Patent GB-190309382-A (GB)
Title: Improvements in Electric Lifts.
Inventor: STEVENS JOHN SANDERS
Filed: 1903-04-25
Granted: 1904-03-10
Abstract: 9382. Stevens, E. C., and Stevens, P. H., [executors of Stevens, J. S.], Major, C. G., Stevens, E. C., and Stevens, P. H. April 25. Lifts, electric. Relates to means for controlling electric lifts, more particularly of the kind described in Specification No. 15,764, A.D. 1902, and consists of improvements in the means for controlling the motor and preventing interference &c., and of improvements in the push-button switches and automatic selecting- devices &c., which may be used in connection with the first part of the invention. Fig. 1 shows one form of the first part of the invention. The motorcircuit switch A, the brake D, and the rheostat switch C, are actuated by a single main solenoid E, the core of which is connected at k to a lever K pivoted to the rods of both switches. The point k is nearer the switch A than the switch C, and consequently resistance is not cut out until the switch A is closed. As a further safeguard, the restraining-device described in the Specification cited above may be applied to the switch C. The reversing-switch B, by which the direction of rotation of the motor is determined, normally lies in one of its two extreme positions, and is only moved when the lift is to start in the reverse direction to its previous journey. The switch B and the main solenoid switch I connected with it, are moved by the up solenoid F or down solenoid G, in circuit, respectively, with the up switches H and down switches J. Interference is prevented by the switch I, and by the fact that whichever of the two solenoids F, G is first energized obtains command over the switches B, I. As a further safeguard and to prevent premature reversal, the tail of the rod a is arranged to lock into one of two slots in the reversing-switch bar. The switch I is then omitted, and the solenoids F, G are in circuit with the solenoid E. Alternatively, the circuits of the solenoids F, G pass through a switch on the bar a, which opens as soon as the switch A begins to move towards its closed position. In another modification, Fig. 4, the switch I only is carried on the core bar i of the solenoids F, G, and is held in its central open position by springs. The switch B is moved from the bar i through tappet levers Q, R, there being sufficient lost motion to ensure that the switch B is moved only when the direction of motion is to be reversed. By this arrangement, the push-button only has to break the current for the direction solenoid F or G, instead of that for the solenoid E, and the arc at the push-button is therefore materially lessened. The Provisional Specification describes the use of a dash-pot for the reversing-switch, means for preventing starting before all the resistance is reinserted, and a bell-crank form of lever K. The cage push-buttons 1, Fig. 8, comprised in the second part of the invention, are arranged in a row in front of a cylinder consisting of two contacts 6, 7, separated by a helical insulation strip 9, and in connection through brushes with the direction solenoids F, G respectively. The cylinder is fitted with a star-wheel 10, which, as the cage passes from floor to floor, engages tappets 14, the arrangement being such that, at any floor, the push-button brush 4 corresponding to that floor is opposite the insulation strip 9, and of the other brushes, those corresponding to floors above are opposite the contact 6 and those to floors below opposite the contact 7. Thus on pressing a particular button the motor is started in the appropriate direction, and, on the cage reaching the required floor, is stopped, owing to the strip 9 coming under the active brush 4 and breaking the circuit. Each cage switch comprises the button 1, the core 3 pivoted to the brush 4, and the retaining - solenoid 2 permanently in connection with one main and with the brush 4. The solenoid 2 may be arranged to blow out the arc at its brush 4. The movement of the star-wheel 10, in passing from one floor to the next, is effected, by two tappets 14, in two steps, one just after leaving a floor and the other just before reaching the next floor. A more accurate adjustment of the tappets is thus possible. To control and limit the movement of the star-wheel, it may be formed with a waved surface 30, Fig. 12, engaged by a spring-pressed wiper 31. In a modification, the cylinder is replaced by a sliding bar formed with two insulated parts corresponding to the contacts 6, 7 described above, and moved stepby-step either by tappets in the well and inclines on the bar or vice versÔ, or by rack and pinion gear actuated by a star-wheel such as described above. To save space in the cage, the brushes 4, solenoids 2, and contact cylinder &c. may be placed below the cage, the buttons being connected to the brushes &c. as described in the Specification before referred to. According to the Provisional Specification, the buttons may be arranged in a semicircle opposite a disc which replaces the contact cylinder.