Supply PowerMaster model "RJ" industrial duty jackshaft type operator to provide lock bar sensing and allow emergency egress on rolling service doors and grilles. Primary reduction shall be by heavy duty V-Belt Drive. Secondary reduction shall be a chain and sprocket arrangement. Reduction stages shall be arranged so that mechanism is self locking when torque is applied at output shaft. All reduction shafts shall be a minimum of 1" in diameter, supported by bronze oilite bearings. Operator shall provide an adjustable torque limiting clutch.