Fig. 1571.
Referring to [Fig. 1570], upon the plate p is pivoted a lever q, carrying a universal joint at z, and a nut pivoted at v, and it is obvious that at each half-revolution of p, the rod r is moved vertically. This rod connects to a universal joint j (shown in [Fig. 1571]) that is pivoted in a toothed segment (k, in the same figure) which engages with a pinion on the feed screw, this pinion being provided with a ratchet and feed pawl (of the usual construction) for reversing the direction of the feed or throwing it out of action.
The amount of feed is regulated as follows:—
Referring to [Figs. 1569] and [1570], the amount of vertical motion of rod r is obviously determined by the distance of the universal joint z from the centre of the plate p, and this is set by operating the hand wheel t, which revolves the screw y in the nut v.
For lifting the tool during the return motion of the work and work table, there is provided in the plate p, [Fig. 1570], a pin which actuates the rod b, which in turn actuates the grooved segment c.
From this segment a cord is stretched passing over the grooved pulley d, [Fig. 1571], thence over pulley e, and after taking a turn around the pulley f, [Fig. 1571], it passes to the other end of the cross slide, where it is secured.
This pulley f is therefore revolved at each motion of the plate p, [Figs. 1569] or [1570], or in other words each time the work table reverses its motion.
In reference to [Figs. 1571] and [1572], f, [Fig. 1571], is fast upon a pin g, at whose other end is a pinion operating a gear-wheel h. Upon the face of this gear-wheel is secured a steel plate shown at m in [Fig. 1572], which is a vertical section of the sliding head. In a cam groove in m, projects a pin that is secured to the sleeve n, which envelops the vertical feed screw o. This sleeve n has frictional contact at p with the bar q, whose lower end receives the bell crank r, which on each return stroke is depressed, and thus moves the tool apron s, and with it the tool, which is therefore relieved from contact with the cut upon the work.
The self-acting vertical feed is actuated as follows:—