System for counterbalancing tool mount loads in a machine tool

In a machine including a frame member having a longitudinal axis, a beam member rotatably mounted to the frame member extending substantially perpendicularly outward in one direction from the axis of rotation thereof, the axis of rotation being substantially aligned with the longitudinal axis of the frame member, and a variable weight mounted to the beam member, a system to counterbalance the static torque produced by the weight about the axis of rotation of the beam member comprising:

• a support member rotatably mounted to the frame member and coupled to the beam member for simultaneous rotation about the axis of rotation, said support member extending substantially perpendicularly outward in the opposite direction from the axis of rotation;
• a pressurizable power actuator having a first end pivotally mounted to the frame member moveable in a horizontal plane and a second end having an output shaft for producing an output force proportional to the pressure level within the actuator;
• coupling means connecting said output shaft to said support member;
• and
• pressure level control means for maintaining said pressure level within said actuator at a value to produce a torque sufficient to counterbalance the torque produced by the weight.