Many people don't know what determines the need for brakes in an RV type trailer. Basically, any trailer weighing over 3,000 lbs., should be equipped with brakes. (For rules specific to your state, contact your local DMV.) So, does your RV trailer, fifth wheel or car hauler have brakes? Approximately 99% of these types of trailers sport electric brakes. So, how do these types of trailers differ from tow vehicles? The big distinction is that while tow vehicles use hydraulics to activate the braking system, 5th wheel, dump trailer & utility trailer types utilize electricity. Other than the way they're activated, electric trailer brakes work in much the same manner as the hydraulic drum brakes found on cars and trucks. This article focuses on the best methods for confirming your 5th wheel, car hauler or RV trailer's electric brakes are working properly, without having to go to the trouble of tearing down the system.
In the front section of your trailer, referred to as the tongue area, you should see a breakaway switch (fig #1) and a small battery (fig #2). These two items work in concert as an emergency backup system. If the trailer should separate from the tow vehicle, this system will automatically trigger the brakes. When the breakaway switch plunger is pulled out, it activates the breakaway switch. This switch allows battery power to be sent to the braking system, which applies the brakes, stopping the disengaged trailer.
What's the best way to determine whether your 5th wheel or car hauler's breakaway system is truly working properly? First off, we recommend a simple test that should be utilized every time you hit the road. First, pull the emergency switch plunger from its receptacle (fig #3). Using a screwdriver, find a wheel with a brake drum and touch the screwdriver to that brake drum. (fig. #4). If the screwdriver feels as if you've touched a magnet, this means your emergency breakaway battery and breakaway system are in good working order. This is because, be it RV trailer, fifth wheel or car hauler, the trailer's braking system uses an electromagnetic brake engagement system. When a current is sent to the brake magnet, the magnet surface comes in contract with the brake drum and magnetizes the drum. Since we're discussing magnetized drums, it's important to know that after several years of use, your RV trailer or fifth wheel 's brake drums may become permanently magnetized.
When this occurs, it's important to be able to distinguish this problem from problems with brake shoes, brake clusters or brakes simply needing an adjustment. This could save you unnecessary part replacement or diagnostic costs as well as the hassle of having your system completely torn down. As soon as you feel that your car hauler or trailer RV brakes aren't working properly, first, disconnect the trailer electrically (fig. #5) from the tow vehicle.
Now, grab a screwdriver and touch it to the brake drum. If the screwdriver responds as if you're touching it to a magnet, your brake drums are history and need immediate replacing. (Figure Six)
If you're unfamiliar with this phenomenon, you're probably curious as to the root cause. Well, it goes like this:  Your braking system's electromagnet receives increased electrical current as you apply more and more pressure to the brakes. This, in turn, causes it to acquire a stronger magnetic force, which draws the brake drum into it, creating friction and slowing or stopping your vehicle. (The beauty of electromagnetic brakes is their rapid pulsing allows you to brake as hard as necessary without locking up your brakes. Mechanical brakes don't have the rapid pulse feature and can create dangerous skids when a quick, braking response causes the wheels to lock up.) However, once a brake drum falls prey to becoming magnetized, the brake drum actually tries to repel rather than attract the electromagnet, causing the brakes to feel continually engaged. As they no longer provide the proper braking response, they have seized to be sufficiently safe and must be replaced immediately and without fail.
Don't let your friends or family discourage you from taking prompt action once this kind of problem surfaces. No trip, no matter how carefully planned, is worth risking an accident over. Contact your RV trailer's dealer and manufacturer for more safety tips and apply them, faithfully.