Brake retarders may not be used in this town, said the sign, just as I
started to go *up* a small hill.

The small town is in a slighty hilly part of Pennsylvania. It's
industrial area is dominated by one company, whose name I can't r ecall
but which might make paper. I'm sure they get qute a few big trucks
coming into town, and they might take this street, for the same reason I
did. (It was the first street that went there, coming from the west.)

What is a brake retarder?

Why don't they want it used? Isn't it good for cars and trucks to
actually stop when the drivers want them to?