Abstract: A constant velocity universal joint has an outer joint member having eight curved track grooves axially extending along an inner circumferential surface, an inner joint member having eight curved track grooves axially extending along an outer circumferential surface, eight balls respectively arranged in eight ball tracks provided as pairs of the track grooves of the outer and inner joint members. The center of each track groove of the outer joint member is axially displaced a predetermined distance from the spherical center of the inner circumferential surface. The center of each track groove of the inner joint member is axially displaced the same distance from the spherical center of the outer circumferential surface in the direction opposite to that of the outer joint member. A PCD gap in the ball track is in the range of 5 ?m to 50 ?m.

Abstract: A novel constant velocity universal joint with eight ball is provided for realizing the improved durability of the joint under high-loaded conditions and the suppressed variations of lifetimes of the joints. The universal joint has an outer joint member having eight curved track grooves axially extending along an inner circumferential surface with a spherical shape, an inner joint member having eight curved track grooves axially extending along an outer circumferential surface with a spherical shape, eight balls respectively arranged in eight ball tracks provided as pairs of the track grooves of the outer joint member and the track grooves of the inner joint member, and a cage having pockets for respectively holding the balls. The center of each track groove of the outer joint member is axially displaced a predetermined distance from the spherical center of the inner circumferential surface.

Abstract: A novel constant velocity universal joint with eight ball is provided for realizing the improved durability of the joint under high-loaded conditions and the suppressed variations of lifetimes of the joints. The universal joint has an outer joint member having eight curved track grooves axially extending along an inner circumferential surface with a spherical shape, an inner joint member having eight curved track grooves axially extending along an outer circumferential surface with a spherical shape, eight balls respectively arranged in eight ball tracks provided as pairs of the track grooves of the outer joint member and the track grooves of the inner joint member, and a cage having pockets for respectively holding the balls. The center of each track groove of the outer joint member is axially displaced a predetermined distance from the spherical center of the inner circumferential surface.

Abstract: A precision machining system for machining a workpiece into a desired surface with two tool driving units. A first drive unit moves the tool along at least two axes to shape the workpiece similar to a desired surface. A second drive unit moves the tool along one of the axes in a very finely controlled manner. A measuring unit measures the tool position with an accuracy higher than that to which the first drive unit can respond. A signal producing unit is responsive to the measuring unit for producing a control signal for controlling the operation of the second drive unit while the first drive unit is operating.