Patent ID: 7992733

Claim:
A vertical actuation system comprising: a cable having a first end and a second end; wherein the first end is configured for operative attachment to a support structure at a first location and the second end is configured for operative attachment to the support structure at a second location, different from the first location; a plurality assist device pulleys, a mass pulley, a fixed pulley, and an actuation pulley; wherein the plurality of assist device pulleys are configured for operative attachment to an assist device that is movably attached to the support structure in a horizontal direction, relative to the ground; wherein the cable is configured to be routed around each of the plurality of assist device pulleys, the mass pulley, the fixed pulley, and the actuation pulley such that each of the pulleys are configured to be operatively disposed between the first and second ends of the cable; wherein the mass pulley is configured to be operatively supported by the cable and a pair of the plurality of assist device pulleys; wherein the fixed pulley is configured for operative attachment to the support structure; wherein the actuation pulley is configured to be operatively supported by the cable and each of the fixed pulley and the second end of the cable; a mass extending from the mass pulley; and an actuator configured to move the cable relative to the fixed pulley such that the actuation pulley moves vertically, relative to the ground, as the mass pulley and the mass move vertically in an opposite direction; wherein the vertical movement of the mass is configured to be independent of the horizontal movement of the assist device.