[Milsurplus] Help with Bendix Dynamotor

[J. Forster]

Reducing the field with a resistor is a VERY BAD idea. Here's why:

If you reduce the field, and the armature of the motor section is connected to a
stiff voltage source, the back EMF generated by the rotation will decrease. This
results in an increased armature current and acceleration of the rotational
speed. If the field gets too low, the machine will 'run away' and destroy itself
because the armature will explode by centrifugal force, or stall and burn out,
because w/o a field there is no torque.

Connect the field in parallel with the input armature.
-John.

Robert Flory wrote:

> Hi,
> I'm new to messing with dynamotors, so I want to avoid any rookie mistakes.
> I have a Bendix DA-1F that seems to have a separate field coil.  I'm
> wondering if that wants to have a rheostat in series with it to adjust the
> output level, and if I am going to get in trouble by running full juice to
> it.  The field coil measures 24 ohms, so it would have an amp running
> through it at full voltage.
>
> Any suggestions?
>
> Thanks,
>
> Rob Flory
>