Born2L8:
The drive system in your lathe was used by
the Barber Colman Company and is known as the
Louis Allis Select-A-Spede. In this system, the
line voltage is run through a full wave rectifer
to suppy the DC motor. The actual field voltage is supplied by a magnetic amplifer, whose core
saturation level is used to maintain the motor
speed under various load changes. Your motor
should have four leads, one for the armature, one
for the field and two for the shunt winding.
With the original control panel, 230 volts DC
would be available as field voltage. The speed
settings are controlled by two wire wound resist-
ors. While no voltage charts are available, a
pencilled note on the schematic indicates that a
200 to 205 volt range was used to set the low
speed, with the speed regulator in the center
position. This would give a base speed of 700rpm
and was done with the low speed resistor. The
high speed resistor was then adjusted, no field
voltage was listed for this setting.
The three position drum switch is used only
to (R)reverse, (S)stop and (F)forward. A separate
push/pull switch is used to stop and start the
motor.
There were many variations of hook-ups and speeds for the ON series of Select-A-Spede motors,
I am just giving you an overview of the basic sy-
stem.
Hendeyman