alangr Posted December 1, 2015 Share Posted December 1, 2015 I have a BG loco that derails itself every time it goes over a point - simple running on straight/curved track is good. I have tried to understand just why this is happening but have found nothing obvious. However, I have noticed that the front tender/driver seems to be weighted down excessively by the main boiler end of the model. This is the one held in place by a magnetic force. To the extent that I am correct, the 'extra weight' could be levering up the leading bogie of the front tender/driver making it more likely to derail at the first possibility. Similarly, the weight distribution would cause problems for the rear bogie when running in reverse. I am not clear that I am correct about the weight distribution but it I the only thing that I can see that might be causing the derailments. Has anyone else had this experience? It is very frustrating as the model is superb and runs very well (on simple track!). Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted December 1, 2015 Share Posted December 1, 2015 I'd recommend a survey of the B-G thread in 'Heljan', plenty of experiences there. Link to post Share on other sites More sharing options...
Grovenor Posted December 1, 2015 Share Posted December 1, 2015 The weight distribution is spoiled a bit as the pivot points for the boiler unit are not in the prototypical place, they are directly over the inner driving axles when they should be between the inner pair of drivers. This has been done, I believe, to avoid problems with the cab-coal bunker interface on train set curves. However I don't think this has any effect on the trackholding in the way you suggest. Can you be specific about which axle derails? I do think the pony trucks are poorly designed and the first thing I would do is take out the excess side play in the axles so that it pivots into the curves rather than the axle sliding sideways and ending up at a poor angle to the rail. Regards Link to post Share on other sites More sharing options...
RMweb Premium Peter Beckett Posted December 1, 2015 RMweb Premium Share Posted December 1, 2015 Alan, Have you checked the back to back on the pony wheels. Originally I had a similar problem but correcting the B-t-B fixed it. Peter Link to post Share on other sites More sharing options...
alangr Posted December 3, 2015 Author Share Posted December 3, 2015 Thank you for your helpful comments, Keith, Peter. Taking your advice, I have played with the pony wheels and reduced the play. Unfortunately this did not help and actually made matters worse at times as the pony sometimes derailed on simple straight track. Aside from the pony, Keith, it is the main driving wheels of the front tender that go haywire and this is on a straight approach to a point set to straight. Even a slow speeds, suddenly the whole (front) tender leans over and derails. I spent some time yesterday trying various approaches and found, for example, that if I turned the whole loco round, this made it ran very well over point work, straight or curved. Also, putting the loco at other locations on the layout often led to smooth running. I have three lifting sections and at one of them the BG derailed regularly although other locos/trains have had no problems here. Inspection showed that over the years, the levels had become slightly different so I packed the bridge to restore a level join and this cured the problem for the BG. I take from all this that, as ever, good track work is important but also that the BG is very sensitive. On the points where derailment occurs, for example, the track work looks OK, if not actually good! So I am finding it difficult to see the root of the problem. But the pony is another matter. I am tempted to try a small weight on top of the truck to see if that helps the track holding. It is really very light and lifts off the rails at the slightest provocation. As a general comment, the depth of the wheel flanges seems small, but I confess that I have not measured them. I will keep on trying but fingers seem to be pointing to track work, even that I have used it all for some time with large range of types of locos/trains. Back to the layout! Link to post Share on other sites More sharing options...
stewartingram Posted December 3, 2015 Share Posted December 3, 2015 If you look in the other BG thread, I posted a comprehensive bit on my strip down (for repaint) and subsequent re-assembly. Without looking back at it, I remember making a new plastic plate to replace one I lost, from around the pivot area. This was absolutely critical to the track holding qualities of the loco; perhaps a pointer for you? Stewart Link to post Share on other sites More sharing options...
alangr Posted December 6, 2015 Author Share Posted December 6, 2015 Thanks for that Stewart. I will have a better look 'underneath'! Link to post Share on other sites More sharing options...
Grovenor Posted December 6, 2015 Share Posted December 6, 2015 If you look in the other BG thread, I posted a comprehensive bit on my strip down (for repaint) and subsequent re-assembly. Without looking back at it, I remember making a new plastic plate to replace one I lost, from around the pivot area. This was absolutely critical to the track holding qualities of the loco; perhaps a pointer for you? Stewart Nb Not the main 77 page BG thread, by the time you get to page 40 odd looking for it you discover it is actually in another thread here http://www.rmweb.co.uk/community/index.php?/topic/87816-Heljan-garratt-problems/&do=findComment&comment=1515939 Regards Link to post Share on other sites More sharing options...
alangr Posted December 7, 2015 Author Share Posted December 7, 2015 Thanks for that, Keith. I had been looking at the main (big) thread without success. From Stewart's comments I guess that I will check the levels againas my starting point was the fact that the weight distribution seems off (too heavy on the leading tender). Regards Link to post Share on other sites More sharing options...
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