Abstract: A manual override mechanism is presented for a motor-driven linear actuator that allows the output rack and pinion of the actuator to be manually positioned. Once positioned, the output may be locked by a locking mechanism to prevent this output from translating to its quiescent position. When incorporated in a spring-return linear actuator, the manual override may be used to apply a preload on the spring before the driven device is connected. When the actuator is used to drive a valve or damper, the preload applies a positive closing force on the valve or damper in its zero position to ensure a tight closure of the valve or damper. The locking mechanism engages the gear train and opposes the closing force applied by the spring return of the actuator. To disengage the locking mechanism automatically, the motor applies a forward kick to the gear train. Manual disengagement is also provided.

Abstract: A manual override mechanism is presented for a motor driven rotary actuator that allows the output of the actuator to be manually positioned. Once positioned, the output of the actuator may be locked by a locking mechanism to prevent this output from rotating to its quiescent position. When incorporated in a spring return rotary actuator, the manual override may be used to apply a preload on the spring before the driven device is connected. When the actuator is used to drive a valve or damper, the preload applies a positive closing force on the damper in its zero position to ensure a tight closure of the valve or damper. The locking mechanism engages the gear train and opposes the closing force applied by the spring return of the actuator. To disengage the locking mechanism automatically, the motor applies a forward kick to the gear train. Manual disengagement is also provided.

Abstract: An angular position sensor is couplable to an actuator for angular positional sensing of a shaft thereof. The sensor includes a base for mounting to the actuator. A diametrically magnetized permanent magnet ring is coupled to, and axially aligned with, the shaft. Further, a magnetic material cylindrical sleeve is coupled to the said base and disposed circumferentially around the magnet ring such that the sleeve is separated from said magnet ring by an air gap. A pair of diametrically opposing cylindrical segments are coupled to the sleeve by a circular support member and extend through the magnet ring. The cylindrical segments having a slot between them in which a hall effect transducer is disposed. The transducer senses the magnetic field flux of the magnet ring in the slot and thereby produces a signal indicative of the shaft's angular position.