Spring Applied Brakes Compared: Hydraulic, Pneumatic, and Electromagnetic Brakes
You have multiple options when it comes to industrial brakes. These include electromagnetic, pneumatic, and hydraulic—as well as spring applied versions of these too. The best choice depends on the purpose, location, preferred (or available) power source, and your budget.
Spring Applied Brakes Assure Fail-Safe Operation
To be clear, an electromagnetic brake can be spring applied, as can pneumatic and hydraulic brakes. These systems work in the opposite way from standard brakes—instead of applying pressure to engage the brake, pressure is applied continuously to hold the spring. When power is removed the spring releases and the braking force is applied. This allows spring-applied brakes to produce greater torque than standard brakes, so they are more reliable and also safer for loads that are suspended or in linear motion.
Pneumatic Spring Applied Brakes
Compressed air is often a staple in industrial settings, which makes pneumatic spring applied brakes a popular choice for facilities where equipment has rotating parts that must be slowed or stopped. Pneumatic caliper disc brakes are a good fit for applications that require less intense pressure, typically between 70-120 psi. (Just 85 psi can release a brake piston and store that released energy in a Belleville spring stack.) If you need greater pressure but only air is available, an air-oil intensifier converts air pressure to hydraulic pressure and can usually give you the boost you need.
Typical applications include:
- Elevator e-brakes
- Overhead gantries
- Rotary indexing equipment
- Smaller wind turbines (up to 50kw)
Pneumatic spring applied brakes offer additional advantages, in that they are:
- Comparatively inexpensive to buy, thanks to their simple design
- Least costly to operate—it’s cheaper to maintain a continuous supply of air pressure than to pay for intermittently needed electricity, and hydraulic systems have inherently greater maintenance needs
- Ideal for clean environments, with no chance of fluid leakage
Hydraulic Spring Applied Brakes
Hydraulics systems can exert tremendous torque, so hydraulic spring applied brakes are commonly used for emergency stopping, tensioning, and holding for heavy-duty industrial equipment as well as off-road vehicles, mining, and oil field equipment, etc. where hydraulic fluid is readily available. They are also a good choice for larger wind turbines (50kw or higher). However, in continuous slip applications, spring torque diminishes as friction pad wear increases, reducing braking power.
Electromagnetic brakes can also provide powerful slowing and stopping, so they may be used in manufacturing and other indoor industrial facilities. However, they are most often associated with railroad trains and circular saws. Powering one of these brakes may be easy because electricity is almost universally available, but it may not be of sufficient voltage to support electromagnetic braking requirements.
Electromagnetic brakes work fast, which is an advantage for emergency braking, and they can be a good choice for environments where potential hydraulic fluid leakage would pose a problem. On the other hand, they are not suitable for applications where space is limited.
These brakes are more expensive to purchase and maintain because of their complex design and expensive components such as copper. They are not a good choice for harsh environments because their internal components are also sensitive to dust or other contaminants that could cause undue wear and unreliable performance. (Pneumatic spring applied brakes, by comparison, operate in a closed system.)
So, Which Brake Is Best?
Industrial settings can vary significantly in terms of space available, operating conditions, and the type, frequency, and amount braking power required. Because the springs in pneumatic and hydraulic spring applied brakes carry tremendous force, they can match the torque output of an electromagnetic brake. So the choice comes down to these other factors—or it may come down to cost.
However, there is one more thing to consider. Do you have an electrical engineer on your design team or equipment maintenance crew? Mechanical pneumatic and hydraulic systems are simpler to understand. That may be another reason they are so popular for industrial equipment design.
If you want to know more about what goes into selecting and sizing a spring applied brake, this video is a good introduction.
Call Us with Your Questions
Our W.C. Branham design engineers understand the nuances that make one type of brake a better (or less desirable) alternative, and help customers find exactly the right solution for their application. Download our complete spring applied brake guide below or feel free to give us a call or drop us an email to talk to us about your application.