The various motions of the machine are as follows: There are 16 speeds of work table, 8 with the single, and the same with the back gear. The cross slide is capable of being raised or lowered, to suit the height of the work, by an automatic motion. Both tool rests are capable of hand or automatic feed motion at various rates of speed, in a line parallel to the surface of the work table. Both are also capable of automatic or hand feed motion, either vertically or at any required angle to the work table, and have a quick return motion for raising them, while each may be firmly locked while taking radial or surfacing cuts, thus preventing spring or vibration to the tool bar. In addition to this, however, there is provided, when required, a tailstock, carrying a dead centre after the manner of a lathe, so that the work may be steadied from above as well as by the work table. In [Figs. 726] and [727] are shown the devices for raising the work table and those for actuating the feed screws and the feed rod; thus operating the sliding heads horizontally and the tool bars vertically. a is the base or bed supporting the work carrying table b′, and affording its spindle journal bearing at d′. A step within and at the foot of d′ rests upon the wedge f′ so that when the wedge is caused to pass within d′ it lifts the step, which in turn lifts the table spindle, and hence the table, sufficiently to relieve its contact with the outer diameter of the bed. f′ is operated as follows: The lever g′ is pivoted at e′ and carries at its upper end a nut h′, operated by a screw on the end of the bolt i′; hence rotating i′, operates wedge f′.
For operating the automatic feed motions, f is a disc upon a shaft that is rotated by suitable gears beneath the work table; g is a disc composed of two plates, having a leather disc between them, the perimeter of the disc having sufficient frictional contact with f to cause g to rotate when f does so: g drives the vertical spindle i, which has a worm at j′ driving a worm-wheel which rotates the gears upon the feed spindles v, f, w, in the figures; f rotates in a continuous direction, but the spindle i is caused to rotate in either direction, according to whether it has contact with the top or bottom of the face of f, it being obvious that the motion of f above its centre is in the opposite direction to that below its centre of rotation. The means of raising and lowering g to effect this reversal of rotative direction is as follows: It is carried on a sleeve g′ which is provided with a rack operated by a pinion that is rotated by means of hand wheel h; hence, operating h raises or lowers g′, and therefore g; h′ is a hand wheel for locking the pinion, and hence detaining the rack (and therefore g) in its adjusted position. This design is an excellent example of advanced American practice for obtaining a variable rate of feed motion in either direction, it being obvious that g, being driven by the radial face of f, its speed of rotation will be greater according as it is nearer to the perimeter of f and less as it approaches the centre of f, at which point the rotary motion of g would cease. Here, then, we have a simple device, by means of which the direction and rate of feed may be governed at will with the mechanism under continuous motion, and conveniently situated for the operator, without his requiring to move from the position he naturally occupies when working the machine.
The means of raising or lowering the height of the rail r on the side standards z are as follows: k is a pulley driven by belt from the countershaft and operating pinion l, which operates pinion n, driving m. o is a gear on the shaft driving the pinions p, p, which operate the gears q, q, on the vertical screws which engage with nuts attached to r; m and n are carried on a bell-crank r pivoted on the shaft of pulley k. Pinion n is always in gear with pinion l, and pinion m is always in gear with pinion n (and not with pinion l). With the bell-crank in one position, motion passes from l to n and to o; but with it in the other position, motion passes from l to n, thence to m, and from it to o. The motion of m, therefore, is always in a direction opposite to that of n; hence o, and gears p and q, may be operated in either direction by regulating which of the two gears n, m shall drive o, and this is accomplished as follows: The bell-crank r is connected by an arm to rod s, and the latter is connected by a strap to an eccentric t, operated by the handle shown. When this handle stands horizontally, both m and n are disengaged from pinion o; but if the handle be raised, rod s is raised, and m is brought into gear with o. If, however, it be lowered from the horizontal position, n is brought into gear with o, and m becomes an idle wheel.
Fig. 728.
There are two feed screws—one for operating each boring bar-head, and a spindle for operating the vertical feeds of the bars in the sliding heads. [Fig. 728] shows the arrangement for engaging and disengaging the feed nuts of these heads. a is the slide that traverses the rail. It carries a nut made in two halves, n and n′, which are carried in a guide or slide-way, and which open from or close upon the screw f when the handle o is operated in the necessary direction. Each half of the nut is provided with a pin projecting into eccentric slots x in the face of a pivoted plate (shown dotted in), to which the handle o is attached. w, w represent bearings for the vertical feed spindle w in [Fig. 726]. a is the annular groove for the bolts b in [Fig. 729].
For a quick hand traverse for the head the ratchet, p is provided, operating a pinion s, which engages with a rack t, running along the underneath side of the cross-rail r. To adjust the fit of a to the rail the gibs y and y′ and the wedge x are employed.
