Patent GB-545809-A (GB)
Title: Improvements in or relating to mechanical power transmission apparatus for lift systems
IPC: B66B11/04
Filed: 1940-11-15
Abstract: 545,809. Lift systems. EXPRESS LIFT CO., Ltd., and DIXIE, W. A. Nov. 15, 1940, No. 16553. [Class 78 (iii)] In lift systems in which the car is levelled at the landings by reducing the car speed from normal to a low value, mechanical transmission apparatus employing simple electrical control means and changing the speed of the car without interruption of power drive between the motor and the car is provided by employing fluid coupling or fluid torque converter in combination with epicyclic or other gearing capable of being engaged under load. Thus the motor 1, Fig. 2, drives the impeller 9 of a fluid coupling and fast with it the casing of reduction gear 4, one sun-wheel 18 of which is fast to the shaft 11 keyed to the runner of the coupling. The second sun-wheel 19 is loose on the shaft 11 and fast with a brake drum 23 and the shaft 11 passing through a bearing 14 is keyed to the lift brake drum 12 and a worm gear 5 driving the lift driving sheave. The brake shoes 24 and 15 for the gear and the lift are fully applied when there is no current to their operating coils, but the gear brake coil has a slow build up, so that to operate the lift the motor 1 is switched in and starts up and its brake 15 lifted, the sun-wheel 19 is held by the slow acting gear brake and the motor drives the shaft 11 and sheave through the slow reduction gear. When the motor has reached full speed and the car has reached levelling speed the slow coil cuts out the gear brake and the fluid coupling takes over the drive at normal car speed. As there is no load on starting a squirrel cage induction motor may be used with simple controls. The fluid coupling may be of the type having a reservoir collecting the most of the fluid below a certain speed or may be of the movable scoop type, as shown in Fig. 6, which also shows the gear casing grooved to take belt drive for a small D.C. generator for the control current. This also shows a one-direction motor 1 and a bevel reversing gear with dog-clutch 42 enabling a simple continuous only motor to be used, the clutch being operated by solenoids and the planetary gear brake shoes being free of the drum while the lift is stationary and applied by the solenoid when the motor is up to speed. At levelling speed, as detected for example by a governor, the scoop 29 is lowered into the fluid and the coupling builds up the drive and takes over, the planetary brake being automatically released by its spring. Instead of a dog-clutch, planetary gear with three sunwheels might be used, two of the sun-wheels being loose on the shaft and having separate brake drums by selected operation of whose brakes the direction could be changed. Fig. 8 shows the use of such planetary gear direction changer fitted with a one-direction motor and fluid-epicyclic combination. In a further modification a one-direction motor may drive reversely through a bevel wheel a pair of bevel pinions, each fast to the impeller casing of a scoop-fluid-coupling the runners of which are keyed to a single shaft, the casings each carrying the spindles of pairs of planet wheels similar to those in Fig. 2, the pairs of sun-wheels being mounted one fast and one loose on the single shaft and the two loose sun-wheels being fast each to its brake drum. Each impeller has a scoop and the direction of travel is chosen by the scoop actuated. A two-speed motor may be used with any of the arrangements above described the scoop type of coupling can then be replaced by the simple traction coupling shown in Fig. 2. The fluid-coupling and gear combination above described not only enables simple electric control means to be used but affords safe and advantageous working in case of faults in the main electric supply. The drive to, the winding sheave of the lift may be of the multi-vee belt kind described in Specification 544,972.