Patent GB-1262829-A (GB)
Title: Change-speed device for a rotary member
Inventor: OLLEARO GIORGIO
IPC: F16H61/26
Filed: 1970-06-03
Abstract: 1,262,829. Change-speed control. ING. C. OLIVETTI & CO. S.p.A. 3 June, 1970 [9 June, 1969], No. 26874/70. Heading F2D. In a two-speed no-neutral gear, operable in a number of different speed ranges, for variably driving a machine tool spindle 13, 20 and comprising a double integral driving gear 11, 12 mounted rotatably free but axially fast on an intermediate shaft 10 which is axially movable to selectively engage one or other gear 11, 12 with driven gears 14, 15 rotatably and axially fast on the machine tool spindle 13, an inching i.e. synchronizing, mechanism 30 is provided for operation when the power drive is disengaged to exactly align gear teeth 73, 71 of the driven gears 14, 15 with gear tooth spaces 69, 70 of the driving gears 11, 12 to enable a precise synchronized gear-change to be effected thereby eliminating the necessity for the usual slipping synchronizing gear connections. The spacing of the integral gears 11, 12 is such that during a ratio shift one pair of gears, e.g. 12, 15, commences to mesh before the other pair 11, 14 has disengaged thus forming a no-neutral arrangement. As shown, the gears 11, 12 are driven directly from a pinion 23 the teeth of which are constantly in mesh with those of the gear 12, the pinion 23 being mounted on a driving-shaft 24 which is driven from an hydraulic motor 25 via a clutch 26. The synchronizing mechanism 30 is operable when the drive clutch 26 is disengaged, and includes a rotatably fixed but axially movable cylinder 35 having two spiral edges 36, 37 converging into a central slot 38, the cylinder 35 being axially movable, by applying fluid pressure at 34 to one side of a piston 46 integral therewith, into engagement with a transverse roller 43 on the shaft 13 which is thus turned until the roller 43 is engaged in the central slot 38 to roughly align the gear teeth 73 71 with the tooth spaces 69, 70 as above, the inward movement of the cylinder 35 depressing a plunger 58 to release a spring-loaded locking pawl 54 normally engageable in one or other of two gear stationing grooves 52, 53 on the intermediate shaft 10, a radially arranged fluidpressure-operated plunger 64 being then inwardly moved to engage a "V" notch in a hub 68 of the gear 14 to effect a fine adjustment of the angular position of the shaft 13 to precisely align the gear teeth and tooth spaces, after which, fluid pressure is supplied to one or other side of a piston 50 integral with the intermediate shaft 10 to axially move the shaft 10 and hence the double gear 11, 12 for precise synchronized gear shift, the cylinder 35 being then withdrawn by fluid pressure supplied at 33 to the other side of the piston 46 whereby the plunger 58 returns to its original position, the locking pawl 54 re-engaging the appropriate gear stationing groove 52 or 53. To vary the range of speeds of the two-speed gear, the driving-shaft 24 is carried in an eccentric housing 28 which may be turned to any one of four positions to permit interchangeability of the pinion 23 with other different diameter pinions providing a low, two intermediate and a high, i.e. four different speed ranges in which the two speed gear may operate.