Engine problem - need help

[MichaelT]

Evening.

I have an Atlas GP40-2 DC engine that has developed a squeal. When I run it at about 1/3 throttle it's fine, but when I get faster than that, it starts an intermittent squeal and bogs down a little, going either direction. It seems to be towards the front of the engine when traveling forward. I gave it a light lubing to see if anything in the gearing might be stuck, but that has had no effect.

I've tried to load a short video on photobucket, but no luck so far...

So, anyone have any ideas for troubleshooting?

[MichaelT]

/>
I was able to get it loaded on youtube...hopefully this works.

[Kisatchie]

It says "This video is private."


Hmm... back to the
drawing board...

[MichaelT]

It says "This video is private."


Hmm... back to the
drawing board...

/>
see if this works?

[Kisatchie]

Hmm... yep, that works...

[carlso]

MT, sounds like a motor bearing to me. Did you lube them when you did your "lube job"?

No expert, by any means, but I think I am right,
Always have fun,
Carl

[Viperjim1]

Sounds to me like the same , lube the armature shaft and the top gear above the truck, on the shaft, I had this happen with a Kato.

[mplsjct]

I've been able to alleviate this issue by lubricating the worm gear shaft, on the insides of the bearing blocks. It requires dis-assembly of the mechanism, but that is fairly straightforward with split frame designs.

[MK]

I can almost bet that the bearing blocks need some lube.  Open her up and put a tiny bit on each block where the shaft goes in.  Been there, done that.

Please report back if that works.

[peteski]

Yup, high-pitch squeals are usually coming from the fastest-spinning parts of the mechanism: Motor and worm shafts. Lube all their bearings.

[jagged ben]

This is one of those where you can also remove the inner bearing blocks.  'Bearden technique'. 

[carlso]

I know this photo does not explain the squeal that OP asked about. This is from an Atlas/KATO GP-30 from 1992-1994'ish production. No wonder the unit would not run. I found this situation while cleaning the trucks. Somebody attempted to glue the two pieces together with ACC. Won't work on Delrin.

However, after Beardenizing the loco and installing different trucks it is a KATO with very smooth basically quiet operation.

Always have fun,
Carl

[peteski]

I know this photo does not explain the squeal that OP asked about. This is from an Atlas/KATO GP-30 from 1992-1994'ish production. No wonder the unit would not run. I found this situation while cleaning the trucks. Somebody attempted to glue the two pieces together with ACC. Won't work on Delrin.

Wow, I have never seen this type of failure on those wheelsets!  Actually I have never seen a cracked axle tube or split gear on the low-friction trucks from any of the manufacturers that use it (Kato, Atlas, Life-Like).  I have been retrofitting new Kato low-profile "semi-scale" wheelsets in Atlas locos and I have few of those Atlas wheelsets. If you need one PM me your address and  I can mail it to you.

[carlso]

Peteski,

Thank you for the offer and I may need to take you up on it. I have some parts coming and I'll know after they come in.

I too have not seen such a failure. If you notice on the good axle there appears to be too much of a gap between the idler gear and the backside of the wheel. What I think happened was somebody was attempting to alter the gauge on the broken axle set and either pried with something or maybe pulled too strong and caused it to crack.

Thank you for the offer and if needed I'll PM you,
Carl

[peteski]

If you notice on the good axle there appears to be too much of a gap between the idler gear and the backside of the wheel. What I think happened was somebody was attempting to alter the gauge on the broken axle set and either pried with something or maybe pulled too strong and caused it to crack.

That sounds like a very reasonable explanation.  I have also adjusted wheel gauge on those wheelsets (the gauge is too tight when they are fully seated on the axle tube), but I take trucks apart to do that.