Athearn BB switcher help

Model Railroader General Discussion (Model Railroader)
1

Hello all! I have been slowly working on compleating my SW7 project. I have the shells base coat of paint done but it needs some touch up.

I thought this was a good time to work on the chassis and get it running correctly. I cleaned the wheels so they shine and cleaned the pickups on the trucks. I sanded the rust off the metal prongs that bring the electricity from the truck to the motors and it ran fine for a few seconds.

Now it does nothing until you press on the motor and then it moves. There are blue sparks coming up from the bottom of the frame. Is there a ground down there?

Any help is greatly appreciated!

2

There is a contact strip on the bottom of the motor (similar to the top one) that has two prongs on it. Those two prongs make contact to the chassis as a ground connection. Remove the motor and clean the prongs and the area they contact on the chassis.

Be careful removing the motor. If those motor mounts are old and dried out, they will just crumble apart when you try to remove the motor.

Mark.

3

[Y]

The motor mounts will break 95% of the time. Might as well order some replacements.

-Kevin

4

I removed the motors from all five of my Athearn switchers and replaced them with smaller and better motors, which also allowed me to add more weight, for improved pulling power.

I then split the copper cladding on a small piece of circuit board, and soldered rail joiners to it, as shown below…

I also soldered wires to what was left of the original metal contact strips, and then added short pieces of rail to the free ends of those wires. The rail was then inserted into each appropriate rail joiner. This allows for easy truck removal, for cleaning or other maintenance, and, if necessary, motor removal, too, should it ever be needed, with no disruption of the other connections.

Performance is much more reliable and servicing much easier.

Here’s four of them, shortly after hauling a 71 car train up the 45’ long 2.8% grade which leads to the partial second level of my layout…

Wayne

5

Thanks for the suggestiona guys! I went ahead and took out the motor (the mounts didn’t break!) and all the contacts and cleaned them till they were shined and looked brand new. Even where they contact the frame.

I then put everything back together and it still had the same issue!

when the shells off, if you push the Motor to the right really hard it moves no problem. I’m stumped.

I think it’s a very old unit. I got it when I was 8 from my dads friends old layout that was torn up years ago.
Wayne, what type of motors did you use and where can you find one?

I have a chassis bin from a few old bachmanns and a BB gp35 chassis. Could I take a motor from one of those?

6

If the strip under the motor is making good contact with the chassis, there is one other place to look - notice on Wayne’s second and third picture there is a flat metal spot on the top of the truck? That’s how power gets from the one rail to the chassis, and thence to the motor via that bottom contact. It needs to be clean there, and on the bottom of the frame where that part of the truck rubs.

Also if you had the trucks apart, you didn;t lose any of the little square bushings, did you? Those are how the power gets fromt he axle stubs to the metal plates of the truck.

Since it goes if you press the motor to the side, there’s definitely a contact issue. You are pushing something into contact that is not touching like it should when the loco is just sitting there.

–Randy

7

That was quite some time ago, but I used Mashima motors which were reasonably priced and work well. There are lots of on-line sites offering good quality motors at far lower prices than I paid. I installed them in the place where the Athearn motor was, using silicone sealant.
Measure the inside of the body shell (width and height) to ensure that the motor you choose will fit, and keep in mind that the cavity in the shell is narrower at the top, due to the draught angle needed to remove casting from the mould.

With all of the electrical connections done with wire and soldered together, contact problems will be solved.

Wayne

8

I think that will be my project for tonight. I will try soldering as many connections as I can. Hope that works! Any reccomendations on what gauge wire to use?

9

For short connections inside of locomotives I use “meter lead wire” which is 18 gauge, super flexible, and insulated with silicone.

-Kevin

10

Hey I have spools of that here at work. Im sure they wont mind if a few feet go missing [:-^]

11

Hello All,

I have a cow & calf set of those same Athearn B.B. locomotives; AKA TR & TR2.

One of the problems with B.B. locos is that they use the frame as an electrical conduit as well as the metal strip on the top for the other electrical path from the rails to the motor.

The motor brushes are held in place by these metal strips and a spring for each brush.

If the spring(s) become compressed the brushes will not make consistent contact between the metal strips and the motors’ armature.

You can carefully remove the metal strips and “pull” the contact springs to elongate them.

When doing this be careful to not lose the brushes. (These aren’t “brushes” with bristles, they are small cylindrical pieces of material that press against the armature. After time they wear down.)

Elongating the springs can compensate for a worn brush(es) but only to a point.

Inspect the brushes, they should be about 1/8-inches long and be concave on one end from contact with the armature. If they are smaller you might need to replace them.

When reinstalling them make sure the concave end is against the armature. This will ensure maximum contact with the flat end of the brush and spring.

The good news is Athearn still sells motor brushes and springs. I recently purchased a pack of replacement springs.

Isolating the motor from the frame will solve a lot of problems even in DC. In DCC this is a MUST.

Check out this thread: Athearn Blue Box motor replacement.

Those old open-frame motors can draw alot of current (amps) and run hot.

Unfortunately, upgrading to a modern can motor will require milling out of a portion of the frame for the new motor to fit.

You can use a rotary tool with a high-quality bit.

I know this because this is one of the projects on my workbench.

Hope this helps.

12

A few feet might be a lifetime supply!

-Kevin