ck is opened or closed around the bar by turning
handwheel _H_. After a finished part has been cut off by a tool held in
cross-slide _J_, the chuck is released and further movement of wheel _H_
causes ratchet feed dog _K_, and the bar which passes through it, to be
drawn forward. This forward movement is continued until the end of the
bar comes against a stop gage held in one of the turret holes, to insure
feeding the bar out just the right amount for turning the next piece. On
some turret lathes, the lever which operates the chuck also controls a
power feed for the bar stock, the latter being pushed through the
spindle against the stop.

The machine illustrated has a power feed for the cross-slide as well as
for the turret. The motion is obtained from the same shaft _L_ which
actuates the turret slide, but the feed changes are independent. The
cross-slide feed changes are varied by levers _M_ and those for the
turret by levers _N_. For many turret lathe operations, such as turning
castings, etc., a jawed chuck is screwed onto the spindle and the work
is held the same as when a chuck is used on an engine lathe. Sometimes
chucks are used having special jaws for holding castings of irregular
shape, or special work-holding fixtures which are bolted to the
faceplate. The small handle at _O_ is for moving the cross-slide along
the bed when this is necessary in order to feed a tool sidewise.

This particular machine is driven by a motor at the rear of the
headstock, connection being made with the spindle through gearing. The
necessary speed changes are obtained both by varying the speed of the
motor and by shifting gears in the headstock. The motor is controlled by
the turnstile _P_ and the gears are shifted by the vertical levers
shown.

While many of the features referred to are common to turret lathes in
general, it will be understood that the details such as the control
levers, arrangement of stops, etc., vary on turret lathes of different
make.

[Illustration: Figs. 2 and 3. Diagrams showing Turret Lathe Tool
Equipment for Machining Automobile Hub Casting]

=Example of Turret Lathe Work.=--The diagrams Figs. 2 and 3 show a
turret lathe operation which is typical in many respects. The part to be
turned is a hub casting for an automobile and it is machined in two
series of operations. The first series is shown by the plan view, Fig.
2. The casting _A_ is held in a three-jaw chuck _B_. Tool No. 1 on the
cross-slide is