How do electric trailer brakes function? Does the magnet act as a brake itself or does it engergize the drum which make the shoes attract and contact the drum?

 

The shoes do the braking on the drum lining surface, the magnet operates them.

 

The sending unit in the truck sends the juice to the magnets on the trailer. The magnets are nothing more than electro magnets. The more juice the unit sends the more magnetic the magnets become. The magnets are attracted to the plate (just sliding on the plate as the wheel goes around) according to how much juice is sent to the magnets. The more juice the magnets get, the more magnetic they are, thus the more they pull against the plate. The more they pull against the plate, the more they pull the shoes against the drum, thus the more braking power. The sending unit determines how much power is sent to the magnets. If you unhook the sending unit and run a straight 12 vollts to the magnets, they are at full power and will lock the wheels. Hope this helps. I think I cofused myself with this one.
Joe

 

Good job JOE-M

Denny