Patent GB-690971-A (GB)
Title: Improvements in speed change transmissions
IPC: F16H61/02
Filed: 1951-05-01
Abstract: 690,971. Change-speed gearing. BOEHRINGER GES., GEB. May.1, 1951 [May 3, 1950], No. 10244/51. Class 80 (ii). In a change-speed gear for the feed motion of a lathe, two sets of discs 191-195 and 196-200, Fig. 8, splined on a spindle 186 and provided with projections co-operating with forks controlling slidable gears, are moved axially apart from the neutral position shown so as to bring in a speed pre-selected by rotation of the spindle, those gears which are not to be moved being held loeked in neutral by members fixed on the spindle 186. As shown, drive from the input shaft 115, Fig. 2, to the lead screw 102 is normally through gears 142, 143 to shaft 138, thence via slidable gears. 4 or 5 to shaft 135, thence via gears 148, 149, 10 to shaft 122, thence via slidable double gears 1, 2 or 3 to shaft 132, thence to shaft 136 via a slidable double gear 6, thence via, a slidable double gear 7 to shaft 133, and thence to shaft 127 coupled to the screw 102. Gear 10, which is splined on shaft 122, normally meshes with gear 149 as shown, the transmission ratio between shafts 115 and 122 involving the ratio 65Î49Î36/61Î37 =2Î25.40097474 so that, although the screw 102 is of metric pitch, threads of British pitch may be cut with great accuracy. The gear 10 can, however, be moved by means of a two-position knob out of mesh with gear 149 and into clutching engagement with gear 142 so as to connect shaft 122 directly with shaft 115 for the cutting of threads of metric pitch. A four-position knob 109, Fig. 4, controls a double gear 9 slidable on shaft 117, so that in one position it meshes with a gear 157 on shaft 133 for the cutting of righthand threads, in another position it is geared through a double idler 158 to a gear 155 on shaft 133 for the cutting of left-hand threads, in another position it is clutched directly to shaft 122, while in another position it is in neutral so that the screw 102 is not driven whereas a shaft 139 coupled to a feed rod 103 is driven through a gear 8 which is moved on shaft 139 into mesh with gear 157. The spindle 170 of knob 109 moves gear 9 by means of a crank pin 172 carrying a fork 173, and also carries a disc 178 with a cam groove engaged by a pin 180 projecting from an arm 175 pivoted on the casing and carrying a fork 177 controlling gear 8. Shaft 186 is rotated by a selector knob 107, Fig. 5, via gears 187, 188, a fixed pin 213, Fig. 8, co-operating with holes on the disc 200 to prevent such rotation unless all the gears 1-7 are in neutral position. The two sets of discs are moved apart by upward movement of a lever 203, the spindle 204 of which has two crank pins 206 engaging vertical slots in members 207, 208 rigid with rods 209, 210 which are thus moved axially in opposite directions, the rods having fingers 211, Figs. 8, 9, which cause one set of discs to move with each rod. Each of seven slidable rods 214<SP>1</SP>-214<SP>1</SP>, connected to the gears 1-7 by forks, has a pair of fingers, the fingers 227, 243, 244 of rods 214<SP>1</SP>, 214<SP>2</SP>, 214' engaging between discs 196, 197 and 191, 192, the fingers 235 of rod 214<SP>4</SP> engaging between discs 192, 193 and 197, 198, the fingers 236 of rod 214<SP>5</SP> engaging between discs 193, 194 and 198, 199, the fingers 237 of rod 214<SP>6</SP> engaging between discs 194, 195 and 199, 200, while rod 214' has two pairs of fingers 238 straddling discs 195 and 200. Those gears 1-7 which are not moved are held locked in neutral position, rods 214<SP>1</SP>, 214<SP>2</SP>, 214<SP>3</SP> each having a rigid arm 229 with a recess in its end engaging over a notched disc 230 fixed on spindle 186, while rods 214<SP>4</SP>, 214<SP>5</SP> have recesses 233, 234 co-operating with notched discs 231, 232 fixed to spindle 186. The. knob 107 has twenty-eight positions, providing for twenty-eight threads of British pitch and 22 threads of metric pitch. Lubrication of the gears is effected by a pump 162 operated by a cam 161 on shaft 138.