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USA diesel idler gears


enginear joe
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I'm contacting NWSL to see if they can offer the idler gears for these engines in delrin. I keep wearing out the plastic USA ones. I may have to make a decent sized order? Does anyone know if the SD70MAC and the SD40-2 uses the same idler for sure? When I ordered from USA they sent me one for the other. When I called them they said to use them but did not insure they were correct?

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I'm pretty certain they are the same.  To be different would mean they would have had to have made more than one motor block type/design/gearing and with the realities of production costs I'm pretty sure all the USA Trains 3 axle drive blocks are the same.  I could be wrong.

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Thanks Ray. That sounds right to me too. I thought the SD70MACs had larger wheels though, at the least. If they are larger, than gearing changes might make sense.

The fact that mine keep eating gears, has me wondering. I don't overload them. They have not even run much since rebuilding. I need to look further at figuring this out. Delrin gears might just be the ticket.

Don't tell the boys! They probably already know.:D

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I do still think though that the gears and everything will be identical.  That is still something on those idler gears.  I do have a few USA PA units but dont run them much, will have to see how they do over time.

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  • 3 weeks later...
 
 
  • 3 months later...
 
  • 4 weeks later...

I would like to hear more about this problem of gear wear. I currently have three USA Trains locomotives: I have a UP GP7-9 that is something like 15 years old (can't remember when I didn't have it) and also recently purchased F# A/B units in Boston & Maine. (I love diversity. LOL)

 

The GP7-9 had cracked gear axle centers when I got it and neither the dealer nor USA Trains would help me out, even though the locomotive was brand new. I took the bull by the horns and sleeved all four axles with aluminum sleeves that I turned on my lathe. The point here is that the gears themselves are still in great condition as I check them every year. I use Lubriplate white grease on the worm gears and have had no problems with gear wear even though this locomotive has hundreds of hours of operation on it.

 

The F3 A/B units are too new to tell, except out of caution, I examined all four motor units for cracks when I received the units and found no cracks - fingers are crossed since these locomotives are noted for problems in this area.

 

Here's what I did to repair the trucks in my USA GP7/9. This was done right after I bought the locomotive and there have been no further problems.

 

USA%20Trains%20GP7-9%20UP%20%2013_zpstgq

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From my experience the idler gear in the 3 axle engine lasts a long time.  We were wearing them out on our public display but not as fast as the 2 axle USA engines.  So I'm not certain what is going on in this particular case with the idlers wearing out but it's not something I've seen personally.   

 

Regarding the cracked axle gears I did just confirm the new two axle wheel sets from USA now have the axle end diameter reduced by .1 mm to reduce the amount of outward pressure on the plastic gear sleeve.  This was the change I heard about that is an attempt to stop/reduce the occurrence of the slitting gears.  I hope it is successful because the splitting axle issue has been chronic on the two axle engines.

 

The wearing out of plastic gears and cracking does underscore why I am such a strong proponent that use all metal gears (worm gear and axle) in their diesels like MTH does for all their steam and diesel engines. 

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NWSL gave up on me. I contacted them per their request with no reply. I gave them the go ahead and phoned in my CC. So they simply sent my old gear back to me?? Maybe no one else inquired?

I have several 6 axle USA diesels. It seems funny to me, that they all had gear wear when I opened them up.

One was upgraded by Ray, and after a year of basically sitting, I noticed it making even louder noises when I finally got to run it on my layout. When I opened it up, I took those pics on the other post. Probably ten or twelve laps is all it took. No heavy train either.

I'm not sure how much Ray ran it.

It was a closeout from ST Aubins so maybe something there? The sliders and wheels are still like brand new.

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On the engine I converted, that would be an SD40-2 and I did that install in Nov 2009 (7 years ago).  If the drive block was taken apart to inspect how the install was done and that idler gear came out and wasn't put back in it's correct position then that might explain what was going on.  I only run the engines enough to confirm speed calibration is correct and that everything checks out.  There really is no reason for these to be failing like that unless they have a lot of hours of run time.  But with that SD40-2 being 7 years old since I had it last it could have some run time on it.

 

On the NWSL making idler gears, if their pricing is anything like what they charge for the 2 axle USA diesels gears which is $25.00 each (which means you need x4 per 2axle engine = $100.00 for four plastic gears) for an engine that costs $343.95 brand new shipped, the idler gears would likely be far more than I would be willing to pay anyway.  

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  • 2 weeks later...

Well this USA SD70 now has over 2,000 scale miles/ 60+ hours of run time with no gear train problems. 

 

IMAG0001.JPG

 

Here's the loco...

IMAG0004.JPG

 

Typical PS3 install...

 

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Remove drives for servicing...Note the brass dust on the motor block covers...

 

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Remove top covers and motors so can blow out motors and oil armature bushings while vertical...all looks fine :)

 

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Install motors and top covers then flip blocks over and remove bottom covers so have easy access to axle & idler shaft bushings for oiling.

Note the axle bushings are orientated with a pointy corner facing up and down. If you install them flat like idler shaft bushings they'll wear out idler & axle gears in short order. 

 

IMAG0020.JPG

 

Smear some grease onto gears (Lucas Red & Tacky #2) then button up and reinstall onto chassis.

 

IMAG0024.JPG

 

Note this loco has been pulling a 20 car train made up of mostly intermodals & auto carriers on my indoor layout that has 20' diameter curves.

 

 

 

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