SG Transmission develops first of its kind hybrid permanent magnet and spring applied brake

Due to the critical nature of the application, a pre-assembled solution was designed with both spring applied and permanent magnet technology to offer double redundant capability in the event of a failure. The hybrid solution offers the benefits from both technologies, combining the high torque and back-lash free capability of a permanent magnet brake, with the extended temperature range of a spring applied brake.

When quick and accurate holding is required, spring applied and permanent magnet brakes are known for their reliable, fail-safe braking capability. Unlike other electromagnetic brakes, they are designed to engage when electrical supply is removed (power-off brake engagement). Spring applied brakes transmit torque through pressure generated by built-in springs, while the holding force in a permanent magnet brake is created by multiple permanent magnets attracting a single face armature.

Paul Short, Technical Manager at SG Transmission, explained: “While a hybrid permanent magnet and spring applied brake provides significant benefits, the design complexity and unpredictability of the two interacting magnetic fields have prevented this concept from previously being explored.

“In addition to the innovative design, the customer required a ‘plug and play’ solution which presented an additional challenge due to its small, compact design and limited axial length. So far, we have successfully supplied three versions of the brake in various sizes.”

The internal design team at SG Transmission worked closely with the customer throughout the project, using video conferencing and 3D data transfer to enable the collaboration of the team’s electromagnetic knowledge with the requirements of the application.

Andy Collinson, Chief Executive Officer at SG Transmission, said: “We were delighted to be approached with this unusual request. We are committed to our position in the industry as the expert in bespoke electromagnetic solutions, and this project has provided the opportunity to add yet another pioneering design to our catalogue”.