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I have a Hornby LMS Royal Scot pre-war 20 volt electric engine.  It barely moved when I got it.  I tore down the motor and cleaned and lubed it and fiddled with the gears and rod alignments and I got it running, but not great.  My basic question is how should I expect an engine like this to perform.  I used a Z-4000 with the throttle all the way up.  The meters read 21 volts at 2.4 amps (no headlight bulb).  It would pull six Hornby 4-wheel Coaches at a moderate speed, but occasionally needed a push to start.  It wont go as fast as a typical Lionel engine.  Hook up MTH LMS cars and it cannot budge them.  It has much less power than a typical Lionel small post-war engine.

I'm maxed out on the transformer, yet it has the feel that the engine could go better if it had more voltage.  I looked up some old Hornby transformers and they say they are 20 volts at 1 amp.  Is that really what they put out or could they go higher?  I imagine that I have worn gears, shafts, etc. that limit its performance.  Would this have had more speed or performance at 21 volts when it was new?

Would more voltage help or is it likely that worn mechanical components are holding it back?  Or am I missing a factor?  Its still very usable and will pull a traditional Hornby consist at a fair speed.  I wonder if there is anything more I could do to improve it.




Last edited by ogaugenut
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I agree with Mitch.

I think more than 1 amp is not good for the Hornby motor and might even heat it up such that the windings are cooked. Given it more Volts will not help. I have a 6 Volt version and it takes less than 1 amp. Since you have to give it a push sometimes this could mean that one of the rotor windings is gone which could be checked with an Ohm meter.



A transformer should provide what ever current is asked of it at a given voltage.  Point is the amount of current drawn is reflective of the load put on it.  If the load draws more current (at the rated voltage) than the transformer is rated to provide, eventually, the factory smoke will be let out which is bad.  So, in the same way the motor windings are designed to provide a certain power at a rated voltage (say 20V in this case).  Given standard conditions, a load less than rated load, and  good mechanical conditions, the motor should not draw more than that rated current at the rated voltage.  The point is, if the motor is drawing more than rated current to run, either you have to much load or there is something wrong with the motor.  The  last comment assumes that you have clean track, good connections, etc.  Maybe set the loco up on blocks and see what current it draws unloaded and if that's high also, or relatively high, that may help you to determine what is at fault.  As Fred suggested, you could have a bad winding, or you could also have something as simple as a broken solder joint at one of the wire connection points on the armature.  As suggested, a check with a volt meter will help, you could also re-solder those joints  between the armature segment wires and commutator segment wires.  One other detail that could remotely come into play.  IF the commutator has spun relative to the windings the windings on the armature will not be energized at the correct moment relative to the field.  They are offset with relation to each other. Someone who is a EE can square me away but this is my limited understanding after spending time in a Holiday Inn Express.

Dennis Holler posted:

If Fred has a video of a similar Hornby loco on his outdoor track, you will get a good idea of what is a reasonable speed etc.  

Of course I have a video, however I had a run with this Hornby loco and all my Exley coaches (at that time) which were only 3, but it is running at a good speed.




I'm pretty sure that "ORIGINAL" O gauge, 3 rail Hornby tinplate trains run on DC current only.

The new Ace Trains and modern replica's have a switch for Ac or DC.

I run many different prewar European trains in 3 rail gauge 1 and O gauge. They will not even move an inch on AC power. They only hum loudly. And running on AC may damage the motor.

And I will add that I think they had it right across the pond! My old prewar DC trains run so smoothly, and will run at lower speeds than a train like a Lionel 262E or 260E does on AC.

Try a DC transformer, or buy a AC to DC rectifier. I remember going through all of this back when I put in a loop of 3 rail gauge 1 to my layout and caught the "European Bug".

And there are Marklin transformers that are AC and NOT DC too for what, I'm not sure (maybe lights). I ended up installing a large "Frankenstein Looking" rectifier with big cooling fins to a large old Marklin AC transformer. Looks cool for prewar trains.

And I may be totally wrong about your loco or you might be talking about DC and I didn't see it. So some of the other Euro Tinplaters might chime in too. But I would stop running it on AC current if you are.


400Bill posted:

I'm pretty sure that "ORIGINAL" O gauge, 3 rail Hornby tinplate trains run on DC current only.


No, these trains (Hornby 6 and 20 Volt) run on AC or DC. Some of the Bassett-Lowke (with permanent magnet motors) run on DC only.

If an engine runs on AC and DC you will not damage the motor by running on AC. 



From the TCA Western web page

As Fred says, you can run an AC motor on both AC and DC.  These motors in our older trains are more correctly termed a "Universal" motor for that reason.  They have a wire wound field and wire wound armature.  Your typical DC motor utilized a solid magnet in place of the field windings.  On the AC universal, the juice flow goes through both the armature and the field windings in series.  Reversing is accomplished by reversing the relative voltage potential two the brushes and armature.  That's why these motors have the more complex reversing units like the Lionel E-unit for example.  On the strictly DC or Permanent magnet motor, you just reverse the potential at the transformer so the motor does not need a reverser on the loco.  The sin wave of AC does not play well with the permag motor and so they just sit and hum on AC.  Bad juju.  The Universal AC motor does not care.  Many people will run these motors off of DC as well, no issues.  Unless your train relies on a dc pulse to activate a whistle or reverse function.  Then you better stick to AC  for that motor.


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  • blobid0

Hi , this may be an old post but the only transformer a pre war O gauge 3 rail 20 volt Hornby will run on is a 20 volt / 3.5 amp original M20 Hornby transformer from the UK and they use 220 volts mains power  . The M20 unit puts out  20 volts AC at 3.5 Amps . Anything less than 3.5 amp and all that you will be  doing is getting the motor hot and watching it do little to nothing . They are not quiet runners either . 

Question: Does the Hornby engine normally need to draw 3.5 amps at 20 volts? A Z-4000 will easily put out 20 volts at 3.5 amps (about 70 watts) without exceeding the available wattage for one throttle. Thus the need for the M20 seems to be negated. More likely a motor field or armature issue, as discussed previously. GRJ at Henning's could diagnose and possibly repair your treasure if you feel you need professional service.

Last edited by Tinplate Art

I have wondered about this question for quite a while , as you might expect the transformer is matched to the loco and two UK based Hornby experts both agreed that the pre war 20 volt work perfectly running on the original Hornby transformer (M20) . So just saying that transformer X can do ...... Isn't really going to cut it , if a modern  3.5 amp rated transformer  is out there today good luck with that . 

The problem with buying a loco like a 20 volt pre war Hornby is that not all people own the Rolls Royce  of transformers like the 4000 . The other problem is that Hornby had a very short life in America ( 2 years ) in the early 1930,s and if they had been successful , parts would not be a problem as they would be plentiful . Even in the UK , very few collector,s and sellers are aware that a parts supply exists at all . Old collectable Hornby trains are now finding their way to the market once again because a lot of folks struck fools Gold thirty years ago  . The Hornby boom didn't happen . The only valuable model is the pre war  LMS " Princess Elizabeth " , at auction maybe a $1000 plus. 

Hi everyone,

when I have spoken to UK based Hornby guys they all say the same thing - use the correct factory transformer for pre war loco,s . Many will say the MTH Z 4000 is great etc but that is what the Uk guys say - Hornby !
The other thing old windings are temperamental at best and if you are patient with an older loco it will remember electrickery like it used to . You may jag a good used strong pulling loco but that’s rare for something of 80 yr,s plus . Yes , a good 20 volt motor will pull 4-6 cars with ease . Get yours rewound and it won’t use 20 plus volts . At least with old engineering you can fix it rather than throw it away . Good on you for buying the piece , don’t give up . Fix tricks ! 🏆

@ogaugenut posted:

I'm the OP on this thread.  I put the engine on a display shelf and have not worked on it.  I plan to get back to it eventually.  I dont know for sure, but I now suspect the problem is mechanical, like binding side rods or wheels not quartered properly.  Will try again some day.


Hi Bill ,

          I recently bought a 6 volt universal Hornby motor and it ran great but with no siderods  , so I got some repo parts from England and I was hopeful but the brass push in bearings had too much wear and the only thing that occurred was that the wheels spun free of the axles . I will use it for a project in the future . I have a pre war American Flyer 3/16 O Hudson and it has a huge amount of axle  bearing play but unlike the 20,s Hornby motor the A/F could run all day . So if your Hornby has a lot of sideways movement on the axle bearings I think its a display item .

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