Patent GB-190405078-A (GB)
Title: Improvements in Elevators
Inventor: CRUICKSHANK JAMES
Filed: 1904-03-01
Granted: 1904-04-07
Abstract: 5078. Cruickshank, J., and Burnham, C. S. March 1. Lifts; safety suspending or retaining apparatus; overwinding, preventing.-Relates chiefly to means for automatically arresting the motion of an elevator or lift cage on an excessive speed being attained. Stretched in the shaft are stout wires 28, Fig. 3, on which bars 29 are mounted at intervals by means of pins 44, between which the wires are flexed as shown in Fig. 4, so that a powerful resistance is offered to movement of the bars 29 on the wires. On the cage 20 are pivoted dogs 47, which when traversing the spaces between the bars 29, occupy their outermost positions as shown in Fig. 3, but are normally retracted when passing each bar. Should the speed become excessive, the dogs 47 remain extended and therefor engage the bars 29 immediately beneath them, and the cage is arrested by the resistance offered to the movement of the bars. The dogs 47 are oscillated from a governor device, Figs. 2 and 3, comprising cams 58 rotated by the movement of the cage and acting on the short arms 61 of weighted levers 62, connected through tappet rods 63, weighted levers 64, and links 65, &c. to the dogs 47. Each cam has a flat face 67, a recess 68, and a concentric part 66. The recessed part of the cam is opposite its arm 61 when the corresponding dogs are passing bars 29, and at safe speeds the arm 61 can then move in. wards far enough to cause the dogs to clear the bars, but at unsafe speeds the momentum of the parts precludes such inward movement, and engagement of the dogs and bars results. Two pairs of diagonally-opposite dogs 47 are provided, actuated from the two cams 58 which are set at 180‹ to each other, so that, when one pair of dogs is retracted, the other is extended, and vice versÔ. The cam shaft 57 is rotated through chain gear from a drum, on which are oppositely wound two ropes, one anchored at the top of the shaft and the other at the bottom. Each retarder bar 29 consists of two plates embracing the wires 28, and having fitted between them a bar 45, with horns 46 to engage the innermost pins 44 and an upper surface which slopes downwards and outwards to engage the corresponding notch in the dog 47. At the bottom of the shaft the wires are passed through eye-bolts 33, Figs. 11 and 14, and by them clamped in recesses 38 in a plate 34 fixed to guide-pins 35 pressed downwards by springs. At the top of the shaft the wires are pressed upwards by springs, and one of the four sets of wires is connected by a lever and cord with the handing-rope, which is thus pulled to stop the motor when the safety devices come into action. The stoppage of the motor may also be effected by a switch operated by the movement of the wires 28. To prevent the cage from rising too high, should it be ascending at excessive speed, a bracket on the cage is adapted to engage retarders near the top of a separate set of wires similar to 28. These wires at the same time rise against the pull of a spring, and thus operate a switch to stop the motor. In a modification, the governor, of somewhat modified construction, is mounted at the top of the shaft and driven from the head sheave, and is connected with a rock-shaft on the cage linked to the dogs 47 by means of a taut rope running round sheaves on arms of the rock-shaft.