An axial (or Y-axis) pressure function common to modern rotary-draw tube-bending machines; a pressure or speed setting driving the pressure (or follower) die forward; a pressure applied parallel with the axis of the tube to be contrasted with “direct pressure” which is applied radially (that is, in the X-axis) to the tube. The importance of assist pressure is that it mitigates the drag caused by the tooling on the tubing at the point of bend, which helps to reduce wall-thinning and deformation of the extrados.