Patent GB-630108-A (GB)
Title: Improvements relating to change speed mechanism for lathes and like machine tools
IPC: B23Q5/14
Filed: 1945-03-28
Abstract: 630,108. Lathe details. POTTER & JOHNSTON MACHINE CO. March 28, 1945, No. 27189/47. Convention date, May 26, 1944. Divided out of 630,068. [Class 83 (iii)] [Also in Group XXIV] A lathe or like machine tool has a changespeed driving mechanism comprising a driven shaft, two pairs of axially-spaced clutch heads rotatably journalled on the shaft, a gear operatively associated with each of said clutch heads so as to be rotated thereby, shiftable clutch-engaging members slidably splined or keyed to the said shaft for axial movement between each pair of clutch heads, whereby when the clutch-engaging member of a pair of clutch heads is in engagement with one clutch head of a pair it disengages the other clutch head of the same pair, an input shaft and input gears fast thereon meshing with the gears associated with each clutch head of one pair, a separate output shaft and take-off gears fast thereon meshing with the gears associated with each clutch head of the other pair, said input gears having operative connection with each other and said take-off gears having operative connection with each other so as to rotate in unison and the input gears and take-off gears being independent of one another except through the clutch heads. The headstock spindle 21 is driven from a constant speed shaft 31 driven either directly by a motor M or through belt gearing. A toothed wheel 32 on the end of shaft 31 drives through an idler 33 and toothed wheel 35 an " input " shaft 36. This shaft may be connected selectively by clutches 39, 40 and gear pairs 49, 45 and 50, 46 respectively, to a parallel shaft 38, this shaft in turn drives an " output " shaft 37 through either of the gear pairs 47, 51 or 48, 52, according to the position of a clutch-operating collar 44. The clutch collar 43 similarly controls the two clutches 39, 40 and thus four different speeds are available at the " output " shaft 37. Pick-off gears 53, 54, accessible through a cover in the headstock end of the machine, continue the drive to a layshaft 56 provided with a sliding twin gear 57, 57a, manually operated to double the range of speeds at the shaft 60. The latter shaft is connected to drive the machine spindle 21 through the gears 59, 61 and splined sleeve 62. The spindle 21 is axially adjustable by means of a sleeve 64 provided with rack-teeth 66 and a handoperated pinion 65. Feed drive.-The feed drive for automatic operation of the turret and cross slides is taken from the main spindle drive at 68, Fig. 3, and drives through gear train 69, 71, 73, 74 a wheel 75, Fig. 4 (gearing spaced out and shown in the plane of the paper for clarity). The wheel 75 is splined to a short shaft 76 freely journalled in the end of a feed output shaft 77. Pick-off gears 101-106 transmit the feed drive at different speeds from shaft 76 to three shafts 78-80, each provided with a clutch 81, 83, 85 respectively, which enables either shaft, selectively, to drive a gear cluster 88-90 on shaft 77 through gear pairs 84, 89 ; 82, 88 ; 86, 90, respectively. A clutch member 96 on the feed output shaft 77 enables either the gear cluster 88-90 to be engaged to drive this shaft for the slow feed movements or a gear 95 to be engaged to drive the shaft at high speeds for all idle movements. The high-speed drive is obtained from gear-wheel 99 which is driven in turn by a pinion 97 secured to the spindle of an electric motor 100 rotating continuously at constant speed. The shaft 77 is coupled to a further feed shaft 30 through a safety shear pin device 108- 110 and gearing 107, 111. The gear-wheel 107 is in adjustable driving connection through face teeth with a bevel wheel 113 which drives through a further bevel 117 and worm gearing 119, 120 a shaft 121 for a speed control device described in Specification 630,068. Provision is made at 118a for hand-cranking the feed train when setting up the machine and safety means are incorporated, whereby engagement of the hand-crank is impossible until the feed clutch 96 is rendered in the neutral position. Specification 630,117 also is referred to.