Patent GB-707515-A (GB)
Title: Machine tool change-speed gear
IPC: B23Q5/14
Filed: 1952-07-30
Abstract: 707,515. Change-speed gear. WARNER & SWASEY CO. July 30, 1952 [Dec. 7, 1951] No. 19239/52. Class 80 (2)  A preselective change speed and reverse drive from a motor-driven input shaft 16 to the parallel work-spindle 146 of a lathe headstock, includes first and second countershafts 44 74, the latter driven at any of three ratios from the former by selectively frictionally clutching wheels 71 or 77, free on the second countershaft 74 and meshing wheels 69, 70 fast on the ends of the first 44, or a wheel 48 free on the first and meshing a central wheel 75 ifast on the second. These three ratios are doubled in each of two separate stages, making twelve in all, by third and fourth countershafts 102, 130, the former having clutchable wheels 99, 105, meshing fast wheels 97, 98 of the preceding second countershaft 74, and a fast wheel 127 meshing a fast wheel 128 on the fourth countershaft 130, which last named also carries a clutchable and a fast wheel 132, 135 meshing respectively a fast and clutchable wheel 145, 147 on the output spindle 146. Adjacent the input shaft 16 is a reverse shaft 21 carrying clutchable and fast wheels 18, 24 respectively meshing wheels 17 and 45 fast on the input shaft 16 and first countershaft 74,  by which the latter is driven reversely when the reverse-wheel 18 is clutched and a forward clutchable wheel 41 on the countershaft and meshing the input wheel 17, is released. All the clutches are identical and of the multi-disc friction type engaged electromagnetically or by hydraulic pressure supplied to a spring-released piston, e.g. 29 through appropriate shaft passages, the latter, in the case of double clutches on the same shaft being separated by internal tubes, e.g. 54. Selector control.-Pressure fluid provided by a pump 154, Fig. 5, is supplied selectively to the ,clutches under control of a preselectively operated distributer-valve S, providing ratio -control only, and a starting-valve C providing neutral, forward, spindle-braking and reverse, braking being by simultaneous engagement of two different ratios. The distributer-valve S, Fig. 11, comorises four separate two-position valves 198, 205, 211, 217, the first 198 and second 205 together controlling communication between lines 169, 170. 171 leading to the clutchable wheels 48, 71, 77, a permanent pressure inlet line 157c and a line 166 pressurized through the starting valve in the spindle-brake position only and exhausted in all other positions. The third valves 211 controls communication between lines 172, 173, of the clutched wheels 99, 105 and a permanent pressure line 157d, whilst the fourth 217 controls lines 174, 175 of the clutched wheels 132, 147 and a line 165 which is pressurized through the starting valve C in all but neutral position in which latter it is exhausted, thus freeing the last two clutches and leaving the work-spindle free. Connections 168 are all permanent drains. The four valves 198-217 are actuated by preselectively turning a shaft 161 carrying four profile discs 226 having selectively positioned peripheral teeth which, when the shaft 161 is subsequently pressed axially inwards against a return spring 234, to establish a preselected shift register with pegs 234 depending from rockers 228, which are thus tilted one way or the other and, through arms 235 engaging notches in the valves, shift the latter into either operative position. In its neutral position the starting-valve C, Fig. 6, exhausts the neutralizing line 165 through passages 192, 193, annular groove 191 and a line 167 leading to a reservoir 156, Fig. 5. In this condition some or other of the leading clutches may be engaged according to the position of the distributer-valve S, but both the lines 174, 175 of the last two clutches are exhausted. In all positions other than neutral, the line 165 is pressurized from the inlet main 157a, leading to a central passage 186 from which passages radiate in the appropriate directions Figs. 7-10 (not shown), In forward and reverse positions a diametral port 189a pressurizes respectively lines 164, 163 leading to the forward and reverse wheels 41, 18, whilst exhausting the idle line 163 or 164 through crescent-shaped axial passages 190 and the reservoir-connected groove 191. In all except the brake-position the brake line 166 is exhausted through one of the passages 190, whilst in the brake-position it is pressurized through the diametral passages 189a, whereby no matter what position the distributer-valve occupies, two of the wheels 48, 71, 77 will be simultaneously clutched, to lock the first two countershafts and one or other of the wheels of each following pair 99, 105 and 132, 147 will also be clutched to connect the work-spindle to the locked shafts.