Alco 2-6-0 DCC pick up issue.

[rogertra]

I have two DCC/sound Alco 2-6-0s and one of them has problems negotiating an Atlas code 83 25 degree diamond crossing.

The one that has no issues I can get it to creep dead slow across the diamond but the other one loses contact everytime.  It seems it's the rear truck, which slightly lurches going through the frogs and that's when the locomotive goes dead.  I've check the tender wheels  gauges and they are fine.  I've loosened both truck retaining screws (Why do Bachmann make them so damn tight?) so the trucks can pivot more freely but none of this helps.

Before I reinvent the wheel, so to speak, and take the tender apart has anyone else experienced this sort of loss of pick up problem and how did you fix it?

Thanks in advance.

[Doneldon]

Roger-

I don't have one of these so I'm kind of shooting off at the mouth, but I had another loco some years ago which behaved similarly. I thought the problem was truck weight (they were plastic) so I changed them out for some CVs and put a little solder on the bottome of the cross piece. They were just fine after that and the loco sailed through crossings and turnouts uneventfully forever after. Well, not exactly forever after. It sailed through uneventfully until my grandson's girlfriend sailed it through a turnout onto the basement floor. It turns out you can break an older (read brittle) cast zamac locomotive into several pieces if you slam it into concrete from sufficient height. But the tender was unscathed and still works great. Or maybe it's just scared. I don't know.

You might also try a close inspection of your trucks. If they are not equalized (I assume they are not in this day of cast plastic everything), the overly tight bolster screw might have distorted them just enough that the edge of a flange is losing contact with its rail right at the gap where the rails actually cross. This would occur for a remarkably short time, even at slow speeds, but electricity only needs a fraction of a millimicron of time to "detect" the loss of current. That's why some sound systems reboot at crossings and turnouts even if a flywheel keeps the loco moving until that instantaneous loss of contact is corrected.

An alternative would be to add a Tomar shoe to slide along the rails so you aren't totally dependent on the trucks for electrical pick up. That does add an appearance issue and you have to be very careful with the shoe's alignment if your pike has crossings as so many do (and yours obviously does).

Good luck with this. I predict you will solve the problem.
                                                                                       -- D

[GN.2-6-8-0]

The bachmann tenders do tend to be on the light Side'I would try setting a couple of 1/4 oz. Weights on the rear deck of the tender and see if that solves the problem....if it does then you can remove the tender body and mount the weights inside with the doublesided tape on the weights.

[rogertra]

The Brahmani tenders do tend to be on the light Side would try setting a couple of 1/4 oz. Weights on the rear deck of the tender and see if that solves the problem....if it does then you can remove the tender body and mount the weights inside with the doublesided tape on the weights.

First thing I do with all Bachmann tenders. 

Doesn't help in this case though. 

[Tom M.]

Did you check the eight of the tender coupler's trip pin?  If it is hanging down too low, it may be lifting the rear truck off the rails just as it crosses over the rail of the intersecting track.

Tom

[rogertra]

It doesn't have a trip pin, I cut them off.  :-)

But thanks.

[Joe Satnik]

Dear Roger,

What happens if you swap tenders?

Where is your decoder located?  How many pins in your tether connector?   Is the tether cable part of the engine, or the tender?

Can you tell if it is loss of contact (electrical "open") or a short?

If it is an "open", I would check all my (electrical pickup) wheels, engine and tender, for continuity.

Put your engine and tender upside down in a padded cradle, tether connected.

With your multi-meter on lowest Ohms (or continuity) setting,  probe all left side pick-up wheels.  They should be connected to one another.

Do the same with the right side. 

If you probe from any left wheel to any right wheel, you should not see a solid connection, perhaps only a higher ohms light bulb.

Typical problems:  turned around truck on tender, broken wire on tether plug.

Whole 'nuther reply needed if the problem is actually a short....

Hope this helps.

Sincerely,

Joe Satnik     

[rogertra]

Joe.

The issue, after careful study, is the tender on all(?) Bachmann steam locomotives does not pick up power on all the tender wheels wheels.  The tender of the 2-6-0 picks up power on the, let's say, left side on the front truck and the right side on the rear truck. 

Given the short wheel base of the 2-6-0's tender, the result, when going over a 25 degree Atlas diamond with plastic frogs, is both trucks are on the frog at the same time.  This results in the electrical pick up wheels of the truck, being on opposite sides of the tender, are both on the plastic frog at the same time.  Result, no power from the tender truck pick ups and loco stops!

Solution?

I need to add electrical pick ups on the insulated side of the 2-6-0s tenders and, in fact, on all the 20 plus Bachmann Spectrum steam engines that I have in stock.  Not too difficult a job but it is a pain.  This was never a problem on the old GER as I'd hand laid all my switches and they all had electrically live frogs.  It's also not an issue with the Atlas "Super Switch" as they all have metal frogs as well and I power those through a "Frog Juicer".  Trouble is, not all the Atlas track components have been upgraded to "Super Switch" standards and other than switches, all still have plastic frogs like the 25 degree crossing.

Thanks to everyone for their advice on this issue.

[Joe Satnik]

Dear Roger,

Shouldn't the six electrical pick-ups (3 left, 3 right) on your loco's drivers help?

Joe 

[richg]

Bachmann tender pickups are common knowledge here. Been mentioned many times. Use Harold's solution. I have with Bachmann steamers. Little #30 wire and problem solved.

http://www.55n3.org/cars/tender_wipers/

Rich

[rogertra]

Bachmann tender pickups are common knowledge here. Been mentioned many times. Use Harold's solution. I have with Bachmann steamers. Little #30 wire and problem solved.

http://www.55n3.org/cars/tender_wipers/

Rich

Thanks Rich.  Bookmarked for future reference.

[rogertra]

Dear Roger,

Shouldn't the six electrical pick-ups (3 left, 3 right) on your loco's drivers help?

Joe 

Not in the case of a diamond crossing, because on the 2-6-0 at least, you also need the tender pickups.

[Joe Satnik]

Roger,

I assume your loco has one decoder in the tender, fed track power from the 6 driver wheels through a tether, plus tender wheel pickups. 

On a straight piece of track (no frogs), your loco should be able to run without the tender pickups,

using only the loco's 6 driver pickups fed through the tether back to the tender and decoder. 

To test this, put a piece of Saran wrap under all the tender wheels, and see if your loco will respond to your controller.   

If not, you have a broken tether.  This is why one loco works fine through the frogs and the other doesn't, as described in your first post.

Hope this helps. 

Sincerely,

Joe Satnik   

[richg]

Some here might search the General and HO forums for tender by Yampa Bob. He did post some tender diagrams a few years ago.
DC only locos pickup from the tender only on one side and the loco, the opposite side.
DCC, as was indicated, one side one one truck, opposite side on the other truck. Some tenders, the trucks can swivel all the way around and create a short.

It would be nice if Bachmann made all wheel pickups on the tenders but that would increase the cost of the locos.
I have some Roundhouse locos also and they come with all wheel tender pickups but a different design than Bachmann tenders. The locos do not look as good as the Bachmann locos though.

Rich

[rogertra]

Joe.

Did your suggested test by just lifting the tenders from the track and in both cases, the engines responded to the throttle without the tender wheels making contact with the rails.

If you look at a 25 degree crossing, the distance between the frogs on the opposing rails closely matches the wheel base of the tender hence, the loss of contact as the pick up wheels on opposite sides of the tender are both on the plastic frog at the same time.  Unsure why the loco wheels don't solve this issue though but that could be because the wheels are not sprung.