29 Nov
2014
29 Nov
'14
9:33 a.m.
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....
Dave
G4UGM
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of tony
duell
Sent: 29 November 2014 17:17
To: General Discussion: On-Topic and Off-Topic Posts
Subject: RE: Relay question
fitted
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
the
opposite direction.
Do Marklin still make AC HO gauge locomotives? IIRC they used an
overvoltage to toggle the reversing relay.
-tony