Tuesday, February 13, 2024

Resistor Axles, Tank Cars and working around all the different truck designs

As my long term readers and any operators of the Richmond Terminal know, the layout is signaled.

How it works is based on the system being able to detect that something - a engine, a passenger car, a freight car, an entire train - is in a block of track. Since I am using DCC, the easiest way to figure out if something is there, is by measuring that there is some amount of current draw.

Engines are easy, as they draw power, even when they aren't moving since the decoder does need a bit of power no matter what (sound decoder or not). For passenger cars, if they are lighted, again easy.

For your standard freight car, they don't draw any power, so that's a problem.

As my rolling stock is standardized on metal wheelsets, I have made a bunch of resistor wheelsets, where I glue a small surface mount resistor and then use conductive ink or paint to make a circuit. You can take a look at a prior blog post where I talk about making a batch of resistor wheelsets here. I fixed the resistor size - they are actually 1206 size SMT resistors. 10K Ohm, 1/8 watt - on that post when I realized I erred.

My standard replacement axle is Intermountain. They sell the axles in bulk packs of 100. They fit in a wide variety of truck designs, but for some truck designs, they do not fit correctly.

As an alternative, especially for cars that the factor axles are plastic, while the wheels themselves are metal, I glue the resistor in the middle of the axle, and then connect each side to the wheel with conductive paint.

It seems that tank cars are a consistent issue with being incompatible with the Intermountain option.

I have been checking the tank cars and also spotting any without Kadee couplers installed, so I grab them for the coupler replacement, and take the opportunity to handle the resistor wheelset issue.

The paint does take a bit to try, so doing this can tie up the foam cradle for a day.

Cradle off the bench so I can do something else.

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