Roco Coach Question (HO Epoche IV)

[Keith Addenbrooke]

I ran into a problem with a Roco coach that arrived today, which I’ve fixed but don’t really understand, so thought I’d ask here…

 

 

Some pre-owned Fleischmann coaches I bought recently came with lights not mentioned in the description.  I’ve therefore taken to testing any new coaching stock just in case (the simple way, with a PP3 battery across the rails).  I didn’t expect these Roco coaches to have lights but tested them anyway, and noticed the battery was getting hot - suggesting a short circuit somewhere.  The coaches come with lighting pick-ups fitted to the bogies, so I just needed to figure out where the problem was.  I wired up a controller and set to work.

 

By process of elimination I worked out which coach it was, using one of the Fleischmann coaches to check.  Some wires visible inside the coach turned out not to be the problem, which I finally worked out was down to one particular wheel set:

 

 

 

 

But the wheel set in itself was fine:

 

 

All I had to do was turn it round.  Somehow it had ended up with the insulated wheel on the opposite side to those on the other three axles - it had probably popped out at some point after last being used and was quickly replaced the wrong way round in error.

 

 

But my question is: why?  Given all the axles are insulated, why would having one the wrong way round cause a short?  Any ideas?

 

The lesson I’ve learned of course is to check each new piece of rolling stock separately before running it in a train: I could easily have spent a lot longer trying to work out if there was a problem with a locomotive if I’d had one to hand this evening.

 

Any thoughts would be most welcome - simply to improve my understanding.  Thanks, Keith.

 

Edited January 12 by Keith Addenbrooke

[SimonHMT]

Is the pick up for the lights through the axles, via a contact strip bearing against them? 

If so, putting the axle in round the wrong way will cause a short circuit as the "live" wheels on both sides will be connected via the strip.

Also, if the insulated sides of the wheels are all on the same side, if lighting is fitted then it won't work...try turning the wheels on one bogie round and it might!

Hope I'm not missing something/getting the wrong end of the stick and trying to teach Grandma to suck eggs...

Simon. 

Edited January 12 by SimonHMT

[Keith Addenbrooke]

Thanks @SimonHMT, makes sense - I was thinking the pick up was via the axle point bearings.  If it’s wipers on the axles, the insulated wheels need to be the same on each bogie, but opposites at each end of the carriage, just as you say: which would mean it was the other wheel set in my errant bogie I needed to reverse.  It’s all packed away now, but next time I get out the coaches I’ll check again.  Thanks for the quick reply, Keith.

[Keith Addenbrooke]

The plot thickens…but first of all some information that may be of more general use:

 

I have a couple of Fleischmann HO bogie coaches with lights exactly as Simon ( @SimonHMT ) describes: wiper pick-ups that brush the centre of the axles, (the insulated wheels are on the same side on one bogie, and the opposite side on the other bogie at the far end):

 

 

I also have some Fleischmann HO 6-wheel coaches, again with lights.  The pick-ups are the bearings:

 

 

The clever thing with these is the metal plate that adds weight across the coach also carries the lighting circuit.  Axles are the thicker insulated type.

 

I then have a few Roco coaches.  A couple have the thicker axles that are recommended when fitting light units, with the others having the metal axles with an insulated wheel at one side (as below).  Pick-up is via the bearings, then there is a thin brass feather / wiper pick-up between the bogie and the coach body (also highlighted):

 

 

 

What is strange is that the coach I had problems with yesterday continues to be the odd one out: three of the four coaches I have with this arrangement have insulated wheels one way round on one bogie, and the other way round at the other end.

 

Not that one - that one produces a short unless all four axles are the same way round.  I don’t know if it has been internally modified at some point - it is the only one with wires inside the coach, which don’t seem to be standard (according to the instructions the light bars - when fitted - are fed by metal rods from the floor to the ceiling, not wires).

 

For now I’m inclined to leave things as they are - but if I ever want to fit lights that coach may need further investigation.  Hope that helps - it appears I have an odd one that caused the issue, Keith.

 

Edited January 13 by Keith Addenbrooke

[SimonHMT]

On 13/01/2024 at 17:06, Keith Addenbrooke said:

The plot thickens…but first of all some information that may be of more general use:

 

I have a couple of Fleischmann HO bogie coaches with lights exactly as Simon ( @SimonHMT ) describes: wiper pick-ups that brush the centre of the axles, (the insulated wheels are on the same side on one bogie, and the opposite side on the other bogie at the far end):

 

 

I also have some Fleischmann HO 6-wheel coaches, again with lights.  The pick-ups are the bearings:

 

 

The clever thing with these is the metal plate that adds weight across the coach also carries the lighting circuit.  Axles are the thicker insulated type.

 

I then have a few Roco coaches.  A couple have the thicker axles that are recommended when fitting light units, with the others having the metal axles with an insulated wheel at one side (as below).  Pick-up is via the bearings, then there is a thin brass feather / wiper pick-up between the bogie and the coach body (also highlighted):

 

 

 

What is strange is that the coach I had problems with yesterday continues to be the odd one out: three of the four coaches I have with this arrangement have insulated wheels one way round on one bogie, and the other way round at the other end.

 

Not that one - that one produces a short unless all four axles are the same way round.  I don’t know if it has been internally modified at some point - it is the only one with wires inside the coach, which don’t seem to be standard (according to the instructions the light bars - when fitted - are fed by metal rods from the floor to the ceiling, not wires).

 

For now I’m inclined to leave things as they are - but if I ever want to fit lights that coach may need further investigation.  Hope that helps - it appears I have an odd one that caused the issue, Keith.

 

It sounds to me like it's been "got at"...after all, why would the factory fiddle about with an existing arrangement that has been engineered to be mass produced, and which works? 

The only Fleischmann vehicle with lights I've got at the moment is a 4-wheel PWG, I haven't investigated how it works yet...will have a look as I'm in the process of changing its couplings.

[Keith Addenbrooke]

3 hours ago, SimonHMT said:

It sounds to me like it's been "got at"...after all, why would the factory fiddle about with an existing arrangement that has been engineered to be mass produced, and which works? 

The only Fleischmann vehicle with lights I've got at the moment is a 4-wheel PWG, I haven't investigated how it works yet...will have a look as I'm in the process of changing its couplings.

 

Hi Simon, agreed.  I need to correct an earlier comment I made about my Fleischmann 6-wheelers:  I thought the metal weight in the carriages carried the current, but on further inspection there are two metal strips beneath it that do the job instead:

 

 

 

 

I could do with some spare bulbs, and am thinking dolls house bulbs might fit as an option if I can’t get any proper Fleischmann ones (in the middle photo they are clearly of two different styles).  Hope that helps, Keith.

[SimonHMT]

Lovely carriage! Seeing this sort of vehicle in the Fleischmann catalogues that Dad used to bring me was one of the things that started my interest in German railways.

I don't know whether original spare bulbs are still available, though I wouldn't be surprised if they are.

Just check the intended voltage of any substitute doll's house (or other) bulbs as i suspect they may vary.

Cheers,

Simon.

[maico]

23 hours ago, Keith Addenbrooke said:

 

Hi Simon, agreed.  I need to correct an earlier comment I made about my Fleischmann 6-wheelers:  I thought the metal weight in the carriages carried the current, but on further inspection there are two metal strips beneath it that do the job instead:

 

 

 

 

I could do with some spare bulbs, and am thinking dolls house bulbs might fit as an option if I can’t get any proper Fleischmann ones (in the middle photo they are clearly of two different styles).  Hope that helps, Keith.

 

Those are standard 12v E5 bulbs screw fit.

 

On my long Roco DB coaches the insulated wheels are, not surprisingly, on the same side. The bogies just pull off revealing axle-point pick ups.

Edited January 16 by maico