Patent GB-671286-A (GB)
Title: Improvements in or relating to safety devices for elevator systems or the like
IPC: B66B5/18
Filed: 1950-06-20
Abstract: 671,286. Safety devices for lifts. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. June 20, 1950. [July 20, 1949] No. 15362/50. Class 78 (iii). An elevator system has a brake mechanism including rollers mounted on the movable body, for movement in a path, adjacent guide rails, the rollers being normally disengaged from the guide rails, brake operating means is mounted completely on the movable body for actuating the rollers into wedging engagement with the guide rails in response to increase of the acceleration of the movable body above a predetermined value. A sling 1 with guide shoes 3 travels on guides 5 and supports an elevator 15. The governor rope 9 has a governor device 11 whereby centrifugal weights in the governor 11 operate a brake to engage the governor rope at a predetermined speed. The governor may have an electric switch 33 which opens when the brake is applied for stopping the motion. At a greater speed the rope slips and the main braking device comes into operation. The sling has a safety device 7 connected with and operated by the governor rope 9. The braking unit 37 comprises levers 41, 43 pivoted on a pin 45, secured to two spaced plates 47, 49 and to channelled members, 51, 53. The levers have jaws 41a, 43a, one on either side of the guide rail. The lever arms 41b, 43b are biased by a spring 55 with a through bolt 57 which limits movement, the arm 43b also has a, stop 63. A spring 61 joins the arm 41b with the channel member 53. The jaw 43a has a cavity 77 in which is a roller 65 retained between lugs 73, 75 on a lever 67 connected to a shaft 69 mounted to rotate in brackets on the channel members 53. As the shaft 69 rotates the roller 65 is moved upwardly to engage the guide rail and produce a braking effect and the jaw 43a is moved away from the guide rail causing the jaw 41a to be moved by the action of the spring 55 toward the guide rail. To release the brake easily, a second roller 81 is provided in a cavity 83 in the jaw 41a which, as the jaw is rotated, is moved into braking engagement with the guide rail. The rollers 65, 81, spread the jaws 41a, 43a and compress the spring 55. The shaft (i9 is rotated by a weight W connected by an arm Wa with the shaft 69, a second arm compresses a spring 89 mounted on a rod secured to the channel member. When the elevator is moving under gravity the couples due to the weight and tension of the spring balance, on greater acceleration the couple due to the weight increases, the shaft 69 is rotated and the rollers move into braking position. A similar braking unit 39 operates on the other guide rail. The brake may be applied by the action of a spring and cam. A shackle 111, Fig. 3, is connected to the rope 9 and can be moved upwardly by compressing a spring 115 which is limited by a sleeve surrounding a rod 113 connected with the shackle and slidably passing through the plate 49. The shackle has a cam 125 beneath the lever 67, upward movement of the shackle rotates the lever 67 and the shaft 69 through the cam to set the braking units. The device 7 is reset by reversing the direction of motion of the elevator. The device may be connected to the elevator counterweight. The traction sheave 17 is rotated by a motor 21 energized by a motor control 23 from a source of energy 25 through a circuit interrupter 27 with an electromagnetic brake 28. The interrupter is retained in a closed position by a latch 27 tripped by a spring 27b. A solenoid tripped 27 d, energized by a battery 29, develops a force opposed to the spring 27b. If the circuit interrupter is closed and the solenoid 27d is energized the interrupter remains closed until the solenoid is de-energized by operating the manual switch 31 or safety switches 33, 35. The safety switch 35 is provided on the safety device 7 and may be operated by rotation of the cross shaft 69.