Loco Okay on Rolling Road, No Go on Track

[Sir TophamHatt]

Hello modellers!

 

I have a really old SBB CFF FFS 18414 loco, passed down by family.  It looks like this:

 

Inside, it's like this:

 

It has traction tyres.  I converted it to DCC.

 

When putting it on the rolling road, it's fine.

However when it's on the track, it simply doesn't move.  Mine is a little over cantered at certain points but even on various bits of straight track, it simply doesn't want to budge.  I know powers going to it as the motor starts if I push it but I can't figure out why it would work fine on a rolling road but not on some track.

 

Any advice on this?

[daltonparva]

I DCC'd a Hornby 2P (or 4f, can't remember which) with traction tyres, and spent ages poking and prodding as it worked when it felt like it, (I have previously done other similar locos with no probs), and when I removed the tyres it worked fine. I couldn't figure out why, ( sometimes fine on rolling road, not on track, and vice versa), but just accepted it. If its easy to get the tyres off give it a try.

Edited February 15, 2020 by daltonparva

[FoxUnpopuli]

Back-to-backs on old models are usually pretty narrow.  If it's physically possible to pull the wheels out further on the axles, more of the flanges will have more of a chance of being in contact with the rails at any one point in time.  It's not perfect, but it will be an improvement.  Adding further pickups to the unmotored bogie would be more reliable.  Nothing to stop you from doing both.

[34theletterbetweenB&D]

2 hours ago, Sir TophamHatt said:

...When putting it on the rolling road, it's fine.
However when it's on the track, it simply doesn't move.  ... I know power's going to it as the motor starts if I push it but I can't figure out why it would work fine on a rolling road but not on some track.

Does it keep going after the push start?

 

If not, a weak motor magnet may be the problem. On a rolling road all the motor has to move is itself through to two wheelsets and the rollers they are on. On track it has to shift all the mass of the loco, and overcome the drag of the pick up bogie. That requires much more force from the motor, and if the magnet is too weak to provide sufficient reaction to the field generated by the motor windings it won't move. I imagine replacement magnets will be available.

 

 

[The Johnster]

Get rid of the traction tyres.  They will not only compromise the reliability of your pickups by preventing the collecting wheels from sitting on the track properly, they will further compromised it by spreading crud all over your layout.  You may find the loco runs fine without the tyres, but the groove in the wheels that they always fail to sit properly in might cause issues where track is not level and smoothly laid, especially turnouts.  If this is the case, you can replace the wheels with suitable plain tyred spares; I suspect Peter's will have something from Lima that will do the job.

[legin]

Two points: (pardon the pun) First, I have a problematic Lima Crab which has featured quite a lot on these pages recently and which would not move properly on the track nor go over dead frogs.  The rear tender pickup wheel was not picking up power from the rails but would respond occasionally to power to the wheel in the cradle. It had not been used since 1988 when nearly new. So the rear tender wheels were removed and thoroughly cleaned with isopropyl as was the wiper which was making good contact.  It still did not work. so the offending wheels were again removed and this time sanded with 180 grit paper. It then worked. The motto of this is that with a loco which has not seen use for a long time might well have badly oxidised wheels and wipers which need some brute force cleaning.

Not all plain sailing though, because when I redid the B2Bs to the correct width, it became a bad runner again but widening them to 14.5mm, despite the thick flanges, did the trick. But it binds on curves which is another story.

Second, I have a Hornby 2P (DCC) on which the traction tyres kept coming off on 2nd radius curves, so I took them off. The result is that the loco runs normally and does not short out on any of my 22 points or anywhere else, despite the groove in the wheel. So at least from my own experience, I can't see any danger in what has been suggested above.

[JDW]

Is it possible that the wheels are turning, but the traction tyres are slipping, so on the rolling road you can see the wheels turning, but they are just slipping inside the traction tyres, and when you put it on the track the same happens, wheels spin but don't turn the tyres?