Power-off brakes are abundant, and their presence is growing in industries such as robotics, warehouse automation, medical equipment, mobile and electric vehicles of all types, and industrial automation as well. These brakes are normally engaged without power and then released when electric power is applied to the coil.

But what if electrical power is no longer available to release a brake? Battery powered equipment might lose their charge, poor weather can cause power outages, or power supplies get damaged. In those cases, it might be necessary to manually release the brake. This could be for safety reasons, but also to facilitate towing or to service a piece of equipment.

The electromagnetic brake has a field coil as a major part of the assembly. When the coil is energized, it becomes an electromagnet and pulls a steel armature plate toward the coil body. This compresses springs inside of the brake. It also releases the brake and allows the shaft to turn. So, in the case of not being able to pull that metal armature plate toward the coil in the case of lost power, it now must be done mechanically.

If the brake is easily accessible for service, the easiest method to release the brake mechanically is by using threaded holes in the brake. By inserting release bolts into those threaded holes, you can mechanically push the armature toward the coil body and release the brake. These holes are standard in Ogura's larger sized brakes when it is too difficult to overcome the holding force by brute force alone.

On other designs, it is possible to incorporate a manual release lever into the brake design. Normally this release device will fit into the small space inside the brake body to be able to move the plate axially with force. Manual release designs actuate the armature with axial movement and some with radial movement. It is possible to have a long lever arm that extends outside of the general brake area to make brake release more convenient. When the brake is totally buried inside of an assembly and it is too hard to reach altogether, equipment designers can use cables to release the brake, much like how a brake might work on a bicycle. The cable just pulls on the manual release lever to release the brake. Special designs are frequently discussed.

Ogura brakes can have manual release holes as standard. Starting with SNB series size 1.2 (12Nm min static torque rating) and RNB series size 3 (30Nm min static torque rating) and larger, all units have three tapped holes in which screws can be inserted for manually releasing the brake in case of emergency, towing, or needed service. All MNB series brakes have the tapped release holes (from 2 to 800Nm min static torque rating).

Benefits of Ogura's manual release brakes:

• Safety
• Experience
• Long life
• Quality
• Manual release options
• Optimization
• Low power
• Preferred mounting
• Low total cost

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