3591. Lake, H. H., [Day, W. F., and Lavigne, J. P.]. Feb. 12. Lathes. - Turret or capstan lathes of the autom a t i c screwing- machine type are provided with special means for reversing the rotation of the main spindle, for intermittently rotating and clamping or holding the turret or capstan rest, and for varying the speed of advance and withdrawal of the tool, special tools and tool-holders being provided. The reversal of the main or chuck spindle D, Fig. 1, is effected by a clutch B<4> which connects the spindle with one or other of the oppositely-driven pulleys C, C'. The clutch lever B<2> is operated by cams a on a cam disc A, which engage a roller B on an arm B<1> connected to the lever. The disc A is mounted on a cam shaft G<3> having a worm-wheel G<2> driven by a worm through difrerential gearing F<4>. The belt driving the fast and slow pulleys of the gearing is controlled by a fork E', shifted when necessary by cams a<1> on the disc A engaging a pin e on the fork. The turret H is mounted on a pivot H<1>, Fig. 6, on a slide I, reciprocating on the rest I<1> on the bed P. The slide is reciprocated by a cam disc P<9> which engages a pin P<7> on the slide. The slide is recessed to receive a notched ring J, Fig. 8, on the turret, and a loose ring J<3>. The ring J<3> carries a spring pawl J<3>, and is recessed to receive a spring J<5>, connected at one end to a pin j<2> on the slide and at the other to a pin J<6> on the ring. The intermittent rotation of the turret is effected as follows :-When the slide is fully withdrawn, the spring J<5> is in compression, the pin J<6> engaging a lug on the rest, and the pawl J<2> engaging one of the notches J' in the ring J. As the slide is advanced, the pin is released, the ring is rotated by the spring, and the pawl J<2> wipes past the ring J and engages in the next notch. During the withdrawal of the slide, the pin J<6> engages the lug on the rest, and, after the turret has been released, rotates it one step by the pawl and notched ring, the spring being again compressed. The turret is clamped by a nut L' and locked by a bar P. The nut L' is locked on a rod L passing through the pivot H<1> and having a lug M at its lower end acted on by a spring O<1>. This spring normally turns the nut on the upper end h<3> of the pivot to clamp the turret by means of a washer L<3>. During the withdrawal of the slide, a spring pawl on the lug M, which, in the advance of the slide, wipes past a pin on the rest, engages this pin and rotates the rod L, unclamping the turret to permit of its rotation. The bar P is normally held in one of the notches J<1> by a spring T. A lever Q, with a spring ratchet pawl R<3> at its lower end, is pivoted in a bracket Q<3> on the rest, its upper end q<4> engaging in a recess in the slide. A pin S, with a lug s, is mounted in the rest. As the slide is advanced, the bar P being in the locking position, the pawl wipes over the lug s, but engages it during the return, and retracts the bar while the turret is rotated, the pawl and lever tripping over the lug s and the bar being returned by the spring T to the position shown. An auxiliary tool carriage U may be mounted in a guide-bracket U<1> on the rest I<1>, and reciprocated by a pin U<2> and cam U<3> on the shaft G<3>. The tool spindle u<1>, driven by a pulley U', has a tool chuck u, and the tool is arranged to operate on the opposite end of the work to that treated by the turret tools. Thus, as the work is being cut off, it might be taken by a work-holder V<5>, Fig. 1, on the turret, and presented to the action of the tool in the chuck u. A tool-holder, Fig. 34, for use in the turret, has a box 15 carried by the holding-pin 17, Fig. 1. The tool 21 is held in the head 18 of a stem 20 sliding in this box. The tool is raised or lowered by a screwed pin 24 engaging the stem and journalled in the box-cover 16. The work passes through a bushing in the ring 34 on the box, so that, by raising or lowering the tool, the diameter of the work is varied. If this is done during the movement of the slide, taper work is produced. To effect this, a pinion 30 on the pin 24 engages a rack 39, mounted on a arm 43 on the headstock 33. By adjusting the position of the rack on the arm, the point at which tapering commences may be varied. A set of pinions may be provided to cut various tapers. A sizing-cutter 35 is mounted on the forward side of the box 15. The tools are made with a uniform cross-section, so that the cutting-edges may be ground without altering their shape. Shaping and parting tools may be mounted on a slide 12 operated by a cam 10 and lever 11. A cam disc 2 may be provided to operate a clutch 7, 8, on the main spindle, through clutch blocks 4, 5 sliding on an arm 6.