What You Need to Know About Hydraulic Assist Brakes

Brakes are all around us. You can find them in cars, trucks, windmills, and just about any piece of industrial machinery. 

Brakes come in all forms, from drums to rotors to electromagnetic to hydraulic.

Keep reading to learn more about how hydraulic assist brakes work and where you can find them. 

Hydraulic Assist Brakes: What Are They?  

Hydraulic assist brakes came about in 1973 and are also known as hydro-boost power assist brakes. They work as an alternative to vacuum boost assist brakes.

Before hydraulic brakes existed, brakes in vehicles used a vacuum booster, drawing pressure from the vacuum system in the engine.

With hydraulic assist brakes, hydraulic pressure from the power steering system in a vehicle or from a different system in the machinery provides the operator with an assist in applying the brakes.

You would typically use hydraulic brakes for three different reasons: 

  1. Your vehicle has no vacuum source available. This is often the case with a diesel engine. 
  2. You do not have enough space for a power-assist device. 
  3. Your vehicle requires more braking assistance than a vacuum booster can give you. 

How Do Hydraulic Assist Brakes Work? 

In a vehicle, hydraulic assist brakes rely on the pressurized fluid that powers the power-steering. The hydraulic brake system will have a line plumbed in with the steering gear.

The power steering pump then supplies pressurized fluid for both the power steering gear and the hydraulic assist.

In short, when you apply the brakes, a spool valve that controls the fluid will move and allow pressurized fluid to assist in braking. This spool valve has a bore that creates a seal and yet still allows just enough fluid to provide the lubrication necessary for effective braking. 

Logically, then, if something would cause a loss of pressurized fluid to the steering, you would lose your brakes as well. However, a hydraulic system will have a backup or reserve.

Let’s say a hose breaks, a belt snaps, or a pump fails, and you lose pressurized fluid in your steering. With a hydraulic assist system, a high-pressure accumulator or back up will store enough power steering fluid for two to three power-assist stops.

That’s the basics of a simple hydraulic brake system. Hydraulic brake systems have evolved since the 70s, though.

Take air over hydraulic brakes, for example. In this case, the system uses compressed air and hydraulic pressure to make the brakes do their job. These brakes have a special air-over-hydraulic power cylinder with an air cylinder and hydraulic cylinder that work in tandem to make brakes function efficiently.

Where Do We See Hydraulic Brakes? 

Hydraulic-assist brakes work well in vehicles, but engineers see other uses as well. For example, a typical windmill brake in a wind turbine used to rely on rotors, but some turbines now have hydraulic-assist brakes. 

Industrial brakes can benefit from hydraulic brake technology. Past braking systems used drum brakes, which could overheat. Engineers are developing brakes where hydraulic oil is circulating behind the brake pads to keep the brakes from seizing. 

Larger, commercial vehicles typically employ air brakes. This system uses compressed air to activate the brake system as opposed to the compressed fluid in a hydraulic system. Smaller, domestic vehicles will use hydraulic over air brakes. 

Brake with Fluid

Hydraulic assist brakes provide an additional safety feature to just about any vehicle. 

For all of your brake needs, contact us

Posted in Industrial Brakes and Clutches.