Automatic gondola for aerial ropeway, which opens and closes by rotating portions of the passenger compartment
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to gondolas for aerial ropeways pertaining to the type of equipment intended for transporting passengers between two terminal stations by means of a cable carrying along a plurality of disconnectable gondolas each adapted to carry only a few passengers. The invention relates more particularly to a gondola for rope- or cableways of this type, which comprises on a same lateral side two apertures spaced from each other and permitting the access of passengers to two bench seats disposed traversely back to back so that in front of each seat a wide transparent windshield affords a wide-angle panoramic forward or backward view for the passengers. 
     2 . Description of the Prior Art 
     A gondola of the general type set forth hereinabove has already been proposed and utilized by the Applicants as recited in the U.S. Pat. No. 3,931,769. In this prior art gondola the lateral apertures are cleared by causing the simultaneous translation of a pair of lateral doors responsive to an automatic control mechanism. Although the exploitation of this gondola is fully satisfactory, notably in that the passengers can step in and out very rapidly and that ski holders can be disposed on the outer surface of the fixed wall disposed between the two apertures, the movements of translation of the doors prevent the passengers from embarking and disembarking in a standing position and make it necessary to provide in the roof an emergency trap for the ingress of possible rescuers into the underlying gondola. On the other hand, the precision required for properly guiding the movements of translation of the lateral doors increases considerably the final manufacturing cost and the maintenance expenses of the gondolas. Finally, the sliding movements of translation of the gondola doors are likely to interfere with the obtaining of the most propitious streamlined shape with a view to minimize the action of wind on the gondolas. 
     SUMMARY OF THE INVENTION 
     It is the primary object of the present invention to provide an improved structure for a gondola of the general type set forth hereinabove, wherein the opening and closing movements are still obtained through the use of the automatic control means contemplated in the above-mentioned patent, which proved quite satisfactory in actual practice, while avoiding the opening and closing of said apertures by means of sliding door movements of translation. 
     It will be noted that aerial gondolas are already known wherein the aperture is obtained by simply causing the gondola to perform a movement of rotation, notably as disclosed in the U.S. Pat. No. 3,556,016 which provides a shell-like gondola with an access door, a lateral opening being obtained by causing a pair of half-shells constituting the entire lateral wall of the gondola to pivot about a vertical lateral axis. However, this structure with a single lateral aperture, adapted more particularly for gondolas designed for carrying only a very small number of seated passengers facing each other, cannot offer to the passengers a truly panoramic and therefore attractive view, and in addition embarking and disembarking passengers through a single aperture constitutes a relatively long operation. 
     It is obvious that an advantageous arrangement would be obtained in combining a pair of two-seat benches disposed back to back with two lateral apertures and also with simple rotational movements for opening and closing the gondolas, instead of using sliding doors requiring accurate guide means. According to this invention, this arrangement is obtained together with other complementary advantages by providing a gondola for an aerial ferry or the like with a gondola structure comprising a transverse central ring rigid with the carrier frame, said central ring being narrower on one side (the access and exit side) than the opposite side, and a pair of half-shells made of molded plastic material which surround the passenger compartment at its front and rear ends, said half-shells being adapted to pivot about vertical axes located in the vertical median plane of the gondola so as to uncover on a same side of the gondola a pair of access openings or cut-outs formed in the wall of the gondola on each side of the narrow side of the central ring, the same half-shells covering externally on the opposite side the wide portion of said ring on surface areas equal to the cut-out opening surface areas. 
     Thus, the gondola can be opened and closed automatically by means of a mechanism very similar to the one already known in the art, for example as disclosed in the above-mentioned U.S. Pat. Nos. 3,556,016 and 3,931,769. Moreover, the structure contemplated in the present patent is such that the gondola dimensions can be kept to a minimum in the open position of said half-shells, in contrast with the known arrangement wherein the two half-shells are moved away from each other at their junction plane, on the side of the aperture to be opened or cleared, which arrangement does not provided two separate accesses in order to reduce the time necessary for the passengers to step in or out. Another feature characterizing the improved structure according to this invention is that the fixed median or central wall can be preserved, the outer surface of this wall being adapted, if necessary, to carry a ski-holder between the two apertures. 
     A further advantage resulting from the structure of this invention is that, according to a complementary feature characterizing this invention, the opening and closing movements are facilitated due to the pivotal mounting of the pair of half-shells about axes disposed in the vertical median plane of the gondola but slightly inclined to the vertical so as to converge upwardly toward each other, whereby, during an opening movement as well as during a closing movement, the centers of gravity of the pair of half-shells describe each a path of circular arc configuration in a slightly inclined plane of which the ends lie at lower points substantially symmetrical to the vertical median longitudinal plane of the gondola. Thus, any opening or closing movement is started against the action of gravity forces but ends with the assistance of this gravity action so that the half-shells are urged either to their fully closed position or to their fully open position by said gravity forces. In other words, the end positions are both stable ones and the opening and closing movements constantly tend to take place completely after clearing a dead center point located substantially in the middle of the corresponding movement. Therefore, the action of the gravity forces will assist the action of the spring means incorporated in the automatic control device which may thus be simplified and operate with the maximum reliability under all circumstances. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a side elevational view of an aerial gondola constructed according to the teachings of this invention; 
     FIG. 2 is a front elevational view of the same aerial gondola; 
     FIG. 3 is a plan view from above showing the gondola in its closed condition, and 
     FIG. 4 is a plan view from above showing the same gondola in its open condition. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring first to FIGS. 1 and 2 of the drawing, the aerial gondola for ropeway systems according to this invention comprises a carrier rope or cable 1, a suspension arm 2 from which the gondola proper is suspended, this arm 2 being pivoted on the one hand at its bottom via a longitudinal fulcrum pin of a yoke 3 carried by the central ring or belt 4 of the gondola and on the other hand at the top via another fulcrum pin having a transverse axis 25 rigid with the clamp 26 provided for locking the gondola to the rope 1. This arrangement is designed for minimizing the risk of collision with the iron framework towers for a same transverse distance between the vertical plane of rope 1 and the towers supporting said rope. 
     The central ring or belt 4 of the gondola is rigid with the frame structure thereof which supports the pair of two-seat benches 5, 6 disposed back to back. Facing each seat is a relatively wide windshield with transparent glazing incorporated in a corresponding half-shell constituting the compartment for the passengers seated on the corresponding bench seat. The pair of half-shells designated at 7 and 8 in FIG. 1 are movable in order to clear the access or exit to and from the gondola, as will be explained presently. 
     As shown in FIGS. 3 and 4, the central ring or belt 4 is narrower on one side 9, between the accesses, than on the opposite side 10, and the pair of half-shells 7,8 completing the gondola housing can pivot between closed and open positions, and vice versa, about axes 11,12 slightly inclined to the vertical, respectively. The narrow side 9 of fixed ring 4 may advantageously carry on its outer surface a ski holder 13 (shown only in FIG. 2 to avoid unnecessary drawing complications). 
     At its top the central ring 4 carries the automatic control lever 14 shown in its closed position in FIGS. 2 and 3 and in its open position in FIG. 4. This lever is fulcrumed about a fixed pivot pin 15 and adapted to oscillate in a transverse plane in order to actuate a mechanism 16 of which the actuating rods 17,18 (shown only diagrammatically in FIGS. 3 and 4) are pivoted at 19,20 respectively to the pair of half-shells 7,8 to permit the pivotal movements thereof about their axes 11,12. Therefore, during the opening movement the half-shells 7,8 move away from the narrow side 9 of ring 4 (FIG. 4), thus clearing the apertures 21 and 22, while on the opposite side the walls of the two half-shells surround externally the wide side 10 of ring 4. The cleared apertures 21,22 are wedge-shaped and extend upwards on the top of the gondola (i.e. above the seat halves located on the access side of the gondola), whereby the occupant can embark or disembark without leaning; furthermore, these apertures 21,22 are such that access to the inside of the gondola can be had from the top thereof in case of emergency, thus permitting a rapid intervention of rescuers in a gondola brought to a standstill or locked against movement between two terminal stations. 
     The automatic control mechanism is very similar to the one well known in the art and therefore its detailed description is not deemed necessary inasmuch as it is no part of the present invention. Suffice it to say that this automatic control mechanism is actuated by means of the above-mentioned lever 14 responsive to the action of automatic control ramps or cam members provided for this purpose at the terminal stations and adapted to engage and push the end roller 23 carried by the top of said lever 14 outwards according to the well-known principle. 
     The axes 11,12 about which the two half-shells are pivotally mounted to the fixed structure comprising the carrier frame and the central ring 4 are disposed substantially in the longitudinal median plane of the gondola, and inclined preferably to converge upwards as shown in FIG. 1. As illustrated in FIGS. 3 and 4, these axes are selected in combination with the curved contour of the gondola half-shells so that the latter perform their movements of rotation substantially within a space of which the over-all dimensions do not exceed appreciably those of the gondola in its closed condition (FIG. 3). Moreover, as already mentioned in the foregoing, as a consequence of the inclination of axes 11,12 with respect to the longitudinal vertical median plane, the center of gravity of each half-shell is caused to move during each opening or closing movement along a part-circular path rising from its ends to an intermediate, dead-center forming point beyond which the gravity forces urge the corresponding half-shell in the direction to complete the movement thus started of which the two ends constitute stable positions. 
     The reference numeral 24 designates front and rear bumpers as usually provided on gondolas of this type. 
     Although a specific form of embodiment of this invention has been described hereinabove and illustrated in the accompanying drawing, it will readily occur to those skilled in the art that various modifications and changes may be brought thereto without departing from the scope of the invention as set forth in the appended claims.