MIL-L-23400E
3.4.6 Spindle speed change mechanism. The spindle speed mechanism shall
be the manual speed change type, the manual speed change with pre-select
power shift type or the variable speed type as specified (see 6.2.1.) The
shifting mechanism shall be designed so that speed change cannot occur
unintentionally.
Except for the variable speed drive, speeds shall be in
geometric progression within 10 percent. The spindle shall operate in both
The manual speed change mechanism shall allow
directions of rotation.
spindle speed changes by positioning gear shift levers or dials located on
the front side of the headstock. Speed shall be selected by positioning the
levers as indicated on a conveniently located speed chart or by positioning
The manual speed change with preselect power shift
a direct reading dial.
shall provide spindle speed selections by manually setting a selector con-
It shall be possible to preselect the
trol to the desired spindle speed.
next spindle speed while still cutting, then automatically initiate the
The variable speed change
shift
upon activation of the spindle control.
mechanism shall permit spindle speed adjustments to compensate for varying
Optimum speeds shall be obtained by gear range selec-
machine conditions.
It shall be possi-
tion and by variable speed adjustment within the range.
The actual spindle
ble to adjust speed within a gear range while running.
speed in RPM shall be shown by a speed indicating device located convenient
to the operator.
3.4.7 Feed thread gearbox. Unless otherwise specified (see 6.2.1), the
lathe shall be equipped with a selective type, combination inch and metric
gearbox to provide a full range of inch and metric feeds and threads as
specified in table I, without the use of transposing gears. The cross slide
feed screw and the compound slide feed screw shall each be equipped with
dials graduated to read measurements in both the inch system and the metric
Power feeds and thread leads shall be provided by the totally
system.
Longitudinal and cross feeds shall be pro-
enclosed quick change gearbox.
vided by a feed rod from the gearbox to a feed mechanism within the apron.
Feeds shall be in either direction regardless of the direction of spindle
rotation. Threading shall be done using a leadscrew from the gearbox and a
The lathe shall be able to
split nut mechanism within the carriage apron.
cut either right-hand or left-hand threads regardless of the direction of
spindle rotation.
The gearbox shall be automatically lubricated.
Safety
clutches or other devices shall protect the feed/thread gearbox, feed rod
and leadscrew from accidental overload.
An interlock shall prevent simul-
A feed and thread
taneous engagement of the feed and thread mechanism.
chart shall be mounted near the gear box as a ready reference for feed and
All feed and thread selections shall be shown without
thread selections.
need for mathematical conversion.
3.4.8 Carriage. The lathe shall have a carriage that supports the apron,
cross slide, compound rest, and other related equipment. The carriage shall
traverse longitudinally on the bed ways.
The carriage shall be fitted to
the bed ways and shall have means of compensating for wear between sliding
Means shall be provided to lock the carriage to the bed at any
surfaces.
desired location between the headstock and tailstock for cross feed type
The carriage shall operate in both longitudinal directions
operations .
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