An apparatus for supporting a load is disclosed. A support arm in accordance with an exemplary embodiment of present invention comprises a first strut, a second strut, a proximal link, and a distal link. A proximal portion of the first strut is pivotally coupled to the proximal link at a first proximal joint. Additionally, a proximal portion of the second strut is pivotally coupled to the proximal link at a second proximal joint. A distal end of the second strut is pivotally coupled to the distal link at a second distal joint. A distal end of the first strut is pivotally coupled to the distal link at a first distal joint. The support arm also includes a cam mechanism comprising a cam and a cam follower.