Kenton Posted June 20, 2011 Share Posted June 20, 2011 Over to you, folks - sensible guesses, please? And yes, it is visible - just - in the picture! It wouldn't be that unfiled-off tag on the gearbox wearing through the blue wire ? Link to post Share on other sites More sharing options...
John_Hughes Posted June 20, 2011 Share Posted June 20, 2011 It wouldn't be that unfiled-off tag on the gearbox wearing through the blue wire ? Good idea, but no! Link to post Share on other sites More sharing options...
ozzyo Posted June 20, 2011 Share Posted June 20, 2011 I'm reviving this thread to share a smile about the oddest things I've ever had cause a loco to stall. The chassis in question - picture below - runs superbly, though I say so myself; sprung on the leading two axles, and with the bogie also sprung down from the frames, it just glides along the track. Except that it stopped doing so, and for no reason I could fathom. At odd intervals it would stall, always in the same relative position of the driving wheels, with no obvious binding anywhere and no short circuit. With the body on it was even worse. Wheels and pickups were cleaned - no improvement; another check of the coupling rods showed nothing wrong; and absolutely nothing was catching on anything else at all. I finally found the problem a few minutes ago, and it only took two minutes to cure once it was spotted - but I won't spoil the end of the story by saying what it was. Over to you, folks - sensible guesses, please? And yes, it is visible - just - in the picture! How about the coupling rod shorting out on the rear brake hanger? OzzyO. Link to post Share on other sites More sharing options...
John_Hughes Posted June 21, 2011 Share Posted June 21, 2011 No, it's not a shorting problem at all. If only it had been the sparks would have made it easier to spot! Link to post Share on other sites More sharing options...
dikitriki Posted June 21, 2011 Share Posted June 21, 2011 Back of the coupling rod catching on the rear brake hanger support wire. Link to post Share on other sites More sharing options...
John_Hughes Posted June 21, 2011 Share Posted June 21, 2011 Back of the coupling rod catching on the rear brake hanger support wire. No, though I did check it out before I finally spotted the actual problem! In fact, none of the parts catch on any others! Which, of course, is what made it a bit of a puzzle! Keep the ideas coming! Link to post Share on other sites More sharing options...
Kenton Posted June 21, 2011 Share Posted June 21, 2011 Foreign body in the gears or brushes? Link to post Share on other sites More sharing options...
Horsetan Posted June 21, 2011 Share Posted June 21, 2011 ....Wheels and pickups were cleaned - no improvement; another check of the coupling rods showed nothing wrong; and absolutely nothing was catching on anything else at all..... My guess would be that it must be motor-related, if the rest of the chassis was fine, and the usual suspects weren't present..... Link to post Share on other sites More sharing options...
John_Hughes Posted June 21, 2011 Share Posted June 21, 2011 My guess would be that it must be motor-related, if the rest of the chassis was fine, and the usual suspects weren't present..... I wondered about that too; indeed, I actually went so far as to change the whole transmission system, taking out the High Level drive and Mashima motor - as in a piccy much further up this thread - and replace them with what's there now. Made no difference at all to the problem! I said that this was an odd one; I've never seen the like before, and hope never to again! Link to post Share on other sites More sharing options...
mikemeg Posted June 21, 2011 Share Posted June 21, 2011 The photo of the offending chassis, in posting number 24. Is it just the photograph or is the rearmost driving wheel - the one adjacent to the bogie - missing a crankpin/crankpin nut? I guess the next question (if the answer to the above is yes) is does that have anything to do with the chassis problem? If the answer is no then over to someone else. Cheers Mike Link to post Share on other sites More sharing options...
John_Hughes Posted June 21, 2011 Share Posted June 21, 2011 Foreign body in the gears or brushes? That can certainly happen, but not this time! I rotated the motor shaft by hand and checked the gears carefully, but nothing there! And the brushes are fine too! Link to post Share on other sites More sharing options...
John_Hughes Posted June 21, 2011 Share Posted June 21, 2011 The photo of the offending chassis, in posting number 24. Is it just the photograph or is the rearmost driving wheel - the one adjacent to the bogie - missing a crankpin/crankpin nut? I guess the next question (if the answer to the above is yes) is does that have anything to do with the chassis problem? If the answer is no then over to someone else. Cheers Mike The nut you mention has a smear of solder on it, which is why it doesn't really show up; but no, it's not the problem this time. Just to add to the mystery: when the chassis was up on a rolling road (the old Humbrol rollers actually) it worked perfectly. You can see why I was scratching my head! Link to post Share on other sites More sharing options...
Kenton Posted June 21, 2011 Share Posted June 21, 2011 As just about everything electrical: pickups, motor, gears, wiring; and everything chassis related: wheels, rods, brake; and everything track related has been eliminated ... We seem to be left with extraterrestrial ... (No, that would be a foreign body) I give in ? Link to post Share on other sites More sharing options...
jwealleans Posted June 21, 2011 Share Posted June 21, 2011 So it's a mechanical issue which doesn't show on a rolling road but does on track. You weren't fouling a track pin or a point mechanism? If it was worse with the body on is it to do with the position of the sprung hornblocks under load? I can understand why you were scratching your head. Link to post Share on other sites More sharing options...
RMweb Premium kevinlms Posted June 21, 2011 RMweb Premium Share Posted June 21, 2011 I'm reviving this thread to share a smile about the oddest things I've ever had cause a loco to stall. The chassis in question - picture below - runs superbly, though I say so myself; sprung on the leading two axles, and with the bogie also sprung down from the frames, it just glides along the track. Except that it stopped doing so, and for no reason I could fathom. At odd intervals it would stall, always in the same relative position of the driving wheels, with no obvious binding anywhere and no short circuit. With the body on it was even worse. Wheels and pickups were cleaned - no improvement; another check of the coupling rods showed nothing wrong; and absolutely nothing was catching on anything else at all. I finally found the problem a few minutes ago, and it only took two minutes to cure once it was spotted - but I won't spoil the end of the story by saying what it was. Over to you, folks - sensible guesses, please? And yes, it is visible - just - in the picture! OK, you said it's not a short or anything binding. So that leaves an open circuit. How about the blue wire under the piece of tape, was that loose? It also seems to change colour, so a join. Not sure how that would relate to it stopping when at one place during the revolution though. Perhaps a tyre is loose? Kevin Link to post Share on other sites More sharing options...
John_Hughes Posted June 21, 2011 Share Posted June 21, 2011 So it's a mechanical issue which doesn't show on a rolling road but does on track. You weren't fouling a track pin or a point mechanism? If it was worse with the body on is it to do with the position of the sprung hornblocks under load? I can understand why you were scratching your head. Very warm indeed, though it wasn't fouling a pin or a point mechanism; it was a mixture of mechanical and electrical, actually, but you're certainly on the right road! Link to post Share on other sites More sharing options...
John_Hughes Posted June 21, 2011 Share Posted June 21, 2011 OK, you said it's not a short or anything binding. So that leaves an open circuit. How about the blue wire under the piece of tape, was that loose? It also seems to change colour, so a join. Not sure how that would relate to it stopping when at one place during the revolution though. Perhaps a tyre is loose? Kevin Yes, an open circuit, so another very warm guess. But no, it's not the wire (which simply caught a bit of spraypaint which made the colour change) and which is firmly soldered at both ends, and isn't failing somewhere in the middle of the insulation - yes, I even tested that! Link to post Share on other sites More sharing options...
ozzyo Posted June 21, 2011 Share Posted June 21, 2011 The rear sand pipe to the center driver on the off side in the photo? If not please tell us. OzzyO. Link to post Share on other sites More sharing options...
RMweb Premium kevinlms Posted June 21, 2011 RMweb Premium Share Posted June 21, 2011 Yes, an open circuit, so another very warm guess. But no, it's not the wire (which simply caught a bit of spraypaint which made the colour change) and which is firmly soldered at both ends, and isn't failing somewhere in the middle of the insulation - yes, I even tested that! Hmm. So its worse with the cover on and is an intermittant open circuit. Is the body slightly distorting the chassis & so causing the chassis to lift on one side? Perhaps only leaving one driver in contact on one side? Kevin Martin Link to post Share on other sites More sharing options...
John_Hughes Posted June 21, 2011 Share Posted June 21, 2011 The rear sand pipe to the center driver on the off side in the photo? If not please tell us. OzzyO. YES! Full marks for spotting it! The wheels - as always - aren't exactly concentric, and so at just one point in their rotation the rear sand-pipe barely grazed the rail, lifting the whole of that side of the loco. The fact that the front two axles are sprung meant that the wheels actually still touched the rail, but without enough weight on them on ensure good contact, so the whole thing almost always stopped dead, though a touch would usually start it again. The additional weight of the body simply meant that the pipe touched the rail even more firmly. Cure - easy, just bend the pipe up a fraction. Well done, and thanks to everyone who had a go! Link to post Share on other sites More sharing options...
Kenton Posted June 21, 2011 Share Posted June 21, 2011 Hey ho - another one of those things to add to the long check list. Still glad it was identified and fixed in the end. Link to post Share on other sites More sharing options...
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