Patent GB-511778-A (GB)
Title: Means for controlling the motion of lift cars and other devices having a similar motion
IPC: B66B1/52
Filed: 1938-02-21
Abstract: 511,778. Lifts. POLLARD & CO., Ltd., E., and FLETCHER, R. C. Feb. 21, 1938, No. 5394. [Class 78 (iii)]. [Also in Group XXXVII] Means for controlling the motion of a lift car or other device having a similar motion between a number of fixed stations comprises a 'number of switch operating members which are each arranged to be actuated in accordance with the position of the lift car or other device and which are arranged to maintain closed the circuit of the motor until shortly before the lift reaches a desired station and a further number of switch members arranged to be rotated upon movement of the movable device so that these members make a number of revolutions during the complete travel of the lift between its terminal stations and which are arranged to maintain the circuit of the motor closed whilst the movable device continues its motion to the desired station and to open the motor circuit upon arrival of the device at that station. On actuation of an appropriate switch in the lift, the circuit is completed by a corresponding switch member 7a ... 7f to operate one of the contactor coils 9U or 9D and in addition one of the relays 4<1> ... 4<4> which locks up over its contact 4<1>b ... 4<1>b. The energised relay operates an associated contact 4<1>d ... 4'd which prepares an auxiliary circuit for the contactor coil 9U or 9D. The switch contact 7a ... 7f is opened when the lift car approaches the desired floor level, and an auxiliary circuit for the contactor is completed by an appropriate switch contact 11a ... 11f controlled by one of a number of cams 21, Fig. 2, mounted on a shaft 17 carrying the driving drum 15 for the car 13. The shaft 19 on which the cams 20 are mounted makes slightly less than one revolution during the complete travel of the car in one direction. A modification, Fig. 3, comprises a slowing arrangement comprising slowing contactor coils SCU, SCD, one of which is energized when a contact 7 is closed. The operated contact SCD prevents the other contactor being energized and over contact SCU2 or SCD2 and conductor 25 effects the operation of contactor coil 9U or 9D. Relay H is also operated and operates the coil EMR of an eddy-brake relay. When the lift is at-a short distance from the floor level desired the corresponding contact 7 is opened, relay SCU or SCD is de-energized and the circuit of contactor 9U is maintained over the appropriate contact 11, contact EMR, contact 9U, restored contact SCU3, and contact 9D2, this circuit being opened by the member 11 when the lift car is at the appropriate floor level. To prevent the contactor 9U or 9D being again energized if the car overshoots a floor, contacts 9U3, 9U4 are arranged in parallel with each other and in series with the coil 9U. The contact 9U3 is normally open and is arranged to close instantaneously on the operation of the coil 9U, whilst contact 9U4 is normally closed and closes slowly after contactor coil 9U3 has been de-energized. Contacts IIX and IIV are provided to control the correct positioning of the lift car if it overshoots the top or bottom floor. The arrangement may be applied to pneumatic or hydraulic lifts if the switches and their operating member are replaced by valves and corresponding operating members in connection with a source of pneumatic or hydraulic power.