Patent GB-339719-A (GB)
Title: Improvements in or relating to safety apparatus for elevators and the like
IPC: B66B5/04
Filed: 1929-10-10
Abstract: 339,719. Westinghouse Electric & Manufacturing Co., (Assignees of Sprague, F. J.). Oct. 10, 1928, [Convention date]. Catch gear and like, safety retaining-mechanism.-In a lift system electrically-actuated means are provided for applying the brakes whenever a predetermined acceleration is exceeded. The braking device comprises two pairs of jaws 15, 16 which grip the guide rails 12, 13. The jaws are connected by threaded rods 17, 18 to a drum 19 on which is wound a rope 20. One end of the rope is secured to the drum and the other end is secured to a rope 23 which passes over a sheave on a centrifugal governor 26. The rope 23 is attached to the cage by a yielding connection 24. The movable rod 36 of the governor extends downwardly through a lever 38 which is pivoted to a standard 39. When the right hand end of the lever 38 is raised, it turns the cam lever 44 to wedge the rope 23 between it and a co-operating jaw 45. When the rope is locked, it will be pulled free from the connection 24, and the rope 20 will unwind from the drum 19 and the brakes will be applied. The other end of the lever 38 extends beneath a weighted actuating mechanism 50 which is controlled by an electromagnet 51 and is pivoted to the bracket 39. The electromagnet 51 is connected to the leads L1, L2 through contact members b of the relay 48 so that when this relay is de-energized, the member 50 will drop and the brake will be applied. A relay 48 for controlling circuits for the electromagnet 51 is reset after being de-energized by a switch 56 on the cage. The acceleration-controlled device 49 comprises a weighted member 60 mounted on the free end of a pivoted arm 61 and a pair of contact members 63, 64 actuated thereby for controlling the circuit of the coil of the relay 48. A contact member 63 is mounted on the weighted member 60, and a contact 64 is secured to the cage in such a position that it engages the member 63 and supports the member 60 in a horizontal position while the cage is running normally. In order that the member 60 may be effective to open the contacts 63, 64 at any selected rate of acceleration less than 32 ft. per sec. it is partially supported by a tension spring 65, the upper end of which is secured to a threaded member 66 mounted in a bracket 67. The tension of the spring is adjusted by a nut 68 on the member 66, and a pointer 69 cooperates with a scale 70 to indicate the adjustment in terms of rate of acceleration. The contact 13 is made of resilient material in order that the circuit may not be broken by the jolting of the cage. The free end of the contact 63 is disposed between stop members 71, 72 on the weighted member. A stop 73 limits the upward movement of the member 60. A normally closed switch 74 on the cage in the circuit of the relay 48 can be opened at any time by the attendant to effect the operation of the safety device. The relay also is de-energized when a switch 75 is opened by the governor. In order that the mechanism may differentiate between down acceleration and up retardation, a discharge resistance 79 is shunted across the terminals of the relay 48 slightly to delay its action. This delay will prevent the actuation of the safety device on a too sudden up stop because the influence of the latter is of very short duration. In a modification a weighted member corresponding in function to the member 60 is rotatably mounted on the hub of a disc secured to the shaft 27.