Patent GB-718665-A (GB)
Title: Machine tool change-speed gear
IPC: B23Q5/14
Filed: 1952-09-04
Abstract: 718,665. Change-speed gear. WARNER & SWASEY CO. Sept 4, 1952 [Oct. 16, 1951], No. 22256/52. Class 80 (2) In a fluid-pressure operated preselected shift of four gearpairs 84, 92, 101, 110 sliding on two countershafts 86, 102 which co-operate with two additional countershafts 43, 96 and forward-reverse friction clutches 49, 50; to give sixteen speeds in either direction between an input shaft 33 and the parallel output work-spindle 32 of : a lathe, the application of fluidpressure to establish the shift is automatically prevented until the torque passing 'through a cam-ball torqueresponsive coupling 197, Fig. 2A, in an inching - drive clutched in at 171 during the shift, is below a predetermined value, whereby meshing of wheels at high relative speeds is avoided. Gear arrangement.-The forward - reverse friction clutches 49, 50, actuated by fluid-pressure applied to annular pistons 56, 57 through concentric shaft-passages 60, 65 and ducts 64, 72 respectively, clutch 'to the first countershaft 43 wheels 41, 47 driven by input wheels 39, 40 the former directly, the latter through a reversing-idler 44. The final output shaft 32 and third countershaft 96 carry all fast wheels with the exception of an inching-drive wheel 172, which, when clutched to the countershaft 96 by the fluid-pressure engaged inching clutch 171 introduces an inching drive to the output spindle 32 from the constantly rotating input shaft 33 (or vice versa) through a path comprising meshing wheel-pairs 192, 193, cam-ball torque-responsive coupling 197 meshing wheelpairs 187, 185 and 184, 172, countershaft 96, and sliding double-wheels 101, 110. The cam-ball coupling comprises balls 197 arranged between facial inclined teeth on a member 190 fast on a shaft 188, carrying the fast wheel 187, and on the wheel 193 which is pinned to the shaft at 194 for limited circumferential and axial movement against a loading-spring 198. Spindlebraking is provided by a fluid-pressure engaged multi-disc brake 73, Fig. 18, on a rightward extension of the first countershaft 43, not shown in Fig. 2A. Manual controls.-These, all acting on valves controlling fluid-circuits, comprise a hand-wheel 134, Fig. 18 turning a distributer-valve 130, Fig. 14, into any of sixteen different positions for ratio preselection with a bevel-geared indicator, Fig. 2, not shown, calibrated in linear cutting speeds; an executive lever 161, Figs. 10 and 18, which is pulled inwardly or outwardly between positions I, II and III to establish preselected shifts (as described below) and turned in a plane at right angles to the first movement between positions F. N, B, R, for forward, neutral, braking and reverse respectively;, and an inching button 213, which, when depressed engages the inching clutch 171 for a slow spindledrive, with immediate release and braking (with the executive lever in B position), during spindle-adjustment for chucking operations. Fluid-pressure system.-The system is supplied by a pump 290, Fig. 18, drawing. from a reservoir 250. The four sliding gear-wheels are operated by two-position differential pistons in cylinders 120, 119, 121, 122, which pistons, are moved from right to left by supplying pressure selectively to their right faces in opposition to pressure which acts simultaneously on all their smaller left faces and sets them in their rightward position in the absence of leftward selector pressure. Cooperating in the control are the following five valves. - One, the preselective distributer-valve 130, having a pressure inlet 228 constantly communicating through a passage 230, Fig. 14, groove 231 and radial passages 232a with the hollow interior of the valve, from which pressure passes to the right ends of the shift cylinders 119 &c. through selectively positioned radial passages 234 &c. in the valve, and ducts 127 &c., which latter are also exhausted through drained grooves 244, 245 having selectively positioned axial extensions. The pressure-supply passage 230 communicates constantly with a port 242, Fig. 18, in the left end of the shift-cylinder 119 and thence with the left ends of all the other shift-cylinders 120, 121, 122, through permanent openings 123, 124, 125. Secondly, the main control valve 152 above referred to for selecting F, N, B, R by rotation of an outer ported valve-body 155, and for establishing a preselected speed by inward axial movement of an inner piston-valve 156 which controls the events cycle of a shift, both movements being effected by the handle 161 which has an offset pivotal mounting on the outer valve-body 152. Thirdly, a valve 170, Fig. 18, actuated through a lever 199 by the torque-; responsive coupling 197 in the inching-drive, serving in its normal rightward position (shown), to which it is biased by a spring 210 and also by excess torque in the coupling 197, to block pressure supply to the preselector valve 130, until torque is below the predetermined limit. Fourthly a combined interlock and timing valve 143 which, after a predetermined delay to allow shift-completion, initiates a pressure-line, completed through valves 268 on the shift-rods themselves, which reacts back on the inner shiftcycle valve 156 of the main valve 152 restoring the operating lever to its initial I position to advise the operator of completion and exhaust the various circuits. The fifth valve is the manual button valve 213 (shown twice in Fig. 18), giving alternate inch-and-brake. For a straight shift without reversal, the operator, after turning the preselector-valve 130 as required, pushes (without turning) the handle 161 from position I to III where it is retained by a spring-loaded detent 167. Prior to this second action the preselecor-valve feed-line 227, 228 had been exhausting through the torqueresponsive valve 170 now held in its rightward position by its spring 210. The establishing movement to position III, Fig. 10, pushes in the inner shift-cycle valve 156 which exhausts whichever of the forward or reverse clutches 49, 50 was effective, directs pressure from a main inlet port 263 to a port 262 and through a line 287 to a port 207 of the torque-responsive valve 170, and simultaneously through a line 285, now communicating ports 224, 223 of the manual inching-valve 213' and line 286 to engage the inching clutch 171. The torque thereby imposed on the cam-ball coupling 197 now rocks a lever 199, Fig. 2A, to its dotted position, in which it retains the torque-responsive valve 170, Fig. 18, in its rightward position in opposition to leftward fluid-pressure which, passing from the now pressurized port 207 through a restrictor 206 comprising a truncated threaded screw-plug, builds up slowly on its right face, so that as soon as the rightward torque-responsive pressure of the cam-ball coupling falls below a predetermined value the leftward fluid-pressure moves the valve 170 leftwards, pressurizing a port 211 which, through the line 227 feeds the preselectorvalve inlet 228 and thence through the bore of the preselector-valve 130 to the selected combination of the shift-cylinders 119 &c. Pressure at the preselector inlet 228 simultaneously passes slowly through a gapped baffle-plate restrictor 151 to act on the right face of the interlock valve 143 which it eventually moves to the left in opposition to line-pressure acting at 150 rightwards on a smaller face of the valve 143. A port 271 of the latter, previously exhausting at 244, is now pressurized from the passage 230, to feed a line 270, which, providing the gearshift has been completed, is communicated through passages 268 &c. in the shift-rods themselves and lines 266, 264 with a space at the right end of the inner shift-cycle valve 156, which is thereby pushed outwards returning the handle 161 back from position III to I, reengaging the forward or reverse clutch 49, 50, informing the operator of completion of the shift, and also exhausting the various lines. The preselector feed-line 227 exhausts through the torque-responsive valve 170 which spring-returns to its rightward position, shown, but pressure is retained in the gear-shift cylinders by a non- return valve, (Fig. 15, not shown) arranged between the feed-inlet 228 and the selector-valve pressure-supply passage 230. Shifts between F, N, B, R, without ratio shift, are made simply by turning the handle 161 to rock the outer valve-body 155 into positions directing pressure to the appropriate forward or reverse clutch 49, 50, or brake 73, ratio-shift in either F or R positions being established as above described by an accompanying inward movement to position III. In neutral position N, the F, R clutches 49, 50 and brake 73 are exhausted, but the sliding gears have no free position. The handle 161 can be rocked freely between B and N positions, but before either F or R can be approached, it must be first pulled out to position II in opposition to a spring-loaded peg 164 to free it from the fixed stop-projections 163. In position B, the main-valve feeds a line 280 leading through the inching-valve 213 and a line 283, 284, to the brake 73. On pushing in the button of the inching valve against a return spring, the line 284 is exhausted and pressure transferred to the line 286 feeding the inching clutch 171, which can thus be engaged and disengaged alternately with the brake 73 by simply pressing and releasing the inching valve-button 213, which may be mechanically interlocked with the main executive valve 152 to prevent movement of the former when the latter is in other than B position. Specification 656,665 is referred to.