In one embodiment of the invention, a link of a counter balanced arm is disclosed including, a hollow housing with a cylindrical cavity having an open end and a closed end with a small opening to allow cables to pass through; a first pivotal joint near the closed end of the hollow housing; a second pivotal join near the open end of the hollow housing; a compressible spring assembly received through the open end by the cylindrical cavity of the hollow housing; and a plug coupled to the open end of the cylindrical cavity of the hollow housing.

In one embodiment of the invention, a link of a counter balanced arm is disclosed including, a hollow housing with a cylindrical cavity having an open end and a closed end with a small opening to allow cables to pass through; a first pivotal joint near the closed end of the hollow housing; a second pivotal join near the open end of the hollow housing; a compressible spring assembly received through the open end by the cylindrical cavity of the hollow housing; and a plug coupled to the open end of the cylindrical cavity of the hollow housing.

In one embodiment of the invention, a counter balanced arm is disclosed including, a first link having a first rotating transmission device, a second link having a first rotating transmission device and a compression spring, a third rotating transmission device coupled between the first and second links, and a cable routed over the rotating transmission devices coupled between the second link and the compression spring. The compression spring forms a tension in the cable to counter balance a load applied to an end of the second link of the counter balanced arm.