Barber Colman Company

Gerald R Parsons

Eugene R Jornod

Lary L Field

The piston of a reciprocating hydraulic actuator carries a pump which is driven by an electric motor and which supplies oil from the low pressure chamber of a cylinder to the high pressure chamber thereof in order to advance the piston. An exhaust valve in the piston is normally held in a closed position by magnetic force created by energizing a coil and, when closed, enables pressurization of the high pressure chamber of the cylinder. When a second coil is energized, the magnetic field of the first coil is negated and the valve is opened by a spring to permit oil to exhaust from the high pressure chamber to the low pressure chamber and permit a second spring to retract the piston. If both the pump motor and the second coil are de-energized, the first coil keeps the valve closed and causes the piston to remain in a commanded position. The actuator may be controlled by a floating single pole, double throw switch and its piston is automatically shifted to its fully retracted position by the second spring if electrical power to the actuator is lost.

Floating fluid-operated actuator

The output shaft of a rotary actuator is rotated in one direction by an electric motor and is returned in the opposite direction by a spring which is wound during driving of the shaft by the motor. The motor drives the output shaft and winds the return spring by way of a speed-reducing, torque amplifying gear train. To enable the use of a lighter return spring and the use of a gear train effecting greater torque amplification from the motor to the output shaft, intermediate gears in the drive train apply winding torque to the return spring differentially of the drive torque applied to the output shaft.

Reversible rotary actuator with spring return

A reversible electric motor supported on a sub-base acts through a reduction gear train to rotate an output shaft supported by a main mounting base, the sub-base being capable of turning through a limited range relative to the main base about the axis of the output shaft. When the output shaft encounters excessive resistance torque in either direction, the sub-base automatically turns relative to the main base and effects the opening of switch means to de-energize the motor.

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Poplar Grove, IL, United States of America

Gerald R Parsons