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Posted By Greg Elmassian on 29 Jan 2010 02:53 PM
Mark, on the subject of USAT motors, there is a long standing "tale" about the current they draw.
I've researched how this came about, and it's from some tests that George Schreyer did long ago. Under a TOTALLY LOCKED ROTOR condition, certain (not all) USAT locos can draw large amounts of amperage.

Over the years, this has been "amplified" by people just repeating the "tale" to be ALL USAT locos draw MORE current ALL the time.

As you have found out, this is not true. Very few people can get to a point where you lock the drivetrain in a full stall condition... wheels slipping are not a full stall... you have to physically restrain the motor.


Not denying what you are saying, but what about George's finding with the wheel pitting? He adds resistors to reduce the current draw, the pitting stops. I have two USAT locos and while I;'ve never measured the current draw, they seem to run just fine. George has a very well-detailed account on his website. What he describes--pitting/plating wear caused by high current draw--seems to apply to the GP 40s.
 

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I don't want to derailing the topic, but the pitting is caused by the excessively low resistance, and it's short duration spikes. The average current is as presented here. It's a lot more complex issue than just putting a meter on the rails. George is, of course, correct, and so am I (as far as I can tell
). There is no conflict between what I have said and what George has said.

You also have to understand the details of his power delivery system and his power supply. When you read all of that, you may understand.

One of the major differences in George's situation and one of the major factors in the pitting he has seen that others have not is his (fairly unique) ability to deliver extremely high current for a short duration. If you want to understand more fully, please start a new thread, and I am sure George can clarify it for you, and if he does not, I do understand it well enough to explain it.

Regards, Greg
 

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Greg,

On your web site you refer to:

"On motors, use 2112-motor bearing lubricant, or act-2752 heavy duty bearing lubricant on larger motors.Use this heavier lube on bearings, side rods and valve gear."

Is that what you use on the Aristo and USA gear boxes?



Thanks,

Mark
 

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I use both Hob-e-lube and Aero-car lubricants. Your reference on my site is preceeded by: "Here's some of the recommended Aero-car lubricants and their applications: "

Recently I have used both products, I have both here at home right now.

The heavy oil is becoming a favorite, it seems to cling better and keep dirt and dust out of valve gear. I know that people recommend lighter lubricants, but we have enough oomph in our motors that lower drag is not as important as keeping things lubed and free of moisture and dirt. I find that I only use the lighter lubes on the eccentric and related gear on steamers.

I like the heavy bearing lube on USAT axles, better than grease, both the USAT axle tips, and the shafts "inside" the wheels. The plating on the axles is so smooth, that grease does not seem to "grab" and stick as well. I prefer the hob-e-lube in this application, it seems heavier.

On gears, the NG gel (and also notice that the Atlas gel grease is the same) is the best I have found. It seems to cling to gears and not fly off. Nothing more disturbing than getting in a motor block and there is grease everywhere BUT the gears!

The gel acts like a heavy oil under pressure, giving very good coverage, but when not in mesh, it thickens back up and clings.

Expensive, but you don't need a lot because it stays on the gears.

In other applications, like axle tips on rolling stock, I prefer moly grease on metal to metal, and graphite/moly powder on metal to plastic.

Regards, Greg

p.s. I don't know what brought this up on this thread, but again, if you want to continue on this topic, I again suggest a new thread, out of respect of all the work and research that Ted has done.
 

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Since I have removed the traction tires on all my USAT locos, it is IMPOSSIBLE to stall the motor, and thus draw these huge amounts of current.



You actually believe this??

So even if a gear breaks and jams the driveline or a pebble gets on the rails and acts like a wheel chock your USA motor won't stall all because you removed the traction tire equipped axles??
 

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Discussion Starter #87
Yes, all kinds of things may happen, including a lightning bolt striking the loco, but I believe Greg was expressing the motor stall issue in the context of typical operation without debris being left on the tracks before a train is allowed to run.

My first non Aristo loco purchases were two USAT SD70s last year precisely because they were newly offered without traction tires - affording wheel slip when under too much load - thereby, avoiding stalled motor/s.

Anyway, I started this thread with respect to the Aristo GP 40 and its problems as I experience them. It was not at issue that the failed GP40 motors were a result of them being stalled. They went up in smoke of their own volition without the help of anything on the tracks or gear box jamming.

-Ted
 

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Yes, and also it's impossible to protect from EVERY thing that can happen.

Anyway, back to the topic... hopefully the next failed motors can be dissected and we can figure out what the failure mechanism is.

Regards, Greg
 

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Aristo 29130 now is $20 from Aristocraft. This means 4 are $80. For this amount you can get an eggliner from some dealers and have all the parts in the drive system.

Or, go to nwsl and for $50 get a set of 8 wheels. see #2607-6 at NWSL
 

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Thanks TED for the excellent article (i obviously missed it last jan. !! ) And thanks for the recent entry regards a cheaper wheel source !

Btw i personally have not acquired a gp-40 yet, but do have a couple gp-38s from usa trains which historically (and mentioned in this thread) have had similiar problems ! I've read thru a couple of G.S. website articles regards these concerns !

I shook my head at AC management when they rolled out the '40 with olde style composition wheels and sadly incandescent(?) lighting vs leds (which they installed in prevous engine units) . . . must have beeen a fire sale in a china parts factory of these olde components, the previous yr. !! :(


imho,
doug c
 

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For all, Ted has done more investigation, and has also had another GP40 develop excessive current draw. He's detailed this in 2 videos.

The first details the current consumption, it is long, but shows the information unequivocally.


The second video shows the current draw before and after motor replacement.

Bottom line, this loco was sort of running ok, but drew 2 amps on rollers! After motor replacement, drew under one amp.

To draw a fine line, many of the GP40 motors are just plain defective, and will get worse over time once they start "hogging" current.


The USAT locos do NOT have defective motors, they draw more current, and have a high current draw when starting. You actually get better motor response in my opinion, but it's simple to add a 1 ohm resistor in series with the motors if the current draw is hard on your power supply, or you have excessive wheel pitting.


Regards, Greg



 
 

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This is a great thread with a lot of info that I just paged through back to front. I'm trying to gain some history on how things got changed while I was away. Seems like there's some USA info mixed in that I'm after.
 

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The missing videos are on my YouTube site, search for "gregeusa"

Ted runs a mix of locos and pulls pretty heavy loads, many trains are 60 cars and the many curves multiply the load.

Greg
 
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