Supply PowerMaster Model GT-51 Drawbar Operator(s) RATED 1/2 HP, 115 VOLTS, 1 PHASE, for use on Standard Lift Sectional Doors. Primary speed reduction shall be by means of an industrial gear box with bronze worm gear in an oil bath. Motor shall be continuous duty industrial type protected from overload by a current sensing or thermal type overload device. Motor shall be of the high starting torque, continuous duty industrial type, protected from overload by a current sensing or thermal type overload device. Motor controller shall be a heavy duty, full voltage, across the line, magnetic reversing contactor, that is mechanically and electrically interlocked. Electrical components shall be installed in a NEMA 1 enclosure integral to the operator. A transformer shall be provided to reduce control voltage to 24 VAC. Separate terminal strips shall be provided for connection of power supply line and all control devices. Operator shall be wired for an open/close/stop control station. Control circuit shall provide instant reverse motor wiring on 1Ø operators. Positive chain driven, rotary type limit switches shall be provided to limit full open and close travel of door. Limit switch adjustment shall not be affected by removal of motor or by manual operation of door. An adjustable torque limiting clutch shall be provided to prevent overloading of the operator. A spring set solenoid released brake, and a disconnect arm for manual operation of the door shall be provided in case of power failure. The final reduction and drive shall be heavy duty # 41 roller chain and sprockets. The drive shaft shall be supported by pillow block bearings and be a minimum of ¾ In diameter.