Patent GB-818021-A (GB)
Title: Improvements in or relating to gear boxes
Inventor: ROMI GIORDANO
IPC: B23Q5/14
Filed: 1957-03-22
Abstract: 818,021. Change-speed gearing. MAQUINAS AGRICOLAS ROMI S.A. March 22, 1957, No. 9493/57. Class 80 (2). A change-speed gear comprises a first gear mounted for rotation with and axial sliding on a first shaft, means for establishing driving between the first gear and a selected one of a plurality of gears of different diameters rotatable with a second shaft and selecting means whereby the driving element may be connected to the first or second shaft and the driven element to the second or first shaft respectively. In a change - speed gear for a machine-tool for producing Whitworth, metric, diametral pitch and module threads from a lead-screw 55 driven from a mandrel gear 57, ninety-six pitches of each thread are obtained. The mandrel gear 57 meshes with a gear 101 rigid with a gear 56, these two gears being engageable by a double gear 8, 9 splined to a shaft 2 carrying rigid therewith gears 10, 11, 12 and 13 selectively engageable by double gears 17, 16 and 14, 15 splined to a shaft 3 to provide eight input speeds to a Norton gear. The double gear 8, 9 is shifted by a fork 58 (Fig. 4) and the double gears 16, 17 and 14, 15 are shifted by forks 64 (not shown) and 60 selectively actuated by two racks and a pinion 61 on an angularly and axially movable spindle 62. The Norton gear comprises a gear cluster 22-33 rigid with a shaft 4 and a single gear 35 slidably keyed to a shaft 5 and engaging the cluster through an idler 36 carried by a pair of plates 38 pivotable about the shaft 5. Axial movement of the plates 38 is produced by rotation of a spindle 68, gears 67, 66 and a rack 44 having additional rack teeth 43 engaging teeth 42 formed on the plates. Angular movement of the plates 38 is produced by rotation of a hollow shaft 69, bevel gears 71, 72, a toothed shaft 41 and teeth 40 formed on the plates. The shafts 68, 69 are normally connected by a detent 70 (Fig. 6) under control of a pin 65, but vertical movement of the pin 65 releases the detent 70 to allow the idler gear 36 to disengage from the cluster gears, partial release of the pin 65 allows the speed-selecting lever to rotate both shafts 68, 69 in unison to produce a helicoidal movement of the idler gear, and full release of the pin 65 re-locks the shafts 68, 69 to their original relative position and engages the idler 36 with the next selected gear of the cluster 22-23. Input drive to the Norton gear from shaft 3 may be either through a dogclutch 19, 20 to the shaft 5, or through gears 18, 21 to the shaft 4. Similarly output from the Norton gear to the output shaft 6 may be through a dog clutch 51, 52 from shaft 4 or through gears 46, 47 from shaft 5. The gear/ clutch elements 18, 19 and 47, 52 are conjointly moved by two racks 75, 76 (Fig. 9) engaged by a single pinion 74 controlled by a handle 73. Thus the direction of the powerpath through the Norton gear may be changed to provide Whitworth and metric based pitches. From the output shaft 6 drive may proceed through a dog-clutch 53, 54 to the lead-screw 55 or through gears 48, 49 to a feed-shaft 50. The clutch/gear element 48, 53 is moved axially by a lever 80 (Fig. 12) and a helical cam 82 rigid with a shaft 84, such that the gear drive to the feed-shaft 50 may be disconnected by rotation of the shaft 84 by lever 85 or by axial movement of the shaft 84 produced by the saddle 92 of the machine having spring-loaded stops 93 contacting a stop 87 on the shaft 84.