## 720Locomotive current demands

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• Dec 31, 1999
Hi All:

During the summer, I raised this topic and got about as much interest in it
as watching the grass grow. But that was the off-season for trains, and the
list did not have the 100 plus members it does now.

I still feel the topic is of value, especially to those who only infrequently
run their locomotives. Or worse, run them and watch the motors burn up in a
few minutes.

I'll try the issue one more time. While we have become believer's in it down
here, I would really be interested to see if our findings compare with anyone
else's.

Bill Kronenberger
Houston

-=-=-=-=-=-=-=- Summer Rerun Follows -=-=-=-=-=-=-=-

To All:

We have made some observations here, with the combined ownership of some 40 z
scale locomotives (4 of us), and I wonder if anyone else has noticed it?

In an effort to determine the safe operating range for our locomotives (some
locos where getting really hot), we ran across the following test:

a. Put the loco on a short test track against a soft bumper at one end
b. Turn the power up until the loco spins its wheels (only do this for a
second)
c. Note the current draw from the powerpack (in milliamps)

What we found is:

Marklin locos draw from 300 to 400 milliamps at 6 volts
Marklin locos in bad need of cleaning/oiling draw 400-500 milliamps at 6 volts
and - they run hot....VERY hot
and - when oiled properly, they drop back to 300/400 milliamps

MicroTrains F7's draw 400-500 milliamps at 6 volts
sorry, we didn't have one in bad shape to identify its overcurrent points

What we are looking for it a go/no-go test at shows BEFORE we put a loco out
there and burn it up.

Since motor current demands are affected by load (number of cars/wagons)
there is no clear definition of what a "standard" load might be. We "think"
wheel slip represents the maximum load condition on a loco. We "think" it
represents that point where any more cars/wagons cannot be pulled by that
particular loco. In any case, it would be the same point for a given loco
every time.