Patent GB-730776-A (GB)
Title: Improvements in or relating to variable speed gearing for screw cutting lathes
IPC: B23Q5/48
Filed: 1952-05-12
Abstract: 730,776. Variable-ratio gearing. ORTLINGBAUS, R., ORTLINGHAUS, A., and ORTLINGHAUS, F., [trading as ORTLINGHAUS, O. H. G., GEB.]. May 12, 1952 [May 12, 1951], No. 11912/52. Class 80 (2). A variable-ratio gear for a screw-cutting lathe comprises a Norton gearing in series with sliding-wheel gearing the ratios being preselected by means of profiled cylinders controlled by a common operating handle in correspondence with a ratio-indicating device, ratio changing being effected by a second operating handle. The gearing is shown developed in Fig. 3 and comprises a Norton gear, having an idler 9 which may slide axially on a shaft 75 and pivot in its own plane, about a gear wheel 10 with which it meshes, into engagement with one of a stepped cone of pinions 1-8; a fourratio gear having a quadruple sliding pinion 16-18 meshing alternatively with wheels 11- 14; and a three-ratio gear having pinions 19 and 22-24 which slide axially together to connect respectively an input. shaft 98 with the wheels 1 or 20 and the wheels 25 or 12 with the wheels 24, 23 or, by clutch teeth 231, 81, the pinions 8 and 23. The power path through the three-ratio and the Norton gear is shown for each of the three ratios by full, dotted and chain-dotted lines and corresponds respectively to the cutting of threads according to the inch, millimeter or module scales of dimensions. Ninety-six ratios are obtainable in three groups each comprising four octaves of eight steps. These latter steps correspond to the eight ratios of the Norton gear which are preselected by stepped-profile cylinders 31, 32 shown in Figs. 5 and 8 and, in development, in Fig. 9. The cylinders are non-rotatable relative to, but are slidable axially along, a shaft 35 with which they are rotatable. A gear establishing member 77 co-operates with the cylinders and, by means of a rack 76, pinions 86, 80 (Fig. 5) and rack 81, moves a selector fork 82 engaging the Norton idler wheel 9. A further pair of stepped cylinders 33, 34, shown in Figs. 4 and 7 and, in development, in Fig. 10, co-operate with a gear establishing member 99<SP>1</SP> (Fig. 7) for actuating the three-ratio gear and with a member 94 for actuating the four-ratio gear. The cylinders 33, 34 are slidably mounted on, for rotation with, a shaft 36 and have twelve angular positions. The member 99<SP>1</SP> slides a rod 100 and selector forks 101, 99 fixed thereto to change the wheels 19 and 22-24. The member 94 (Fig. 4) actuates the sliding pinion 15-18 through a lever 96. With the cylinders in the position indicated in Figs. 9 and 10 the ratios are preselected by rotating a knob 29, Fig. 7. Three quarters of a turn of the knob 29 rotates the cylinders 31, 32, by means of a shaft 41 and bevel wheels 37, 42, through their eight steps each of which is definitely located by a spring- loaded ball 46 engaging depressions in a collar 38 on the shaft. Rotation of the knob 29 through the remaining quarter of a turn actuates a Geneva mechanism, comprising a pin 39 on the collar 38, a slotted member 43 and a stop plate 40<SP>1</SP>, to turn a gear wheel 44 integral with the member 43 through one quarter of a revolution. A gear wheel 52 keyed to an indicating dial 26 meshes with the wheel 44 and has a ratio thereto of three to one. The dial 26 therefore rotates through one twelfth of a revolution during the final quarter of a revolution of the knob 29. The shaft 36 is rotated in exact correspondence with the dial 26 through a train of spur and skew gears 53-57. Whilst the knob 29 rotates through the eight steps of the cylinders 31-32 a pointer 27 is arranged to move over one twelfth of the periphery of the dial which has altogether ninety-six divisions in three groups, each of thirty-two steps, sub-divided into four octaves corresponding to the gear ratios. This motion is effected by a cam 40 on the shaft 41 which actuates a follower 49 to drive, through a rack 491 and gear wheels 50, 51, the pointer which is returned by a spring 48 to zero when the dial passes from one octave to the next. The cylinders 31, 32 and 33, 34 are moved towards each other to establish a preselected ratio, and away from each other to allow the preselection of another ratio by means of a handle 28 driving, through a bevel wheel 62, a shaft carrying spur wheels 70, 63<SP>1</SP> which mesh respectively with a sector 72 and racks 65, 66. The sector 72 and a meshing sector 71 are pivoted to blocks 73 engaging grooves 31<SP>1</SP>, 32<SP>1</SP> in the cylinders 31, 32 and the racks 65, 66 are attached to members 67, 68 which are slidable on rods 59, 69 and which have forks engaging slots 33<SP>1</SP>, 34<SP>1</SP> in the cylinders 33, 34. The Norton gear is locked after and unlocked before each change by means of a knob 30, Fig. 5. A skew gear 78 coacts with a sector 79 on the idler shaft carrier 74 to position the idler in correct radial position relative to the stepped core for each ratio. A stop 90, which may be adjusted to vary the mesh of the gears, indexes the shaft 87 which carries the gears 86, 80, 78 in its eight positions. A screw thread 91 causes a member 92 to move the shaft 87, to the right when the knob 30 is rotated the idler 9 then moving out of mesh with the cone of gears 1-8.