How Electric Brakes Work

Written by Hitchweb Team
Monday, January 7, 2013 — 25 Comments

Take a look at the major parts that make up a brake assembly:

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

Components of an Electric Brake

The large center circle represents the hole through which the trailer spindle goes, so we can install the backing plate on the axle. The 4 smaller holes represent bolt holes which are used to bolt the backing plate onto the Brake Flange which sits behind the spindle.

How does electricity make this brake work? The magnet in the backing plate has 2 conductor wires which tap directly into the trailer wiring. When electricity is on, it magnetizes the brake magnet. The magnet is attracted to the drum face. When it contacts this area, the friction causes it to rotate, which moves the actuating arm, and pushes the shoes out against the drum. Those shoes have a special brake pad material on them that resists the heat caused by that friction. When the shoes press against the inside of the drum, they prevent the hub, and consequently the wheel that's touching the ground from spinning.

How does the electricity get to the trailer brakes? Where does it come from? How do we know which brake to use? Here's how it works: An electrical connection on the trailer plugs into the connector on the vehicle. There are electrical wires running from the trailer connector back to each brake on the axle, as well as to the trailer lights, to create a complete circuit. When the driver steps on the brakes it sends a current to the brake control in the vehicle. The brake control then sends a current back to the trailer to activate the brakes. Here's what that looks like:

How an Electric Brake works

  

OTHER TRAILER ELECTRIC BRAKE RESOURCES

What Are Electric Brakes?Do I Need Electric Brakes?
Testing Trailer Brake MagnetsHow Do I Detetermin My Bolt Pattern?
Electric Brakes in Salt Water 

Now that you know how an Electric Brake works, go ahead and find the part you need from the trailer brake assembly

Trailer Electric Brakes

Trailer Electric Brakes

Electric Brake Components

Electric Brake Parts

Trailer Complete Idlers

Trailer Complete Idlers

Trailer Hubs & Drums

Trailer Hubs & Drums

Trailer Bearing & Races

Trailer Bearings & Races

Trailer Bearing Seals

Trailer Bearing Seals

Trailer Wheel Studs & Bolts

Wheel Studs & Bolts

Electric Over Hydraulic

Electric Over Hydraulic

 

Posted in Trailer Parts

Comments


Hitchweb Team
Friday, April 21, 2017
Hi Matt - tech support is going to be the best option here to figure out exactly what the issue is but here are a few common things to check: Check the plugs on both sides of the setup for any white or green corrosion. If you see any, clean the plug thoroughly or just replace it. If there is no buildup in either of the plugs, check the connections of the black and white wires. The black wire should be run to the vehicle positive battery with a 20 or 30 amp circuit breaker in line, and the white wire should be attached to the negative battery terminal. If you used a plug-in brake control wiring adapter, check the wires to make sure none are loose on their pins. If neither of these steps take care of your problem I'd call tech support for further assistance at 1-800-632-3290 (and ask for tech support). If there is anything else we can do to help please let us know! Thank you - Hitchweb Team
Matt
Friday, April 21, 2017
New TT with everything hooked up works until the truck is moving then green light changes very quickly from green to orange to red then back to green repeatedly. I have a Tekonsha Voyager and it worked on my old TT but does not work on 2017 Keystone bullet. Any ideas would be appreciated. I have a new Tekonsha P3 coming to see if this is the answer.
Hitchweb Team
Friday, April 7, 2017
Hi Kody, We discussed this with a tech and it might be doable but you'd need to do some modifications to make it work. The tech team would like to speak with you directly to get more information and go through your options - 1-800-632-3290 If there is anything else we can do in the meantime please let us know - info@hitchweb.com Thank you, Hitchweb Team
Kody
Friday, April 7, 2017
Will a 6 volt vehicle run today's trailer brakes?
Hitchweb Team
Tuesday, March 7, 2017
Hi George - here are a few things to take a look at: Many times, dirt or corrosion can cause a short in a trailer connector. Make sure the truck and the trailer side connectors are clean and free of corrosion inside and out. You can test the brake output pin and it should only show power with the manual override. If it shows power any other time then there is a short somewhere between the connector and the brake controller you will need to track down. If the truck side checks out fine then it could be the wiring to the brake magnets or the magnets themselves. Make sure the brakes are properly adjusted (there should be a slight but constant drag of the pads on the drums when the wheel is turned). Inspect the power wires to the magnets and look for pinched, frayed, or damaged wires and fix as needed. Make sure the ground wires are attached to clean and corrosion free bare metal surfaces. If you're still having troubles please let us know at sales@hitchweb.com or 1-800-300-4067 and we'd be happy to get you in touch with further tech support. Thank you! - Hitchweb Team
George Robson
Monday, March 6, 2017
HI i have a 1999 22ft Tahoe fifth wheel i have replaced the left rear magnet,however rather than grabbing the drum it just hums its a 3amp magnet i cant see any markings on the other three as to their amperage,i am thinking that i possibly have the wrong amperage ,your thoughts george,
Hitchweb Team
Tuesday, October 18, 2016
The humming sound is the brake magnet being activated. This is happening because the 6-way or 6 pin trailer connector on the vehicle or the trailer needs to be rewired.
Larry
Tuesday, October 18, 2016
Why do the brakes hum when hooked up and standing still
Hitchweb Team
Thursday, October 15, 2015
Hello Martin, Proportional Brake Controls can sense how quickly the tow vehicle is stopping and apply the same amount of braking power to the trailer. When the tow vehicles brakes are applied, a motion sensing device inside the controller knows how fast the tow vehicle is stopping, applying power to the trailer brakes equally as fast (or slow) as the towing vehicle. A proportional controller is enabled by the brake pedal switch. It is then activated by a pendulum circuit that senses the vehicle's stopping motion and applies a proportional voltage to the trailer's brakes. For further information, please see our blog post: https://www.hitchweb.com/blog/post/2011/10/14/what-is-a-brake-control
Martin
Thursday, October 15, 2015
How is braking force controlled proportionately? ie. if I touch the brakes to slow slightly I don't need the caravan brakes to come full on, do I?
Anonymous
Monday, July 20, 2015

Hello Gowrithas, There are a number of advantages for electric braking systems such as: Safety, less stress on your vehicle, and it's the law. Click on the blog post WHAT ARE ELECTRIC BRAKES to learn more.

 

 

https://www.hitchweb.com/blog/post/2012/02/02/what-are-electric-brake-assemblies

Hitchweb Team
Monday, July 20, 2015

Hello Geo, It could be a few different issues. Since brake controllers are activated by trailer magnets, we suggest testing those first. You can read our blog post TESTING TRAILER BRAKE MAGNETS if you are not sure how to do this. If this doesn't work, the issue could be the electric brakes, or the brake controller itself. Please contact us with your brake and brake control information and we can assist you further.

 

https://www.hitchweb.com/blog/post/2012/02/21/testing-trailer-brake-magnets

gowrithas
Monday, July 20, 2015

what are the advantages of electric braking system. ..?

Geo
Monday, July 20, 2015

Sometimes I loose my trailer brakes! the truck tells me check trailer brakes, I checked all the wires I even ran an extra ground wire it still does it! When im parked I have brakes I wiggled all the wires applying the brakes everything works! When I drive it starts acting up on and off! Can the problem be in the brake assembly in one of the wheels?

Hitchweb Team
Monday, July 6, 2015

Hello Wayne, In order to control your brakes you first need to wire your vehicle to a 7, and to get a 7 you need a 4 flat on the vehicle first. Do you already have a 4 flat on your vehicle? If not, what is the year make and model of your vehicle so we can provide one for you? Once your vehicle is wired for electric brakes, you then need to purchase a brake controller.

Wayne Fisher
Monday, July 6, 2015

Is the electric brake wiring connected to the pin or plug that I plug in to the back of my vehicle for brake and turning signal lights or is there a completely separate wire system that I need for the electric brakes ?

Hitchweb Team
Tuesday, June 16, 2015

Hello Mark, We need some further information before we can assist you such as what brake control do you have? We will contact you via email for this information.

Hitchweb Team
Tuesday, June 16, 2015

Hello Gary, We have a few questions for your before we can assist you. What brake control do you have? We need the model number or name, and manufacturer. Who installed it?

mark
Monday, June 15, 2015

I was wondering where abouts do I hook up the electric brake wire from the tongue to my hitch so that the electric brakes will work when applying brake

Gary
Wednesday, June 3, 2015

My 17 ft. Coachmen TT electric brakes lockup when brake is applied on any setting. Do I have A brake problem?

Hitchweb Team
Wednesday, April 15, 2015

Hello Bob, You can just plug it right back in, this will not hurt the trailer. The only reason to replace it is if the pin is or became damaged.

Bob
Wednesday, April 15, 2015

While pulling away from my unhooked trailer the emergency wire got caught up and pulled out. I pushed the large plastic pin back into the small rectangular controller on the hitch. Do I have to do anything else to make sure they are not locked up and or will still function when I hook back up to leave the campground.

bob
Tuesday, April 14, 2015

What should I do If the emergency pin on the trailer brakes is pulled out when not attached to the vehicle. Their was no electrical hook up at the time. Is everything the same when I push the large plastic pin back into the little box it came out of? Do I need to do anything special.

Hitchweb Team
Monday, November 25, 2013

Hello Ronald,

That is a very common question. Throughout the U.S. and Canada, there are laws in place regarding towing practices depending on the State or Province. Since most RV's and campers travel over several States and Provinces, it is always safest to go with the average-to-stringent laws as a guideline for any given step. Towing laws can change so make sure to check that the trailer passes the requirements on a yearly basis.

Ronald McDougal
Monday, November 25, 2013

How do I know if my trailer needs to use electric brakes?

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