Doughnut brakes

[valleydweller1]

Hi all,

I recently purchased a trailer with old-style "doughnut" brakes, the actuator is a ring inside the drum that charges the drum itself, attracting the brake shoes to it for braking power. It's old-school, the brakes aren't wired in but a quick check of each drum with a 12v power supply shows that they work.

So here's the question: There are two wires coming out of each actuator, and from what I can tell through the grime they are both black. Does it matter which wire is hot and which is ground?

Greg

 

[George2615]

It sounds like you are talking about a standard electric brake that uses DC voltage to attract a metal coil (electromagnet) to the drum. As the drum turns with the magnet stuck to it the arm of the magnet is attached to rotates a cam pushing the brake shoes out exerting pressure on the drum applying the brakes. In any case there are two wires coming from the coil. One wire goes to the trailer plug as the brake wire. The other goes to ground. It doesn't make a difference which one goes where as long as they complete the circuit to energize the coil when DC voltage is applied through the trailer plug.

 

[Bird]

I guess you're right, George, but I never heard of "doughnut brakes" before.

 

[valleydweller1]

I guess you're right, George, but I never heard of "doughnut brakes" before.

I had never heard of nor seen them before either, that's what the guy at the trailer parts store called them. I got them wired up tonight and they all work! Near as I can figure they are original to the trailer from the late 60's (it started life as a travel trailer).

They haven't been hooked up for the better part of 15 years that the previous owner has had it, I'm amazed they all work!

I've only done half the bearings so far, I'll take pics of the other side when I get to it.

Greg