Bachmann 9F Running Problems

Not a duff loco, just the mechanics of a long coupled wheelbase having to be got round a curve. The diesel chassis have considerable flexibility with a pair of independent short wheelbase bogies with centre gear coupled wheels. On the steamers the powered wheelbase is usually longer, and the coupling rods create binding as the wheels move laterally in the chassis for the curve: every additional pair of flanged wheels makes the effect worse, so your 9F will be worst of the lot. If you have not done so already, check that all the 9F's wheels have unconstrained sideplay and that all the coupling rod pins are lubricated, as this will help.

It may interest you to know that I loco motorised the original tender drive Triang Hornby 9F when it first came out, and that ran on a layout with mostly set track curves. Despite attending to the lubrication this loco wore through the coupling pin holes in the rods after a few years operation, and had to have them rebushed.

Of all the large steam locos I have tried, my Bachmann 9F Evening Star struggles the most on setrack curves, even radius 3,
it does not actually stop, but it does slow significantly.

I am in the, perhaps fortunate, position of being about to construct a new layout after a house move, I will still need to use setrack curves, but in the past year both Peco and Hornby (I think) have released radius 4 setrack curves, so I am thinking of using these for the outer mainline.

It depends on how 'finished' your current layout is as to whether a move to radius 4 curves could be accommodated with minimum disruption.

I have to say that, despite the problem, I am generally quite impressed with the 9F, the flywheel makes a big improvement to the general running characteristics.

Good Luck
Ashley