Abstract: A flexible curtain rollup door is driven between open and closed positions by an adjustable frequency AC electric drive motor including a controller which is operable to accelerate and decelerate the motor by supplying AC electrical power at variable frequencies over a predetermined time period and for operating the motor at selected speeds during a continuous run phase of operation. A programmable logic controller (PLC) is operably connected to the controller for the drive motor and is operable to receive signals from upper and lower door position sensors, door bottom edge bar breakout sensors, a door bottom edge bar contact sensor, area sensors on one or both sides of the door for detecting the presence of an object within certain areas adjacent the door opening and manually operable switches to control opening and closing movements of the door. A position sensor is connected to the motor and generates signals correlated with motor and curtain roll drum revolutions to provide backup door position signals.

Abstract: A counterbalance mechanism for a sectional garage door includes an elongated shaft mounted above the door opening and supporting spaced apart cable drums connected to respective cables which are connected at one end to the door for exerting a counterbalance force thereon. Opposed torsion springs are connected to the cable drums at one end, respectively, and to respective hub members which are axially slidable on but nonrotatable with respect to the shaft. The cable drums are provided with detachable bushing members for engagement with the support brackets. The shaft is connected to a non-reversible worm gear drive at one end. The worm gear drive may be actuated to selectively vary the torsional deflection of the counterbalance springs by rotating the worm and a ring gear meshed therewith.

Abstract: A sectional garage door is formed of rectangular door sections which include hollow extruded plastic rail members interconnected by hollow extruded plastic end and intermediate stile members to form a door section. The rail members and stile members may be fitted with internal tubular or channel shaped metal reinforcing members to minimize deflection of the door sections during use. The door sections may each include an externally fitted strut which is secured to a longitudinal side edge of a section and is connected directly to a reinforcing member disposed within one of the rail members without being forcibly connected to the rail member itself to allow for differential thermal expansion between the rail member and the reinforcing members. Rectangular panel inserts may be removably supported on each door section by removable retainer members and may include insulated panel inserts which may be added to the door sections before or after installation.

Abstract: An upward acting sectional door is formed of rectangular door sections which are interconnected to each other by a continuous hinge comprising opposed partial arcuate hinge members formed on a lower rail of an upper section and an upper rail of an adjacent lower section and engaged with a third hinge member comprising an elongated tubular pin having a D-shaped cross section. The hinge pin is secured against rotation by retainer members at opposite ends of one of the door sections. The hinge permits lateral assembly and disassembly of one door section relative to the other. Additional load bearing hinge members are provided connected to the lateral side edges of adjacent door sections and are interconnected by support members disposed in the tubular hinge pin for transferring part or all of the forces between adjacent door sections thereby allowing the arcuate hinge members to function substantially as cooperating light and weatherseal members and to provide a substantially pinch proof door.

Abstract: A twin post, telescoping jack hydraulic elevator system has a pair of dynamic sensors to determine when the jacks are out of synchronization, by determining any relative differences in height between the two intermediate cylinders. The elevator also includes static sensors to determine if one or both intermediate cylinders are more than a predetermined distance away from their normal positions when the car is stopped at each floor. The controller actuates a resynchronization if the distance between the intermediate jacks exceeds a first threshold, and shuts down the elevator if the distance exceeds a second threshold or if resynchronization demands are issued too often. Preferably, the static sensors are positioned to detect the seal housing at the top of the intermediate cylinder, which projects outwardly from the cylinder.