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How do Trailer brakes work?

Last post 10-25-2007, 5:18 PM by Joe_914. 6 replies.
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  •  10-25-2007, 1:01 PM 270557

    How do Trailer brakes work?

    got a 18ft open steel car hauler.  tandem axle looks like 10" brakes on just the rear axles and they don't work.  wires have been cut some time by previous owner.

    Pulled a wheel off and looked in there.   Indifferent   Best as I can see there is a magnet thing that swings on a pendulum arm.   Hooked 12V to it and nothing.  So does it need to have the drum on it for the magnet to attract too?   The shoes are movable by hand so it should work.

    Where does the power come from.  F150 has a brake controller in it so which wires in the round pigtail to the trailer does the power come in on.


    Want to go faster, please send money.
  •  10-25-2007, 1:17 PM 270567 in reply to 270557

    Re: How do Trailer brakes work?

    I haven't had my trailer brakes open yet - they get taken over to a shop. 

    However, the brake controller send a voltage over to the brakes.  The more voltage, the harder braking.  The round pigtail on your truck and trailer must match and there is a diagram that came with your brake controller (truck owners manual)  that shows you how to wire it up. 


    Rob Leone

    '07 Solstice GXP in AS
    '87 Toyota Corolla in EP
    ex - '91 MR2 Turbo in SM2 <- If you can't set a good example, serve as a horrible warning.
  •  10-25-2007, 1:22 PM 270571 in reply to 270567

    Re: How do Trailer brakes work?

    Don't know the inner workings, but it sounds like you have surge brakes.  No controller...operates by decelerating g forces.  Pendulum controls it maybe?
    Patrick Washburn
    STU Evo
    www.winghats.com
  •  10-25-2007, 1:42 PM 270580 in reply to 270557

    Re: How do Trailer brakes work?

    The drum is required for the electric brakes to work.  The brake controller regulates the current the electromagnet receives, which in turn controls how hard the magnet is attracted to the inner, vertical face of the brake drum.  You'll notice that face of the drum usually has some texture to drive up the coefficient  of friction against the magnet.  That attraction and thus force on the lever arm controls how hard the brakes are applied.

    -Steve

  •  10-25-2007, 1:46 PM 270583 in reply to 270571

    Re: How do Trailer brakes work?

    Nah they are electric.  The thing on the end of the pedulum is the electro magnet.  Ok I guess it's more like a lever arm.

    We have had trailers with operational brakes behind this truck before.  So that part of it works I'm pretty sure.  Guess I will do like you said Rob and trace out the wiring.  So I  guess 12V should be MAX braking power?   Heck I might just buy new units and be done with it.   Brakes are a good thing to have and not worry about.


    Want to go faster, please send money.
  •  10-25-2007, 4:26 PM 270633 in reply to 270583

    Re: How do Trailer brakes work?

    Once upon a time I found some good instructions on how to troubleshoot and adjust trailer brakes on the Dexter Axle Web site. You might want to do some research there.
  •  10-25-2007, 5:18 PM 270640 in reply to 270633

    Re: How do Trailer brakes work?

    That's EXACTLY what I am looking for.   Thanks.
    Want to go faster, please send money.
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