necessarily the connection between the two longitudinal sides must be formed by one or more elements which are rigidly fixed to them. In addition or alternatively, the connection between the two opposite longitudinal sides may be formed by two elements fastened rotatably to both the longitudinal sides of the frame. The rocker arm frame 24 of the example shown in Figures 7 to 9 has two pairs of fixed transverse spindles 37 at the free ends of which the respective rollers 20 are idly mounted. Alternatively, the transverse spindles 37 may be mounted rotatably on the two opposite sides 25 and 27 of the rocker arm frame 24, helping give the frame the torsional rigidity which in other embodiments is provided by the fixed connection elements 34-37.

A roller assembly, denoted in its entirety by 32 (Figures 10 to 13), comprises a plurality of oscillating beams 28, 30 which connect in cascade a series of roller units 16 to the crossbar 14 of the supporting tower 9. In the example shown, the rocker arm frames 24 are mounted in pairs in an oscillating manner on a secondary oscillating beam 28 about a respective transverse and horizontal oscillation axis B. In this example, the oscillation axis B is arranged equally spaced between the axes of rotation of the rollers 20.

The secondary oscillating beams 28 are mounted in pairs in an oscillating manner on a single primary oscillating beam 30 about a respective transverse and horizontal oscillation axis C, in this example arranged equally spaced between the oscillation axes B. The primary oscillating beam 30 is suspended in an oscillating manner, about a horizontal and transverse oscillation axis D, from support elements 31 integral with the crossbar 14 and therefore the supporting tower 9 (Figures 1 and 2). The oscillating beams 28, 30 and the rocker arm frames 24 lies substantially in a same vertical plane.

The number and the dimensions of the oscillating beams and the roller units, the number of rollers, and the position of the various oscillation axes may vary depending on the specific design requirements.

The hinged configuration of the roller assembly 32, which combines the oscillating capacity of the oscillating beams and the rocker arm frames, allows the loads exerted by the cable on the rollers to be redistributed so that these loads are spread equally over all the rollers which engage the same cable. The various oscillation axes allow the roller assembly to adapt to the envelope of the cable, namely to the trajectory followed by the cable in a vertical plane passing through the middle of the rollers.

As already mentioned and as illustrated in Figure 6, the possible separation of a roller from a conventional rocker arm results in an uncontrolled rotation of the associated rocker arm which rotates about the oscillation axis B and is oriented in the vertical direction, thus dangerously intercepting the trajectory along which the suspended vehicles move.

On the other hand, as can be seen in Figures 12 and 13, in a roller unit according to the present invention, the loss of a roller unit does not result in the uncontrolled rotation of the associated rocker arm frame. In fact, the loss of a roller causes only a reconfiguration of the envelope of the cable in the longitudinal direction, namely a slight repositioning of the cable in the vertical plane which passes through the middle of the rollers 20, without resulting in any collision with or damage to the arriving suspended vehicles and subsequent stoppage of the cable. In Figure 13, LI denotes the position of the cable assumed normally by the cable on the roller R; L2 denotes the position of the same cable if the roller R is missing.

Figure 14 shows a further embodiment of a roller assembly 32. According to this variant, a (third) order of oscillating beams is added compared to the embodiment of Figure 13. In Figure 14 two secondary oscillating beams 28 aligned consecutively in a same longitudinal vertical plane and suspended directly from the primary oscillating beam 30 in an oscillating manner about the respective second oscillation axes C are provided. The roller assembly 32 comprises a plurality (in this case four) third oscillating beams 29 aligned consecutively in a same longitudinal vertical plane. Each third oscillating beam 29 is suspended from one of the secondary oscillating beams 28 in an oscillating manner about a respective third oscillation axis E parallel to the second oscillation axes C. A plurality of roller units 16 - in this example eight roller units - are suspended from the third oscillating beams 29 about their respective oscillation axes B.

A roller unit, configured according to the present invention and associated with a pair of cables which support the vehicle, creates the advantage of stabilising the vehicle, reducing significantly the possible transverse oscillations along the line and eliminating these oscillations when passing over the supports. As a result of these reduced oscillations it is possible to provide systems with a smaller distance between the lines and therefore stations and supports with a smaller width. Owing to the fact that the passing movement over the roller units occurs with the clamps in a certain position, namely without deviations, devices for retaining and guiding the cable may be provided on the outer side such as to prevent derailment in all - i.e. both operative and non-operative - conditions.

The innovative roller unit, combined with the two cables, ensures that the vehicles are correctly positioned both when passing over the supports and when entering the station; therefore, even in strong wind conditions or anomalous behaviour of the passengers, there are no dangerous deviations or oscillations.

In particular, the fact of guiding and transporting the vehicle correctly positioned for entry into the station, via the guide of the two cables, avoids the impact which occurs with conventional cable cars when the so-called third wheel comes into contact with the position stabilization guide; this allows, among other things, higher operating speeds to be employed compared to the speeds possible with conventional cable cars.

Moreover, as can be seen in Figures 15 A and 15B, the peripheral track of the roller 20 on which contact with the cable 10 occurs is conventionally lined with an elastically yieldable coating 21a extending substantially over the entire transverse width of the peripheral track situated between side flanges 21b of the roller 20.

A transverse oscillation of the suspended vehicle may incline the jaws 11 a so as to cause them to strike the yieldable coating 21a (as visible in Figure 15B).

With a roller unit according to the present invention, since the jaws 1 la pass over the rollers 20 in a central position and in a condition which is not inclined, the yieldable coating 21a may be provided only around the contact zone of the cable, reducing the volume of elastic material subject to deformation and therefore reducing the amount of energy used by the roller.

In fact, according to an embodiment of the invention, the yieldable coating 21 a may be flanked and confined transversely (i.e. relative to the axial direction of the roller 20) by two rings 21c which are made of a rigid material (or in any case a material which is less compressible compared to the yieldable coating 21a) and are arranged between the yield- able coating 21a and the side flanges 21b of the roller 20 (as can be seen in Figure 16B). In this way, the less compressible material of the rings 21c limits or eliminates the elastic deformation stress affecting overall the roller.

The side rings 21c may be made of a low- friction plastic material, for example high- density nylon.

The side rings 21c made of rigid material may extend at least over the entire axial dimension of the roller 20 situated between the yieldable coating 21 a and the side flanges 21b.

According to an alternative not shown, the yieldable coating 21a may be received inside a circumferential groove formed in the peripheral surface of the roller 20 comprised between the side flanges 21b, optionally so as to lie flush with this peripheral surface of the roller. Alternatively, a strip made of the same material as the rings 21c may be applied along all or part of the peripheral surface of the roller lying between the flanges 21b, and the yield- able coating 21a may be received inside a circumferential groove formed in the peripheral surface of this strip, so that the groove has a radial thickness smaller than the radial thickness of the strip. In this way, the rings 21c would coincide with the side shoulders of the groove, confining inside them all or part of the yieldable coating 21a.

Different aspects and embodiments of a roller unit according to the invention have been described. It is understood that each embodiment may be combined with any other embodiment. The invention, moreover, is not limited to the embodiments described, but may be varied within the scope defined by the accompanying claims.