Abstract: A safety braking device for a roll up or sliding door having a door curtain guided for movement by guide channels engaging its edges, the safety braking device comprising a tilt bar hingedly attached to the leading edge of the door curtain, and brake means carried on the tilt bar and arranged, upon appreciable tilting movement of the tilt bar, to frictionally engage with the door curtain guide channels for braking the movement of the door.

Abstract: An obstruction sensing and control arrangement for door or gate opening-closing mechanisms. The arrangement compares the operating rate of change of a predetermined characteristic with a preset rate of change and stops or reverses the motor in the opening/closing mechanism. The characteristic preferred is motor body temperature which is monitored indirectly. The control arrangement also includes a back up static control threshold to sense a second static operating characteristic of the motor and a second comparator means set at a preset threshold level to stop or reverse the motor. A common motor sensor is used for both the dynamic and static control thresholds. The invention also includes means to sense operating temperature and to alter the preset static threshold level automatically in response to temperature changes.

Abstract: Briefly, in this invention, a reversing device comprises a rotational wheel or other device in contact with one face of the curtain, which is caused to rotate upon descent of the curtain, and imparts a series of impulses each of which recommences a timing sequence of a timer at normal descent rate, but upon reduction of descent speed (caused for example by an obstruction), the timer times out its entire period and actuates a timer switch and relay circuit which reverses the motor to raise the curtain.

Abstract: An electrically operated roller door driving mechanism for operating a roller door comprising a reversible electrical motor fixedly mounted to one of the roller door supporting drum wheels and housed within the core of the roller door curtain, the motor and drum wheel being arranged to rotate simultaneously, and a ring gear operatively associated with said motor via a reduction gear mechanism, the ring gear being capable of being held stationary with respect to the rotating drum wheel but also being capable of rotating in unison with the drum wheel to thereby enable the roller door to be manually opened and closed in the event of a motor malfunction or power failure.