Abstract: A rotary/linear convertor which comprises a first member may be in the form of a piston (14, 15, 16, 17, 114, 115, 116, 117) and a guide which is preferably in the form of a cylinder (12, 112) the first member being arranged for linear movement within or along the guide and a second member (23, 24, 137) which is adapted for rotational movement. The convertor further includes connecting means operatively connecting the first and second members so that the respective linear or rotational movement of one member causes the respective linear or rotational movement of the other member.

Abstract: A piston-rack rotary actuator having four pistons each with an integral rack and each displaceable along a cylinder unique thereto, the racks meshing with a center gear at equiangularly spaced points and causing angular movements of a shaft about its rotational axis when said pistons are displaced along their respective cylinders, said gear being secured to said shaft. The racks are formed in respective webs which are supported by the actuator body in such a manner as to prevent piston-slewing which would otherwise occur due to the separating force generated by the meshing gear and racks when said racks are moved relatively to the gear.