When you’re trying to decide which type of brake is best for your particular application (such as mechanical, pneumatic, or hydraulic brakes), it’s important to understand both the reasons for braking and the differences in the types of brakes available for industrial equipment and on- and off-road braking applications.
Understanding the Reasons for Braking
1. Dynamic Braking
The primary reason for braking is, of course, to get something to stop — also known as “dynamic braking.” A disc is moving and your goal is to get it to come to a complete stop. Any on- or off-road vehicle, aircraft service vehicles, golf carts, construction machinery or even wind turbines refer to this as “active braking.”
2. Holding Position
A second reason involves a “holding position,” which is common with industrial machinery with rotating parts. A winch is a good example of holding position braking. When payout or reeling is complete, a holding position can be of critical value.
3. Controlling Speed
Lastly, there’s “tensioning,” which falls between dynamic braking and holding, and is used for controlling speed. Anything that comes on a roll, such as newspaper, foil, or tape, is manufactured by a web handling system and involves tensioning. Tensioning brakes are applied often, so their pads have high wear rates, but are easily replaceable.
However deciding on which type of brake to use will depend on what’s best for your application, so let’s “brake it down” further…
Understanding What Powers Brakes
There are as many types of brakes as there are countless applications, however, there are three main categories of brakes, determined by how they are powered: mechanical, pneumatic, and hydraulic brakes. Here are some of the ideal applications for each.
1. When to Use Mechanical Brakes
Just as it sounds, mechanical brakes are actuated by the use of a lever, for which no power supply is required. Mechanical brakes are best suited for applications that require static braking that can be manually applied. The best example of this would be a parking brake.
Mechanical brakes can be well suited when nothing more elaborate is required. You pull a lever and the system stops. This is a common way to stop 5–10kw class wind turbines providing safety for service.
2. When to Use Pneumatic Brakes
The power used in these type of brakes is air, supplied primarily by a pneumatic pump. Air brakes typically operate at lower pressures than hydraulic brakes, around 70-120 PSI for most applications.
Pneumatic brakes are commonly used on industrial machinery requiring brakes, because manufacturing facilities most often have a pneumatic compressor on site. For this reason, we typically see pneumatic brakes in factories where machinery with rotating parts need brakes.
3. When to Use Hydraulic Brakes
Most often these brakes are powered by brake fluid, such as hydraulic oil for industrial machinery or DOT 3/4 automotive brake fluid (polyethylene glycol). When pressurized the fluid creates force in PSI. Hydraulic brakes tend toward the high pressures needed for proper stopping, holding, or tensioning. Be sure to specify the fluid type to ensure your brake is equipped with fluid compatible seals.
Hydraulic power supplies are common in most vehicles, such as commercial and off-road type braking. These brakes can be service brakes to stop the vehicle, or used to hold position on machinery. For example, a utility vehicle may have a wire cable reel that needs to be controlled and hydraulic power is available.
We often see hydraulic brakes used in applications requiring higher torque braking. Oil field and mining equipment typically use hydraulic brakes for this reason. Wind turbines from 5–50kw often have pneumatic brakes. Wind turbines at 50kw and higher most often have hydraulic brakes.
One More Decision
Your application may require one of two types of brakes, “Double-Acting Brakes” (with two live sides) or “Floating Brakes” (with a single live side).
1. Double-Acting Brakes
A double-acting brake is fixed mounted with pistons on each side that, when actuated, engage against the brake disc. It’s critical for the brake to be well-centered over the disc, with run-out +/- 10 inches, otherwise, the brake pad on one side will wear out faster than the other.
2. Floating Brakes
The floating brake with a single live side is the most common type. This type of brake has a piston (or pistons) on one live side, which press on the rotor (or disc) when engaged. A floating brake is mounted on rods, bushings, or shoulder bolts that are smooth and allow the brake to move when engaged. The disc is fixed, which allows the brake to move to the center so the live side and dead side pads brake with equal and opposing clamping force.
These are the basic things to consider when choosing the best brake for your industrial or vehicular off-highway application. W.C. Branham has a wide line of brakes including pneumatic or hydraulic spring applied and hydraulic/mechanical combinations for many different types of applications.