The feed motions for the work table are shown in [Fig. 3189], and the construction is such that for ordinary work the table has a quick return motion, while for heavy work the feed and return motions of the table are speeded alike.
The driving pulley b, [Fig. 3189], for operating the feed mechanism, receives motion by belt connection from the countershaft, and drives the shaft on which are the bevel gears b and d, and from these gears the feed motion and quick return are derived, while from gear e and pulley r the cutter head may be raised and lowered by belt power as occasion may require. Beginning with the feed motion, the gear d drives gears e and f, which are a working fit on the shaft s. Between these two gears is the clutch r, r, which is operated by the handle shown in the perspective view, [Fig. 3187], at v.
To operate the feed, clutch r is operated to engage gear e with the shaft s, upon which is the friction wheel m, which engages with the internal surface of the wheel or drum g, which drives the rope wheel a, which drives the rope for the work table traverse—wheel a and the rope being seen in the perspective view, [Fig. 3187]. The shaft n has bearing in a piece that is virtually a sleeve eccentric, because its bore is eccentric to its circumference; to this sleeve is attached a lug h′ to which the handle h, [Fig. 3187], is bolted. Now suppose that handle h is depressed, and then g will partly revolve wheel g and cause it to engage with the friction wheel m, which will drive g, and therefore a.
Diametrally opposite to m is a friction wheel n, which is driven by the bevel gear c, and which is brought into or out of action with g by the eccentric action of sleeve g, it being obvious that when the sleeve g moves g in the direction of n, m is engaged and n disengaged from contact with g. Raising the handle h therefore places n in gear with g, which revolves it in the direction necessary to draw the work table on the back or return stroke.
The return motion of the table is more rapid than the feed motion because gear c is of smaller diameter than b, and n is larger than c and than m.
In the case of heavy work, however, the return motion may be made to have the same speed as the feed motion by simply moving the clutch r so as to engage wheel f with the shaft s.
The rope groove in the pulley a is waved as denoted by the dotted lines, and this prevents the rope from slipping, notwithstanding that the rope envelops but half the circumference of a. The wire rope from a operates a drum, in which are waved grooves for the table traversing rope which winds around this drum, and attaches to pins (k, [Fig. 3187]) carried in brackets at the ends of the table, and one of which is shown in [Fig. 3187], at z.
The slack of the rope is readily taken up (as occasion may require) as follows:
The pin k, to which the rope is fastened, has at one end a squared head to receive a wrench to revolve the pin and wind up the rope, set screw l locking the pin after the rope tension is adjusted.
We have now to explain the method of holding the work, which is as follows: