USAT Alco PA-1, PB-1




They have great detailing, and are handsome locomotives.




Drive system:







First: pay attention to the different screw sizes:

    • The 10 body screws are the longest and thinnest
    • The fuel tank screws are smaller and different


  • Lay the loco on it's back.
  • Remove the fuel tank with 2 screws.




Disassembling the trucks:










Rear truck right rail is black, left rail is red.
Front truck right rail is red, left rail is black.
Rear truck motor + is black, motor - is red
Front truck motor + is red, motor - is black


Tips and modifications:


The Kadee site does not list a conversion for the PA/PB, but the coupler pedestal looks very similar to the F units, which use an 831.

On the F units, there is a second hole in the coupler "tang" and you trim the end of of the tang to allow the hole in the 831 to align with the pre-drilled hole in the tang (which is not the hole that is used for the pivot).

There is no such second hole in the PA's tang. I need to measure the coupler location to see where to mount the 831. So far, I have let them stick out quite a bit, and aligned the "button" on the tang with the circular depression on the coupler body. They are a bit far out, but it looks if I mount them in the original hole and trim the tang, the front coupler will interfere with the pilot.






Swiveling/floppy axle problems:

Some people have tremendous problems with the swiveling outer axles, picking points is the most common complaint. Others have absolutely no problems.

I would ensure that the spring/suspension mechanism in the chassis is lubricated, but I believe the people having problems have bad trackwork, either gauge issues, or vertical transitions.

Some people have bolted a plate on the bottom of the motor block to lock the swiveling axle, but of course it restricts the minimum radius, the whole reason the mechanism was designed.

Recently I think I found the reason for the complaint: The swiveling axle has a pin in the top of it's separate motor block. This pin slides in a curved groove in a chromed metal plate to guide it.

I noticed mine were very hard to move. The metal plate is not real smooth. I put some moly grease on the plate and worked it back and forth, it made a huge difference in the ease of swiveling. Now, if this took a lot of effort when the loco was laying on it's back with no pressure other than gravity, just think how much worse it would be when the loco was pressing on it. Check this out on your loco before you swear at these trucks.





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