I have a Galley Maid 12 volt windlass on my trawler. It has a DC
motor with separate terminals for the field winding (F1, F2) and the
armature (A1, A2). Measuring the terminal voltages under load, I'm
getting readings of about 6 volts on each set of terminals. The
polarity on the armature winding reverses to change rotation
direction.

My first reaction at seeing 6 volts was that I was getting a lot of
voltage drop somewhere in the cables, controller box or terminals.
Now that I take a close look at the controller circuit however, it
looks like the field and armature windings end up in series instead of
parallel. If that is in fact the case, 6 volts at each winding would
be just about right.

Is there anyone here familiar with the normal way of connecting up the
field and armature windings on DC motors?

Wayne.B writes:

Is there anyone here familiar with the normal way of connecting up the
field and armature windings on DC motors?

Can work either way, series as you say you have, or parallel. Series vs
parallel yields different speed/torque characteristics depending on which
way it is wired, so which you want depends on the application.

"Wayne.B" wrote in message
...
I have a Galley Maid 12 volt windlass on my trawler. It has a DC
motor with separate terminals for the field winding (F1, F2) and the
armature (A1, A2). Measuring the terminal voltages under load, I'm
getting readings of about 6 volts on each set of terminals. The
polarity on the armature winding reverses to change rotation
direction.

My first reaction at seeing 6 volts was that I was getting a lot of
voltage drop somewhere in the cables, controller box or terminals.
Now that I take a close look at the controller circuit however, it
looks like the field and armature windings end up in series instead of
parallel. If that is in fact the case, 6 volts at each winding would
be just about right.

Is there anyone here familiar with the normal way of connecting up the
field and armature windings on DC motors?

This is called a series motor. Shunt (=parallel) motors do also exist, as
well al compound motors which have both. But the wiring method is not
interchangeable. If you have a series motor, you cannot rewire it to be a
shunt motor because the field windings are different for both types. A
series motor has only few fiels windings of thick wire while a shunt motor
has many field windings of thin wire. Applying a series field winding as a
shunt will simply be a short-circuit and blow (hopefully) your fuses.
The advantage of a series motor is a high starting torque, but the
disadvantage is that it runs away with no load, until it explodes into bits.

Meindert