Abstract:
Disclosed is an aerial transport system which comprises an aerial track having therealong a pair of electric current-carrying cables in a parallel relationship with respect to one another and with respect to the track, and self-propelled carriages. Each carriage has an electric current collector to collect electric power from the current-carrying cables and to supply the power to an electrical driving mechanism mounted thereon for driving wheels engaging with the track. The current-carrying cables are separated at longitudinal given intervals so as to define respectively independent electric power supply zones. The transport system further includes a system for controlling electric power supply for the vehicle or carriage including a mechanism for detecting a vehicle or carriage position in the track provided in each power supply zone. The vehicle or carriage position detecting mechanism has a circuit which is closed when the vehicle or carriage is present within the zone, and a detector for detecting an electric current flowing in the zone when the circuit is closed. The detector is associated with a holding relay control circuit. The holding relay controls an electric power supply control circuit having a controlling contactor connected with a contact of the holding relay.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to an aerial transport system having a self-propelled vehicle or carriage, such as a tramway or cableway. More specifically, the invention relates to an improvement in a means for controlling an electric power supply for the vehicle or carriage, in which the means includes a means for detecting a vehicle or carriage position in the aerial tramway or cableway. Further, the invention relates to an improvement in a vehicle or carriage position detecting means capable of detecting a position of the vehicle or carriage on the track. The invention yet further relates to a control system for controlling an electric power supply for the vehicle or carriage and being co-operative with the vehicle or carriage position detecting means. 
     2. Description of the Prior Art 
     The aerial transport system, such as a tramway or cableway system, generally comprises a tramway or cableway, a self-propelled vehicle or carriage, having electrical driving means moving the tramway or cableway, and an electric power supplying means including a pair of electric current-carrying cables which are positioned apart from one another and in parallel relationship with respect to each other and the tramway or cableway. 
     One of the typical and general constructions of the aerial transport system will be schematically illustrated and shown in FIG. 1. In FIG. 1, a cable 1, for supporting a carriage 2 and defining a cableway is supported by stationary towers (not shown) arranged at regular intervals along the cableway. A pair of electric current-carrying cables 3 are supported by the supporting cable 1 by means of known suspension members such as a plurality of brackets (not shown). 
     The carriage 2 has driving wheels 4 engaging or riding on the supporting cable 1 so as to suspend the carriage 2 through suspension member 5 and move the carriage 2 along the tramway or cableway. The carriage 2 has an electric current collecting means 7 including current collecting shoes 8 for sliding contact with the current-carrying cables 3 and collecting electric power from the cables 3. The carriage 2 has an electric driving means, such as an electric driving motor (not shown), to be driven by the electric power collected by the current collecting means 7. Thus, the vehicle or carriage is propelled to move along the tramway or cableway by the driving means whose driving power is transmitted to the driving wheels through transmission means (not shown). Practically, in such a self-propelled vehicle or carriage, the transmission means is received within the suspension member 5. 
     In a transport system such as the aforementioned, the operation of the carriage or vehicle is generally performed under an automatic centralized control system without a driver riding in each carriage or vehicle. Therefore, to provide sufficient safety or security in operation is one of the most important matters for such a system. To fulfill safety requirements, the carriage or vehicle is provided with a automatic braking device, such as an electromagnetic brake, which is operative when power is not supplied to the carriage or vehicle. 
     The current-carrying cables are separated or divided at regular intervals to define, independent power supply zones. In each power supply zone, there is provided a means for controlling the power supply with respect to carriage or vehicle positions in the tramway or cableway; namely, the control means operates to cut the power supply for the carriage or vehicle so as to actuate the braking device, when the preceding carriage is in an adjacent zone. 
     A typical and general electric power supply control system is schematically illustrated and shown in FIG. 2. A pair of current-carrying cables 22, 24 are respectively separated or divided by insulating members 26 at regular intervals so as to define, respectively independent power supply zones I, II, III . . . The following explanation applies, by way of example, to the power supply to zone I; only the corresponding control circuit for zone I is shown in FIG. 2. Respective current-carrying cables 22, 24 are connected to power supply cables 28, 30 respectively through a power supply controlling circuit 40. The power supply control circuit 40 is connected to a holding relay circuit 50. The holding relay circuit 50 is connected to carriage or vehicle position detecting means 62, 64 provided in the power supply zones II and III. In FIG. 2, the detecting means 62 in the zone II is connected to a reset-input R of the holding relay circuit 50; the detecting means 64 in the zone III is connected to a set-input S of the holding relay circuit 50. Thus, when the detecting means 62 detects a vehicle or carriage in the zone II, the holding relay circuit 50 is put in the OFF position so as to actuate the power supply control circuit 40 for breaking the power supply to the zone I. When the carriage or vehicle leaves zone II and is detected in zone III by the detecting means 64, the holding relay circuit 50 goes into the ON position and the power supply control circuit 40 supplies power to the current-carrying cables 22, 24 in the zone I. This position of the holding relay circuit 50 is maintained until the next occasion when the carriage or vehicle position detecting means 62 of the zone II detects the following carriage or vehicle in the zone II. 
     The power supply control circuit 40 according to the prior art will be schematically illustrated and shown in FIG. 3. The current-carrying cables 22, 24 are connected to the power cables 28, 30 through circuit breakers 42, 44 and contacts 46, 47 of a contactor 48. The contactor 48 is operated or controlled by a contact 52 of the holding relay 50. 
     In practice, circuit breakers and/or a contact 46 or 47 need only be provided in one of the leads connecting the power cables and the current-carrying cables. However, FIG. 3 shows circuit breakers and contacts being provided on both leads, as in the usual manner. 
     The carriage 2 travels through the cableway with the current collecting means 7. The current collecting means 7 includes the current collecting shoes 8 contacting the current-carrying cables 22, 24. An electric current thus flows through the power supply circuit to the driving means 9 of the carriage. 
     Upon the absence of a prior carriage in the adjacent forward zone, the holding relay circuit 50 operates so as to close the contact 52. The contactor 48 is then excited to close the contacts 46, 47 so that electric power can be supplied to the respective current-carrying cables 22, 24 from the power cables 28, 30. 
     If there is a prior carriage in the adjacent forward zone, the holding relay circuit 50 is inoperative, thereby opening contact 52. The contactor 48 is not excited and thus opens the contacts 46, 47. The electric power supply circuit is thus broken to cease supplying power to the current-carrying cables 22, 24. If there is a carriage in the present zone, it may be stopped by actuating the automatic braking device, such as the electromagnetic brake (not shown) mounted on the carriage. 
     The automatic braking device has a braking member which can be pressed against the driving wheels or driving means by a spring, when an actuation means of the braking device is not energized. When the electric power is not supplied to the brake means, the actuation means is inoperative. Thereby, the brake means is free from the force of the actuation means so as to contact the driving wheels and so on. Preferably, the automatic braking device may also be actuated when less than a predetermined current is supplied. 
     Meanwhile, to control the power supply to the independent zones I, II, III . . . in the aerial transport system, it is necessary to detect whether or not a vehicle or carriage is present within each zone. Therefore, there are provided vehicle or carriage position detecting means 60, 62, 64 . . . , in zones I, II, III . . . , respectively, as shown in FIG. 2. 
     In the prior art, there are various vehicle or carriage position detecting systems. One of the systems comprises one or more limit switches mounted on arms of cable supporting brackets which support the current-carrying cable in each power supplying zone. A flange portion of the wheels of the vehicle or carriage contacts at least one of the switching arms of the limit switches so as to actuate the same. Another system comprises one or more proximity switches mounted on the arms of cable supporting brackets in each power supplying zone. The proximity switch actuates when the lower portion of the current collecting means of the vehicle or carriage passes through the nearest point to the switch. 
     In the prior systems, the limit switches or proximity switches are mounted on the arms of the brackets which are positioned at high elevations and which may cause danger, inconvenience and further problems in mounting or mending the same. Further, the limit switches or proximity switches merely detect passing of the vehicle or carriage at the points where they are provided. Therefore, the switches may not detect for example a stationary carriage which has broken down in the power supplying zone. For accuracy in controlling the power supply, further scanning systems have been required, for example an electric sensing system of the vehicle or carriage position. 
     The present invention aims to improve the afore-mentioned disadvantages and difficulties in the prior art and to provide a novel and useful vehicle or carriage position detecting means which can detect whether or not there is a vehicle or carriage within the zone. Further, the invention aims to provide a control system for controlling the electric power supply to the zone, and thus control the driving of the vehicle or carriage. 
     SUMMARY OF THE INVENTION 
     Therefore, it is an object of the present invention to provide an electric power supply control means including a vehicle or carriage position detecting means which can detect whether or not there is a vehicle or carriage within a power supply zone. 
     Another object of the present invention is to provide a vehicle or carriage position detecting means which is operative even when the driving means of the vehicle or carriage is in the braked position or has stopped at a station. 
     Still another object of the invention is to provide a vehicle or carriage position detecting means which detects the vehicle or carriage within the zone by detecting an electric current flowing in the zone. 
     Still another object of the invention is to provide a vehicle or carriage position detecting means detecting the vehicle or carriage within a power supply zone by a relay which detects electric current flowing in the zone and is electrically associated with the relay provided in the power supply control circuit in the other zones so as to maintain an interrelational control system for safe operation. 
     A further object of the present invention is to provide a power supply control system for an automatically driven aerial transport system, said control system co-operating with the vehicle or carriage position detecting means. 
     A still further object of the invention is to provide a power supply control system having a plurality of relays co-operatively associated or connected with respect to respective adjacent relays so as to control the power supply of respective power supply zones. 
     A still further object of the invention is to provide a power supply control system which operates to break the power supply circuit to stop the supply of electric power to the driving means mounted on the vehicle or carriage, when the vehicle or carriage position detecting means in the adjacent forward zone detects a vehicle or carriage within the adjacent forward zone, for safety and security of the automatic operation of the aerial transport system. 
     The other objects and advantages will be illustrated and made clear by the following descriptions. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be more fully understood from the detailed description given below, and from the accompanying drawings of a preferred embodiment of the present invention, which, however, are not to be taken as limitative of the present invention in any way, but are for the purposes of elucidation and explanation. In the drawings: 
     FIG. 1 is a schematic side elevational view of a typical construction of an aerial transport system; 
     FIG. 2 is a schematic diagram of an electric power supply system for the aerial transport system; 
     FIG. 3 is a schematic diagram of the conventional power supply control circuit; 
     FIG. 4 is a schematic diagram of a power supply control circuit including a vehicle or carriage position detecting means, in accordance with the preferred embodiment of the invention; 
     FIG. 5 shows a circuit construction for controlling the holding relays of the power supply control circuit of FIG. 4; 
     FIG. 6 is a time chart showing the delay operation of a delay-on relay employed in the preferred embodiment of the invention; 
     FIG. 7 is a time chart showing the delay operation of a delay-off relay employed in the preferred embodiment of the invention; and 
     FIG. 8 is a time chart showing the operation of contacts in the holding relay circuit of the first zone, as shown in FIG. 5. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIG. 4, there is illustrated an improved electric power supply control means co-operative with a vehicle or carriage position detecting means, which in FIG. 4 is illustrated in a manner similar to FIG. 3. 
     For convenience of description, features and elements corresponding to the features and elements in the prior art, shown in FIG. 3, and having substantially the same functions, are indicated by the same reference numerals. 
     A pair of current-carrying cables 22, 24 are both separated at regular intervals by insulating members in order to define independent electric power supply zones in a way similar to that illustrated in FIG. 2. The intervals between respective insulating members will be determined with regard to the expected maximum speed of the vehicle or carriage. In other words, the minimum length of each zone may be determined from the braking distance, for the safety and security of the automatic centralized control of the vehicles or carriages. Thus, the length of each power supply zone will normally be longer than the braking distance of a vehicle or carriage travelling at the maximum speed, so that even in the worst possible case a carriage cannot overshoot more than one power supply zone, and collisions between carriages can be prevented. 
     The vehicle or carriage 2 has an electrical driving means 9 such as an electric driving motor which is associated with an automatic braking means (not shown). The automatic braking means may be mounted on the vehicle or carriage and operates to brake the vehicle or carriage when electric power is not supplied or is less than a certain required current. In practice, an automatic braking device which operates when an electric power is not supplied thereto, can be embodied in various fashions. In the purpose sought in such vehicle or carriage, it may be apparent to those skilled in the art that one of the preferred constructions may comprise an electromagnetic brake having a braking member biased by a resilient member toward the driving wheels and a means pulling the braking member in the direction away from the driving wheels against the force of resilient member. The means is operated by electric power. Thus, the electromagnetic brake operates to brake the vehicle or carriage when the means for pulling the braking member is in an inoperative position. 
     The vehicle or carriage 2 further has a current collecting unit 7 including a pair of current shoes 82, 84 which resiliently contact the current-carrying cables 22, 24. The shoes 82, 84 supply electric power to the vehicle or carriage 2. Between the shoes 82, 84 is provided a bypass circuit 92 parallel with the driving means and directly connecting the shoes 82, 84. A resistor 94 is provided in the bypass circuit 92 so as to limit the electric current flowing therethrough in co-operation with hereafter described resistors in the electric power supply circuit. 
     The current-carrying cables 22, 24 are connected to power cables 28, 30 through an electric power supply control means 40. 
     The power supply control means generally comprises a switching circuit including a contactor 48 electrically associated with a holding relay circuit 50, further described below, through contact 52 of the holding relay 50. The contactor 48 has a pair of contacts 46, 47 respectively interposed between the power cables 28, 30 and current-carrying cables 22, 24 in an electric power supply circuit 54. A pair of bypass circuits 55, 56, including resistors 57, 58, respectively, are provided in the power supply circuit 54 in parallel with the contacts 46, 47 of the contactor 48 and directly connecting with the power supply circuit 54 to the current carrying cables 22, 24. Thereby, even when the contactor 48 is not excited and thus the contacts 46, 47 of the contactor 48 are opened, a small electric current may flow in the power supply circuit 54. 
     The bypass circuit 92 of the carriage 2 thus co-operates with the bypass circuits 55, 56 to form an electric circuit, even when the driving means of the vehicle or carriage is stopped for some reason, for example, because a previous vehicle or carriage is still in the adjacent zone. The current flowing in the power supply circuit through the bypass circuit 92 and the bypass circuits 55, 56 is given by the following formula: 
     
         I=E/2R.sub.1 +R.sub.2 +R.sub.0) 
    
     wherein 
     R 1  : value of resistors 57 and 58 
     R 2  : value of resistor 92 
     R 0  : resistance of power cables and current-carrying cables 
     E: supplied voltage 
     In the preferred embodiment, the values of the resistors 57, 58 and 94 are selected so as to pass a current in the range 10 mA to 30 mA, when a carriage 2 is in the zone but the driving means thereof is not operating. 
     The current flowing in the zone is detected by a current transformer 70 provided between the current-carrying cable 22 and contact 46 of the contactor 48. A gate 72 having a contact 74 which is closed when the current flowing therethrough exceeds a predetermined value, and which is in practice a leakage detector, is connected to the current transformer 70. The contact 74 of the gate 72 is connected to detecting relay 76 which detects a current flowing therethrough. 
     Thus, if there is a carraige in the zone, at least the predetermined minimum current, for example, 10 mA to 30 mA, flows within the power supply circuit. The current transformer 70 then supplies a current to the gate 72. The gate 72 is thus energized to close the contact 74 to allow a current to flow to the detecting relay 76, which then operates. Thus, the existence of a carriage in the zone can be detected. 
     Clearly, if a carriage 2 within the zone is being driven, the current flowing will exceed the predetermined minimum value and will be detected, the same as if it is stationary. The gate 72 is not an essential feature of the invention, and in a simpler embodiment the current transformer 70 may be directly connected to the detecting relay 76. In the preferred embodiment, however, the gate 72 is used to ensure that tiny stray currents do not affect the power supply control means. 
     Now referring to FIGS. 5 through 8, there are illustrated control circuits including holding relays, corresponding to the holding relay 50 of FIG. 2. In FIG. 5, are shown control circuits 100, 200, 300 . . . which correspond respectively to independent electric power supplying zones I, II, III, . . . The control circuits 100, 200, and 300 include holding relays 150, 250 and 350 respectively which correspond to the holding relay 50 of FIG. 2. 
     Each holding relay 150, 250 and 350 has a set-input terminal S and reset-input terminal R both of which are connected with carriage position detecting means in the electric power supply control means of the following power supply zones. Namely, the holding relay 150 of the first power supply control means in the first zone I is connected to the vehicle or carriage position detecting means of the second power supply zone II. 
     Each holding relay 150, 250, 350 further has contacts connected with the contactor of the power supply control circuit, as generally shown in FIG. 4. Thus, each holding relay 150, 250, 350 is electrically associated with the power supply control circuit in order to break the power supply control circuit when a preceding carriage is in the adjacent zone. This function of the holding relay and the contactor of the power supply control circuit will have been understood from the above description with reference to FIG. 4. 
     Now, we go into further detail of the holding relay control circuit. For better understanding and convenience for illustration of the preferred embodiment, the features and elements of the holding relay control circuit will be described in terms of the functions thereof. 
     With respect to the holding relay control circuit 100 of the first zone I, the set-input terminal S of the holding relay 150 is connected with an auxiliary power source 600 through normally closed contact 276b of a detecting relay (corresponding to the detecting relay 76 of FIG. 4) of the vehicle or carriage position detecting means in the second zone II, normally opened contact 280a of an off-delay relay 280 co-operative with the detecting relay of the vehicle or carriage position detecting means in the second zone, normally opened contact 376a 2  of the detecting relay of the vehicle or carriage position detecting means in the third zone III and normally opened contact 384a of an on-delay relay 384 co-operative with the detecting relay of the third zone. 
     The on-delay relay 384 is connected with a normally closed contact 382b of an on-delay relay 382 so as to be operated as the on-delay relay 382 is operated. The contacts 276b, 280a, 376a 2  and 384a in series constitute and AND circuit, so that to connect the set-input terminal S of the holding relay 150 to the power source 600 requires all the contacts 276b 280a, 376a 2  and 384a to be closed. 
     The time delay relays, referred to as on-delay relays and off-delay relays, are of a well known type and the operation thereof will be briefly described with reference to FIGS. 6 and 7. 
     Suppose that an off-delay relay is turned on at a time t 1  and turned off at a time t 2  as seen in waveform (A) of FIG. 6, its contact a closes at the time t 1  and opens at a time t 2  &#39; which comes a predetermined delay time τ after the time t 2  as seen in waveform (B) of FIG. 6, whereas its contact b opens at the time t 1  and closes at the time t 2  &#39; as seen in waveform (C) of FIG. 6. Again suppose that an on-delay relay is turned on at a time t 1  and turned off at a time t 2  as seen in waveform (A) of FIG. 7, its contact a opens at a time t 1  &#39; which comes a predetermined delay time τ after the time t 1  and opens at the time t 2  as seen in waveform (B) of FIG. 7, whereas its contact b opens at the time t 1  &#39; and closes at the time t 2  as seen in waveform (C) of FIG. 7. 
     The operation of the keep relay control circuit of FIG. 5 will be described with reference to the circuit 100 of FIG. 5. 
     The reset-input terminal R of the holding relay 150 is connected with the power source 600 through normally opened contact 276a 1  of the detecting relay of the second zone II. 
     When a vehicle or carriage is present within the zone II, at least a predetermined minimum electric current flows within the second zone II. Thus, the detecting relay of the vehicle or carriage position detecting means in the second zone II operates to open the normally closed contact 276b thereof to break the circuit connecting the power source to the set-input terminal S of the holding relay 150 and to close normally opened contact 276a 1 . This results in supplying electric power to the reset-input terminal R of the holding relay 150 to open the contact (corresponding to contact 52 of FIG. 4) thereof and thus to open the contacts of the contactor (corresponding to contactor 48 of FIG. 4) of the power supply control circuit in the first zone I. Thereby, in the first zone I, as shown in FIG. 4, the current-carrying cables 22, 24 are connected with the power cable 28, 30 through the bypass circuits 55, 56 to limit the electric current to between 10 mA to 30 mA. Now, if a vehicle or carriage enters into the first zone I, only this very small current is supplied to the driving means 9 of the carriage, so effecting power is shut off, and the driving means is not actuated, but on the other hand a sufficient minimum current flows to enable the vehicle or carriage position detecting means for the first zone I to operate. The reduction of current to this minimum value may also be used to operate the automatic brake device contained in the vehicle or carriage to stop the vehicle or carriage within the zone I. 
     It should be noted parenthetically that by employment of such automatic braking, when electric power supply to the power cables is interrupted and all the control circuits become inoperative, the vehicle or carriage will be safely stopped by actuation of the braking device. 
     At the same time, because contact 276a 1  is closed, the off-delay relay 280 is energized to close the normally opened contact 280a. The state of the remaining contacts 376a 2  and 384a depends on whether or not there is a vehicle or carriage in the zone III. If there is, then the vehicle or carriage in the zone II will be reached when zone III is empty. For the purpose of this explanation, therefore, it may be assumed that there is no vehicle or carriage in the zone III. Accordingly, contacts 376a 1  and 376a 2  will be opened and on-delay relay 382 will not be operated. Therefore normally closed contacts 382b are closed and the on-delay relay 384 operates to close the normally opened contact 384a. 
     When the vehicle or carriage leaves the second zone II and enters the third zone III, the detecting relay of the vehicle or carriage position detecting means in the second zone II becomes inoperative, thereby allowing the normally opened contact 276a 1  to open, thus cutting off power to the reset-input terminal R of the holding relay 150. In turn, then, the normally closed contact 276b moves to a closed position. When the contact 276a 1  is opened, the off-delay relay 280 is deenergized, but the contact 280a remains closed for the predetermined delay τ 1  (as shown in FIG. 6). At the same time, the detecting relay of the third zone III detects an electric current above the predetermined minimum value flowing through the power supply circuit in the third zone III; it closes normally opened contacts 376a 1  and 376a 2 , and opens normally closed contact 376b. Therefore, just after the moment the carriage enters the zone III all four of contacts 276b, 280a, 376a 2  and 384a are closed, and power is supplied to the set-input terminal S of the holding relay 150. Power continues to be supplied until either of contacts 280a and 384a opens. Contact 280a is opened when the time delay τ 1  of the off-delay relay 280 has elapsed. The contact 384a opens when the time delay τ 2  of the on-delay relay 382 has elapsed. On-delay relay 382 is energized when the contacts 376a 1  are closed; after the delay τ 2 , contacts 382b are opened, on-delay relay 384 is deenergized, and immediately contact 384a opens. Thus power is supplied to the set terminal for a pulse of length the minimum of τ 1  and τ 2 , and the holding relay is energized, and connects the power supply to the zone I by means of the contactor. 
     In the preferred embodiment, the delay time τ 2  of the on-delay relay 384 is shorter than the delay time τ 1  of the off-delay relay 280, and thus the pulse duration is τ 2 . 
     FIG. 8 shows the state of contacts 276a 1 , 276b, 280a, 376a 2 , 376a 1 , 382b and 384a and the supply of power to the set-input terminal of holding relay 150. The presence of a single vehicle or carriage in zone I, II or III is shown respectively by sections A, B and C. If we now consider the vehicle or carriage leaving zone III, contacts 376a 1  and 376a 2  open immediately, and on-delay relay 382 is deenergized. Immediately, contact 382b closes, and energizes on-delay relay 384. After the delay τ 3  associated with the on-delay relay 384 has elapsed, contact 384a closes. It will be seen from FIG. 8 that this delay τ 3  prevents a spurious pulse to the set-input terminal S of the holding relay 150 at the moment a vehicle or carriage just happens to enter zone II. 
     With respect to the holding relays 250 and 350, and control circuits 200 and 300 of the second and third power supply zones II and III, each control circuit 200, 300 is constructed substantially the same as the control circuit 100 of the first zone I. The function of each control circuit is also substantially the same as that of control circuit 100. 
     The set-input terminal S of the holding relay 250 is connected with the power source 600 through normally closed contact 376b of vehicle or carriage position detecting means of the third zone III, normally opened contact 380a of off-delay timer 380, normally opened contact 476g 2  of the vehicle or carriage position detecting means of the fourth zone IV and normally opened contact 484a of on-delay timer 484. The on-delay timer 484 is associated with an on-delay timer 482 through normally closed contact 382b of the on-delay timer 382. While, the reset-input terminal R of the holding relay 250 is connected with the power source 600 through normally opened contact 376a 1  of the vehicle or carriage position detecting means in the third zone. 
     The set-input terminal S of the third holding relay 350 of the third zone III is connected to the power source 600 through normally closed contact 476b of the detecting relay of the vehicle or carriage position detecting means in the fourth zone IV, normally opened contact 480a of off-delay timer 480, normally opened contact 576a 2  of the detecting relay of vehicle or carriage position detecting means in the fifth zone and normally opened contact 584a of an on-delay timer in the fifth zone, corresponding to on-delay timers 384 and 484, associated with an on-delay timer corresponding to on-delay timers 382 and 482 through a normally closed contact corresponding to closed contacts 382b and 482b. The reset-input terminal R of the holding relay 350 is connected with the power source 600 through normally opened contact 476a 1  of detecting relay of vehicle or carriage position detecting means in the fourth zone. 
     In the second zone, the normally closed contact 376b, the normally opened contacts 380a, 476a 2 , 484a and the normally opened contacts 376a 1  are respectively corresponding to the normally closed contact 276b, the normally opened contacts 280a, 376a 2 , 384a and the normally opened contact 276a 1  of the first zone. The contacts 476b, 480a, 576a 2 , 584a and 476a 1  of the holding relay control circuit 300 are also corresponding to the contacts 276b, 280a, 376a 2 , 384a and 276a 1  of the first holding relay control circuit 100. Thereby, the functions of respective contacts of the second and third holding relay control circuits are substantially same as the contacts of the first holding relay control circuit 100. 
     It should be noted, since respective holding relays 150, 250 and 350 can keep their operative and inoperative positions until the next charge of electric power from the power source 600, the pulse-like voltage supplied to respective set-input terminals S of the holding relays 150, 250 and 350 may efficiently change the position of the holding relays from inoperative to operative. 
     At a junction or confluence of the cableway or tramway, or at a portion within or adjacent to a station, the power supply control circuit may be provided on each branch of the cableway or tramway. Each control circuit will be arranged with holding relays and contacts (corresponding to the contact 52 of FIG. 4), so that they allow the selective supplying of electric power to either branch circuit. Each control circuit will be associated with vehicle or carriage position detecting means in each branched zone. 
     Thus, the present invention, constructed as above-mentioned, fulfills all the objects and advantages sought in the invention. 
     While the present invention has been shown and described with respect to the preferred embodiment, it should not, however, be considered as limited to this embodiment or other detailed embodiments. Further, variations could be made to the form and the details of any parts or elements, without departing from the principles of the invention. For example, the pair of time delay relays 282 and 284 in FIG. 5 may be replaced, in an alternative and equivalent circuit, by a relay with both on and off delays. Therefore, it is desired that the scope of the present invention, and the breadth of the protection sought to be granted by Letters Patent, should be defined solely by the accompanying claims.