Can I run my old AC powered loco's on DC ?

Most older motors are series wound universal motors that will run on AC or DC.

They should run just fine on DC.

Running on DC won't harm the motors.  They're universal: AC or DC.

There have been some reports that running on DC may magnetize your E-unit plunger, causing it to stick.  That won't happen right away, if at all.  The solution is simple-- just run your loco on AC again for a little while, which will demagnetize it.

I am not sure about the E-units on DC.    The motors should be fine, but the E-unit may not work, you may only be able to run one direction.     

No the E-units will work, at least for a while.  SOME folks have reported the plunger sticking after a long while, because it has become magnetized.  If you change to DC permanently, you can rewire the motor to bypass the E-unit and control direction by changing polarity on the rails (as they do in HO scale, etc.)

Thank you so much "ROYBOY", "TEDS", & "PRRJIM" for helping out with your knowledge and advice. I did a little "test" yesterday with one of my early AC "301" Buco loco's, and it seemed to run very well around the track on DC power. The field winding did not get "hot" to touch after 5 min of continual operation, which is a good sign.

I used my DC transformer in the same manner as I do with the AC transformer - both are Buco transformers but one has a DC rectifier fitted - (power off - E-unit goes into neutral - power on again and the loco starts travelling in the forward direction - power off again - the E-unit goes into neutral again - power on again and the loco starts travelling in reverse)

The loco also seemed to run a little smoother and quieter, and also seemed to have a little more speed at basically the same control position on the transformer- or it maybe just me.

Anyway, I will keep my eye on the E-unit pivot arm becoming "magnetized" - but also now know what to do if it should happen.

Thank you so much guys, and it looks like my train life will be just that little bit more easier with only one transformer to worry about. Great forum to belong to!!

Peter on the fabulous Gold Coast in sunny Queensland, Australia.

DC will typically run the old universal motors a bit smoother, no surprise there.

A Lionel 'universal' motor has a wire wound field. What an E unit does, is reverse the polarity of the field with respect to the armature to make the motor reverse. If you ran a universal motor without an E unit on DC and switched the track polarity, the engine would still NOT reverse, because you're switching the polarity of both the field and the armature.

Unlike a permanent magnet motor, where the field polarity is 'permanent' (duhh) and track polarity switches the armature only. THEN the motor reverses.

Or am I wrong? (I don't think so....)

CJ, you're just wrong in this context as he has an E-Unit to reverse only the armature.  This will indeed reverse the direction. 

You'd be right, of course, if this were just a series wound motor running directly on DC.

Ted S posted:

No the E-units will work, at least for a while.  SOME folks have reported the plunger sticking after a long while, because it has become magnetized.  If you change to DC permanently, you can rewire the motor to bypass the E-unit and control direction by changing polarity on the rails (as they do in HO scale, etc.)

In order to do this you need to wire in a bridge rectifier in place of the E-unit such that reversing the DC polarity of the rails also reverses the polarity to the motor field winding with respect to the armature windings.

From here:

On Edit: I did this way back in the '90s and it works quite well.

Lew

This question comes up quite often.  As noted, both early conventional power engines with universal motors and mechanical E-units and later can motor engines with electronic E-units will operate on DC power. In this case, the standard forward-stop-reverse-stop, etc. protocol will be intact. There is one additional option with DC power. To take advantage of the DC polarity control of direction, with universal motor engines, bypass the mechanical E-unit and substitute that well documented bridge rectifier circuit  and with can motor engines bypass the electronic E-unit and wire the can motors directly to the pickups.  With either of these methods, engines appear to run a bit smoother. 

Once again forum members, thanks for all of the positive feedback. I can rest easy at night knowing I am not slowly burning out the fine wires in the stator coils of these collectable Swiss 3 rail "O" gauge loco's.

Thank you "GUNRUNNERJOHN" for also chipping-in - I really appreciate the advice you give. You set me straight about using "Loctite 660" to secure the slipping pinion gear on the Lionel Can motor shaft I had. Worked a treat!!! Thank you.

Peter (Buco tragic) - Queensland, Australia.