Patent ID: 6921056

Claim:
A mechanical assembly, comprising: a first arm connected to and free to rotate about a pivot point; a counterbalance extension link connected to and free to rotate about the pivot point; a yoke including a first slot in which a pin of the counterbalance extension link resides, wherein the yoke is enabled to translate in a plane responsive to rotation of the counterbalance extension link pin about the pivot point; and a force generating device connected between the counterbalance extension link pin and a fixed point on the yoke to exert a force on the counterbalance extension link pin, wherein the orientation of the force produced by the force generating device remains constant as the yoke translates responsive to the counterbalance extension link pin rotating about the pivot point; wherein the yoke includes at least a second slot perpendicular to the first slot and a pin attached to a fixed reference through the second slot to guide the motion of the yoke as it translates.