QUICK CHANGE GEAR BOX By means of the tumbler gear handle (9, figures 3-4), the tumbler gear can be rocked into engagement with any of the change gears in the cone formation. This is done by pulling out the handle plunger and depressing the handle to disengage the tumbler gear, then sliding the tumbler along the sleeve to the proper location and lifting the handle up to bring the gears into engagement. When the gears are in engagement, the plunger in the handle locks the tumbler in place so that it cannot kick out when cutting left-hand threads.
A series of slots milled in the quick change box sleeve and a pin engaging these slots prevent the tumbler from engaging two change gears at one time. On the 13" and 15" lathes the eight feed changes ob- tained through the tumbler gear and quick change gear are multiplied three times by means of the three posi- tions of the lower lever (see 7, figures 3-4), which oper- ates a sliding gear and gives different gear ratios to the feed shaft. In the feed train two ratios are obtained by compounding feed gears in the head. They are con- trolled by the small handle near the center of the head (refer to 5, figure 3). The 13"-15" Regals provide 48 changes of feeds and threads.
The 17"-19" Regals offer 56 feed and thread changes; the 21"-24", 63 changes. The direct reading index plate is mounted on the quick change box directly over the tumbler sleeve. The numbers on the plate refer to the threads or feeds that the leadscrew and the gear combinations will cut when the tumbler is engaged directly under the number on the index plate. "Coarse" and "Fine" refer to the location of the compound feed handle on the head, and the location of the lever refers to position of the coarse change lever (7, figures 3-4). OPERATION OF APRON The 13" and 15" Regal apron is a double-walled, one- piece casting in which all shafts and gears are supported on both ends.
The splined feed rod passes through the feed bevel pinion. A key in the bevel pinion engages the spline (keyway) on the feed rod. The bevel gear is always in engagement with the bevel pinion, which slides on the feed rod. The feed trip (1) controls both the cross and longitudinal movements, but it is interlocked to prevent accidental shifting from cross to length feed or vice-versa. When the shifter handle (1) is moved to the right to clear the safety lug (2) and pressed down, it slides into engagement, the sliding gear with a gear that is always in mesh with the cross feed screw.
Thus, the cross slide will move toward or away from the operator, depending upon the position of the feed reverse lever on the headstock. When the feed reverse lever on the head is in the left-hand position, that is, in the position farthest from the operator, the cross slide moves to the front, toward the operator. When the shifter is moved to the left, past the safety lug, and pulled up, with the feed reverse lever to the left, the carriage moves toward the tailstock. The direction is toward the head if the feed reverse lever is moved to the right.
When the feed trip (1) is in the neutral position, the interference safety rod is out of the slot in the half-nut and allows the half-nuts to be closed on the leadscrew by lever (3) to chase threads. When the feed trip is moved up or down, the safety rod moves to the right and locks the upper half-nut so it cannot be moved. When the half-nut is closed, the safety rod is in the slot of the shifter shaft and prevents the movement of the feed trip. Manual movement of the carriage is by means of FIG. 7 – 13”-15” REGAL APRON FIG. 8 – 17”-24” REGAL APRON 10