Atlas new run GP35

[djconway]

Has Atlas found a slower slow motor?

Picked up 2 late November, installed Digitrax DN163A4 decoders, and started to tune them.
Found that I could not get the speed over 45SMPH.  On other runs of Atlas locos I have had no problems setting the speed curves to max-out at 70SMPH.

Did Atlas or Digitrax Change? 

One loco did show a marked increase in speed after about 10 hours of operation (45 to 68smph), but I have not seen this kind of change in Atlas loco since going to DCC in 1996.

[peteski]

Is it possible that the motors are binding? How is the slow speed performance (can they crawl at a steady speed).  45 Smiles/hr seems really low for a standard N scale model (unless they changed the gear ratio).  The drastic speed increase after some run time also seems a suspect.

[djconway]

Pete that's what I'm thinking also. 
Maybe I'll pull them apart again, but the decoder to motor connection is so fussy.  Project for next wedk.
While I have it apart I may pull the inner bearing.

[u18b]

Pete that's what I'm thinking also. 
Maybe I'll pull them apart again, but the decoder to motor connection is so fussy.  Project for next wedk.
While I have it apart I may pull the inner bearing.

I could post....

...... but you already know what I'll say.   

 

[djconway]

LOL

Ya I'm going to pull the inner blocks - noticed a bit of a slowdown going from curve to straight on my time trials this afternoon. 

[peteski]

LOL

Ya I'm going to pull the inner blocks - noticed a bit of a slowdown going from curve to straight on my time trials this afternoon.

That is all well and good (BTW, I'm not a big fan of this method) but a brand new model should not behave as badly as djconway described, running with all the parts it was designed to work with.

[u18b]

Even though it's new  (assuming it's new)

I'd take it apart and clean it.

Toothbrush, soap and warm water.
Dry
Then assemble and lube myself.

Sometimes the lube from some manufacturers gets gummy.

[djconway]

Took the two apart, cleaned, and relubed.
One got Ron's bearing treatment, the other did not.

The non-modified has about 7.5 hrs run time.
I am using the full 28 step speed table with start setting of 18/255, and a maximum of 128/255. 
The loco creeps along at just over 3.5 smph, top end is just under 70 smph. 

The modified loco, only has about 2 hrs run time.
There has been a good bit of improvement but, the starting level is 32/255 and it runs a bit rough and noisy, lowest stable speed is around 15 smph.
Top speed is 50smph.

I'm thinking that if a few more hours of breakin don't show more improvement, I'll pull it apart again, and check alignments more closely.


These two locos have required more burn-in and tuning than any other Atlas locos in 44 years of N-scale.

[peteski]

I find this odd. The mechanism is the popular low-friction design Atlas uses on other models, right?  Similar to Kato?
If you took the worms out and pushed the chassis on rails it should coast nicely.  The only possible resistance could be if it was grossly over-lubricated with a heavyweight grease. That low-friction mechanism should nto require a break-in to make it run better.

That leaves the motor.  Did you check whether the armature had end play and turns relatively freely?  The only thing that could possibly need a break-in would be the brushes. But to fully seat a brush would require dozen's of hours of running.  I wonder if Atlas is now using some sort of new ultra-slow-speed motor?

Or maybe the worms do not have any play between their bearings?

[Albert in N]

Anyone else have problems with the new GP-35?  The MoPac blue one caught my eye and I am toying with ordering one.

[Ngineer]

Anyone else have problems with the new GP-35?  The MoPac blue one caught my eye and I am toying with ordering one.

I bought an Atlas PRR GP-35 (item # 40 003 147) and the motor (item # 427 100) was DOA. Never happened before. Never ever. (The motor turns very slowly and gets extremely hot after 45 to 60 seconds at 9 Volts. With extremely hot I mean you can't touch it.)

My dealer is trying to get me a new motor.

   Javier

[peteski]

I bought an Atlas PRR GP-35 (item # 40 003 147) and the motor (item # 427 100) was DOA. Never happened before. Never ever. (The motor turns very slowly and gets extremely hot after 45 to 60 seconds at 9 Volts. With extremely hot I mean you can't touch it.)

My dealer is trying to get me a new motor.

   Javier

That is an important clue. I think we have here another example of what we were just discussing in this thread and the other thread it points to.  Atl least couple of the models I fixed were brand new (from BLW).

[djconway]

After 6.5 hours run time, top speed is still under 45smph.  Looks like a full tair down is in order - next week's project.

[AKNscale]

I bought an Atlas PRR GP-35 (item # 40 003 147) and the motor (item # 427 100) was DOA. Never happened before. Never ever. (The motor turns very slowly and gets extremely hot after 45 to 60 seconds at 9 Volts. With extremely hot I mean you can't touch it.)

My dealer is trying to get me a new motor.

   Javier

I had this happen 4 years ago on a gp40 if I remember correctly. Call Atlas and let them know so they can get it taken care of for you.

[peteski]

After 6.5 hours run time, top speed is still under 45smph.  Looks like a full tair down is in order - next week's project.

It will be interesting to see what you find. Also, check if the motor gets hot while running the mechanism (without a shell) for few minutes.  Before tear-down of course.