Fluid Power
HANDBOOK
PNEUMATICTIPS.COM
AIR BRAKES
& clutches AIR
IMAGE COURTESY OF EATON
30
FLUID POWER WORLD
AirBrakes_FPWHandbook_V1.indd 30
brakes serve as the main brake to provide parking and E-stop braking functions in a variety of applications, including draglines, grinding mills and shovels in mining, drawworks for drilling rigs, and marine winches. They provide the quick actuation and stopping times that are necessary in emergency situations or to stop large industrial machines for routine maintenance. They are actuated with compressed air rather than hydraulic fluid or oil. Air clutches help transfer torque between the engine and transmission, rather than providing stopping power. They rely on compressed air for engagement and disengagement. By controlling the air pressure applied to the clutch, you can achieve smooth controlled deceleration and even rapid stops. In addition, they offer quick and safe disengagement. Air brakes are rotors or discs attached to a driveline shaft that, when the brake is applied, bring the rotating machinery to a stop. When the brake is applied, a piston is pneumatically actuated, forcing the friction pads to clamp the rotor discs. Several factors go into sizing an air brake; most notably, the required horsepower, stopping time and total energy are musts for selecting the right brake for the application. Drum-style constricting clutches are pneumatically actuated and are used to connect and disconnect to rotating shafts to transmit power and motion. Air-actuated brakes and clutches offer a number of advantages, such as fast response rates and safe operation. Since they are pneumatically actuated versus hydraulically actuated, the risk of spills, leaks and fires is eliminated. Leaked or spilled oil can create an incident that can take hours or days of downtime to clean up, creates a hazardous working environment and puts end users at risk of expensive environmental fines. Unlike electrical options such as variable frequency drives and other AC drive motors, air brakes are capable of not only stopping motion, but also manual operation in the case of a power failure. Electrical options are usually more complex as a result, and may require some type of a fail-safe brake to slow or stop motion in case of power outage. To meet the needs of more complex machinery, newer brakes and clutches can include sensing and monitoring technology to make the equipment more responsive and able to provide feedback or warn users of problems. Solutions on the market today include brake and clutch products with embedded temperature sensors or slip detection. 6 • 2016
www.fluidpowerworld.com
6/17/16 11:14 AM