Hydraulic Brakes vs Electric Brakes

hyd_brake_2_2Trailer brakes are an essential part of the installed towing equipment needed to make a trip safe. The majority of states have towing laws that stipulate that trailer brakes (separate from tow vehicle brakes) are mandatory when the trailer exceeds a certain weight limit; often times, that limit is around 3000 pounds (although in some states it’s 1500 pounds, and in others it’s 4500 pounds). The information for your state can be found at the Department of Transportation (DOT) or the National Highway Traffic & Safety Administration (NHTSA). This article will discuss the difference between hydraulic brakes and electric brakes.

Electric or Hydraulic?

There are two categories in which trailer brakes fall into: electric (controlled by a brake control in the tow vehicle) and hydraulic surge (actuated by a special trailer coupler with no control from the tow car). Hydraulic surge brakes are usually fitted to boat trailers and rental utility trailers.

Surge Brakes

There have always been questions about the actual legality of surge brake systems. As specified in DOT regulations, trailers with brakes must be fitted with an actuator that allows the tow vehicle driver to operate the trailer brakes independent of the tow vehicle brakes. In other words, the driver must able able to actuate the trailer’s brakes without stepping on the tow vehicle brake pedal. With surge brakes, this feature is not offered. Surge brakes use the deceleration force present as the tow vehicle stops.When the tow vehicle brake is applied, the surge brake coupler’s internal master cylinder compresses against the coupler body, forcing 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 is no way for the driver to independently apply the trailer brakes in case of emergency.

Surge brake maintenance can be time-consuming and troublesome. Trailer brakes must be maintained and serviced regularly to ensure that they’ll work properly when they’re needed most. With surge brakes specifically, this involves changing the brake fluid, checking and/or replacing the lines and fitting carefully when corroded or leaking, and replacing the brake shoes and related parts. Additionally, just like when servicing tow vehicle brakes, surge brakes must also be bled in order to work properly.

Electric Brakes

Electric trailer brakes operate without hydraulic fluid, master cylinders or brake lines. An electric brake controller is mounted in the tow vehicle, usually under the dashboard and within easy reach of 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 tied directly to the tow vehicle’s wiring. It is only triggered (energized) and begins to send power back to trailer brakes, however, only when activated. There are two ways it can be activated. One way is when the driver steps on the tow vehicle brake pedal he also activates the brake control, since it is wired directly into the tow vehicle’s brake light switch. 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 is modified as it is sent 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 voltage to be applied to the trailer brake system wiring, energizing the trailer brakes so that they trailer helps the tow vehicle slow down or stop completely.

A magnet mounted inside the wheel hub assembly is employed with electric brakes, that when energized by the brake control, 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 magnet, wires, brake shoes and return springs, and there’s no hydraulic fluid to replace and bleed. There is no master cylinder or lines to leak either.


Contact Gooseneck Trailers today for more information about hydraulic brakes or electric brakes!



17 thoughts on “Hydraulic Brakes vs Electric Brakes”

Leave a Reply

Your email address will not be published. Required fields are marked *