Abstract: A universal joint comparable in construction to a ball and socket joint in that it comprises a ball member (14) attached to a first shaft (10) and a socket member (16) attached to a second shaft (18), wherein the ball member (14) and the socket member (16) are both equipped with slots (A.sub.b, B.sub.b ; A.sub.s B.sub.s) at their adjoining slotted surfaces and are disposed so that the slots at least partially overlap to form pin passageways. A pin (22a, 24a) is disposed in each pin passageway to transfer rotational motion without variation from one shaft to the other. In preferred embodiments, the ball member and the socket member each have three slots (A.sub.b, B.sub.b, C.sub.b ; A.sub.s, B.sub.s, C.sub.s). In some embodiments, the ball member may be hollow and the pins may be interconnected within the ball member to form a pin mechanism 42. In other embodiments, the ball member may be solid, and there may be a girdle member 26 surrounding the socket member, into which the pins extend.

Abstract: A dual piston rotary pump (10) having a housing (12) equipped with two ports (13a, 13b) to accommodate fluid flow through the housing (12) and having two generally cylindrical chambers (14a, 14b) within which cylindrical pistons (16a, 16b) are disposed. The chambers (14a, 14b) intersect to form a passage (15) therebetween and to allow the pistons (16a, 16b) to engage in tangential contact. Each piston (16a, 16b) rotates within its chamber (14a, 14b) in a direction counter to the direction of the other piston while maintaining tangential contact with the other piston and at least one piston is in tangential contact with its chamber wall. The pump includes variable offset transmission means (52a, 50a, 48a, 54a) to change the offset of the center of the piston from the center of rotation of the piston during the course of each rotation to allow the pistons (16a, 16b) to remain in mutual tangential contact at all times.