2-8-0 shorting out

[shawneehawk]

Hi, I need advice on my Bachman 2-8-0.  I've had this loco since 1999 or 2000, most of that time spent in the box.  It ran fine on DC, then I decided to drop a Tsunami into it.  After a difficult fit, I was able to get the decoder and speaker in the tender.  The Tsunami was programmed, sound worked, and it made it around the loop a couple of times.  Then ti started acting up, stalling and jerking when it did run.  I removed the Tsunami, put the jumper plug back in the tender, and returned it to DC operation.  It still stalls.  I can see sparks around the front truck on the tender, especially around the wiper.  All connections appear intact.  I cannot find any reason for these sparks, but apparently this is what is causing the problem.  I hope I did not fry the Tsunami...don't think so as I can still read it on the programming track.  Any ideas on what I can do about the short?  I need to address this issue before proceeding further.  Thanks.

[jayl1]

Did one of the tender trucks get turned around?  Make sure both insulated wheels are on the same side.

[Yampa Bob]

I assume you removed the tender wheelsets while installing the speaker. Look at the wheels, make sure they are installed correctly as Jay mentioned. 

Typically, the tender comes from the factory with the front wheels getting track power from the right rail, the rear wheels picking up from the left rail.  However, I have seen one with the wheels oriented opposite, and the PC board wired accordingly.

If you have one or both of the front wheels wrong, and the axle pickup wiper is only making intermittent contact, you could also have intermittent shorts.

Notice the wheels have a plastic insulator on one end of the axle.  When installed, front wheels have the insulator on the left side, rear wheels with insulator on right side. (as viewed from the top)

If the wiper is not making continuous contact with the axles, you may have to bend the tabs a bit. Apply a tiny amount of conductive lubricant to the axles for better contact and less friction.

This may not be the problem, but something to check first.

[richG]

It could be the tender trucks. On my Spectrum 4-4-0 and 4-6-0, one truck picks up on the right rail and one truck picks up on the left rail. I do not have to 2-8-0 so I cannot comment on it.
I have since modified my trucks so they cannot swivel around and short out. I got that idea from the Roundhouse steamer tenders.
Check continuity with a ohm meter.

Rich

[Yampa Bob]

On my 2-8-0s with vandy tenders, there were small tabs that only allowed the front tender truck to swivel in one direction, the rear in the opposite direction.  That's ok for going around a left curve, but for a right curve the trucks wouldn't pivot. I don't know what designer (I'm being polite) figured that out.

I removed the tabs and installed new ones so the trucks swiveled both directions, but stopped at just a few degrees.

The USRA tender doesn't have the tabs, but the trucks can only swivel about 20 degrees, then the wheels hit the center channel or the coupler box.

Seems we have to re-engineer everything these days.

[shawneehawk]

Thanks for the replies.  I think we are on the right track...pun intended.  The front truck on the tender did get reversed.  I thought nothing of this, as my old Roundhouse steamers had all of the tender wheels insulated on the same side.  I corrected the front truck, and did apply some 2-26 to the axles and bent the brass wipers down some.  I have ran the loco for 20 minutes in both directions on DC; the only time it stalled was at a creep going through a turnout.  I'm going to try to adjust the wipers some more, and if all goes well, put the Tsunami back in tonight or in the morning.

BTW, this is the USRA tender; my main complaint is that the kingpin holding the trucks on is not big enough, and the trucks often slip off when the loco is picked up.  Thanks again, and I will post my progress.

[rogertra]

I'm going to try to adjust the wipers some more, and if all goes well, put the Tsunami back in tonight or in the morning.

BTW, this is the USRA tender; my main complaint is that the kingpin holding the trucks on is not big enough, and the trucks often slip off when the loco is picked up.  Thanks again, and I will post my progress.

If this is a Spectrum 2-8-0, you didn't say?

For the Spectrum 2-8-0 there is NO kingpin holding the trucks in place.  They are held in place by a small bolt up through the truck and a securing nut inside the tender.  You shouldn't really remove the trucks as this may either loosen the nut so that the truck becomes too loose or release the nut so that the truck will be free.

[shawneehawk]

I'm going to try to adjust the wipers some more, and if all goes well, put the Tsunami back in tonight or in the morning.

BTW, this is the USRA tender; my main complaint is that the kingpin holding the trucks on is not big enough, and the trucks often slip off when the loco is picked up.  Thanks again, and I will post my progress.

If this is a Spectrum 2-8-0, you didn't say?

For the Spectrum 2-8-0 there is NO kingpin holding the trucks in place.  They are held in place by a small bolt up through the truck and a securing nut inside the tender.  You shouldn't really remove the trucks as this may either loosen the nut so that the truck becomes too loose or release the nut so that the truck will be free.

Yes, it is a HO Bachman Spectrum 2-8-0.  My DCC system is the NCE PowerPro.  I only have a test loop set up, 4' x 16', a long loop with 2 passing sidings.  I test DC operations on a 4 x 8 powered by a MRC 2500 and a MRC Control Master 20.

Maybe what I am calling a kingpin is actually a bolt, as it is held in place by the securing nut you described.  As for me removing the truck, I first became aware of this problem when I found the truck and wiper laying loose on the track.  It has not wanted to stay in since.

I put the Tsunami back in, and the sound is fine.  The loco, however, is stalling very easily...at every turnout and going into any curve.  Other decoder equipped locos with sound traverse this same track with zero problems.  So the loco runs pretty good on DC, but stalls easy on DCC.  Help, I am ready to pull my hair (what's left) out.

[rogertra]

Make sure the track wipers are correcting installed.

Put the nut back on the bolt, tighten it up so that the truck still swivels easily and secure it with just a drop, on a pin point tip, of AC glue.

That will retain the nut.

[Yampa Bob]

The tender pickups are redundant with the pickups from the loco drivers.  So in effect you have 6 wheels on each side picking up current. If you are losing power on curves or turnouts you may have some problems with both the loco and tender pickups.

The reason the Spectrum 2-8-0 works so well on tight curves is because the driver wheelsets can move from side to side to "follow the curve".  In contrast Roundhouse uses blind drivers (flangeless) on #2 and #3.

The loco pickups are long and springy, and as the wheels move sideways, the wipers must maintain contact.

A few years ago, Bachmann made a design change in the "underframe" that holds the wipers. The new "bottom plate" can pinch the wipers, preventing side to side movement to follow the wheels.

The piece should be called the "top plate" as it fits on the top of the assembly.

The change made it harder to reinstall the 2 piece assembly.  The plate is supposed to snap onto the underframe, but when you turn it over to install the assembly, the plate falls off.  To solve this, I fastened the plate to the underframe with tiny optical screws, making sure the wipers weren't pinched in the process.

I consider it a poor design, the "bottom plate" should be on the bottom, so that removing it would allow access to the wipers without removing the assembly. Also, the assembly should be attached to the chassis with separate screws so as to not be unintentionally disturbed.

Turn the loco over and support in a foam cradle. With good lighting move each driver wheelset from side to side and observe the tiny wipers. They could be bent or pinched and not making contact, or there could be excess oil that has coated the inside wheel surface.

I took all my 2-8-0 apart to fine tune them. It is a rather delicate procedure, and not for everyone.  But the wipers should be at least examined.  Sometimes you can use small tweezers to (gently) move the wipers, but if they are pinched, the only recourse is to remove the 2 screws and take off the entire assembly to repair the wipers.  Replacing the assembly takes a lot of finesse, as the plastic "brakes" hang up on the wheels, and the wipers can be badly damaged if you are careless.

If the wipers are badly damaged, order part # H11410, Underframe set with front wheel set, bottom plate, and connector #2.  It's a prewired assembly with the 2 conductor plug on the wires. 

The tender truck bolt has a shoulder that will prevent overtightening, unless you get real brutal with a nut driver.  There should be a small star lock washer under the nut, I prefer a light coating of removeable "Loctite" on the bolt threads.

Good luck

[rogertra]

The tender pickups are redundant with the pickups from the loco drivers.  So in effect you have 6 wheels on each side picking up current. If you are losing power on curves or turnouts you may have some problems with both the loco and tender pickups.

Bob.

There's no such thing as "tender pickups are redundant".

You can never have enough power pickups, steam or diesel, every wheel possible should pick up power.  The more wheels you have picking up power, the less chance you have for loosing contact. 

The Athearn 4-6-2 and 2-8-2 came without tender pickups and were critised for it.

I added brass pickups to my Proto 2000 0-8-0 which originally came withoput pickups.  One of my Spectrum 2-8-0s has a P2K ex 0-8-0 tender and I added power pickups to that and rewired the loco and tender to get power to the motor.  And, of course, I added them to my Athearn steam.

Again, the more pickups, the less chance of a stall due to loss of electrical contact.

[Yampa Bob]

I agree you can never have "too many pickups", especially with DCC.  Perhaps I should have used the word "complimentary" or "extra", I was at a loss for a better word.

Technically speaking however I was correct. "Redundant" is defined as "Exceeding what is necessary".  So in that respect, Bachmann is to be commended for going beyond the basics and providing the "extra" pickups in the tenders.

Still, having lots of pickups can't overshadow or minimize the importance of good trackwork and keeping locos well maintained. Whether I have 4, 8, or even 10 pickups I want every single one of them doing their job.

[rogertra]

Yes Bob, nothing beats great care taken when track laying

[shawneehawk]

rogertra, thanks; I will try putting a small drop of AC to hold the nut in place.

Bob, I examined the wipers on the inside of the drivers.  When I pushed on one with tweezers, it extended and stuck in the driver spokes.  I ended up having to remove the plate...btw, mine was on bottom.  The wipers looked ok...they are supposed to be bent at a 45 degree angle, correct?  I got the errant one repositioned where it should be.  You're right, the operation involves some finesse, and I had to get the rods corrected on one side.

Anyway, I did get everything back together, or so I thought.  Tested the loco on DCC; got sound from the decoder, but no movement.  I removed the tender shell and decoder and put the jumper plug back in, then tested on DC.  I got a shorting sound immediately from the loco, but could see no sparks.  I did get it to run a foot or so in each direction before it would short out again.  This, after the loco ran almost perfectly on DC earlier in the day.  I might add that the mechanism rolls fine with the motor removed, nothing seems to be binding.

Super-frustrated over what I thought was a simple project.  Thanks for the input; I'll look at the loco again in the morning.

[Yampa Bob]

I looked back at your first post, you apparently have the earlier wiper assembly with the cover plate on the bottom. Jim Banner has a pictorial on adjusting the older style wipers, I'll try to find it and post the link.

IIRC from the pictorial, the older wipers were mounted at a 45 degree angle.  The new ones are positioned parallel to the assembly sides, and longer, which provides more side to side flexibility to maintain contact with the wheels.

I have another Connie to modify, I'll take some pictures this time and do a write up on the wipers. I would think the newer assembly would be a retrofit for your loco.