BRAKES & CLUTCHES
Brake and clutch basics ONE
of the unsung heroes of mechanical power transmission
are brakes and clutches. Often hidden away, these humble components are indispensable in many machines and systems. Fundamentally, they’re used to stop, hold, or index a load. More specifically, brakes are used to stop a load, usually a rotating one. Brakes are used where accurate stopping of the load is a must, and typically the motor needs to stop as well. Clutches, on the other hand, are typically used to transfer torque. So a clutch is used where it’s required to engage or disengage a load and motor while leaving the motor running. With a clutch, the load coasts to a stop. Other application needs may call for a brake and clutch combination; for example, if the load must be stopped and started while the motor continues to rotate. Brakes and clutches can mount to a motor shaft or can even be basemounted with input from a belt drive, chain drive, or coupling. Sizing and selecting the right brake or clutch for the job requires knowing a few parameters, specifically the horsepower and frame size of the motor. Manufacturers typically provide selection tools making it easy to pick the right component size by finding the intersection of the motor horsepower and speed at the clutch shaft. These selection charts are constructed using the dynamic torque capacity for the specific clutch and the motor torque capacity plus an overload value. This method works well in most uses; for
motioncontroltips.com | designworldonline.com
A new line of micro brakes from Ogura is designed specifically for servo motor applications, especially in robotics and medical equipment. Ogura micro holding brakes come in both square and round designs with the newest round design being 10 mm in diameter with length as short as 9 mm. Micro brakes can weigh 20 g or less allowing for reduced inertia on fast moving robotic arm applications.
5 • 2020
DESIGN WORLD — MOTION
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