GB1000233A - Regulated variable-ratio toric race friction gear with overspeed control - Google Patents

Abstract

1,000,233. Variable-speed gear; gearing for stopping and starting machinery. AVCO CORPORATION. July 15, 1963, No. 27965/63. Headings F2D and F2L. A continuously-variable-ratio toric race friction gear is controlled by an input-powered centrifugal governor which is operative first to bias the toric races into engagement with non- planetating idler discs and then, with increasing speed, to tilt the idlers. The gear may be used to maintain substantially constant the speed of an output member, and includes a toric race planetary friction gear driving non-tilting idlers in a driven cage, a second input-powered centrifugal governor acting through a snapacting spring system on overspeeding to throw out-of-mesh a gear train transmitting drive from the carrier of the friction planets to a driven element, e.g. the drive control of an A.C. generator. As shown, a driving gear 20, Figs. 1, 2, is fast on a shaft 14 rotated to cause the masses 74 of a centrifugal governor 58 to fly out and thus slide axially a friction disc 22 keyed to the shaft so that a toric race formed on its inner side engages non-planetating tiltable idlers 32, in turn engaging a toric race on one side of an intermediate disc 28 journalled about the shaft. A toric race on the other side of the intermediate disc 28 is engaged by non-tiltable planetating idlers 38 journalled upon the radial arms of a carrier 46 mounting an externally toothed ring gear 52 meshed by an output gear 198, the planetating idlers also engaging a toric race on a disc 40 keyed fast upon the shaft 14. After initial engagement of the toric discs 22, 28 with the idlers 32, when a predetermined speed has been reached, further increase in speed causes the centrifugal governor 58 to abut against and react through a thrust bearing 84 and a lever 100 upon a rod 102 and thence upon a spring engaging a stop 114, the spring being adjustably compressed by a screwcontrolled lever, Fig. 3 (not shown), to determine the working characteristics of the governor. The rod 102, Fig. 7, is connected by pins 134, 136 to radial arms 248 on two support shafts 236, each journalling in a yoke one of the non- planetating idlers 32 by means of a ball-andsocket joint 252. Pins passing through each ball 252 engage slots 260 in the yoke and bearings 250 journal each idler upon its ball. Thus as the centrifugal governor 58 slides the rod 102 axially with increasing input speed, the idlers 32 precess to a new angular position and maintain constant the output speed of the gear 52. If the speed of the input powered shaft 14 exceeds a maximum, a second centrifugal governor 64 mounted thereon acts through a thrust bearing 146 to cause the sudden collapse of a stack of spring washers 152, the resulting axial movement of a mounting cup 148 and pivoting of interconnected levers 158, 162 sliding a thrust rod 178 to act through a sleeve 182 and disengage the output gear 198 from the ring gear 52. The mounting cup 146 is then retained in the disengaged position by a spring- biased catch 214 until overspeeding ceases, when a handle 232 may be operated to withdraw the catch and allow the spring washers 152 to re-engage the gears 52, 198.