Patent GB-955943-A (GB)
Title: Hydraulic gear shifting arrangement for lathes
Inventor: HERMANN OTTO
IPC: B23Q5/14
Filed: 1962-12-10
Abstract: 955,943. Change-speed control; converting rotary motion into oscillating motion. R. K. LEBLOND MACHINE TOOL CO. Dec. 10. 1962, No. 46569/62. Headings F2D and F2Q. A change-speed control for a lathe which permits a ratio to be preselected but prevents establishment of the ratio until the driving shaft 114 is stationary comprises a selector valve 52 between ratio establishing jaw position servomotors 46, 50 and a hydraulic pump 148 which is driven by an electric motor 146 to supply pressure liquid to the servomotors only when the driving shaft 114 is stationary. The driving shaft 114 is driven from a reversable electric motor 154 through a fixed ratio reduction belt gear 112, and a zero speed switch 156 on the electric motor output shaft 152 completes the circuit to the electric motor 146 when the shaft 114 is stationary. On breaking the circuit to the electric motor 154 an electromagnetically operated brake 118 is energized to stop the shaft 114. A normally non-rotatable plate 120 of the brake 118 carries a pin 124 engaged by the forked end of a lever 126 which is oscillated by a cam 132 driven from the electric motor 146 through a reduction gear 134 ... 144 during ratio establishment. The oscillating motion of the plate is transmitted through the engaged brake 118 to the driving shaft 114, thus facilitating engagement of axially - slidable pinion 32, 34 of the change-speed gear. The pinions 32, 34 are moved axially for ratio shift either by levers 28, 30 fast with manuallyrotatable shafts 24, 26 or by levers 36, 38 fast with the operating rods 46, 50 of the servomotors. The jaw position servomotors 46, 50 comprise pistons 54, 66 respectively fast with the operating rods 46, 50 and floating pistons 60, 64; 72; 76 and a single valve spool 52 selectively connects the chambers between the pistons and between the end pistons and servomotor casings to a line 80 from the pump 148 and exhaust. The selector valve spool 52 is moved axially to preselect a ratio by manually rotating a shaft 86 carrying a pinion 82 which meshes a rack 84 fast with the valve spool 52. A ball detent 92 retains the selector valve 52 in the preset position and during selection the ball 92 rides over the rack teeth to rock an arm 90 which momentarily closes a switch LS1. In Fig. 19 the electric motor 154 is connected between supply lines L1, L2 through a reversing switch 166. During preselection, closure of the switch LS1 energizes a relay R2 to close a contact 188 which is held closed by a detent 186. To stop the lathe the switch 166 is conditioned as shown, to stop the motor 154 and to energize a relay R1 the contact of which completes a circuit from the secondary winding of a transformer 174 through a line 176, variable resistor 178 and rectifier 180 to the winding 182 of the brake 118. When the driving shaft 114 stops the switch 156 completes a circuit through a contact 188, which is closed if a ratio has been preselected, to energize a relay R3 which closes contacts 190, 192, 194. Closure of the contact 190 starts the electric motor 146 which drives the pump 148 whilst the contact 192 completes a holding circuit for the relay R3 and the contact 194 energizes a solenoid S1 to release the detent 186. The establishment of a new ratio is indicated by the manual control shafts 24, 26 moving to the new ratio position.