Gilloverland Posted March 31, 2015 Share Posted March 31, 2015 I thought I would post this incase it helps anyone else... I received a new to me 9F in the post this morning, so this afternoon I stuck in a dcc concepts chip along with a stay-alive. At the corner the loco shorted out my Z21 controller, I double checked the pick-ups, valve gear and wiring and tried again. It still did it so I tried a spare Hornby chip and removed the capacitors off the motor - no luck it still did it! I then tried it in the dark and saw a bright blue flash from the driving wheels, there was just enough play in the axle that the flanges are shorting on the metal firebox! When I get chance later I will strip the loco down and grind a bit of metal away... anyway I hope this will help someone... I'll try to get some pics as I do it. mods please feel free to move if this is in the wrong section Link to post Share on other sites More sharing options...
Gilloverland Posted March 31, 2015 Author Share Posted March 31, 2015 I should add that its the 4th axle from the front that is touching! Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted March 31, 2015 Share Posted March 31, 2015 The fourth driver, immediately in rear of the flangeless driver? That's the sprung axle. You might be able to avoid filing clearance by putting a very thin shim - think 5 thou - on top of the sprung plunger to limit the upward travel of the wheelset, provided that doesn't then place this axle centre below the common centreline plane of the other axles. My highest mileage Bach 9F, there's just scuffing of the paint on the bottom edge of the firebox casting both sides, so the flanges are rubbing a little (there are bumps in the track at one or two places on the layout). But if the axle is pushed fully up both flanges still just clear (light seen through the gap), so no chance of a short as yet. Something to watch out for though, so thanks for the 'heads up'. (This is the ongoing model review process that this forum does so well BTW.) One thought, my 9F's are all very early production, it's possible that with tool wear the firebox casting has 'grown' slightly. Already had similar trouble on K3's, barely any clearance above the pony truck wheelset flanges, paint wears through within the year. But there's plenty of meat to cut concealed arches in the underside of the footplate casting on these. 1 Link to post Share on other sites More sharing options...
Gilloverland Posted March 31, 2015 Author Share Posted March 31, 2015 The shiny metal is where I've removed material with the dremel. I'll paint it up when I weather the loco but at least its all working now. Link to post Share on other sites More sharing options...
philsandy Posted October 31, 2017 Share Posted October 31, 2017 The fourth driver, immediately in rear of the flangeless driver? That's the sprung axle. You might be able to avoid filing clearance by putting a very thin shim - think 5 thou - on top of the sprung plunger to limit the upward travel of the wheelset, provided that doesn't then place this axle centre below the common centreline plane of the other axles. Hi 34C, I know this is an old post, but I've just received a new Bachmann 9F (32-858) which I will be converting to EM. I have not taken anything apart yet, but it does not appear to have any sprung axle, no movement in any of them, and no sign of one on the exploded diagram service sheet. Is yours a different Bachmann model? Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted October 31, 2017 Share Posted October 31, 2017 All mine were purchased a good while back, probably before 2008.The service sheet in the file is E3285 - IS001, ( if my pencil scrawl on it may be trusted it came with 32-853) and not a hint on the diagram that the fourth axle is sprung. It was only when I had the first one apart for hardwired decoder installation that I found this feature, And then promptly fiddled with it to give it a little more movement. Link to post Share on other sites More sharing options...
Les_Gregory Posted September 19, 2020 Share Posted September 19, 2020 (edited) I bought a second hand 9F a little while ago and it ran very well. I've just got around to fitting a sound decoder and speaker, after reassembly I was occasionally getting a fleeting short at the same position of the motion but only when moving backwards, I found this thread and was delighted to have a pointer as to where to look for the problem, thank you! I couldn't be sure the flanges of the fourth driver were touching the edge of the firebox so rather than disassemble completely I ran a sharp knife down the edge of the firebox to cut a little metal off. Unfortunately it didn't solve the problem but it meant I was looking in the right area as it turned out to be the sanding pipes, which are made of a single piece of wire running across the loco and one of them was sometimes touching both flanges of the same wheel. A bit of bending sorted that out, so the problem was almost certainly caused by my handling of the loco. I thought I'd add this in case it helps someone else in the future. Edited September 19, 2020 by Les_Gregory 3 Link to post Share on other sites More sharing options...
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