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How to Select a Clutch and/or Brake

Clutches and brakes are crucial components in systems that require stopping, holding or indexing loads. They help to transfer torque from one point (shaft) to another through clutching or stopping and holding load through brakes.


When starting or stopping a system, energy is passed between the input shaft and output shaft via contact points. This energy is converted to heat and is equivalent to the amount imparted or absorbed. If you are looking forward to buying a brake and/ or clutch, here are the main steps to follow:


Decide if you want a Clutch and/ or Brake


Does your system need a clutch, brake, or combination of the two? Note that though these two parts are sold as different parts, their operations are in many cases combined. However, your system design determines whether you need one or both.


The clutch is used in applications that engage and disengage the motor and the load when the motor is still running. If a clutch is used, the load needs to come to a standstill.


Brakes are used when you are running applications that require accurate stopping of the load and the motor. In most of the systems, the clutch and brake are used together to ensure that the load is started and stopped while the motor continues rotating. Here are other components that you need to factor when buying clutches/ and or brakes.


March to Motor Power


The horsepower of the motor is crucial in determining the brake or clutch to pick. If you have base-mounted units, it is important to get the right rpm (roll per minute) where the brake or clutch will mount.



Many manufacturers have guiding charts that provide different unit sizes. This makes it easy for engineers to determine the correct match of speed and horsepower at the clutch shaft. The charts utilize dynamic torque capacity for the product under consideration and torque capacity for the motor. The overload factor could increase the torque rate for the motor.


If you use this strategy, it is presumed that the selected motor is sized correctly. If your system is considered aggressive because of inertia, it is prudent to seek assistance from an expert or machine manufacturer to determine the heat dissipation rate of the brake/ clutch.



Match to Motor Frame Size


The next step is determining the frame size of the motor. In some instances, you might have multiple options for a specific quantity of horsepower. For example, a single-horsepower motor can be either a 143TC frame motor or a 56C frame motor. This information is very important because it has a direct implication on the shaft size.


Manufacturers provide charts with unit sizes and frames so that you can easily pick the correct one. Note that the shaft size is predetermined by the frame size.


Pick the Right Mounting


The next consideration you need to get right is the unit mounting. Both clutches and brakes can be mounted on the base or motor shaft. Then, their input can be connected via belt drive, coupling, or chain drive.


Coil Voltage


The last variable that you need to get right when selecting clutches and brakes is the coil voltage. The common ratings are 6, 24 and 90 volt DC options. In North America, the preferred option is the 90 volts option while 24 volts power supply is common in Europe. Note that in both situations, manufacturers provide converters to change power from AC to DC.


To have an optimally running system, you need the right clutch and/ or brake. This post provides all the info that you need to select the right clutch and/ or brake.