Counterbalance For A System For Providing Cyclic Motion

Abstract

In one embodiment, a system for providing cyclic motion includes a magnetic drive having an electrically conductive coil defining a bore and a magnetic member movable through the bore. A control provides current to the coil and selectively reverses the direction of the current to move the magnetic member through the bore. In another embodiment, the system includes a counterbalance. The counterbalance includes a biasing member for reacting against a load applied to a support, and a lever arm coupled to the biasing member for varying a preload of the biasing member. In another embodiment, the magnetic drive and the counterbalance may be incorporated into an apparatus for reciprocating a person.

1 . A counterbalance, comprising:
 a biasing member adapted to be coupled to a load support for reacting against a load applied to the load support; and   a lever arm operatively coupled to said biasing member and selectively positionable relative to said biasing member to vary a preload of said biasing member.   
     
     
         2 . The counterbalance of  claim 1 , further comprising a pivot selectively positionable with respect to said lever arm and cooperating with said lever arm to vary said preload of said biasing member. 
     
     
         3 . The counterbalance of  claim 1 , wherein said biasing member is a spiral torsion spring. 
     
     
         4 . The counterbalance of  claim 1 , wherein said biasing member and said lever arm cooperate to maintain a constant resonant frequency with respect to the load applied to the load support.