USAT F3A problem

spike

spike

It's me
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I have a USAT F3A and have had a job to get it to run reliably recently.

Wonder if anyone has had a problem like the following.

The F3A seems to be burning the skates on one side only, this makes it stutter badly in some areas of the track.
The skates on that side are not shiney but appear black and its hard to remove the
burnt stuff.
I have run other USAT locos and all their skates stay shiney.

Anyone know anything to cure this??

Ta!
spike.
 
My guess is that the wheels on the side of the burnt skates aren't picking up for some reason.
Attach one lead of a 12V ish dc power supply to one of the good side skates and then touch the other lead to each of the bad side wheels and skates in turn. If, as I suspect, some of the wheels don't pickup I suggest you start to to investigate the cause by removing the motor block baseplate.
 
Yes!
Have looked in the gearboxes as well but did'nt see anything obvious out of place.

Have double headed with other locos......other locos skates stay ok.
 
Neil Robinson said:
My guess is that the wheels on the side of the burnt skates aren't picking up for some reason.
Attach one lead of a 12V ish dc power supply to one of the good side skates and then touch the other lead to each of the bad side wheels and skates in turn. If, as I suspect, some of the wheels don't pickup I suggest you start to to investigate the cause by removing the motor block baseplate.
Click to expand...


Just tried the wheels on each truck, they seem to pickup ok.
In the past I have noticed this loco does seem to dirty it's wheels very quickly
compared to the others.......wether thats something to do with it, don't know.

After cleaning the burnt skates it takes about 3 laps of approx 250feet of track before it messes about again.

Mike
 
Idiot question. Are the skate springs strong? That is when compared with the others.

Blackening/burning suggests arcing or bad contact. :thinking:
 
Rhinochugger said:
Idiot question. Are the skate springs strong? That is when compared with the others.

Blackening/burning suggests arcing or bad contact. :thinking:
Click to expand...

Good point.
Yes they seem the same as other locos that are ok.
 
Is the loco sitting level, and riding level?

Otherwise, checked all of the motor connections?

What about the motor brushes?

That's me done - all of my bright ideas in one go :nerd::nerd:
 
Rhinochugger said:
Is the loco sitting level, and riding level?

Otherwise, checked all of the motor connections?

What about the motor brushes?

That's me done - all of my bright ideas in one go :nerd::nerd:
Click to expand...

As far as I can see yes.
External motor connections appear ok although I ain't been inside the body yet.
Would have thought the brushes would be ok, not much mileage on them from new.
Have a feeling it was doing it last year but passed it off as just dirt.

Did'nt want to strip the whole lot down if it was something simple.

Mike
 
What if one of the brushes wasn't seating properly?

Years ago, as a boy in short trousers, I bought a Piko N gauge loco as part of a set ( I think they came from Eastern Germany in those days?) humugus flanges that would only run on their own track, which was folded tin rail onto plastic sleepers.

But the loco got jittery, and a friend of my parents took it apart and found that one of the brushes was a piece of rolled up brass gauze. He spent all evening fashioning a carbon brush from a piece of pencil lead. The only problem the loco suffered after that was on standard n gauge track - it bumped over every sleeper as the flanges fouled the imitation rail chairs :laugh::laugh:

I think it was a V180?

so check the brushes :rolf::rolf::rolf:
 
I'm intigued by this.
In an attempt to help determine where the problem lies you may wish to consider the following. Clean then swap the wheels and skates on one bogie with those of another similar but trouble free loco. After running both locos for a few laps observing which blacken/dirty first should determine if the problem is with the wheels/pickups or motor/on board electronics.
 
As I own only a USAT 44 ton, I have to assume that the F3 follows the same design -- one axle on each bogey w/two traction-tyred wheels with the other being plain. The traction tyres seem to cause an overload of that axle/gear assembly. After very little light use, both of my tyred axles were slipping and needed replacement.

I would power the F3 up while turned upside down and see whether all wheels are turning at relatively similar speeds, thus seeing if there is some sort of motor/electrical fault. I would then apply a braking force (finger or wood block) to each wheel to determine if there is slippage under load - particularly the traction-tyred ones. If either of these conditions is upsetting the balance of the drive train, then excessive current draw/sparking or wheel slip couild be fouling your skates. The other consideration is that traction-tyred wheels are not reliable as current pickups; I replaced mine w/plain ones. It will be interesting to see what the answer to your situation is!
 
If I remember rightly Spike, you run on DC and in one direction only, so try running the loco in the opposite direction and see if the 'blackening/pitting' happens on the wheels/skates on the other side....
 
Ok chaps.
Weather permitting will have a play tomorrow.

The F3A has the usual one axle per truck tired and being an electric motor
engineer I think the brushes are ok Ian but will check just in case.

All wheels rotate at the same speed whichever truck is energised.
It's the same if wheels or skates are used to power.

At first I was thinking on the lines of electrolytic corrosion as the most juddering takes place on the short lengths of brass track I have, 90% of track here is stainless.
I think I am barking up the wrong tree here though.

Mike
 
The skates could be binding. When pushing the adainst the spring )to check the spring) try applying some forward or backward pressure (as when the skate is being dragged along). You may finf the skate binfs - clean out the slide with a very fine file.
 
Not sure but after some testing I think I have found the problem.

First off looks like the wheel plated layer has worn through to the brass.
The main proplem though I think is on the side the skates burn the untired wheels appear to be riding
up the flanges......there is a distinct line of piting 2>3mm up the flange, strange but not on the other side.
Anyway after a good clean of the wheels and a slight bend in the burnt skates, they seemed to stay shiney.

I also looked at my two GP9 wheels, the plated layer is starting to peel away, they have had little mileage.

Anyone know of good replacement wheels?
 
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