|
|
Posted by APB in tropical NY on Monday, August 25, 2008 at 17:44:26 :
In Reply to: Re: Confusion, I think? posted by John in NH on Monday, August 25, 2008 at 07:35:05 :
It is an electric trailer brake controller.
Variable truck brake pressure is converted to variable electrical current, which is connected via a wire to the electrically-operated trailer brakes.
The device is a precurser to today's under-the-dash controllers. The rheostat is the fine adjustment for the circuit.