Abstract: A torsion spring cartridge assembly for supporting an oscillating member, the assembly including a bearing assembly, a torque assembly mounted for rotary motion in said bearing assembly, a counter-torque hub, and a set of torsion bars connecting the torque assembly to the counter-torque hub, the cartridge assembly being adapted to be removably mounted in a support structure with the bearing assembly and counter-torque hub mounted in a fixed relation so that the torque assembly is free to rotate within the limits of the torsion bars. A dampener can be provided to restrict the motion of the torque assembly in one direction of motion.