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Note: Click on the desired specific locomotive on the left. There are tips and techniques on each one in the menu.


USATrains is owned and operated by Charles Ro Sr. This will help explain when you see the Charles Ro advertisements. Their first loco was the NW-2 "cow" and "calf". They started making cars at a high level of detail, much sooner than Aristo. Their "Ultimate" line is highly detailed and well scaled. This is often the point of distinction between the "camps" of "who is the best".

I mostly will concern myself with their 1:29 line of products. They also have a line of 1:24 products that don't have the same level of detail, and I model 1:29.

They have a pretty extensive line of diesels, and while the drive mechanisms of their diesels do not have ball bearings, a much touted feature of Aristo, yet, overall reliability in the drive trains, i.e. motors and gears and bearings is about the same.

The diesels have a few, but consistent weaknesses:

  • loops that hold the coupler cut bars can be easily broken.
  • Cab doors have small springs and often something will break loose, either the spring or hinge if you play with them. Leave them alone!
  • "cracked" axles, where the metal half axles pressed into the plastic gear casting slip because the plastic casting has cracked. This happens

Variations and versions:

Smoke units:

The newer products have fan-driven smoke units. You can see the fan motor, and they have a little power board either nearby, or on the chassis. These units work well and rarely burn out.

The older smoke units are smaller, square, and flat and will definitely burn out if left on with no fluid. They do not have fans.They are not great smokers.

Interestingly, they both mount in the same "bracket", so you can swap the newer ones for old, for example in the F3s. The new units do need a small regulator board.

USAT Electrical variations:

The type and method of lighting varies from loco to loco, and also several locos have different versions. Many of the diesels have classification lights that change color from green to red according to direction.

  • Earlier locos tend to have low voltage lighting, 5 volts or so, and often a single set of 2 wires will power the number boards, the headlights and the classification lights. These usually use a large 2 pin connector.
  • Newer locos will use a smaller 3 pin connecter (but not always) and use track voltage to this connector, and 18v lamps for the headlights and number lights, or have the dropping resistors for LEDs.

The cab lights vary also. 

The bottom line when converting a USAT loco to DCC or something similar and you want to retain the original lights is to put the loco on rollers, power with DC, and then measure the voltage to the connectors and see if it is fixed or variable, reverses polarity or not, and what the max voltage is.

Don't follow this advice and I will guarantee you will burn out lights during an install.

Typical diesel drive mechanism:

The drive mechanism is basically a motor with worms on each end, driving an axle assembly which is a plastic gear casting, with 2 metal half axles (that have the wheels)  pressed into it. The axles ride in brass bushings in the motor block which ride up and down in the motor block.  There is a wire that presses down on the axles between the bushing and the gear to pick up power. The ends of the axles ride in bearings in the side frames, which also have power pickup wires. 

Some locos, like the 3 axle trucks have an additional idler gear to change the gear ratio.

Drive Problems:

All units have "splitting" of the gear where the metal half shaft enters it (on either side). The fix is a new gear, or better yet a new axle set. As far as I can tell, the way to tell is the old axles have "splines" along the length of the axle shaft. The newer axles have a helical knurling. The new ones still split the plastic housing, but not as often.

There are some ways to repair them, see the section on "Split Axles" on the left. Many people just buy new axles. 

Also, VERY IMPORTANT:  The assembly/alignment of the "brass" bushings on the axles is different between 2 axle trucks and 3 axle trucks. Failure to observe this and re-assemble properly leads to stripped gears. Many of the negative comments you may hear is from someone who actually screwed up their own locomotive, and then blame it on USAT. You are forewarned.

Details in each specific loco page, but the short answer is 2 axle locos have the flat side up, 3 axles have the point up (aligned like a diamond). The bushings on any "idler gear" shafts fit "flat".

Electrical systems:

USAT locos have very few electrical problems. The electrical pickup is normally from metal bearings at the ends of each axle and LGB style "skates" or "sliders" that bear on the rails. On some locos there are additional wires "whiskers" that bear against the axles for even more pickup (inside the motor block). The only problem I have ever seen is when an extended short circuit has overheated the slider springs or the pickup "brushes" on the axles. This can overheat them and they will lose their temper. Overall a superior and redundant pickup system.

The wiring can vary, and if you will remember only one piece of advice: NEVER assume what voltage the lights are inside the loco, check the voltage with a meter BEFORE any alterations.


Common screws:

With all the different brands, each has screws a little different. Swapping in the wrong screws can lead to stripped threads or loose parts.

First, the "body shell" screws, like the ones that hold the F3 body to the chassis. they are 2.6 mm thick, and the thread length is 11.9 mm. These screws are particularly important as if you substitute them, a smaller head will pull through the chassis bosses and not secure anything, strip the threads and the loco will fall apart when you lift it.

Another screw of interest is the one that holds smoke units in place. It can also be used to hold speakers in place in the roof of a loco. Get one too long and it will pierce the body, very unsightly!  3mm x 7mm thread length, with a "washer" head.


Common USAT part numbers (note I have listed wheels in increasing size):

Wheels & trucks:

Please note: the dimensions given on wheels are from the manufacturer, and not all are exact.

R2040 - wheel and axle set - solid - freight cars ( 2 axles)  

R22-011 - wheel & axle set - solid - NW-2/S4 (2 axles)

R22-135 - wheel & axle set - solid - F3/GP7/GP9/GP30/GP38-2 (2 axles) (1.126" tread diameter)
R22-136 - wheel & axle set - w/traction tires - GP7/GP9/GP30/GP38-2/F3 (2 axles)

R22-170 - wheel & axle set - solid - 44 Tonner (2 axles)
R22-171 - wheel & axle set - w/traction tires - 44 Tonner (2 axles)

R22-419 - wheel & axle set - solid - end axles - SD40-2 (2 axles) (1.265" tread diameter)
R22-420 - wheel & axle set - solid - center axles - SD40-2 (2 axles)
R22-421 - wheel & axle set - w/traction tires - inner axles - SD40-2 (2 axles)

R22-518 - wheel & axle set - solid - center axles - PA-1 (2 axles) (1.377" tread diameter)
R22-519 - wheel & axle set - w/traction tires - inner axles - PA-1 (2 axles)
R22-520 - wheel & axle set - solid - end axles - PA-1 (2 axles)

R22-622 - wheel & axle set - solid - end axles - SD70 (2 axles) (1.461" tread diameter) (1.695" over flanges)
R22-623 - wheel & axle set - solid - center axles - SD70 (2 axles)
R22-624 - wheel & axle set - w/traction tires - inner axles - SD70 (2 axles) (note that later production does not have traction tires)


R22-301 - F3 horn, set of 2R22-304 2 ea (F3 windshield wipers, set of 2)
R22-534 - PA air horn (pk of 2)
R2060 Brake wheels. 10 in a pack, Cost $3.95
R17PN - intermodel container pins (8 each) $4.95
R22-315 - F3 ladders (hang down below body and fall off all the time)
R22-333 - F3 air hoses (one unit of 4 hoses)

Coupler parts:

R22-317 - coupler centering spring
R22-332 - coupler mounting block and pivot


R22-127 - screw in bulbs, number boards in diesels, low voltage - $3.50
R22-110 - gow bulbs for headlights in diesels, low voltage - $3.50
R22-17- sliders with springs

An Unofficial USA Trains Locomotive Catalog

Shawn Conahey, a.k.a EMD Trainman, has started a Yahoo group that has the best information on USAT loco and rolling stock part numbers. See the files section:



Click the links below to go "deeper" into details on USA Trains motive power

  Split Axle Problems     Diesel Motor Block Tips    DCC Installation Techniques   0-6-0 Docksider  
  4-6-4 Hudson    4-8-8-4 Big Boy    44 Tonner    F3 
  GP7    GG-1    GP38-2    NW-2  
  PA    S4    SD40-2    SD70 
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