owentherail Posted March 11, 2012 Share Posted March 11, 2012 Help!! this only just started happening recently, a lot of my Bachmann mk1s derail. After coming off a 3rd radius curve a bogie dont straighten up and de-rails, it happens to more than one coach but not all coaches, anyone any ideas, cheers owen. Link to post Share on other sites More sharing options...
Baby Deltic Posted March 11, 2012 Share Posted March 11, 2012 Check to make sure the bogie securing screws aren't too tight. Are the bogies easy to rotate by hand? Is the track level, or is there a slight dip or misalignment in the track coming off the curve? Are the bogies BR1's, Commonweaths or B4's? I think the coupling arrangements differ between the bogie types on Bachy MK1's. Link to post Share on other sites More sharing options...
Ravenser Posted March 11, 2012 Share Posted March 11, 2012 If they used to go round fine but now don't, something must have changed. If the coaches that come off are all of them recent purchases then maybe Bachmann have changed something on the Mk1 . If not and you've had the coaches a while, then presumably something's changed on the track at this point. Sorry if this sounds a bit general , but I'm afraid you will need to do some systematic checking here to pin down where the fault lies. If it's only at one spot, then the chance is that it's the track, not the stock, and if it didn't happen before, the implication is that something in the track has changed (A shot in the dark - expansion and contraction due to recent sharp changes in temperature?). If it's always the same piece of stock , and in several places then that means it's the vehicle. 3rd radius is tight, and not ideal , but the first task is to pin down where the fault lies Link to post Share on other sites More sharing options...
RMweb Premium John M Upton Posted March 11, 2012 RMweb Premium Share Posted March 11, 2012 I would echo what has already been said. Bachmann Mk 1's are one of those types that are very sensitive to sudden changes in gradient, particularly when it occurs on or just exiting a curve. This happened to me recently, it highlighted that in fact part of the trackbed had sunk a bit, not visible to the naked eye. A bit of packing up with slips of card under the offending section identified and fixed the fault. Also as already said, Bachmann can sometimes fit the bogie securing screws too tightly and loosening them a little will help. Link to post Share on other sites More sharing options...
RMweb Gold Dagworth Posted March 11, 2012 RMweb Gold Share Posted March 11, 2012 If it is the commonwealth bogies then try trimming the top of the damper off which protrudes above the top of the bogie and fouls the chassis. The mod is not visible once the bogies are under the vehicle. Andi Link to post Share on other sites More sharing options...
owentherail Posted March 11, 2012 Author Share Posted March 11, 2012 Cheers guys, ill look at the track on that corner and the bogies on the few coaches. Link to post Share on other sites More sharing options...
JeremyC Posted March 11, 2012 Share Posted March 11, 2012 It could be that a hump has developed in your track. I've found a cause of derailments with these coaches is the hook for the close coupling mechanism spring preventing the bogies pitching nose down. Removing the bogie and shaving the hook to about 1/2 its thickness seems to solve the problem. When you remove the bogie look for a mark on the bogie stretcher, there'll be a polished mark if the hook is touching. Jeremy Link to post Share on other sites More sharing options...
RMweb Premium BR60103 Posted March 12, 2012 RMweb Premium Share Posted March 12, 2012 What couplings are you using? I've found that some Kadees will touch various bits of bodywork (buffer beams, coupling hooks, corridor connections) or the screw holding them will bind against something. Some of mine go in for buffer locking if I've tried for too close a coupling. (don't have the B'man Mk 1s, myself). Link to post Share on other sites More sharing options...
Adrian Wintle Posted March 12, 2012 Share Posted March 12, 2012 How many coaches are in the train and what couplings are you using? Tension locks or Kadees in the close coupling mechanisms with a significant tail load (6+ coaches) can cause the bogies to run skewed - a wheel flange can then climb a track gap. Adrian Link to post Share on other sites More sharing options...
owentherail Posted March 12, 2012 Author Share Posted March 12, 2012 How many coaches are in the train and what couplings are you using? Tension locks or Kadees in the close coupling mechanisms with a significant tail load (6+ coaches) can cause the bogies to run skewed - a wheel flange can then climb a track gap. Adrian Hello, there is 7 in the rake, with tention lock couplings, seems to be the usual few coaches, it gets round curve ok but bogie stays at angle when coach straightens, ive not been in attic for a few days but will try the ideas out, its the same corner and coaches ive used for a year or so now!! first problems with it last week... cheers owen Link to post Share on other sites More sharing options...
RMweb Premium Gwiwer Posted March 12, 2012 RMweb Premium Share Posted March 12, 2012 As you say, Owen, it is the same stock you have been running for a while on the same layout and not something just out of the box. Something has changed. Load 7 is quite modest and while it is as many as a lot of us can run the actual drag of 7 Mk 1 vehicles behind a loco isn't excessive. I run a large number of Bachmann Mk1 coaches some of which are on leaf-spring style bogies and some Commonwealth. I find a few will do exactly as you describe and it is usually the same few in the same spots every time. I use the fitted Bachmann tension-lock couplers. Experimenting with the alternative vacuum-pipe couplers helped in some cases but not others but has the twin disadvantages of making it harder to assemble and break up a rake of coaches (and impossible to split and shunt in traffic) and of extending the gap between them somewhat. I have checked the bogie fixing screws and found some to be overly tight. Backing them off by a quarter-turn at a time until they rotate very freely has helped. A tight bogie may also not have sufficient ability to yaw (that is to rise and fall in the front-to-back plane) which is required for safe travels over track no matter how well it is laid. I checked the coupler arms were not catching on their swing mechanism nor remaining in an angled position after taking a curve - that is not the problem and all work fine. Some coaches self-rectify if reversed in the formation and some simply prefer to be in a different position. I have noticed the leaf-spring bogies tend to derail more often than the Commonwealth but have no way to prove this is due to the design or moulding as it may equally be that those had tight fixing screws. None of mine exhibits a rub mark from wheel rims or couplers. My trains are up to 12 vehicles in length and I can run 16 on a good day. Above 12 the drag does become a factor and it is harder to persuade a summer Saturday holiday train of 14 - 16 coaches to stay on than a "normal" rake of between 8 and 12. I would also pay very careful attention to the track itself. I have found a few irregularities creeping in over the years which have caused a few upsets. A thin card shim beneath the sleepers either the full width or, sometimes, just on the outside of a curve will usually effect a cure and result in everything running better not just the errant Mk 1s. If you have a rail join on a curve check this has not attempted to straighten itself as flexi-track may try to unbend over time leading to slight angles across the joiners. If that is found then a minor realignment may be required with some new pinning of the track but it isn't the end of the world. As with so many of our problems the answer may lie in trial and error and there may not be one answer for every coach which derails. I hope we have managed to give you food for thought and lead towards a positive outcome as I know how frustrating this problem can be. Link to post Share on other sites More sharing options...
Adrian Wintle Posted March 12, 2012 Share Posted March 12, 2012 Hello, there is 7 in the rake, with tention lock couplings, seems to be the usual few coaches, it gets round curve ok but bogie stays at angle when coach straightens, ive not been in attic for a few days but will try the ideas out, its the same corner and coaches ive used for a year or so now!! first problems with it last week... cheers owen Watch the coupling on the problem coach as it comes out of the curve. Does it stay pulled off to the side? Because of the interaction between the coupling arm and the bogie, this can hold the bogie at an angle to the track which can cause derailments. In this case, a possible cure is to use the pipe couplings or the Hornby Roco-style close couplers within the rake - the fixed-bar nature of thos couplings will re-centre the coupling arm, allowing the bogie to track properly. As mentioned above, I would check the bogie fixing screws as well. Adrian. Link to post Share on other sites More sharing options...
RMweb Premium BR60103 Posted March 13, 2012 RMweb Premium Share Posted March 13, 2012 You can ignore most of my last post. Does this happen when the coach is by itself or only in a train? Link to post Share on other sites More sharing options...
owentherail Posted March 13, 2012 Author Share Posted March 13, 2012 You can ignore most of my last post. Does this happen when the coach is by itself or only in a train? Both, in a train and on their own, ill get up in attic tonight to try a few things out. cheers for all the ideas so far. owen Link to post Share on other sites More sharing options...
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