TowRig.com - Diesel Discussion and Tow Tech

Help guys! I started to set up my trailer brakes today and wanted to test them. First, I took the red lead and touched it to a bat (+) & the white to a bat (-). I expected the brake to lock up. It did nothing. So I pulled the drum off and it looks like this inside:
http://coloradok5.com/photos/data/517/161trailer_brake_1.jpg
http://coloradok5.com/photos/data/517/161trailer_brake_2.jpg
http://coloradok5.com/photos/data/517/161trailer_brake_3.jpg



Basicly the same as anything else, just no wheel cyl and some type of pick-up looking thing at the bottom. So do I need to do something else to test it, or am I going to the trailer place to buy stuff? TIA.

I've done a little research & measuring so I know this much now; the deal at the bottom is an electro magnet (Dexter style) and my shoes are 12" x 2". (yes, its a big-ass trailer) Also, I was applying juice to both brakes on this axel while doing this, but not the other axel. Has anybody messed w/ this stuff????

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I can't say for sure , but I think all electric brakes operate on the same basic principle. You have an electro magnet that is at the end of a long lever. That electro magnet sits against the flat spinning surface of the drum. When you allpy the brakes it sends current to the electro magnet. Now the brakes only apply if the wheel is spinning. If it's just sitting there the pads won't move, but you should hear a low hum. Now the magnet is energized and trys to stick to the inside of the spinning drum. This makes the lever the magnet is attached to rotate. At the top of this lever is a cam between the top of the 2 brake pads. When the lever moves the cam forces the pads out against the drum.

So to check the brake operation without the drum on put current to the brakes and see if a metal wrench sticks to the magnet. If so then the electrical part is working. Then manually move the magnet towards the rear of the trailer. This should move the lever and force the pads out. If something is wrong here it should be pretty obvious.

Thanks, now we are getting somewhere. Once the rain stops I try that.