Hydraulic Brakes vs. Electric Brakes: What’s the Difference?

Hydraulic Brakes vs. Electric Brakes

Trailer brakes are necessary to make a trip safe. Most states have towing laws that stipulate that trailer brakes are mandatory when the trailer exceeds a certain weight limit. You can find this information at the DOT or the National Highway Traffic & Safety Administration (NHTSA). We will discuss the difference between hydraulic brakes vs. electric brakes.

Hydraulic Brakes vs. Electric Brakes

Electric or Hydraulic?

There’s two categories in which trailer brakes fall into: electric and hydraulic surge. A brake control in the tow vehicle controls electric brakes.

However, a special trailer coupler with no control from the tow car actuates a hydraulic surge. Hydraulic surge brakes are usually for boat trailers and rental utility trailers.

Surge Brakes

DOT regulations specify that trailers with brakes must be fitted with an actuator. This actuator allows the tow vehicle driver to operate the trailer brakes independent of the tow vehicle brakes. Simply put, the driver must be able to actuate the trailer’s brakes without stepping on the tow vehicle brake pedal.

However, surge brakes use the deceleration force present as the tow vehicle stops. When applying the tow vehicle brake, the surge brake coupler’s internal master cylinder compresses against the coupler body. Therefore, this forces brake fluid through the brake lines to the wheel cylinders which forces the brake shoes against the drum (or pads against the rotor, if equipped with the newer disc brakes). Surge brake systems are very much similar to that of car or truck brake systems. Although, there’s no way for the driver to independently apply the trailer brakes in case of emergency.

Surge brake maintenance can be time-consuming and troublesome. Regular maintenance and servicing of trailer brakes is necessary to ensure that they’ll work properly when you need them most. With surge brakes specifically, this involves the following:

  • changing the brake fluid
  • checking and/or replacing the lines
  • fitting carefully when corroded or leaking
  • replacing the brake shoes and related parts.

Additionally, just like when servicing tow vehicle brakes, surge brakes must also be bled to work properly.

Electric Brakes

Electric trailer brakes operate without hydraulic fluid, master cylinders or brake lines. An electric brake controller is in the tow vehicle, usually under the dashboard and easy to reach for the driver.

This controller is a simple device that takes 12 volts DC from the tow vehicle’s electrical system and sends it back to the trailer brakes through a wiring system.  The brake controller is always powered “on” as it is ties directly to the tow vehicle’s wiring. It only has triggering (energizing) and begins to send power back to trailer brakes. However, this is only when activating.

Brake Controls

Additionally, all brake controls have a manual actuation lever or button that allows the driver to send power back to the trailer brakes without stepping on the tow vehicle brake pedal.

The majority of brake controls employ some type of internal electronic control. Whereby, the 12-volt input from the tow vehicle’s electrical system requires modification as it sends back to the trailer brakes. The types of brake controls include: inertia-activated and time activated. While both of these have their advantages and disadvantages, they perform essentially the same function. They allow application of voltage to the trailer brake system wiring. Therefore, this energizes the trailer brakes so that they trailer helps the tow vehicle slow down or stop completely.

A magnet inside the wheel hub assembly employs with electric brakes. When energized by the brake control, this causes the brake shoes to move outward toward the drum and push against it. Compared to surge brakes, servicing electric brakes is relatively easy. The only parts to service or replace are the following:

  • magnet
  • wires
  • brake shoes
  • return springs

There’s no hydraulic fluid to replace and bleed. In addition, there’s no master cylinder or lines to leak either.


These are just the basic differences between hydraulic brakes vs. electric brakes. Contact Gooseneck Trailers today for more information about hydraulic brakes vs. electric brakes!



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