Mechanism for detecting an obstacle preventing the proper operation of a roller-type door with sectional shutters

A detection mechanism for terminating the lowering of a sectional shutter of a warehouse-type roller door in response to an obstacle engaging the sectional shutter as it is being unwound from about a horizontal shaft driven by a motor, the detection mechanism comprising;

• a switch means operatively connected to the motor, at least one strap member operatively connected to said switch means, said at least one strap member extending adjacent to the horizontal shaft and being normally spaced from the sectional shutter wound about the horizontal shaft and being positioned so as to be engaged by a slack portion of the sectional shutter created by the engagement of an obstacle with the sectional shutter as the sectional shutter is being lowered to thereby activate said switch means to control the motor and prevent further lowering of the sectional shutter by the motor.