Abstract

A rolling element or ball swashplate has a part-spherical surface covered in latitudinal grooves and ridges, in cross-section resembling parts of a spur gear wheel. The ball is mounted on a well-known rolling element bearing on its polar axis. The bearing and ball are carried on shaft so that the axis is at an angle to that of the shaft. Rotation of the latter causes the ball to precess. Cylindrical racks have circumferential teeth along their length (equivalent to a screw thread with a zero helix angle) which mesh with the ridges and grooves on the spherical ball surface. The racks may slide on rods, or may commonly form part of a larger component such as an hydraulic piston which itself moves bodily. As shaft rotates, the meshing ridges and teeth cause linear motion of the racks, or vice versa. At any time, the ball and racks may rotate about their respective axes, moving the meshing contact point to different parts of the same teeth and distributing the wear evenly.