초록 ▼

A height adjustable load support structure has a base frame and a generally planar support surface. Preferably, two extendable vertical support assemblies support the surface for vertical movement relative to the base frame. Each support assembly is engaged by a spring biased pivotable arm to counte

A height adjustable load support structure has a base frame and a generally planar support surface. Preferably, two extendable vertical support assemblies support the surface for vertical movement relative to the base frame. Each support assembly is engaged by a spring biased pivotable arm to counterbalance the weight placed on the surface. A cam system cooperating between the distal ends of the pivotable arms and the support assemblies serves to compensate for the changing spring force on the arms by varying the effective moment arms of the arms thereby equalizing the force on each support assembly through its complete range of vertical travel.

대표청구항 ▼

An adjustable height load bearing support structure comprising: a base frame; a generally planar support surface member; support assembly means configured to support said support surface member for vertical movement relative to said base frame; at least one arm biased by a spring, said spring imposi

An adjustable height load bearing support structure comprising: a base frame; a generally planar support surface member; support assembly means configured to support said support surface member for vertical movement relative to said base frame; at least one arm biased by a spring, said spring imposing changing biasing force on said arm, said arm being pivotable about an axis disposed beneath said support surface member and having a free distal end; said arm further having an effective moment arm; and cam means provided at the distal end of said arm and cooperable with said support assembly means for biasing said support assembly means throughout a range of vertical travel and continuously varying the effective moment arm of said arm to compensate for the changing force of the spring biasing of said arm wherein an upward force imposed by said arm on said support assembly means is substantially constant through the range of vertical travel of said support assembly means.