A counterbalance apparatus for supporting a load is provided. The apparatus includes a base, a load bearing arm, a toggle linkage, and first and second resilient members for applying a force to the load bearing arm. The load bearing arm consists of a plurality of pivot points forming a parallelogram linkage, may project from the base at an attachment point and is adapted to support the load at a distal end. The toggle linkage may be pivotally connected to the base and moveable between a non-load bearing position and a load bearing position. The toggle linkage may also comprise an adjustment member positioned to define a distance relative to the attachment point. The first resilient member is adapted to apply a force to the load bearing arm and may have a first end connected to a first portion of the parallelogram linkage and a second end connected to the adjustment member； and the second resilient member is also adapted to apply a force to the load bearing arm and may have a first end connected to a second portion of the parallelogram linkage and a second end connected to the adjustment member. Movement of the toggle linkage from the non-load bearing position to the load bearing position engages the forces of the resilient members and movement of the adjustment member varies the distance to adjust a support vector adapted to counterbalance the load vector.L'invention concerne un appareil d'équilibrage permettant de supporter une charge. L'appareil comprend une base, un bras porteur, une liaison à genouillère, et des premier et second éléments élastiques permettant d'appliquer une force sur le bras porteur. Le bras porteur est constitué d'une pluralité de points de pivot formant une liaison en parallélogramme, peut faire saillie à partir de la base au niveau d'un point de fixation et est conçu pour supporter la charge au niveau d'une extrémité distale. La liaison à genouillère peut être reliée pivotante à la base et mobile entre une position non porteuse et une posit
