AML 0-6-0 USRA Type Switcher

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Overview

I took these two pictures individually to show the detail. The tender is not larger than the loco!

The superstructure is all brass, the siderods and wheels are made of stainless steel. 

As usual, a beautifully detailed and executed model from AML.

 

The tender is large! This picture is not to scale with the above picture, but the tender is about 3/4 the length of the loco.

 

I unboxed it and put it on the track, a couple of times it slowed down on a curve, I think it was the carbon pickups seating, and cleaning any gunk off the backs of the wheels. After 2 laps it ran like a swiss watch, and would throttle down to very slow speeds. Top speed at about 24v is 92 smph. It's geared a bit tall. I put 10 box cars on a mostly level track and it pulls them no problem.

After about 45 minutes, I pulled it off the track to lube and inspect. I found one of the 4 carbon brush holders on the tender dangling, no screws. The screws on the other 3 were not as snug as I think they should be. Check this out first. A quick call to Cliff at AML had a spare brush and screws in a couple of days. Everything is perfect now.

There is the same 12 pin plug between the tender and loco as the K4, so wiring for DCC or battery will be easy. The schematics supplied show wires for a smoke unit, should you want to fit one.

As on the K4, the wiring diagram was inaccurate, more on that later.

Here's the back of the cab, nice detail:

The front of the loco does not have a lot of detail, but the smokebox door opens, a nice touch and may save time to service headlight or smoke unit:

A second picture without fill flash:

The drive train is different and improved from the K4. The K4 had a motor on an angle, and a long shaft with a universal to the gearbox on the middle driver. The 0-6-0 has the motor parallel to the ground, and basically attached directly to the gearbox. This should (and did) result in less slop. The loco does run fast, so I am guessing there is no planetary reduction gearbox on the end of the motor like the K4.

The picture below shows the motor:

The loco is on it's back and the motor is between the driver and the air pump. 

Underneath is another improvement, a much better chuff drum:

The chuff drum on the K4 had brass strips "on top" of the drum, so the contact wires "bounced" at speed. The wires on the K4 tend to go off sideways after a while.

The 0-6-0 drum has 2 improvments: first the brass is now "embedded" into the drum, so no "bumping" of the contact wires.

Second, there are two grooves milled into the drum, which now controls the wires so they cannot get out of alignment. Great!

Power pickup is on the first and third axles, BUT there is another huge improvement, ALL EIGHT wheels on the tender have power pickup, with carbon brushes. This loco has great power pickup.

In general I'm not thrilled with carbon brush pickups, but the quality of the machined surfaces on the back of the wheels makes me believe this will work well, as opposed to cheap cast wheels on some other manufacturers' locomotives and rolling stock. While there is some drag, it's important to remember that ball bearing wheels are NOT a good idea for high current pickups, the small contact patch in a miniature ball bearing means high currents will pit the races and they will not function well.

Therefore, I'm very happy with this arrangement on this loco.

Some miscellaneous tools and parts were supplied:

I can figure out the nut driver and the allen wrench and the spare nuts and bolts, but what the heck are the two cylindrical things? If you figure it out tell me!

 

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