The FT series drives were designed especially for fire doors. They form a complete series from 250 to 2200 Nm. A roller chain connects them to the shaft of the door. They close independently and automatically in case of fire, with no energy supply. In normal operation, the power-operated door is opened and closed again by a three-phase current motor. The gear mechanism consists of a non-self-arresting spur gear unit, a centrifugal and magnetic brake, an electric motor and limit switches. A magnetic brake supports the load of the gate and is released immediately in case of fire. The centrifugal brake limits the movement speed of the gate.