555,786. Grinding. JONES & LAMSON MACHINE CO. Aug. 7, 1941, No. 10053. Convention date, Aug. 17, 1940. [Class 60] A machine for grinding a work-piece, such as a tap, comprises an adjustable headstock and tailstock provided with axially movable spindles which are connected to move in the same direction. The headstock spindle may be driven through change-speed gearing by a reversible electric motor arranged in automatic control circuits. The machine shown in Fig. 1 comprises a headstock 3 and a tailstock 4 provided with spindles for supporting a tap or other workpiece in position for engaging a grinding-wheel 36. The headstock and tailstock are adjusted axially by means of pinions 7, 8 which engage racks 5, 6 on the bed. The headstock spindle 15 can rotate and move axially in a sleeve 21 on the headstock, and is provided with a face plate 16 having a skirt 17 which works between packing rings 18, 19. A lead-screw 27, splined to the spindle and clamped between collars 31, 32 by a nut 33, co-operates with a lead-nut 40 which is splined to a revolvable sleeve 41 and is secured thereto by a sleeve 46 and a nut 47. The securing arrangements enable the leadscrew and lead-nut to be readily changed. The sleeve 40 is connected by a key 52 to a housing which can be clamped, to lock the lead-nut, or can be released to permit initial adjustment of the lead-nut by means of a hand-wheel 51 on the housing. The clamp device consists of a non-rotatable ring 55 having pins 74 engaging a sleeve 54. On operation of a hand-lever a shaft having an eccentric part supporting the ring 55 causes the ring to tilt, and the housing is clamped or unclamped. The spindle is provided with a double pinion 95, 97 cooperating with a long pinion 93 driven through change-speed belt gearing 83, 87 and toothed gearing 91, 92 by a motor 80. The tailstock spindle is caused to move axially with the headstock spindle 15 by means of a coupling rod 105 having a yoke 101 which engages a ball-bearing 100 on the gear 95, 97. A box 110 having a pin engaging the tailstock spindle, is normally locked to the rod 105 by co-operation of rack-teeth thereon with a pinion frictionally mounted on a shaft 120 carried by the box and provided with a hand-lever 130 which is normally locked by a pin 134. When the handlever is pulled forwards the pin is released and the hand-lever can then be rocked to retract or return the tailstock spindle to permit of removal or insertion of the tap. The motor 80 is reversible and is controlled by a circuit containing switches 260, 261. Dogs 262, 263 for operating the switches at the limits of travel of the work-spindles are mounted on a rod 264 carried by an arm 265 on the rod 105. Specification 478,757 is referred to. The Specification as open to inspection under Sect. 91 comprises also the following :- Means may be provided for oscillating the tailstock centre for grinding reliefs on taps. The carriage 210, Fig. 11 (Cancelled), of the grinding-wheel is connected to feed-mechanism comprising a nut 230 engaging a non-rotatable threaded shaft 228 which is threaded into a rotatable sleeve 225 on the carriage. The nut is frictionally coupled to a pinion 231 gearing with a hand-wheel 234 provided with a ratchet wheel 282 co-operating with a pawl 285, Fig. 1, on a rocking collar 283 which is connected by a spring 299 and a slotted link to a lever 274 in connection with the core of a solenoid 270. The carriage is pulled rearwards by means of a chain in connection with a sprocket wheel 216 on a shaft 217 provided with another sprocketwheel 218 which is connected by a chain to tension-springs. The sleeve 225 is splined to a shaft 244 which is geared to a shaft 240 provided with a ratchet-wheel 277 co-operating with a pawl, 280, Fig. 1, on a collar 278 which is connected by a yielding link 290, 291 to the lever 274. A trueing-tool carriage, mounted on the carriage 210, carries a feed-screw which is geared to the shaft 244 and engages a nut on the carriage 210, the gearing being so arranged that normally the carriages receive equal feeds. The feeds are adjusted by means of pawl-shields 335, 332. Feed of the trueing- tool carriage can be prevented by a latch 313 which is moved into and out of engagement with a pin 311 on the collar 278 by means of adjustable dogs 320 on the pinion 231, and thereby prevents operation of the pawl 280. This subject-matter does not appear in the Specification as accepted.