Patent ID: 6814658
Filing Date: 2004-11-09
Classification: B08B,E05D

Abstract:
In an enclosure having an interior chamber, an access opening in said enclosure providing access to said interior chamber, a closure member movable between closed and fully open positions in said access opening for selectively allowing and restricting said access to said interior chamber, the improvement comprising:at least one primary counterweight, a primary connecting member interconnecting said primary counterweight and said closure member for movement therewith, and a primary roller member mounted for rotation about an axis of rotation, said primary roller member being engaged by said primary connecting member intermediate said primary counterweight and said closure member for rotation by said primary connecting member in response to movement of said closure member; at least one secondary counterweight, a secondary roller member arranged to rotate with said first roller member, and a secondary connecting member interconnecting said secondary roller member and said secondary counterweight, said secondary member movably winding and unwinding on said secondary roller member in response to movement of said closure member; said closure member being movable to at least one predetermined intermediate position between said closed and fully open positions, with said secondary connecting member winding and unwinding from said secondary roller member in a first moment-producing direction on said secondary roller member when said closure member is moved between said closed position and said intermediate position, and with said secondary connecting member winding and unwinding on said secondary roller member in a second moment-producing direction on said secondary roller member when said closure member is moved between said intermediate position and said fully open position, said second moment-producing direction being opposite to said first moment producing direction.