| 摘要 |
A linear actuator includes an electric drive motor which is connected to a drive screw through a gear train. Rotation of the drive screw causes the drive nut to move axially in order to impart axial motion to an extension member. Limit switches function to disengage power to the electric motor upon the extension member reaching the outer or inner limits of its stroke. Also, a thermal sensing element located in the windings of the electric motor interrupts power to the motor upon the heat-up of the motor windings above a predetermined temperature, as when the drive nut jams or locks up. A sealed housing contains the drive screw, drive nut and extension to protect against entry of dust. The housing has reaction surfaces which cooperate with the drive nut to permit linear movement of the nut while holding the nut against rotation.
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