How to prevent the door from falling on the European-style rolling door

How to place a door fall on a European style rolling door

               There are two ways in which the motors of European-style rolling doors are usually mounted, the

             a) Direct drive, where the motor directly drives the shutter shaft.

             b) Chain drive, the motor drives the shutter shaft through the chain

            In the case of direct drive, the motor has a built-in over-torque protection device, which is triggered by a device built into the gearbox when the door is overloaded by the weight of the door or when the door operation is blocked for other reasons.

            Locks the door to prevent it from falling down

                 When the chain is driven, by installing a fall prevention device at the other end of the shaft (similar to the function of a car seat belt), when the door body falls down and the speed of the door shaft exceeds the limit

           (normally no more than 40 rpm), fall arrest device triggered

           The above two for the European-style rolling door how to prevent the door body fall when the method is used