Clamp assembly for bend arm of tube bending machine

A clamping assembly for use with a bend arm of a tube bending machine. The assembly comprises a force multiplier linkage that applies a controlled and variable force to a workpiece. In one embodiment, the force multiplier linkage comprises a bearing member pivoted by an actuator acting on one end of a force multiplier arm that is attached to the bearing member. A pivot member supporting a drive link is fixedly attached to the bearing member at a location offset from the bearing member's pivot axis. The drive link pivots about the pivot member axis so that in cooperation with additional links it moves a bend arm slider. The drive link also pivots about the bearing member axis. As the bearing member is pivoted about its axis by the force multiplier arm, the drive link also pivots about the bearing member's axis providing the required force for application to the workpiece.