How Do Electric Trailer Brakes Work? Working Mechanism is reader supported. When you buy through links on our site, we may earn an affiliate commission.

Driving a car with an electric trailer brake is called being “trailer ready.” This means you have enough power to stop the vehicle in any situation. Electric brakes are not only available for cars, but also for trailers and RVs.

They’re easy to install and maintain, which makes them popular among people who travel often. How do electric trailer brakes work? You might have thought about this. Well, let’s find out the working mechanism of these brakes along with what they are and why they are necessary.

What Are Electric Trailer Brakes?

An electric brake system for trailer makes use of electrical power to operate. The brake drums in the system get activated by drawing power from the tow vehicle. A brake controller in the system orchestrates the movements. Its wiring is attached to the tow vehicle, which activates the brake system whenever you step on the pedal.

The electric brake system uses electrical force to slow down or stop your vehicle, which then applies pressure to the brakes when you need them most.

How Electric Trailer Brakes Are Better Than Hydraulic Brakes?

For completely stopping a trailer and its tow vehicle, the braking system must have plenty of power. The tow car’s brake cannot generate so much power alone. The trailer’s brake needs to join the force for safely stopping both vehicles.

An electric brake is only necessary for a towable trailer. It’s not needed in the case of a motorized RV since you don’t need to tow it with another vehicle.

There are several reasons to use electric brakes for trailer instead of traditional hydraulic (drum or disc) brakes. Some of their unique advantages are:

More Efficient

They’re more efficient because you can get up to three times the amount of stopping power from hydraulic pressure than what a typical air-brake system would provide.

How Do Electric Trailer Brakes Work? Working Mechanism 1
Electric brakes are more efficient than hydraulic brakes. Photo:
Ghostses / Youtube

Survive Bad Weather Conditions

Electric brakes generally work in all weather conditions. It means there’s nothing to worry about them freezing or getting corroded when it’s wet outside.

Low-cost Parts

The repair and upkeep expenses of any mechanical system increase when its components are expensive and not really available in the aftermarket. Electric brakes don’t have these problems. Their parts are quite available and cost less than those of hydraulic surge brakes.

Less Maintenance

The travel trailer electric brakes require occasional check-up and repair work. On the contrary, the actuator and brake assemblies in a hydraulic system need regular check-ups. Also, it’s mandatory to replace the brake lines after a collision.

Ease of Installation

From the mid-90s, most manufacturers have started designing their trucks, travel trailers, and vans compatible with the brake controllers of the electronic trailer brake. The installation system is quite easy because it works in a plug-and-play system. Many recent vehicles come with a pre-installed brake controller.

Against all advantages, there is a minor drawback too. This brake system requires electricity to run, which means you need to make sure your vehicle’s battery is fully charged before heading out on a long drive.

Interested in learning how do electric trailer brakes work? Let’s move into the following section.

How Do Electric Trailer Brakes Work?

Before jumping into the technical part, remember that all electric brakes have almost the same working mechanism. Their main function is to stop the trailer wheels from rotating when you press on the brake pedal.

So, how do electric trailer brakes work? How does it use electricity for its operation? Let’s find out.

Brake Assembly Components

  • Primary and Secondary Shoes
  • Shoe Hold-Down Spring
  • Adjuster and Adjuster Spring
  • Reactor Spring
  • Actuating Arm
  • Magnet

Some components are similar to hydraulic brakes but the overall mechanism of the electric brake assembly is quite different.

Mechanism of Electric Brakes

A trailer with an electric brake assembly is likely to have two brakes on every axle. Depending on the type of trailer you have, there could be two to four brakes on the axles.

The braking system has a backing plate that has a magnet in it. Two conductor wires from this magnet come out and go into the trailer wiring. When you run electrical power into the system, the magnet is activated and moves toward the drum face. When these two components contact each other, the actuating arm moves because of the resulting friction, forcing the brake shoes against the inside of the drum. The generated power forces the wheels from rotating and then stops them completely.

How does the electricity pass from the source to the brake system? Well, there is a brake controller or brake box in the brake assembly. You will find this controller in the tow vehicle. When you push the brake pedal, this box transmits electric power through the trailer plug to the brake system. For each brake on the axles, there is a separate wire originating from the controller. This box/controller decides the power application capacity of the pedal. If it’s a digital controller, it can dictate the pedal to exert the maximum braking power, irrespective of the existing setting of the brake system.

Pressing on the brake pedal sends electric power to the vehicle’s braking system, which in turn transfers that power to the trailer for triggering each brake on the axles.

electric brakes for trailer
Electric trailer brakes need less maintenance. (Credit: Total Landscape Care)

How to Tell the Brake System Has a Problem

How to find out if the electric trailer brakes are functioning or not? This is really important when buying a used trailer.

Well, it’s not possible to find out if a brake is working or not just by pressing the brake pedal. To do that, check the slide bar on the controller. It should have indicator points from 0 to 10.

Drive the vehicle slowly while pulling on the slide bar inch by inch. For a perfectly working brake, you should feel more and more resistance when moving the bar from 0 to 10 points. The brake system may have a problem if there is no or little resistance.


How do electric trailer brakes work? By learning this you will better understand the working mechanism of this system and how important it is for your travel trailer. This braking system is a great solution if you need something simple yet effective. They’re easy to install and maintain which makes them popular among people who travel often.

About Chris Coleman

Chris Coleman is an interesting travel blogger and outdoor photographer with a great sense of humor. He owns an RV Accessories shop in New York City so he has the knowledge necessary to provide thorough reviews and give advice on how to choose the right products for RV travel. He puts all that RV knowledge and experience to good use in his sharing posts. Besides product buying guides/reviews, Chris also writes informative articles, how-to articles and RV camping guides in his own interesting viewpoint. Chris’s blog is one of the most reliable information sources for RV campers no matter if you're an expert or a determined beginner.

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