Relay question

Dave G4UGM dave.g4ugm at
Sat Nov 29 11:33:15 CST 2014

I had a 3-Rail Hornby "O" gauge that used a toggle relay to reverse. I think
rather than over voltage it was set up so the relay had a very low "hold-in
voltage". It had a pawl that drove a commutator shaft that generated the
reversing. I think it was 24volt but might have been higher....


> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at] On Behalf Of tony
> Sent: 29 November 2014 17:17
> To: General Discussion: On-Topic and Off-Topic Posts
> Subject: RE: Relay question
> >
> > Anyone remember Lionel trains?  The power packs were AC (not DC as in
> > HO) and there was an impulse relay for reversing called an "E-Unit":
> The old O gauge Hornby trains (old meaning 1930s) were also AC. The motors
> were series wound, a single field coil on a pole piece assembly that
> round a 3 pole armature. The pole piece was in 2 parts, spring loaded to
> open. When the motor was running the magnetic field kept it all together,
> but with no supply voltage it would open up. There was a pawl mechanism
> operated by the moving part of the pole piece which swapped the
> connections to the brushes, so reversing the motor. So every start was in
> opposite direction.
> Do Marklin still make AC HO gauge locomotives? IIRC they used an
> overvoltage to toggle the reversing relay.
> -tony

More information about the cctalk mailing list