Abstract: A method and apparatus for counterbalancing and spring-assisting the swinging movement of a horizontally hinged upwardly extending mass is disclosed wherein a spring (preferably a gas spring) and a mounting bracket or hinge of unique configuration is pivotally attached at one end of the spring, the bracket (hinge) including means for selective engagement and disengagement from the spring during pivotal swinging movement of the mass between alternate terminal positions and through an over-center position, in order to minimize the forces necessary to move said mass toward and through the over-center position.