Dapol A3 & A4 trailing wheels constantly derail

[Gremlin]

The trailing wheels on two new Dapol locomotives, and A3 and an A4, continually derail.  They don't seem to have the ability to sit/track on the rails in forward or reverse.  Does anyone have a solution to the problem?

[Andy Reichert]

Unless it's a common fault that already has a well-know fix, you have to do a little checking to see what's possibly wrong first.

 

1 Check the gauge of the trailing wheels to make sure they are not set too wide and turn freely. And that they are not wobbly or have left on sprue material anywhere on their rims/flange

2 Make sure the truck swivels freely to follow the curves

3 Make sure the truck rests fully down on the track. It should be free to drop slightly below the driving wheels (and should do so when lifted off the track)

4 Make sure the truck is free to tilt (roll)  to the left and right and still have its wheels slightly below the driving wheels.

5 Check for any missing parts (like a hold down spring pushing the truck down).

 

If none of the above seem wrong, also see if the problem occurs only at certain places on your track.

 

Andy

[Gremlin]

Thanks for your suggestions

1. Gauge appears OK and the wheels rotate freely in the chassis component
2. Trucks swivel freely, perhaps too freely?
3. This may be the problem, in both locomotives the trucks rest on the tracks but are extremely lightweight - there is no weight or spring or anything to exert downforce and the truck/chassis mechanism weighs next to nothing.  The front trucks have springs of one sort or another to exert downforce.
4. Tilt/roll is fine, so fine that the trucks pop of the tracks due to (4) above, whenever they choose
5. No spring on either an apparently no mechanism provided for one to exist - and it seems unlikely that two different models from the same manufactgurer would both be missing the identical component.

So, looks like a design flaw on the rear trucks, I will experiment with adding weight/downforce...

[hallmodelspares]

Another solution might be to fit a wheel similar to Hornby on their Super detail loco drive a4 with no flange on the wheel

[Dr Al]

Another solution might be to fit a wheel similar to Hornby on their Super detail loco drive a4 with no flange on the wheel

 

These will be N gauge models, the Hornby is OO, so not an option!

 

Best,

Alan

[hallmodelspares]

I'm talking about doing something similar to the Hornby model for the n gauge Dapol

which is why i said a wheel similar to the idea of the Hornby which is just Tireless wheels on the pony truck