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Position controlled linear actuator

  • US 4,858,481 A
  • Filed: 05/09/1988
  • Issued: 08/22/1989
  • Est. Priority Date: 05/13/1985
  • Status: Expired due to Fees
First Claim
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1. A linear actuator comprising:

  • a housing;

    a drive screw rotatably supported within said housing;

    a drive nut in threaded engagement with said drive screw;

    a body tube assembly connected to said housing and positioned above said drive screw, said body tube assembly containing reaction surfaces for preventing rotation of said drive nut;

    an extendable member having a load connecting member on its free end and having the opposite end thereof connected to said drive nut, said extendable member adapted for axial movement so as to extend out of said body tube;

    drive means including an electric drive motor containing windings for rotating said drive screw; and

    a limit switch assembly attached to said housing and adapted for operation by movement of said drive means, said switch assembly controlling operation of electrical power switches for disengaging said electric drive motor when said extendable member reaches predetermined positions, and said limit switch assembly containing a position indicating means, operated by said drive means through limit switch gear means rotated by said drive screw, and adapted for generating an electrical signal proportional to the position of said extendable member.

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