Rotork Plc

Frederick A Smith

A control unit responsive to axial movements of a motor shaft coupled to an actuator. The control unit provides torque and limit switches which are connected to disable the electric motor. The rotation of the output shaft of the actuator is used to operate limit switches in the control unit so that the motor will be deenergized when the actuator has moved to its full limit or when an excessive torque is encountered. Limits are established by connecting a counting mechanism to the electric motor output shaft. The actuator is controlled in first and second directions by first and second switches. A switch actuator is associated with each switch which is latched into position by the motion of the actuator members. The latch member prevents relative movement of the actuator until the motor direction is reversed, thereby preventing hammering and repeated actuation of said motor upon detection of the torque limit.

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Bristol, United Kingdom

Frederick A Smith