Large Scale Central

USAT pickups problem

Problem Solving
#1

I have a well used track powered USAT S4 and it is not as smooth as my other USAT engines. When it takes a trip around the RR it starts to sputter with poor electrical pickup. I checked it yesterday on my bench and all wheels and shoes are picking up current. When I run the NW2 and the S4 at the same time with seperate trains it seems the S4 wheels get dirty really fast. Comparing the wheel sets on both engines they are both worn but the NW2 will run many smooth laps without a hiccup. The wheels on my GP38 are nice and shiny. Could it be that the plating has worn off the S4 and that is what is causing the problems? If so the NW2 can’t be far behind.
Is there anything that can be done short of buying new wheels which are $20 per set and do you think worn wheels is the problem?

Thanks.

#2

Open the bottom of the motor blocks (4 screws each) and check the axles wipers. As they are very fine wire, they tend to become brittle from being heated with the current load and arcing. I have opened several USAT diesel motor blocks to find they have become blackened and so brittle the ends have broken.

#3

Thanks for the tip Paul but I think those wires are Ok since I was able to touch each wheel and shoe with a powered jumper and all 8 wheels would turn. I checked all the pickups in various combinations and they all worked.

#4

If the copper under the chrome plating is showing, the wheels will get dirtier faster. Does the S4 run smoother after cleaning the wheels?

If so, then buying the new axle sets may be the best solution.

#5

So, since the wiring has been validated, the things to look at are the travel of the shoes (sometimes a spring collapses and it does not make good rail contact, but upside down on a bench it will be fine)

the plating question should be answered by a visual inspection, I don’t have big issues and the plating is worn on several of my USAT locos… I do not think this is the problem.

One issue is check the wheel gauge, if the wheelset is overgauge, then the axle will ride up out of the track and on the flanges, that will affect power pickup.

Also, if there is some restriction in the movement of the trucks, maybe not all wheels are touching, again that I have seen happen.

Regards, Greg

#6

I just checked the shoes and they are springy. The wheel gauge is fine and no restrictions in the trucks.

I think Paul has hit on what I suspected that the plating is worn off and the wheel get dirtier faster because of it. I remember this being an issue with Bachmann products. The engine does run smoothly after a wheel cleaning but not for long.
The trouble is with inspection the wheels look just as worn as the ones on my NW2 but that engine runs fine, in fact with both engines pulling trains I have had to park the NW2’s train on a siding and send it to pick up the stalled out S4 and tow it back to the shops.

Is there a way to replate these wheels?

#7

There is another possibility, that the pickup continuity is not really what it should be.

I really learned this problem with Aristo, a cursory investigation showed power pickup ok, but investigation with a meter showed continuity to be 50 to 75 ohms on some drivers. Turns out in this case it was a steamer, and the pickup on some wheels was defective, but my test neglected to realize that there was a “sneak path” to another working driver through the metal connecting rod…

I wonder if there could be an issue “philosophically” similar in your case? Like a poorly functioning pickup on the end of an axle?

An intermittent wire in the wiring harness that “Behaves” when laid on it’s back and tested?

An intermittent that goes bad when the truck swivels?

I’ve got lots of USAT locos, and the plating wearing does not seem to be an issue AND I do not have sliders, but have replaced all the rubber-tired wheels with “solid” ones.

Something still does not add up.

Greg

#8

Todd Haskins said:

Thanks for the tip Paul but I think those wires are Ok since I was able to touch each wheel and shoe with a powered jumper and all 8 wheels would turn. I checked all the pickups in various combinations and they all worked.

That’s not necessarily the case. The piano wire picks up current from the axles and sends it to the output pins. But the wheel bushings also pick up current and it too is sent to the output pins. In other words, there is a level of redundancy here.

So if either the wire is in place, or the axle end/bushings are in place, things are great on the test bench. But once out on the track, pulling current with grease slinging around, without this redundancy there can be drop outs in the power.

#9

Grease!!!

That sounds like the problem a friend had with one of his diesels. He runs it a lot and the axles were slathered with black grimy grease. I cleaned the side frames, bushings and wheel axles with vegetable oil. After reassembling the motor blocks, the bushings and axles were lubricated with Conducta Lube & Cleaner (Aero-Locomotive Works ACT-3753). The diesel ran fine after that. The occasional drop on the axles is all that is needed.

#10

Todd, you got the gist of my story on a steamer, alternate, but not really good conductive paths.

Will be interesting to see what is found. I agree with Paul also, check for cleanliness… this particular pickup system always seems to accumulate gunk from everywhere, mine get black and gunky pretty fast, but easy to clean, you can pull the motor block away from the sideframes and clean the axle tips easily… bit harder to clean the journals without getting goo on the rest of the loco, unless you remove them, but they still have wires.

Greg

#11

I use dollar store Q-tips dipped in vegetable oil to clean the grease out of the side frame bushings. Don’t buy the good ones as they are too fat. Pipe cleaners would work as well, but being a non-smoker I don’t know where you would find them.

Vegetable oil is also good for cleaning that horrible USAT black grease off your hands.

#12

Nice tip (pun intended!) Paul, will put on my site if you don’t mind.

Greg

#13

That is a good tip Paul. Who would have thought vegetable oil would be a good cleaner?

I removed the motor covers and cleaned the axles and as much of the axle end that rides in the frame bushings that I could get to. It was amazing how dirty this stuff was.

Back together I gave the wheels another cleaning and let it head out onto the main. It ran much better for a longer time.

I think it is now fixed and operatiing as well as the NW2.

Thanks for the tips guys.

#14

Paul Norton said:

I use dollar store Q-tips dipped in vegetable oil to clean the grease out of the side frame bushings. Don’t buy the good ones as they are too fat. Pipe cleaners would work as well, but being a non-smoker I don’t know where you would find them.

Vegetable oil is also good for cleaning that horrible USAT black grease off your hands.

Vegetable oil should be used with a great deal of caution .

It dries into a crusty film very quickly .

The amount of stuff I’ve cleaned the veg oil off is a bit sad really , people get a $500 loco and don’t bother to get the proper lubricants at less than $10 .

I would not use it at all ; this crops up every so often in rail forums , people get problems with continuity by oiling the brushes with the stuff , and it also causes drag if you use it in the axle boxes .

I don’t want my stock smelling of KFC chips anyway .

Mike Brit

#15

I do not use vegetable oil as a lubricant, just something to break down grease and clean my hands.

From my previous post.
“After reassembling the motor blocks, the bushings and axles were lubricated with Conducta Lube & Cleaner (Aero-Locomotive Works ACT-3753). The diesel ran fine after that. The occasional drop on the axles is all that is needed.”

#16

So , as I said in my post , use it with caution or not at all .

These little innocuous warnings may save someone a bit of trouble .

Mike Brit

#17

Mike, so instead of vegetable oil, what would you use to clean the crud off the bushings, bearings and pick ups?

#18

I generally use white spirit applied with an artist type paintbrush .

I then (if necessary) wick the fluid out with the corner of a tissue .

Using the small paintbrush means it’s easier to keep the stuff under control and not spatter across the bodywork .

I do not have much trouble with mucky bearings because I use conductive grease which is fairly thin , and I do not apply too much of that either . Overgreasing just wastes the stuff and makes a good collecting surface for dust ; LGB wheel pickups particularly benefit from conductive grease , it doesn’t go black and horrible like other greases do and works better than the proper LGB oil , which , by the way is another good cleaning agent .

Both may be slightly more costly , or even unavailable in the case of the LGB oil , but in the longer term I think they are beneficial .

I have also used alcohol , but got smashed outta me brain on the dregs , so had to stop doing that.

Mike Brit

#19

Ah, ok. I usually use Goo Gone.

#20

Is this grease really conductive, or is it “conductive” like LGB “conductive” grease?

Greg

p.s. Goo Gone can attack some plastics, I’d use a more gentle solvent.