Patent GB-190716636-A (GB)
Title: Improvements in and connected with Brakes for Elevators.
Inventor: MEECH ALFRED HARRISON
Filed: 1907-07-20
Granted: 1908-06-11
Abstract: 16,636. Meech, A. H. July 20. Lifts; safety suspending-apparatus; brakes.- Compressed-air lift brakes of the kind descrihed in Specification No. 6176, A.D. 1903, are controlled either by hand or by a centrifugal governor, and the driving-motor is automatically cut out when the pressure is inadequate, or when the brakes are applied, the available air-pressure being shown by indicators in the cage. Fig. 1 is a general view of the mechanism, the parts being diagrammatically arranged. The main features of the apparatus are a reservoir 4 on the base of the cage, a handoperated valve 5 and a governor 8 for controlling the brakes, braking-mechanism 6, and automatic power cut-off mechanism 7. The reservoir 4 on the cage is connected through a one-way valve and flexible tubing 10 with a main reservoir 4<a>, Fig. 13, the air pressure in the reservoir 4 and in the flexible tubing 10 being indicated by a pair of pointers on a dial 25. The reservoir communicates by means of a pipe 28 with the valve casing 5, a second pipe 50 leading from this casing to a pair of brakeoperating cylinders 6 secured to the lower portion of the cage close to the guides 3. The brake cylinders, Fig. 9, are preferably formed integral with guide brackets 56 which slide on the guide rails, and contain a spring-pressed piston, which is connected by a rod 59 and toggles 60 to levers 63 pivoted in lugs on the cylinder. The opposite ends of the levers are pivotally connected by links 66 to pendulum-like brake blocks 57 enclosing the guide or auxiliary rail 3. The operator's brake valve, Fig. 11, comprises a casing 30, having a cylinder 32 at one end and an operating-handle 33 at the other. The reciprocating valve member 40 is held in its seat by a spring, and is provided with a recess 40<a> adapted to connect either the pipes 28, 50, or the pipes 50, 51. In the former position, air is supplied from the reservoir to the brake cylinder ; and in the latter position, the brake cylinders are opened to the exhaust pipe 51. The brake-operating lever 33 moves over a sector having three notches, the intermediate one giving a gradual application of the brakes. The valve is also operated by means of the piston 47, when air is admitted through the pipe 52, which is in connexion with a governor-controlled valve, Fig. 8. The governor is driven by a pulley 123, round which passes a rope 136, Fig. 1, secured at the top of the lift well, and passed round a tensioning sheave at the base. The rope 136 is guided by sheaves 138 mounted at the edge of the cage, and is then crossed and passed round the sheave 123. The governor comprises a number of flexible straps 125, carrying balls at their centre and connected at their ends to the sheave 123 and to the sliding-member 124 respectively. The spring- pressed valve-rod 114 carries an adjustable collar 119 lying in the path of the sliding-member 124. The valve 114 normally closes a port 112, but on the occurrence of excessive speed, air is admitted from the reservoir to the pipe 52 connected to the valve-operating cylinder 32. The inner end of this cylinder is always open to exhaust by means of the duct 39. The governor is enclosed in a casing secured to the base of the cage and provided with suitable openings for the passage of the driving- rope. The bearings of the sheave and the sliding-member 124 are provided with suitable lubricating-means. Fig. 6 shows one form of a device for cutting off the driving-power when the brakes are applied. A cylinder 81, adjustaby supported on the cage, contains a spring-pressed piston 86, the rod of which has a head 89 adapted to engage a tappet arm 94 on the shaft of the starting-handle 77. The stroke of the piston is adjusted by means of a nut 93 screwed on a boss projecting inwardly from the cylinder cover. The piston is operated by compressed air supplied by a pipe 95, which is normally connected by a two-way valve 96 with the pipe 50 leading to the brake cylinders. To release the starting-handle without taking off the brakes, the valve 96 is swung over so as to connect the pipe 95 to the exhaust pipe 51. The controlling-device shown in the drawings forms no part of the invention ; it consists of an horizontal rock-shaft 72, carrying laterally extending arms 73, to which is connected a crossed cable 75 passing around rollers 76 mounted on opposite sides of the motor-controlling sheave 74. When the invention is applied to the form of controlling-gear in which a hand rope is used, the head 89 on the piston-rod is adapted to press the hand rope 98<a> against fixed rollers 99, as shown in Fig. 7, and thus cut off the driving-power. Figs. 13 and 14 show a device for automatically throttling or cutting-out the driving- motor, when the air pressure in the main reservoir 4<a> is inadequate for the operation of the brakes &c. In the form shown, the cage is raised by an electromotor driving a drum 146, the motor controller 148<a> being connected by a rod to a pulley 147 geared to the sheave 74. A cut-out in the motor circuit comprises a pair of pivoted elbow-levers 169, adapted to be swung out of engagement with the contacts 166 by the spring 163, when the pressure falls within the cylinder 160. This cylinder communicates by a pipe 161 with the main reservoir, which is supplied with compressed air by compressors 155, driven by steam-engines 154. Steam is supplied through a pipe 56 having two branches in each of which is mounted a hand-valve, and an automatic valve, the latter being held closed by the pressure in the reservoir, and adapted to open when the pressure falls below a certain point.