Patent GB-711420-A (GB)
Title: Improved headstock speed change transmission for machine tools, particularly for lathes
IPC: B23Q5/18
Filed: 1952-07-03
Abstract: 711,420. Change-speed gear. BOEHRINGER GES., GEB. July 3, 1952 [July 5, 1951], No. 16787/52. Class 80 (2) A lathe headstock change-speed gear, including a pair of compound sliding-gears 18, 26 controlling two and three ratios respectively, making six in all, has exchangeable selector assemblies whereby in one the two gears are selected by individual levers 49, 51, Fig. 6, whereas in the other preselection is effected by a single dial 86, Fig. 2, and establishment by a lever 98. The gear arrangement comprises a motor-driven input shaft 13 driving a parallel intermediate shaft 31 through a first countershaft 17, providing two speeds by the sliding couplet 18, and a second countershaft 23 providing three speeds by the sliding triplet 26. A further sliding wheel 29 doubles these ratios, making twelve overall. The intermediate shaft 31 drives a final output work-spindle 10 through either of two paths, one, for finishing, including a wheel 34 free on a shaft 35, a wheel 36 splined on a shaft 37 and movable axially to mesh 34, and a belt 39; whilst the other path, all-geared, is from a wheel 41 fast on the shaft 35 and a sliding gear pair 42 providing two further ratios. The last three sliding wheels 36, 29 and 42 are cam-selected as described in Specification 688,512, this invention being concerned only with selection of the first two wheels 18, 26. A slidable couplet 159 splined on a separate shaft, can be meshed with wheels 167, 168 or 169 for feed or lead-screw drive through fast wheels 159 or 162. In its first condition, Fig. 6, assembled for individual selection of the wheels 18, 26, selector-forks 60, 61 for these wheels are actuated separately by individual hand levers 51, 49 respectively, secured to concentric transverse shafts 50, 48 carrying pinions 57, 58 meshing toothed segments 55, 56 which also mesh rackteeth on the respective selector-forks 60, 61 both of which slide on a common rail 59. To adapt for preselection a bracket 53 carrying the gearsegments 55, 56 is removed, as are also the meshing pinions 57, 58 and the selector-fork 60, and the following assembly is substituted therefor. A frame 69, Fig. 2. carries a shaft 76 having splined thereon a pair of profile-members 77, 78 each comprising a pair of axially spaced discs with selectively arranged radial lugs, which after being turned by the shaft 76 into selective registry with axially spaced pairs of projections, e.g. 80, associated with the selector-forks, move the latter to appropriate gear-positions in either direction when the two selector members 77, 78 are closed axially together. The original selector-fork 60, Fig. 6, is replaced by a selectorfork 64, Fig. 2, directly carrying the projections (not appearing in Fig. 2) engaged by the lugs on the selector members 77, 78, whilst the original selector-fork 61, and its support rail 59, Fig. 6, remain undisturbed, the fork 61 being now actuated by a block 74, Fig. 2, carrying the selector-engaging projections 80 and a pinion 75 engaging rack-teeth on the underside of a fixed rail on which the block slides and also the existing rack-teeth on the fork 61 which is thus moved axially in the same direction by, but through twice the distance of, the axial movement of the block 74. Preselective turning of the shaft 76 is effected through a vertical shaft 83, bevel-geared to the shaft 76 and to the existing inner shaft 50, Fig. 6, now carrying the sixposition dial 86, whilst closing movement of the profile members 77, 78, opposed by springs, is effected by forks 95 secured to racks 91 moved in opposite axial directions by turning a common pinion 92 free on the vertical shaft 83 and bevel-geared to the existing outer shaft 48. Fig. 6, which is now geared at 99 to an executive lever 98 journalled in an originally vacant casing-boss 96. Spring-detents in housings 101 locate the selector-forks in gear positions. Specification 707,243, [Group XXII], also is referred to.