USA Trains GP7 Inconsistent Operation?

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trailsideGguy

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I have a GP7 which runs for a short distance then completely stops. If I push it down the track a bit it starts again. Since it's track powered I thought I might have bad rail connections except that two other engines run fine on the same track, making the complete track circuit without hesitation or stopping. I removed the GP7 wheels and cleaned them as well as the wheel contact points. No improvement. Did I not clean everything thoroughly or is there something else I need to check?
 
Track, wheels including faces where the contacts run, and contacts. Does it stop in the same place, if yes then it is the track, if other locos run over this, then maybe it is two problems, dirty track, and broken contacts in one (or more) of the pick ups. Test is easy two wires with power going from wheel to wheel, wire on one wheel on one side the other on each wheel on the other side, and then swap over - hope this makes sense.
 
What are the other two locos? And your power pack is.......
If they are single motor block units, and as most USA trains diesels are well known for high current draw, it may be that you are overloading your controller. Not enough to trip it out immediately, but after a short time period. One way to prove this is leave the controller set with the gp7 running, let it stop, then see if it restarts, and runs a short distance before stopping.
If so, you need a controller with more amperage capability
 
Don't let it sit too long, especially if you can check there is power to the track..
You don't want to burn anything out.

PhilP
 
Usat picks up power through the axle tips through the journals in the sideframes, whiskers on the axles (inside the motor block) and skates.

All have their individual failure points, but these would be consistent. It's possible that it is a pickup issue, but not likely from the description.

We do need more data, about how long before it happens, does it happen in the same place, how are the skates, etc.

But I would start with what Brixham suggested... finding the reason why it restarts... so what is the make and model of your power/controller.

Greg
 
Other two locos - USA Trains SD40 Amtrak w/skates
USA Trains GP7 U.S. Army w/skates.
Power pack - G Scale Graphics No frills 10 amp track throttle.
Both the SD40 and the Army GP7 run a complete track circuit (no stops, hesitations) with this track throttle.

The GP7 in question has no skates.

I did the suggested run test. The loco runs for a short distance, stops and never starts back up. If I remove it from the track, lift it slightly or push it along the rails it will start up and repeat the run short distance, stop and never start back up.

I may have isolated the problem to one set of wheels. As first suggested, I applied power to each set of wheels on both trucks. Both sets of wheels on one truck allowed the motors to run consistently with no hesitation. When I applied power to each of the sets of wheels on the other truck, one set allowed the motors to run smoothly while the other set caused the motors to sputter and hesitate. Would this be caused by dirty axle tips, whiskers on the axles, dirty wheels or all of the above?
 
Just for the icing on the cake, does it have traction tires?

not dirty wheels...

sounds like your power supply is overloading and then only resets if the load is removed, but it makes no sense...

need a look inside, perhaps it has been modified...

there could be a problem that was drawing enough current to trip the throttle...

you need to remove the trucks and open them up, use my site... be CAREFUL to reassemble correctly
 
Does the loco have plungers that touch the rear of the wheels? These pick up power and they can sometime have wasted springs thus not connecting correctly or even at all.
 
It might not be a power pick up issue but that's where I would start. Refit the skates; they do an important job in power pick up. Check all the wires are connected and not broken. This includes the wires to the axle boxes on the bogie sides. Clean the axle ends and re-lube them with conductive grease. Take the bottom plate off the trucks and clean the pick up spring wires that lie against each axle. While the trucks are open re-grease the gears with white grease but obviously only use grease that is suitable for nylon gears. When re-fitting the bottom plate take care. It is absolutely essential that the axle bearings must fit fully into the housing slot before tightening otherwise you might damage your gears. I get mine carefully in place, push the plate down with one hand while ensuring all the bearings are correctly placed and then put the screws in with my other hand while keeping the bottom plate in place. Three hands would be useful for such work! Screws should be no more than quite tight but not over tight; you don't need them to be tightened to their limit. If the bearings are correctly placed the wheels should not be able to spin round without the motor but they should move from side to side freely.
 
To prove it’s not the power pack, which seems to have plenty of amperage,run both gp7’s at the same time ( uncoupled and spaced apart ). If the suspect loco stops, but the other one doesn’t, then that confirms that the power pack is fine.
Happy troubleshooting.....

Malcolm
 
I must have had a power pickup issue. I removed the truck with questionable wheels, cleaned the wheels and wheel tips, cleaned the brushes, slightly expanded the brush springs, cleaned the copper metal strips (journals?) on the truck sideframes and reconnected the truck wires to the chassis circuit board. Both trucks now run smoothly when running on my shop test track. I'll take it for a real run a little later in the day. Hopefully, I'll see the same result. Thanks to all for the suggestions and assistance!

As a side note, I've learned this loco isn't a USA Trains GP7 but an Aristo RS3. Earlier in this thread several mentioned skates which this loco clearly didn't have. That made me wonder if I really did have something made by USA Trains. There were no manufacturing markings anywhere so I did a little investigating and discovered my error.

Also, when I pulled off the engine housing from the top of the chassis I noticed a speaker and a disconnected speaker wire connected to a circuit board. Does anyone know if Aristo engines came with sound and how the sound operates after the speaker is plugged in? When I connected the speaker wire and ran the engine I heard the speaker come to life but no train sounds.
 
Sound was an add-on, and the original units plugged into connector(s) in the tank under the loco.

Are you *sure* you plugged to the speaker connector, and not a sound power connection? - This would give you a 'click' in the speaker.

The sound came with a small battery, but these were not really of a high enough capacity, and needed the loco running quite briskly to charge them.

PhilP
 
OK, this is a different kettle of fish.

A question, do the tips of the axles enter the journals of the sideframes?

If so you have the early style motor block, which actually has the best power pickup.

I have quite a few pages on the RS-3.

Sound was an extra cost option, fit in the fuel tank, and you had to remove the fuel tank weight.

RS-3

Greg Elmassian web site on large scale trains and garden railroads, cigars, and computers
elmassian.com elmassian.com

That is the main entry page.... scroll to the bottom, there are EIGHT more pages on the RS-3

In addition, there are also pages on the Aristo motor blocks, which had many versions:

Old Style Diesel Trucks

Greg Elmassian web site on large scale trains and garden railroads, cigars, and computers
elmassian.com elmassian.com

Greg
 
By the RS-3 description, photo (showing the lash screws) and examination of the chassis board on my RS-3 it's version 1. So yes, the tips of the axles enter the journals of the sideframes.

There is no fuel tank weight. It must have been removed. With that removed, I'm wondering if there's enough pressure for an even power pickup on the track? I ran the loco this afternoon on the layout and it functions a bit better since I cleaned all the electrical contacts but it still doesn't perform as well as the USA locos with skates.
 
Works fine without weight, you have pickup problem, axle tips, internal to motor block or burned up motherboard.

read this page and the appropriate sub pages:

RS-3

Greg Elmassian web site on large scale trains and garden railroads, cigars, and computers
elmassian.com elmassian.com

lots of possibilities, and I am not re-typing all my web site here.

Read

Greg
 
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