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Bachmann Spectrum 4-8-2 Light Mountain - Thumping

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Bachmann Spectrum 4-8-2 Light Mountain - Thumping
Posted by richhotrain on Friday, November 11, 2011 5:00 AM

I have a 7-year old Bachmann Spectrum 4-8-2 Light Mountain that has had nothing but problems since I first bought it new back in 2005. 

The original problem was erratic starts and stops.  I returned it to Bachmann for repairs in July 2005.  Then, the same problem recurred again in January 2006, so I returned it for repairs again.  Then, in May 2006, it wouldn't run at all, so I returned it for the third time to Bachmann  for repairs.

As a result, this loco has spent most of its recent life sitting in the round house because it is so unreliable.  The past few days, I have been running all of my steam engines to decide once and for all which steamers I will keep, sell or junk.  When I put the Bachmann Spectrum 4-8-2 Light Mountain on the main line, it ran fine without starting and stopping but there was a constant audible thumping sound coming from the driver wheels.  Unfortunately, I cannot identify which set of driver wheels is the problem.

Another problem is occurring with tender derailments.  I imagine the problem there is insufficient weighting, but right now I am more concerned with the thumping.

I could return the loco to Bachmann once again for repairs, but there is a $25 basic repair charge plus the shipping costs.  I am not sure it is worth it at this point.

Any suggestions or ideas?

Rich

 

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Posted by cudaken on Friday, November 11, 2011 9:35 AM

 Rich, I would guess it has a cracked tower gear. My BLI M1a was making that kind of sound and it was a cracked gear.

 

    Ken

I hate Rust

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Posted by mononguy63 on Friday, November 11, 2011 9:56 AM

I'm with Ken on this one. As the proud owner of a few older Proto locos with the infamous cracked gear problems, I'm well acquainted with that thump-thump-thump noise. If you see the engine make a little twitch with each thump, then it's almost certainly a gear issue.

I have a couple of Specturm Mountains, too. Very handsome engines with those long sleek lines. One of them runs like a top. The other is a bit of a coffee grinder, particularly when running in reverse. Might just be a lubrication issue, but I've never been ambitious enough to investigate it.

Jim

"I am lapidary but not eristic when I use big words." - William F. Buckley

I haven't been sleeping. I'm afraid I'll dream I'm in a coma and then wake up unconscious.  -Stephen Wright

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Posted by richhotrain on Friday, November 11, 2011 11:27 AM

Thanks guys.

I hadn't considered gears.  I was more focused on the driver wheels.

I need to remove the shell to get a look at the gears.  I have never opened a Spectrum.  Do I need a special wrench to remove the connecting rods?  Or, is removal of the shell a simpler process?

Rich

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Posted by Heartland Division CB&Q on Friday, November 11, 2011 11:48 AM

I have 2 Bachmann 4-8-2's, and have been pleased with them. One of the 2 was sent to Bachmann, and I was happy with how well they handled everything.

If I were you, I would call Bachmann and explain the story, and I would ask if thye would repair it without additional charges. It never hurts to ask. Just ask them not to charge $25.00 this time becasue of the long history of problems with one model. Who knows? They might agree not to charge $25 in this particular situation.  

GARRY

HEARTLAND DIVISION, CB&Q RR

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Posted by richhotrain on Friday, November 11, 2011 12:35 PM

Heartland Division CB&Q

I have 2 Bachmann 4-8-2's, and have been pleased with them. One of the 2 was sent to Bachmann, and I was happy with how well they handled everything.

If I were you, I would call Bachmann and explain the story, and I would ask if thye would repair it without additional charges. It never hurts to ask. Just ask them not to charge $25.00 this time becasue of the long history of problems with one model. Who knows? They might agree not to charge $25 in this particular situation.  

I suppose it is worth a try.  I wouldn't mind having a look at it first though.

I gotta figure out how to open it up.

Rich

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Posted by doctorwayne on Friday, November 11, 2011 4:23 PM

I also have one of those USRA Light Mountains and found the electrical problem to lie within the plug system between loco and tender - this is also the mechanical cause of many tender derailments, as the wires can interfere with the drawbar..  Since I operate with DC power, I re-wired the loco to run without need of the tender, then replaced Bachmann's cumbersome (but necessary for DCC) plug system with a simpler version, giving tender pick-up with a non-intrusive plug.

Sorry, but I can't help you with the thumping issue.

However, only partial disassembly of the loco is required, as the only gears are the worm (unlikely to be the problem and encased withing the two halves of the weight which also enclose the motor, flywheel, and drive belt) and the axle gear.  To gain access to the axle gear, support the loco upside down and remove the three screws holding the bottom coverplate in place.  You may also need to remove the screws holding the lead and trailing trucks - I don't recall, as it's been some time since mine has been apart. Smile, Wink & Grin  Beneath, and attached to the coverplate is the wheel wiper assembly - pay close attention to this when re-assembling the coverplate, as it's very easy to bend or misalign the wheel wipers.  With the coverplate removed, you should be able to see the axle gear.  If it's split, you should be able to manually rotate the wheelset of the geared axle (the gear will be held stationary by the worm, with that axle slipping within the gear's bore) or you can apply power to turn the gear until you can see the crack (the crack, however, may not be easily visible without magnification).
Hope this helps.

Wayne

 

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Posted by jerryl on Friday, November 11, 2011 5:11 PM

It does sound like a cracked gear. Same old story.  Seems to be an epidemic, not just not bachmann.  Never had this problem with Mantua, Varney or Roundhouse.  You would think they would have figured it out by now.

   Just ordered new Climax gears from NWSL. about $40 including shipping + special Loctite at about $20 to repair a loco that ran about 10 minutes.   Enough said......

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Posted by CAZEPHYR on Friday, November 11, 2011 5:29 PM

Wayne

That is a nice looking 4807 mountain type locomotive.   Does the modifications to the model reflect your private road look?  Did you copy the basic look from a prototype railroad? 

CZ

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Posted by richhotrain on Friday, November 11, 2011 6:41 PM

doctorwayne

I also have one of those USRA Light Mountains and found the electrical problem to lie within the plug system between loco and tender - this is also the mechanical cause of many tender derailments, as the wires can interfere with the drawbar..  Since I operate with DC power, I re-wired the loco to run without need of the tender, then replaced Bachmann's cumbersome (but necessary for DCC) plug system with a simpler version, giving tender pick-up with a non-intrusive plug.

Wayne

 

Wayne, you were correct about the tender issue.  It doesn't need additional weight as I first suggested.  The drawbar is the problem.  For the moment, I have disconnected the drawbar, and the derailments have ceased, but that is not a long-term solution because the pull on the wires will eventually break them.  I will have to study a possible solution.  Thanks for the tip.

Rich

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Posted by richhotrain on Friday, November 11, 2011 6:47 PM

doctorwayne

Only partial disassembly of the loco is required, as the only gears are the worm (unlikely to be the problem and encased withing the two halves of the weight which also enclose the motor, flywheel, and drive belt) and the axle gear.  To gain access to the axle gear, support the loco upside down and remove the three screws holding the bottom coverplate in place.  You may also need to remove the screws holding the lead and trailing trucks - I don't recall, as it's been some time since mine has been apart. Smile, Wink & Grin  Beneath, and attached to the coverplate is the wheel wiper assembly - pay close attention to this when re-assembling the coverplate, as it's very easy to bend or misalign the wheel wipers.  With the coverplate removed, you should be able to see the axle gear.  If it's split, you should be able to manually rotate the wheelset of the geared axle (the gear will be held stationary by the worm, with that axle slipping within the gear's bore) or you can apply power to turn the gear until you can see the crack (the crack, however, may not be easily visible without magnification).
Hope this helps.

Wayne

 

I was able to remove the plastic piece that holds the driver wheel sets in place and expose the worm gear.  I could not see any cracks, but that does not mean that there aren't any.  I put it all back together and now I just have to figure out my next move.  It runs OK, but the thumping bothers me.  So, I may just sell it because at this point I have developed a mild hatred for it.   LOL    What am I bid?  Do I hear two cents?  Oh, that's right, we cannot sell stuff on the forum.  Can I give it away?

Rich

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Posted by doctorwayne on Friday, November 11, 2011 8:42 PM

Thanks for your kind words, CZ.  The loco was modified with some influence from the NYC's L-1 and L-2 Mohawks (mine is also known as a Mohawk, but named for the nation rather than the river).  The main changes include the shrouded turret and associated piping, the Delta trailing truck, and the re-worked front end.  The latter necessitated lengthen the loco's frame slightly, in order to accommodate the shielded pumps, new headlight, and Cal-Scale pilot.  I also added some weight, both within the boiler and in the new air tanks, which are lead-filled brass tubing.  I kept the short tender, as it's more appropriate for my shorter railroad, although I did modify it somewhat.

Wayne

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Posted by richhotrain on Saturday, November 12, 2011 5:36 AM

Wayne, those modifications that you made are most interesting.  When you were done, I assumed you repainted the entire loco.  Can you explain that a little more for our benefit?

Rich

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Posted by HaroldA on Saturday, November 12, 2011 7:27 AM
I have a Berkshire to which I once applied Bullfrog Snot and it started thumping, so I took it all off. As I remember the problem went away - but then about a month ago I re-applied it and over time it started thumping again, especially on curves. So, it now sits aside waiting for me to remove the snot - and hopefully the problem will once again go away. If not, I will look into the gear issue.

There's never time to do it right, but always time to do it over.....

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Posted by doctorwayne on Saturday, November 12, 2011 1:15 PM

richhotrain

Wayne, those modifications that you made are most interesting.  When you were done, I assumed you repainted the entire loco.  Can you explain that a little more for our benefit?

Rich

Thanks, Rich.  The loco was painted but undecorated when I got it, so painting was fairly simple.  After the modifications were finished, the boiler, cab, and tender shell went into a sink full of warm water and dish detergent, and then all parts were rinsed thoroughly and set aside to dry.  The frame didn't need to be disassemble in order to airbrush the new front end parts (mostly brass) with Floquil grey primer, and I probably primed the boiler, cab, and tender, too, as all had new detail parts and white styrene modifications.  I followed my usual routine for painting steam locos, as outlined in the Word document below.  Note that some areas apply more to brass steamers than to r-t-r ones, as this loco's running gear (drivers, side rods, and valve gear) didn't require any more than a light overspray with the appropriate colour.  The replacement trailing truck did get a coat of paint, though.

PROCEDURE FOR PAINTING STEAM LOCOMOTIVES

Before painting anything, it should be clean and free of grease, oil, fingerprints, dust, fuzz, and hair.  I usually disassemble the loco as necessary, but except for the motor, everything goes into the sink with hot(ish) water and liquid dish detergent.  The main areas to be careful are the insulated drivers and, occasionally, insulated tender, lead, and trailing trucks.  The insulation is often a paper-type product and shouldn’t be left in the water more than a few minutes.  Other than that, you can let it soak for a while, then rinse well and allow to air dry, preferably overnight.

For painting steam locomotives, I use Floquil paints, applied with an airbrush.  I like to mix three or four shades of black, starting with Engine Black.  For the cab and tender body, I lighten it slightly with the addition of some Roof Brown and Grey Primer.  Some of this “lightened black” is further lightened by the addition of more Roof Brown and Grey Primer, which is used on the boiler, smoke box front, pilot, cylinders, appliances (pumps, compressors, etc.) and tender deck.  An oily black is created by adding Roof brown and Platinum Mist to Engine Black , suitable for the running gear and frames of both loco and tender.  Finally, for the smoke box and firebox, I use Engine Black, with Roof Brown, Grey Primer, and a little Reefer Orange and/or Caboose Red.

Here are the paint proportions which I use:

CAB & TENDER:

5 parts Engine Black
1 part Roof Brown
1 part Grey Primer

BOILER, SMOKEBOX FRONT, & APPLIANCES:

3 parts Engine Black
1 part Roof Brown
1 part Grey Primer

SMOKEBOX & FIREBOX:

1 part Engine Black
3 parts Roof Brown
1 part Grey Primer
Plus a little Reefer Orange and/or Caboose Red to suit

FRAME & RUNNING GEAR:

4 parts Engine Black
1 part Roof Brown
1 part Platinum Mist

I almost always pre-paint some parts of the running gear using a brush, especially the frame, drivers, and rods and valve gear.  Much of this can be done without disassembly, but don’t hesitate to disassemble if necessary.  Most of these areas are tough to cover using spray only - the spray will eventually get in all those tight spots, but meanwhile, the adjacent areas will receive too much paint.  When this pre-painting has fully dried, re-assemble the loco into sub-assemblies:  running gear (frame, drivers, rods and valve gear), superstructure (boiler and cab), tender body, tender floor and frame, and tender trucks, lead, and trailing trucks.  I usually remove or mask the motor, and disengage the worm from the worm gear - this allows the loco’s chassis to be rolled back and forth in your spray booth, ensuring even coverage of the drivers and other moving parts.  Yes, I said brush paint them first, but this overspraying evens-out the finish.  Other than axle bearings, which are fairly-well shielded by the drivers and frame, I purposely do not lubricate any of the other moving parts, such as the side rods and valve gear.  This is because the oil quickly migrates to areas which you intend to paint (see Step 1).  After the paint has dried but is not yet fully hardened, roll (or run) the loco back and forth a few times - this will remove paint from any bearing surfaces.  After the paint has fully cured (a minimum of 24 hours) you can lube all these moving parts as required. 

When airbrushing, the colours are applied to the loco (dis-assembled to whatever degree necessary) without masking, although I do use a card or piece of paper to shield adjacent areas, as required, switching back and forth between colours, as necessary, as I paint.
On areas such as the smoke box and firebox, where pipes or handrails run across (but not touching) these hot surfaces, use a suitably-sized brush to touch up the colour to match that of the other pipes or railings.  The same goes for any appliances, such as feed water heaters, which would have been painted.

After the paint has cured for several days, it’s ready for lettering.  I generally use dry transfers, so no clear coat is required on the flat Floquil paints.  When using decals, I airbrush only the areas to be decaled with a fairly shiny semi-gloss finish - usually the cab sides, tender sides and rear, and air tanks and cylinders if they’re to receive lettering for test data.  This finish, of course, is allowed to harden fully before applying the decals.
Once the loco has been lettered, I apply various clear finishes, again, applied without masking.  The cab and tender sides and rear get a spray of fairly shiny semi-gloss, while the boiler, smoke box front, pilot, cylinders, and appliances receive a coat of “less-shiny” semi-gloss.  An even flatter semi-gloss is applied to the running gear and frames of the loco and tender.  The tender deck and interior of the coal bunker get an overspray of Dullcote, while the firebox and smoke box get no clear coat, as, to my eye, the dead flat finish of Floquil gives the effect that I want.

I usually re-assemble the running gear, then lightly weather it and the bottom of the boiler before re-assembling the entire locomotive and tender.  I don’t weather my locos too heavily, so I usually also install any window glass and headlight and marker lenses at this time, but if you like heavy weathering, it may be best to leave the glass and lenses until after weathering.

For weathering colours, I again use Floquil, mixed to whatever I think looks appropriate:  I usually use at least four or five different colours or shades of colours, and all are thinned, using lacquer thinner, about 70% to 90%.  It’s much easier to build up layers of different colours than it is to try to remove “too much”.  For “soot” along the boiler top and cab roof, straight Engine Black, thinned severely, works well for me.  The running gear is weathered with the loco moving in the spray booth, either under its own power or pushed by hand, with the motor disengaged.
  
 After the loco has been weathered to your satisfaction, don’t ruin it by applying Dullcote over the entire model - the contrast in the finishes between the weathered and unweathered areas is one of the things that contributes to making your weathering look realistic.

 

Probably more than you wanted to know, but thanks for asking. Smile, Wink & Grin

Wayne

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Posted by richhotrain on Saturday, November 12, 2011 1:25 PM

Wayne,

I am going to save this little tutorial because it seems to be a comprehensive overview of how to repaint a loco.  I have never done one, but the whole idea interests me greatly.

When I look at the photo you posted, it looks as good as, if not better, than a factory painted job.

Rich

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Posted by doctorwayne on Saturday, November 12, 2011 2:27 PM

Thanks for your kind words, Rich.  While it's certainly not the only way to paint a steam loco, the method has evolved over many years and gives the results that I want.  I also works using PollyScale paints, although I'm still using Dullcote and Glosscote for the clear finishes.

Wayne

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Posted by doctorwayne on Sunday, November 13, 2011 4:53 PM

Rich and I have been "conversing" on this problem, and he feels that I should share a few things which I discovered about my Bachmann Light Mountain.  Hopefully, it may help others with similar problems.

When I first got it, it was a bit on the noisy side and seemed to have a slight thump as it ran, too.  I added a .010" or .015" shim between the frame and the cab and with a little running, it seemed to quiet down.  I did have a problem with the valve gear on one side of the loco striking the main rod and discovered that it was due to the reverse lever being bent.  A careful attempt to straighten it with pliers resulted in it snapping in two, but a replacement was easily fabricated from .010" sheet brass.

While the noise issue seemed to be under control, I had intermittent electrical problems and traced them to internal problems in the plugs between loco and tender - the plugs were making contact with one another, but the wires within the plugs occasionally weren't.  To rectify this, I removed the circuit board from the tender (I run DC and don't use working headlights) and removed both components of both plugs.  The loco was then re-wired so that it would run without its tender, then a simple two-prong plug was added between the tender and loco for additional electrical pick-up.  This also cleared-up the issue with the original plugs interfering with the drawbar and causing the tender to derail.  Here's a photo of the new plug system, although it's shown on an Athearn Mikado:

 

I was somewhat surprised when it was suggested that Rich's loco might have a problem with the gear, (I've heard of none with Bachmann locos) but I decided to pull the bottom coverplate on my loco to re-familiarise myself with the set-up.  This loco has a drive belt, like the Bachmann Consolidation, so the only gears are the worm (enclosed, along with the drivebelt and motor, within the boiler weight) and the axle gear.  I took a quick look and put mine back together.  When I placed it back on the layout, I ran it back to where it had been parked earlier and...
....it had apparently caught a case of the thumps from Rich's loco. Bang Head

Back into the shop, the first thing I noticed was valve gear interference with the main rod, but this unrelated problem was easily corrected with some judicious bending of the offending reverse link.
The other thing I noticed, while running the loco upside down with power leads attached, was that the second driving axle (the only one on my loco that's sprung, even though the exploded parts diagram shows the fourth one sprung, too) was oscillating back and forth (alternate sides from front of loco to rear) - this is an indication of either binds in the running gear (usually siderods) or out-of-quarter drivers.

Next, I removed the coverplate again and decided to check for a cracked gear.  If the axle gear is split, manually rotating the wheels on that axle should result in the wheels and axle turning while the gear, held from rotating by the worm, will remain stationary.  I was very surprised when the wheels actually turned while the gear did not, but then noticed that the axle wasn't turning either - I now had one driver set out-of-quarter.  Sigh

I removed the screws holding the side rods on this driver set, then lifted it out.  The first thing I noticed was that one wheel was not fully seated on what appeared to be a plastic bushing on the axle's end.  Upon further investigation, all wheels on both ends of all axles are mounted on such bushings.  The bushings themselves are pushed onto the axle ends so that the outer end of the bushing is flush with the end of the axle, then the wheel is seated on the bushing, its outer face flush with the outer end of the bushing and its inner face against a flange which is part of the inboard end of the bushing.  The bushing on the unseated wheel appeared to be deformed, but after pushing the wheel off the axle, I discovered that the apparent deformation was actually hardened ca, and quite a bit of it, too.  Careful work with a #11 blade removed all traces of the hardened ca (the bushings appear to be made from some type of engineering plastic, so were unaffected by the cement). 

I pulled off the other wheel on the same axle, found no trace of ca at all, so applied some to the bushing and pushed the wheel back on, seating it fully against the flange.  After checking the other drivers to see which side's counterweight should be leading, I applied some ca to the other end, pushed the driver onto the axle, then twisted it into quarter "by eye".

While re-installing the repaired wheelset, I had the adjacent set also slip out-of-quarter Bang Head but it was a simple take apart, clean, apply ca, and re-install the drivers operation.  The re-assembled loco runs without thumping at all, although I'm wondering now if I should have re-done the other two axles, too.  At least I know now where to look if the thumping returns.

 

Wayne

 

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Posted by ChadLRyan on Sunday, November 13, 2011 6:14 PM

Doc Wayne,

Yes, thanks for that excellent writeup, I enjoyed it & will put it into practice! Thanks

Rich, hope that works out, do you have any of those BallBearing rollers for testing?? I like them, they also help for finding power sources on the boards for accessory lights, using a meter.  A third hand sometimes. 

Chad L Ryan
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Posted by richhotrain on Monday, November 14, 2011 5:13 AM

Wayne,

Thanks for posting the results of your investigative efforts to find the source of the thumping. 

And, my apologies for the on line transfer of this illness from my loo to your loco.  I was unaware of the severe degree of contagion that can occur when communicating via the Conversation feature on this forum. 

Oops - Sign

After back and forth dialog over the weekend, Wayne discovered, then corrected, the thumping issue on his Spectrum 4-8-2 Light Mountain - - the same problem that occurs on my same type of loco.  I will continue the same process today to see if I can discover and correct the thumping issue on my loco.  I suspect that my issue is the same as Wayne's issue - - the wheel bushings. 

I will report back with my findings.

Rich

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Posted by twhite on Monday, November 14, 2011 1:03 PM

Rich:

I don't know whether this will help or not, but I just picked up a brass 4-8-4 at the Roseville train show.  I got it for a 'steal' but the guy who sold it to me said it had a slight 'hitch' problem.  Took it home, test-ran it and--yup--it definitely had a 'hitch in it's getalong'.  My first thought was a stripped gear in the reduction tower, but the gears were all fine.  It turned out that one of the eccentric rods was bent in just enough to hit a main rod, causing the 'thump.'  I bent out the rod slightly, got some LaBelle light oil, went over all of the rods, turned it upside down and ran it in both ways for about fifteen minutes, and now it's smooth as silk.  So I don't know whether or not you've gone over the eccentric rods on your Bachmann, but there could be a chance that one of them is bent in just enough to be causing your 'thump.'

Just a thought.  Steamers are like Operatic Sopranos--they need a lot of 'coddling', LOL!

Tom Big Smile

 

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Posted by richhotrain on Monday, November 14, 2011 3:43 PM

Tom,

Thanks for that info. 

I checked all of the connecting rods closely, including the eccentric rods, and they all seem fine, no binding or jamming.

I have also ruled out gear problems, and the driver wheelsets all appear to be quartered correctly.

So, I suspect the bushings which is the problem that Wayne found on his loco.

Rich

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Posted by doctorwayne on Monday, November 14, 2011 9:37 PM

Rich, I'm not sure that the bushings were the problem, or at least the only problem.   The oscillation of the sprung driver  (one driver moving forward slightly while its counterpart on the same axle moved rearward) was a possible indication of a very slight out-of-quarter problem.   Admittedly, I then accidentally forced the drivers out-of-quarter while trying to see if the axle gear was split, but had I not done so, I may not have removed the geared driver and would therefore have not noticed the mess on that bushing. 

If the bushings all check out okay, re-assemble your loco and run it, upside-down, at a fairly low speed.  If you see that oscillation, it may indicate that there are drivers out-of-quarter.

 

Wayne

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Posted by richhotrain on Tuesday, November 15, 2011 5:23 AM

doctorwayne

Rich, I'm not sure that the bushings were the problem, or at least the only problem.   The oscillation of the sprung driver  (one driver moving forward slightly while its counterpart on the same axle moved rearward) was a possible indication of a very slight out-of-quarter problem.   Admittedly, I then accidentally forced the drivers out-of-quarter while trying to see if the axle gear was split, but had I not done so, I may not have removed the geared driver and would therefore have not noticed the mess on that bushing. 

If the bushings all check out okay, re-assemble your loco and run it, upside-down, at a fairly low speed.  If you see that oscillation, it may indicate that there are drivers out-of-quarter.

 

Wayne

Wayne, thanks for that clarification.  When you restated it that way, it became even clearer to me what actually happened in your situation.  I had not fully grasped, from your prior explanation, that the oscillation of the sprung driver  (one driver moving forward slightly while its counterpart on the same axle moved rearward) had occurred.   That is to say, one driver wheel moving forward while the opposite driver wheel on the same axle was moving rearward.

I will call that oscillation "wobbling" which clearly could cause the thumping sound as the loco runs down the track.  I will have to look for that oscillation on each of my driver wheelsets.  That second set of drivers (from the front) is where I have suspected the thumping all along.  Incidentally, like you, loco diagram shows springs on both the second and fourth driver wheelsets but, in fact, only that second driver wheelset is sprung.

Rich

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