The cutter slide f is operated through the medium of a screw and bevel-gears from a shaft h1, which is arranged to revolve alternately in opposite directions from a continuous motion of the driving cone pulley t, receiving, motion from the feed pulley i, through the means of a swinging arm, carrying a receiving pulley and cone as is shown in [Fig. 2069].
The method of obtaining these opposite motions of the shaft h1 will be seen in [Fig. 2071]. To the block h2 which supports the shaft h1 is secured a gear h3, which engages with a pinion h4 mounted loosely on the cone pulley i1. Side by side with this gear is placed a second gear h5 also engaging with the pinion h4 and having one tooth less than the gear h3. This gear is mounted loosely on the shaft h1 and is sleeved through the block h2, and to it is secured a ratchet clutch j.
This arrangement produces a motion analogous to that of worm gearing; the revolution of the cone i1 carrying the pinion h4, causes the gear h5 to be moved in the opposite direction to that of the cone i1, and at a speed of one tooth for each revolution of the cone. The cone i1 carries on its outer end a second clutch j1. The shaft h1 is made hollow, and two clutches are secured to a rod playing loosely on the hollow shaft, and arranged to be engaged alternately with the clutches j and j1. This engagement is effected by means of a bell crank k, operated by a shipper rod k1 on which adjustable dogs are placed, arranged to be operated by the cutter slide f.
This arrangement of feed shipping motion is very positive in its action, and allows of a very quick return of the cutter slide. The parts are so proportioned that the slide returns thirty-three times as fast as the forward motion, and yet on the very fastest speeds there is no perceptible jar of the parts. The entire mechanism can be disconnected from the feed screw, when desired, by disengaging the clutch j3 on the feed screw. The means employed for spacing the wheel blank are shown in [Figs. 2070] and [2072]. At the rear end of the spindle c is secured a worm-wheel l. This worm-wheel is made in two parts screwed firmly together. By this construction the wheel is made very accurately. The screw holes in the ring l1 are slightly elliptic. After the wheel has been hobbed out the position of the ring is changed and the wheel re-hobbed, and so on until the teeth will match perfectly in any position of the ring, when the ring is pinned and screwed on permanently. This wheel is driven by a worm m in connection with change gearing m1, m2, in such a way that one turn of the shaft m3 serves for all divisions. To the shaft m3 is secured a graduated plate o, to which is secured a latch plate o1 by means of a T-slot and bolts. The latch plate o1 is secured in this manner in order that the plate o may be turned any desired amount of “set over” in bevel-gear cutting, without disturbing the change gearing or latch. This dividing mechanism is driven by an independent belt from the countershaft to the pulley p, which is secured to a pinion p1, running loose on a stud. The pinion p1 engages with a gear p2 mounted loosely on the shaft m3. This gear is made to drive the latch plate o1 at the proper time by means of friction plates, which are set to the required tension by check nuts. The latch plate o1 is held by a spring latch v, which is secured to an arm v1 mounted loosely on a stud. The arm v1 is moved by a disk v2 carrying a secondary latch v3. This secondary latch v3 has on one side a roll which engages with a fixed cam v4 which trips the latch v3 from its connection with the arm v1, thus allowing the spring on the latch v to return it to its seat in the latch plate o1.
The disk v2 is moved by a steel ribbon (s, [Fig. 2070]) which is connected to a pair of plates, t t1, held together by a T-slot and bolts, and mounted loosely upon the carriage which carries the cutter slide f. The object of the double plates is to take up the slack ribbon, in any required position of the carriage, on the knee e. To the inside plate t1 is connected a shipper rod t2, which carries a dog and is operated by the return motion of the cutter slide f. A spiral spring coiled on the stud supporting the disk v2 returns the disk to its original position on the forward motion of the cutter slide f and reseats the secondary latch v3 in its seat in the arm v1. This arrangement of dividing mechanism requiring but one turn of the shaft m3 possesses some very decided advantages over the ordinary way of simple gearing and multiplied turns. The latch v is tripped immediately after leaving its seat in the plate o1, and is returned by its spring against the periphery of the plate, and is surely seated by means of a lip on the upper side of the plate. Should it, however, fail by reason of any accident no harm will be done as the gear will be correctly spaced whenever the latch is seated, only one or more spaces will have been missed. Another advantage is that the feed gear can be disconnected and the latch withdrawn, thus allowing the gear to be revolved for the purpose of examination without any necessity for remembering the exact number of turns. When the latch is again seated the gear will be always properly spaced.
Fig. 2073.
[Fig. 2073] represents the same machine made half automatic, or in other words the feed is automatic, but when the cut is through, the worm that actuates the feed is thrown out of gear by a catch which lets the box or bearing at the left hand of the worm shaft drop vertically, this catch being operated by a stop on the side of the cutter slide. The method of arranging the feed mechanism so that it shall remain undisturbed, and require no alteration or adjustment at whatever height the knee carrying the cutter slide may be, is substantially the same as that already described with reference to the universal milling machine in [Fig. 1893], while the dividing mechanism and other general features are the same as in the full automatic, with the exception of the mechanism for operating the cutter during the return stroke, and operating the dividing mechanism, both of which operations are done by hand in the half-automatic machine.
