A device for ensuring safety by preventing mechanically raised and lowered components, roll-up gates for example, from crashing down when the motor or transmission fails. The device is characterized by a friction clutch. The friction clutch comprises a stationary half and a moving half. The stationary half is secured to the shaft inside a housing. The moving half is mounted on a base and can be electromagnetically displaced axially in relation to the base and against the stationary half. The force exerted by the moving half against the stationary half is augmented by resilient components that engage between the housing and the moving-half base.