Power off brakes stop or hold a load when electrical power is either accidentally lost or intentionally disconnected. In the past, some companies have referred to these as “fail safe” brakes. These brakes are typically used on or near an electric motor. Typical applications include robotics, holding brakes for Z axis ball screws and holding brakes for servo motors. Many custom designs are available and can be made for use with different motor applications.
Features
- Small profile: High torque in a small space makes for a very compact design brake.
- Zero backlash option: Some designs contain a zero backlash hub that can be critical in registration applications.
- Fast response time: In most units, a series of coil springs are used so pressure plate travel is minimized.
- Multiple voltages available: Depending upon the size, 24, 45 or 90 volts are available; however, voltages can be modified to meet your special requirements.
How It Works
Engagement: When no current/voltage is applied to the brake, a series of springs push against the pressure plate, squeezing the friction disk between the inner pressure plate and the outer cover plate. This frictional clamping force is transferred to the hub, which is mounted to a shaft (customer supplied).
The power off brake is considered engaged when no power is applied to it. It is typically required to hold or stop a load in the event of a loss of power, when power is not available to run a machine.
Disengagement: When the brake is required to release, voltage/current is applied to the coil creating a magnetic field. This magnetic field pulls in the pressure plate pulling against the springs, creating an air gap between the pressure plate and the friction disk, allowing it to turn freely with the shaft.