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- Wired properly? Polarity for power off brakes
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Wired properly? Polarity for power off brakes.
You might be wondering if polarity matters when wiring your power off brake. Before you take another step, consider the type of brake first. There are two basic types of power off brakes: spring applied brakes and permanent magnet brakes. They are used for safety and precision in numerous applications including: robotics, medical equipment, surgical tools, wheel drives, warehouse automation equipment, servo motors, hoists, elevators, escalators, gates, doors, security, stage and theater, conveyors, actuators, pill dispensing, and general industrial automation.
For permanent magnet brakes, yes, polarity matters. Without power, the brake engages because the permanent magnets inside of the brake create electromagnetic flux that attract the armature plate toward the brake body. This causes the hub to be held in place. That magnetic flux is directional. When you apply power to the brake, you want the polarity to be correct because the coil needs to create magnetic flux in the opposite direction to cancel the permanent magnets' magnetic flux. If you have it wired backwards, when you apply power the brake torque or magnetic strength is actually increased and not cancelled out.
For spring applied brakes, polarity does not matter. This is because it does not matter which direction the magnetic flux of the coil travels. All that matters is that the pressure plate attracts to the coil body in order to disengage the brake. When power is removed, the flux breaks down and the springs' force on the pressure plate brings the shaft to a stop or holds it in place.
Ogura has several brake series, but common series of spring applied brakes are MCNB and RNB with static torque ranging up to 148 lb-ft (200 Nm). Larger models are available as well. PMB series are permanent magnet brakes with static torque rating up to 88 lb-ft (120 Nm).
Benefits of Ogura power off brakes:
- Long life
- Long life
- Quality
- Compact dimensions
- Customization and optimization
- Low total cost