Coupling for spiral counterbalance

  • US 5,694,664 A
  • Filed: 07/10/1996
  • Issued: 12/09/1997
  • Est. Priority Date: 07/10/1996
  • Status: Expired due to Term
First Claim
Patent Images

1. A coupling between a twisted rod and a torsion spring arranged within a tube of a spiral counterbalance, the coupling comprising:

  • a. a rotation transmission extension gripped by terminal convolutions of the torsion spring, the extension comprising a metal sleeve resisting inward compressive force from the surrounding grip of the terminal convolutions of the torsion spring;

    b. the rotation transmission extension surrounding the twisted rod and allowing the twisted rod freedom to extend and retract from the counterbalance tube;

    c. a molded resin follower engaging opposite faces of the twisted rod so that the follower rotates when the twisted rod extends and retracts from the counterbalance tube; and

    d. the rotation transmission extension being rotated by the follower as the rod extends and retracts from the counterbalance tube so that the extension turns the torsion spring.

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