How Do Hydraulic Trailer Brakes Work? (Simply Explained!)

How Do Hydraulic Trailer Brakes Work

Do you know how hydraulic trailer brakes works? Well, you are at the perfect place to find the answer to such a question.

There are several different trailer braking systems. Two of the most popular are mechanical brakes and hydraulic brakes. On this page, we are going to focus on the latter.

Not only are we going to tell you exactly how hydraulic trailer brakes work, but we are also going to answer some of the most burning questions that people have about them.

This guide is pretty much going to tell you everything that you really need to know.

How Do Hydraulic Trailer Brakes Work

As a note here, we are going to be focusing purely on hydraulic trailer brakes. We are not going to be talking about electric over hydraulic brakes (EOH), which are a slightly different concept.

Unlike electric brakes, hydraulic trailer brakes do not need to be wired up to anything. They are simply installed on your trailer.

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They will then be connected up to the hitch, and that is about as far as the connections will go. It really is a simple concept.

Here is how Hydraulic Trailer brakes work:

  1. The hydraulic braking system detects that your vehicle is slowing down (via that connection at the hitch)
  2. A surge actuator is triggered. This is just a small component close to the hitch on the trailer.
  3. The surge actuator releases hydraulic braking fluid.
  4. This fluid is pushed down the various tubes to the actual brakes.
  5. As the hydraulic fluid pours into the brakes, they put pressure against the vehicle’s wheels, allowing the trailer to slow down.
  6. The trailer continues to slow down until it is traveling at the same speed as the towing vehicle.
  7. Once this happens, the fluid is ‘reset’. 

Yes, there is a lot going on here. However, the system is very effective and, when it comes to non-electrical hookup brakes, there is no method more effective for slowing down.

Read also >> How Do Mechanical Trailer Brakes Work? (Are They Safe?)

Are Hydraulic Trailer Brakes Effective?

Absolutely. Hydraulic trailer brakes have superior stopping power. This means that they have the potential to ensure that some of the heaviest trailers can be brought to a stop.

There is one major issue with hydraulic trailer brakes, though. This is the fact that they take a while to actually start the braking process. It isn’t long. However, if you are not used to how hydraulic brakes work, it can feel like an eternity.

Because of this, a lot of people find that they need to practice a little bit with hydraulic brakes to discover how they work and when the braking process begins.

As we mentioned before, because of the way that hydraulic brakes work, they are going to be slowing down a lot slower than you may expect.

Therefore, you may need to have more of a slow, controlled stop when you are driving with them.

Of course, once you have nailed the braking speeds, then hydraulic trailer brakes are very effective.

Read also >> Why Do My Trailer Brakes Lock Up In Reverse? (Troubleshooting Trailer Brakes Controller)

Are Hydraulic Trailer Brakes Safe?

Absolutely. You may run into a few issues if you are not used to them i.e. the braking distances. However, hydraulic trailer brakes are not inherently unsafe.

One of the great things about hydraulic trailer brakes is the fact that you don’t need to spend too much time maintaining them. Because hydraulic brakes are completely sealed units, the chances of there being fluid leaks will be pretty slim.

There isn’t really a whole host of complicated components that you need to tend to constantly either.

The fact that these are completely sealed units will even have an extra benefit when you are using them. There is no way for dust, dirt, and small rocks to get into the braking system. This isn’t the case with other braking methods.

This means that you don’t need to worry about your driving tearing the system to shreds. Hydraulic braking systems are incredibly well constructed.

Although, of course, we are eager to point out that you probably should get your hydraulic brakes looked over at least once per year. While there is nothing that really can go wrong with them, it is still a case of ‘better safe than sorry’ยจ. 

Read also >> Should Electric Trailer Brakes Lock Up? (Explained)

Are Hydraulic Trailer Brakes Better Than Mechanical Trailer Brakes?

Yes, to an extent. If you are pulling a very heavy trailer, then mechanical trailer brakes aren’t going to quite cut it. They do not have the stopping power of hydraulic brakes, which means going down the hydraulic route is one of only two routes that you can go down (the other route would be electric brakes).

That being said, when it comes to lighter trailers, hydraulic brakes are not going to be as good as mechanical trailer brakes. As we mentioned previously, hydraulic trailer brakes take a little bit of time to kick in, which can make slowing down a bit more difficult.

That is not the case with mechanical trailer brakes. They should kick in almost instantly if the trailer starts to travel faster than the towing vehicle. 

How Do Boat Surge Trailer Brakes Work? >> Check out the video below:


Hydraulic trailer brakes do not require any electrical hookup. This makes them ideal for use with certain trailers. Hydraulic brakes have a huge amount of stopping power and they require little to no maintenance.

All these brakes really are is a set of tubes, brake fluid, and the actual brakes. Brake fluid is forced down these tubes when the system detects the vehicle is slowing down.

This puts pressure on the brakes, allowing the trailer to slow down too.



Jeff is an automotive technician, technical writer, and Managing Editor. He has held a lifelong passion for cars, with a particular interest in cars like the Buick Reatta. Jeff has been creating written and video content about transportation, automotive, electric cars, future vehicles as well as new, used for more than 18 years. Jeff is based in Boulder, Colorado.

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