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Determining If Surge Brake Actuator Has Lockout or If Brakes are Free-Backing  


Hi. I recently purchased a 1997 eagle boat trailer in excellent condition. It has what looks like an original Demco trailer head with a brake fluid cap like the ones shown on your website. The cap shows on to turn one way and off to turn another way. The question I have is how do I know the surge brakes are on and working? When I back the boat up it does not lock up like other surge brakes I have seen. I also see in your website there are free backing brake drums. How would I know if that is what I have on the trailer?


Expert Reply:

The only way to turn a surge brake actuator "off" is to engage a lockout on the actuator. Some actuators have manual lockouts, others have electric lockouts, and some have no way to lock out the actuator. Typically, free-backing brakes are used with actuators that have no lockout. As long as the trailer brakes engaging when your tow vehicle is stopping, the brakes are working correctly.

I have attached photos showing a manual lockout and electric lockout to help you determine if your actuator has either of these lockouts. The electric lockout is wired to the trailer connector to get signal from the vehicle's reverse light circuit.

The "on" and "off" indication on the cap are simply to let you know which way the cap screws on and off.

If you take the hubs off of your trailer's axle, you will be able to determine if you have regular hydraulic drum brakes or if you have free-backing brakes. Free-backing brakes have a fall-away shoe that is designed to only engage when the trailer is moving forward. When moving in reverse, the fall-away shoe provides only limited friction to the brake drum.

I have also attached a photo showing a free backing brake assembly with the fall-away shoe compared to a standard brake assembly.

expert reply by:
Victoria B
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