Patent GB-252093-A (GB)
Title: Improvements in overspeed and overwinding prevention gear for winding engines
IPC: B66B5/08
Filed: 1925-05-15
Abstract: 252,093. General Electric Co., Ltd., and Whitmore, F. L. May 15, 1925. Stopping automatically at end of run ; speed, controlling.-A overspeed prevention gear for a winding engine intended especially for use during pit sinking is arranged to come into operation throughout a predetermined range from the pit bottom and is adjusted automatically so as to act through the same range as the depth of the pit is increased. The apparatus includes also mechanism designed to stop a descending load at a predetermined distance from the bottom less than that at which the overspeed prevention gear comes into action, this mechanism also being adjusted automatically as the depth increases. A long pinion 25, Fig. 2 fast on a shaft 21 driven by the engine gears with a spur wheel 26 fast on a shaft 27 having a threaded part 28 which engages a stationary out 29. The plain end of the shaft 27 turns and slides in a fixed bearing 29<a> and carries the parts 30, 31 of a coil clutch which can rotate independently but are constrained to move together along the shaft. A pawl 35 pivoted on the gear 26 engages a notch in a rib 37 on the clutch drum 30 when the load reaches the predetermined distance from the bottom. The depth of the notch is such that the gear 26 can continue to move along the shaft without causing any thrust upon the clutch during the last part of the run. A gear 38 formed on the clutch member 31 engages a long pinion 39 fast on a shaft 40 which is connected by bevel gearing to a vertical shaft 45, Fig. 1. A nut 49 mounted on a threaded part of the shaft 45 normally is prevented from turning by the engagement of a bifurcated arm 50 with an upright fin 51 on one arm of a, bell-crank trip lever 52, the other arm of which normally engages a spring- influenced lever 54 coupled in known manner to the stop gear of the winding engine. A sleeve 56 turns with and moves along the shaft 45 and carries loosely in a groove a ring which is connected to the bifurcated end 57 of a lever 59 pivoted at 58. The lever is attached to the piston rod 60 of a cataract cylinder 61, and is connected by a slotted link 64 and pin 65a to a pivoted arm 65 held against the top of the nut 49 by a spring 63, which prevents also the descent of the piston of the cylinder 61 until the nut 49 commences to rise. The rate of descent of the piston is adjusted to give a rate of ascent of the sleeve 56 corresponding with the rate of ascent of the nut 49 when the load is being lowered at the maximum permitted speed during the last part of the wind. When this speed is exceeded, the nut overtakes the sleeve, and as their adjacent surfaces are serrated, the sleeve turns the nut to release the lever 52 thereby stopping the engine. The automatic adjustment of the clutch 30, 31 on the shaft 27 as the depth increases is effected by the following mechanism. A rib 78 on the clutch member 30, Fig. 3, is engaged by a forked shoe 76 pivoted to a short arm of a sleeve 73 mounted on a shaft 66 and having a weighted radial arm 74. The sleeve 73 is disposed between shoulders of a sleeve 69 which is connected to the shaft 66 by a key 72, Fig. 6, and has a weighted arm 70. The key 72 moves along the shaft with the sleeve 69 and works in a keyway of such cross-section that the key is wedged between the shaft and sleeve and prevents longitudinal movement as long as the weight 71 is free. When the weight is lifted, the key becomes slack and the position of the sleeve can be adjusted. At the original end of the wind the upturned end 33a of the clutch coil 33, Fig. 1, is in proximitv to a projection 79 on the sleeve 69, and if the winding is continued owing to an increase in the depth of the shaft, the end 33<a> engages the projection and as the clutch rotates raises the weight 71. The sleeve 69 is now free to move along the shaft 66, and as the clutch is no longer held in position by the shoe 76, it is moved along the shaft 27 by the gear 26 as long as the winding continues. At the end of the wind, the clutch is left in a position which ensures the actuation of the overspeed preventing gear throughout the former predetermined range from the new pit bottom. Overwinding at the pit head is prevented by the engagement of a collar 80 on the shaft 27 with a lever 82 connected by a link 83 and bell-crank lever 84 to a pin 85 bearing against the fin 51. The load is stopped on a downward run at a predetermined distance from the bottom by the arrest of the lever 59 by a bolt 87 controlled by a solenoid 92. The bolt is withdrawn from the path of the lever bv energizing the solenoid, and if after a momentary energization of the solenoid, delay occurs in restarting the engine, the return of the bolt is prevented by the dropping of an arm 93 pivoted at 94 and carrying a pin 95 which rests on the lever 59 when the arm is not resting on the bolt. In a modification the clutch 30, 31 is replaced by a toothed snail cam which actuates the trip mechanism through a catch plate.