GB819187A - Improvements in or relating to lift control systems - Google Patents

Abstract

819,187. Lift control systems. HALL Ltd., J. & E. Dec. 23, 1957 [Jan. 14, 1957], No. 1360/57. Class 78 (3). A selection mechanism for altering the modes of operation of a multi-car lift system comprises means for changing to a mode suitable for peak operation in one direction when a predetermined time relationship exists between the periods during which cars loaded in excess of a predetermined weight are travelling in said one direction. A system comprising cars A, B, C is described in which contacts bearing the prefix LSR are closed when the associated car is loaded above the predetermined weight, and contacts bearing the prefix U or D are closed when the associated car is travelling upwards or downwards respectively. Considering the operation of car A with manual selector switch MA on contact A and contacts LSRA1, UA1, LSRA2 and UA2 closed, due to car A travelling upwardly in a loaded condition, relay ULA is energized, thereby closing contacts ULA1- ULA4, and positive potential is supplied to the grid of valve TX thereby energizing relay UPT, connected in the anode circuit of this valve, and maintaining the energization for a period of time of about two minutes, determined by the time constant of the timing circuit of the valve, after either of contacts LSRA1 or UA1 have opened. Relay UPT closes a self-locking circuit for relay ULA over contacts UPT1 thereby holding closed contacts ULA1-ULA4 for the predetermined time period. Similar sets of contacts ULB1- ULB4 and ULC1-ULC4 are associated with cars B and C. When the contacts ULA2, ULB2 and ULC2 are closed at the same time, an " up peak " selector relay USR is energized thereby altering the mode of operation of the system to cope with " up-peak " conditions. A similar circuit including a timing valve TY operates a "down-peak " selector relay DSR. If during " up " or "down-peak " operation any two cars become loaded above the predetermined weight in the opposite direction, a relay BL is energized thereby de-energizing relay DSR over contacts BL2 and transferring the system to a "balanced peak mode of operation. If the " up " or "down-peak " traffic subsides the relays USR, DSR and BL are all de-energized and the system returns to a " normal " mode of operation. A clockcontrolled switch MA1 closes contacts 9, 12, 15 and 18 at predetermined times during the day thereby automatically overriding the above described mechanism and changing the system to up or down peak modes of operation. Switch MSS is also provided with overriding "up" and "down-peak" controlling contacts C and D. The selector mechanism is stated to be suitable for use in the system described in Specification 807,046.