Chuck

USA Trains 1:29 Big Boy Manufacturing Problem

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Chuck   

Okay, I'm not bashing the excellent finely detailed USA Trains Big Boy at all...Well it is too heavy but that's another topic. What I am bringing to attention here is a major manufacturing flaw that I discovered after running it for a few days. What it would do is short itself out electrically for no real reason. Sometimes it would short itself out when changing direction. The dang problem drove me crazy trying to figure it out.

 

Every drive wheel has a carbon brush rubbing against the backside to pickup power from the rails. Problem is the brushes are located in the frame incorrectly. The stainless steel drive wheel tires are insulated from the black wheel centers/ discs by some kind of insulating material that's applied to the drive wheel before the tire/ rim is pressed on. But the power pickup brushes are positioned so once they start wearing/ or shift in their holder and rub on the driver center they bridge the insulated section then they energize the whole damn engine & tender as it's all die-cast metal. If both sides happen to do it the engine shorts out and blows the fuses I have at the power supply. If there's any bare wires touching the inside of the boiler then either the lighting voltage boards or in my case the ProtoSound 2 boards will get fried at the same time.

 

Here's a pic of the problem...the red arrows show where the red electrical insulating material is between the tire/ rim and the driver center and clearly shows how the power pickup brushes are incorrectly positioned..major manufacturing flaw!

 

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Yes USA Trains is aware of the problem but they offer no support other than to change the brushes when they start wearing  :angry:

 

Off course this is no problem for the battery power crowd.

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Chuck   

So what I did to correct this very serious problem was to start over and remove all of the stock USA Trains brushes and associated holders & wiring and then mount MTH passenger car power pickup brushes to the bottom of the frames...but I could only make this modification fit/ work on 6 axles instead of 8 because of the lower gearcase covers. But with the tender picking power from 2 axles/ 4 wheels and the engine picking from 6 axles/ 12 wheels that gives it 16 power pickup points...more than enough.

 

To start this complicated modification I completely disassembled the locomotive to make it easier to work on.

 

post-23-0-15305600-1393382435.jpg

 

Then I removed all the stock power pickup brushes, holders & wiring and then make my own wiring harnesses that will plug into the MTH power pickup assemblies.

 

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After that it was time to modify the bottom covers so the new brush assemblies would have a place to sit nice & safe...thank goodness for the Dremel w/ the flex-shaft drive  :)

 

post-23-0-50943800-1393383207_thumb.jpg

 

Here's the MTH brush assemblies that I'm using..of course I buy all my parts thru Raymond  :D

 Oh, I made some plastic bottom covers for the brush assemblies so the bare wires stay safely tucked away.

 

post-23-0-41147300-1393383355_thumb.jpg

 

 

 

 

 

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 I got a MTH O scale Allegheny that I had converted to two rail. It suffered the exact symptom you show. I had to re-design the pickups to keep them from shorting out the tires to the frame. I ended up adding power pick-up points in the trailing truck and the tender to lessen the power draw on these wheel/tire pick-ups alone.

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benshell   

This is great to know about Chuck, thanks for sharing and including such detailed photos and description! Since my Big Boy is in almost as many pieces right now (trying to fix a few issues caused when UPS dropped it in shipping!), do you think this is something I should take care of now? Or will I have a few years before the brushes wear down? Considering how heavy this locomotive is I can't imagine I'll be running it often.

 

By the way, my design complaint is the little protrusions from the gearboxes. One broke off in shipping, and the other broke off when I took the locomotive apart. I glued them back on with JB Weld, but it didn't hold. The gearbox metal is really thick, and the little protrusion bracket is barely supported with any material. It's really a very weak design. I have an idea for a workaround, but do need to re-glue something over the hole left by the protrusion to keep the oil in. I've been meaning to start a thread about my own Big Boy adventures. I'll start gathering my pictures (some from my cell, some from my DSLR).

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Chuck   

I never had any problems with those breaking but if the engine is rolled over and once up-righted the front square driveshaft will slip apart because the front engine assembly swung on way or another too far. I always remove the boiler top before working on it as makes it easier to handle esp. when it's upside down.

 

Joe, That's very interesting that a O Scale Allegheny has the same problem..and that we came up with the same fix! Those kind of electrical shorts will drive you crazy trying to locate them because they're so intermittent.

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Chuck   

Okay as here's the new brushes installed on the bottom covers...even though they're mounted with a screw I used some hot glue to help keep them positioned, even though it won't really help as the glue doesn't really stick to die-cast.

 

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More pics...

 

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And here I'm testing the rear engine with it's new power pickups  :D

 

post-23-0-82651500-1393514379_thumb.jpg

 

I also have completely isolated any electrical boards & speakers from the chassis by using plastic washers under them. I also installed plastic tophat bushings in the drawbar to electrically isolate the tender from the engine.

 

Another modification I did was to remove the stock 6 wire electrical tether from the tender to the engine and install a custom Molex 12 wire tether..but that's a whole 'nother topic!

 

 

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Nice work Chuck!  The quality of workmanship on your work and modifications is always second to none. :-)  What dremel bit/head did you use to smooth out the surfaces do you recall?  

 

Look at the size of the gear on the third axle... man that is huge.  Just like the USA Hudson, massive, you will never wear that out.

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Chuck, I got lucky with mine. When it shorted nearly right away, the spark was so bright, I saw it across the RR bench. When I inverted the loco, there were burn marks between the wheel and tire where the carbon brush rubbed. The carbon was pointed OK but the arc jumped!

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Chuck   

Nice work Chuck!  The quality of workmanship on your work and modifications is always second to none. :-)  What dremel bit/head did you use to smooth out the surfaces do you recall?  

 

Look at the size of the gear on the third axle... man that is huge.  Just like the USA Hudson, massive, you will never wear that out.

 

Thanks Ray as I do try and make things look like factory...sometimes I get way too anal though!

 

The bit I used is one of those Dremel burrs...this one I like as it has "teeth" on the end so you can come straight down and use it like a end mill/

 

post-23-0-11528100-1393685984_thumb.jpg

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Chuck   

 Joe, You got lucky catching where the Allegheny was shorting esp. with it being a O Scale die-cast metal locomotive. I mean the O Gauge manufacturers like using the body itself for the negative/ ground return. All it would have taken to blow the PS2 boards was the engine shorting on the positive rail unless of course all the wiring had been isolated from the body.

 

That's what I don't like about all metal loco's being made of brass or die-cast...the potential for unseen shorts such as a swinging lead or trailing truck where a wheel can touch something or a brake shoe too close to a wheel that will rub when conditions are right like a high spot on the rail or bouncing thru a switch. I'll take a plastic loco any day.   

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