Machinery Repairman

Figure 6-4 shows this plate for the geared headstock
in figure 6-3. Always stop the lathe when you shift
gears to avoid damaging the gear teeth.
Figure 6-3 shows the interior of a typical geared
headstock that has 16 different spindle speeds. The
driving pulley at the left is driven at a constant speed
by a motor located under the headstock. Various
combinations of gears in the headstock transmit the
power from the drive shaft to the spindle through an
intermediate shaft. Use the speed-change levers to
shift the sliding gears on the drive and intermediate
shafts to line up the gears in different combinations.
This produces the gear ratios you need to obtain the
various spindle speeds. Note that the back gear lever
has high and low speed positions for each
combination of the other gears (fig. 6-4).
Figure 6-4.—Speed index plate.
Figure 6-3.—Sliding gear-type headstock
6-4
The headstock casing is filled with oil to lubricate
the gears and the shifting mechanism it contains.
Parts not immersed in the oil are lubricated by either
the splash produced by the revolving gears or by an
oil pump. Be sure to keep the oil to the oil level
indicated on the oil gauge.
The headstock spindle (fig. 6-5) is the main
rotating element of the lathe and is directly connected
to the work, which revolves with it. The spindle is
supported in bearings at each end of the headstock
through which it projects. The section of the spindle
between the bearings carries the pulleys or gears that
Figure 6-5.—Cross section of a headstock spindle.