Clutch and/or Brake
At the most basic level, an engineer can identify if the application calls for a clutch, a brake or a combination of industrial brakes and clutches. A clutch would be used in applications where it is needed to engage or disengage the load and motor while leaving the motor to run continuously. When a clutch is used, the load will be allowed to coast to a stop. A brake would be used in applications where accurate and precise stopping of the load is required together with the halting of the motor. A clutch and brake combination would be used where the load will be started and stopped while the motor continues to rotate. For C-face mounted designs, all three choices are available. When making a unit selection there are several key steps that are common.
The next choice is unit mounting. Both clutches and brakes can mount to the motor shaft or be base mounted. Either can have input via a belt drive, chain drive or coupling.
Motor Horsepower and Frame Size
After the function is determined, the next step is to decide motor HP and frame size. For base mounted units, it is necessary to define the exact RPM at the location. Manufacturers provide quick selection charts where unit size is determined by finding the intersection of the motor HP and the speed of the clutch shaft. These charts are commonly created using the dynamic torque capacity of the product and the torque capacity for the motor plus the overload factor. Using this method presumes that the engineer has selected a motor that is appropriately sized for the application. In applications where cycle rates are considered aggressive for the inertia of the load, consulting with the application support staff of the manufacturer regarding heat dissipation capacity would be wise.
In some cases, a given motor HP may have more than one frame size choice. Since this impacts shaft size, it is critical to know this. As with HP/RPM selection, manufacturers will provide charts where unit size and frame size are shown as a guide. Since frame size determines unit shaft size, that factor would be pre-determined.