DP2

[thesteambuff]

Heljan DP2 keeps derailing has any one else had this problem.

[The Johnster]

More info needed, steambuff.  Is it a a particular location (in which case we need to look at the track) or does the loco derail all over the place (in which case we need to only look at the loco)?  Does it only happen in one direction, and are both bogies involved?  Are you using setrack, and if so what radius?  We'll take it as read that track is level within spec., each piece is smoothly connected to it's neigbour, that the loco is running on curvature of at least the specified minimum radius, and that facing turnouts have their flangeways cleaned of grit, ballast, or other obstructions. 

 

First thing to check on the loco is the back-to-back measurement of each axle.  This is done with a back-to-back gauge, and if you haven't got one they are available from most model railway outlets and the likes of Gaugemaster, and are a very worthwhile investement.  You insert the gauge over the axle so that the backs of the wheels are a tight fit, either easing them out or squeezing them in along the axle if they are not such a fit.  Apologies if this is the granny and the eggs thing.

 

Then check that the bogies are free to pivot and move vertically in their prescribed limits; it is possible that crud or poorly dressed wiring is hindering their movement.  Check that the NEM couplings are mounted correcly and that the droppers do not foul on turnout rails or barrow crossings (trimming them by a mm will not harm their function), and that they engage properly with the next vehicle, as fouling may pull the bogie off the rails.

 

Btw, it may be better to put this thread in 'Modelling Questions, Help, and Tips'; people in this section will be looking for prototype information and help may be more forthcoming in the other section.

Edited May 23, 2023 by The Johnster

[thesteambuff]

Hi thank you for your advice it's nothing to do with the track but the loco basically derails on different points which are medium or long, bogeys working fine no couplings are attached at the moment.

20 other locomotives do not derail on those points. I've tried the back-to-back gauge and it's very tight so hopefully that's the problem.

[MikeParkin65]

DP2 is particularly sensitive to track irregularities in my experience - I believe it is a consequence of the long body, the scale gap between bogie and body and the amount of free play in the centre undriven axle. Both Bachmann and Accurascale have had to make different compromises to get their models of the Deltic (basically the same mechanically in model form) around trainset curves and/or variable tracklaying standards.

[JSpencer]

Heljan used very thin wheel profiles and a deformed (slightly wide) nose in order to allow the loco to keep to scale ride height and deal with toy curves.

 

Others did:

Sitting high on the bogies 

or smaller wheels