Bachmann 4-8-4 (Santa Fe model w long tender), blue box

[railandsail]

Bachmann 4-8-4 (Santa Fe model w long tender), blue box

I have a couple of these Bachmanns 'Northerners' , which I believe are their latest models of this loco, but are not Spectrums. Item 50801

They are nicely detailed models,.... and run very smoothly,...and pull very good.
 
I posted this back in 2021, and I think i need to make some new notes.

Their pulling power is NOT that good,...at least in my current state of judgement. Its not terrible, just not that good.

I have found they have a tendency to 'pick a turnout' with their front driver wheel. I have a couple of Peco 3-way turnouts on my layout, and the radi for the diverging routes is quoted as 24"r. I have measured those turnouts before I installed a number of them on my layout, and it does appear to be true,..24".

Several of those Bkmann 4-8-4 are derailing their front drivers as they reach the frog,...and one of them constantly. Fortunately there is one of those 3-ways right at the front edge of my upper deck, so its easy to run some diagnosis test on.
 
TRACK or LOCO ?
Like most early Peco turnouts the guide rail slots across from the frogs are too 'roomy',..the slots were built for those Euro cookie cutter engines, and they need a little shimming to help get some of our modern engines thru with less frog picking.
 
So I am relooking at my shim to make sure I have it correct. It did seem to work with lots of my other fleet or engines.

I am experiencing what appears to be a lifting off the rails by the leading driver wheel,...which is really like a picking of the frog. I removed the leading truck on the engine so as to eliminate it as a potential source of the problem,...that did not work. I also added some extra weight (externally) up on the front of the engine,...that did not work.
 
I noticed that the body/shell of the loco did not seem to what to fully rotate towards the turning direction, and this was contributing to the derail of that front driver. This loco does have a very extended back body/ frame that would need to come around a bit more to help the situation out,...and of course the drawbar and tender connecting wiring doesn't help matters,...in fact they can exacerbate the situation by holding back some of the needed rotation.
 
I've identified one other item that I think could be contributing to the problem. This loco was built with a LOT of sideways axle play,...likely done so it can negotiated tight radi. But the back driver has too much sideways play such that it doesn't act to help 'turn' the body/shell. I think I am going to have to find a way to cut down on some of this excess 'play'.
 
Experimentation under way,...

[trainman203]

Did you check the gauging of the driver itself?  Maybe it's a little too wide?