Patent GB-189921778-A (GB)
Title: Improvements in Electrically Controlled Elevators or Lifts.
Inventor: ROWNTREE HAROLD
Filed: 1899-10-31
Granted: 1900-06-23
Abstract: 21,778. Rowntree, H. Oct. 31. Lifts, cage. Relates to electrically operated and controlled lifts, in which (1) the cage being at rest at any landing, it can be sent to any other lauding by pressing a button at any one landing ; (2) once started the motion of the cage cannot be arrested or reversed until it has arrived at the landing to which sent ; (3) the cage slows down and stops automatically ; and (4) the cage cannot be operated so long as a door at any one of the landings is open. Fig. 1 shows an end view of the controlling- apparatus, and Fig. 2 a side view. An electromotor of any type drives a winding-drum E, which is geared to a screw H, carrying a nut J, which is prevented from rotating. The position of the nut J therefore depends upon the position of the cage in the well. Above the screw H a shaft M is mounted, carrying a number of projections 0, one for each landing, arranged spirally. This shaft can be rotated by the operating-rope passing down the well, which acts through a sprocket-wheel 39, and it is also free to slide a short distance longitudinally, thus causing a depending bar Q to rock on one or other of the bearings R and S. The bar Q is linked at 69 to a bar 68, pivoted at its lower end to the frame and connected at its upper end to a rod 67, the outer end of which projects into the path of the reversing-switch, and thus locks it during motion of the lift. The contact-bars 20 and 21 of the main switches are mounted on a frame 18, which swings on a bar 19, and is linked by a bar 15 to the bar Q. A third contact-bar 28 connects at the proper moment the terminals 29 and 30, thus establishing a shunt circuit to slow down the motor, as the stopping-place is approached, by diverting part of the armature current either through a resistance and the field coils or through auxiliary field coils. The reversing-switch consists of four spring contacts mounted on a plate 50, which is free to rock on the sleeve 38 from its one position to the other. This rocking motion is effected by ratchet-wheels 57 and 58, which engage with oppositely-disposed pawls pivoted to the plate 51, these pawls being automatically disengaged by contact with a stop as soon as the desired position is attained. Beyond this point further rotation of the shaft M and wheels 57 and 58 in the same direction produces no effect on the reversing-switch. The action ;is as follows :- When the cage is at rest at a landing the nut J is in contact with a pawl 0, the bar M is in one of its extreme positions, and the reversing-switch is consequently unlocked. At the same time the main switches 20 and 21 are open, and the slowing- down switch 28 is closed. When the rope is operated to move the cage to another landing, the shaft M is rotated to bring the corresponding lug D into the path of the nut J. The shaft M is thus free to move longitudinally under the action of a spring acting through the rod Q, until the latter rests on both rocking bars R and S. The reversing- switch 50 is simultaneously locked by the rod 67, the switch 28 is opened, and the switches 20 and 21 closed. The motor is thus started. As the cage approaches the required landing, the nut J strikes the corresponding pawl 0, and moves the shaft M longitudinally against the spring, thus rocking the bar Q, and through the connection 15 closing the slowing-down switch 28, and finally opening the main switches 20 and 21. The reversing- switch 50 is also unlocked by the withdrawal of the bar 67. A band brake, which during the motion of the cage is kept off by a solenoid 74, is put on when the current is broken. The application of the invention is shown to a lift of the dumb-waiter type in which the shaft M is operated by a sprocket chain which engages with a sprocketwheel at each landing on the axle of a dial indicator. Each sprocket-wheel is locked, when the well-door is open, by a catch operated by the balance weight of the door.