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Electric Brake Question

Discussion in 'Trucks and Trailers' started by ed2hess, Jul 23, 2005.

  1. ed2hess

    ed2hess LawnSite Fanatic
    Messages: 14,442

    I assume that you should have some resistance on the brake coil that drags on the wheel hub. The brakes aren't working on one side and I cut the wires and measured no resistance? And, is it normal that the coils buz when they are actuated? The one that is working has an audible buz if I hold the controller actuated, and it is does give me braking.
  2. PLM-1

    PLM-1 LawnSite Bronze Member
    Messages: 1,640

    Yes the coils should buzz. I really don't understand trailer brakes. I've had hella problemos with mine. They basically either work or they don't. I would just run new brake wires and adjust the shoes. I adjusted mine 3/8", which is a lot! They still aren't great, but they're better.
  3. greywynd

    greywynd LawnSite Member
    Messages: 132

    With electric brakes you can test them using a 12volt battery charger. Each magnet (at each wheel) should draw about 3 amps, and that should also lock up the brake on that wheel. Since you said you cut the wires, it should be fairly easy to check each wheel. If there is no current flow, there is a break in the circuit, either the leads, or in the magnet 'puck' itself. The pucks do wear out and have to be replaced occasionally. Chances are if one is worn out, they all are, plan on replacing the whole works.

    If the puck draws current ok, then it's a problem with the brakes themselves, either needing adjustment, or worn beyond repair. Again, plan on replacing all of them.

    Make sure that you pull the trailer plug out of the vehicle before testing this way, you don't want to backfeed into the truck and cause damage.

    While you're in there, plan on checking and repacking the bearings and springs too. The pivot bolts for the springs (at each end) are in bushings, the bushings wear out. (Some manufacturers use plastic bushings, but you can also get a metal one (a type of bronze maybe? I forget). The metal ones aren't much more $$$ either.

    Let us know how you make out, and ask if you have any other questions, I'll see what I can do to help.
  4. GarPA

    GarPA LawnSite Silver Member
    from PA
    Messages: 2,585

    my trailer brakes also drive me nuts. They either grab, or dont grab enough and sometimes push the truck when having to make a fast stop.
  5. ed2hess

    ed2hess LawnSite Fanatic
    Messages: 14,442

    The side that is working does grab and is not smooth. Unfortunately I only ordered one magnet so I bet I'll need another one. When it started raining the other day the trailer pushed me along in a curve and scared the heck out of me. It has happened before even when brakes were both working,
  6. ed2hess

    ed2hess LawnSite Fanatic
    Messages: 14,442

    I finally got around to putting the new coil on. As I was removing the protective shroud from the wiring on the old coil I found that the wiring had been broken by rubbing on the spring inside the wheel. Anyway I put the coil on and tied the controller on and the coil began to buzz just like it should. I had put on new linings so I adjusted the linings to the hub and buttoned it up. The brakes are working again. I knew the old coil was open since I measured it with voltmeter but never looked at the wiring very close. Another little thing to look at.
  7. ed2hess

    ed2hess LawnSite Fanatic
    Messages: 14,442

    I learned one more thing today about brakes... I adjusted the bands to tight relative to the wheel cylinder. On a truck/car you adjust them so you got a little drag. With electric brakes you need to back them off so that the actuating arm travels further and thus you get more spring force to pull the coil loose when you let off the brake. The coil was staying actuated even though my foot was off the pedal. Them babies were hot as hell when I got home :angry:

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