Abstract: A linear force centralizer adapted to be supported on a downhole tool is set forth. In the preferred and illustrated embodiment, the centralizer includes multiple sets of long and short arms extending outwardly to define a protruding knuckle, the knuckle having a roller adapted to be contacted against the surrounding well borehole. The arms are connected to similar, spaced apart, facing crosshead assemblies slideable on a central mandrel. The crosshead assemblies cooperate with first and second spring means. The first spring means increases in resilient force acting on the arm as the arm is deflected radially inwardly. The second spring means forms a resilient force which increases as the arm is deflected radially outwardly. The sum of the two spring forces is approximately constant through a range of deflection of the arms, thereby providing a relatively constant force.