Pressure balanced torsion system for a backrest and the like

Abstract From the Canadian patent

A pressure balanced torsion system for use in a backrest and the like is shown. The system comprises a plurality of pairs of pressure bearing plates coupled to a torsion spring means. The torsion spring means is pivotally mounted to a support back plate. When an external pressure is exerted onto the pressure bearing plates by a human body resting against them, the counter reactive force generated by the torsion spring in the system will cause both pressure bearing plates to push against the human body until the counter reactive force is balanced in both pressure bearing plates; thus providing a balanced counter pressure against the human body to provide a uniform support therefor.