Abstract: A driving shaft (3) includes an inner tube (1) and an outer tube (2) having a modified cross-section. These tubes (1, 2) are axially movable but not rotatable relative to each other for transmitting torque therebetween. The driving shaft (3) comprises a partition unit having a pair of partition walls (8a, 8b; 16) hermetically sealing at least part of the inside of the inner tube to define a grease reserving space (8A) in the inner tube on the side of its distal end. The partition wall (8a, 16) on the side of its proximal end is provided with a hose mounting portion (8c; 23) having an oil hole (9). The driving shaft (3) further comprises an oiling port unit (10; 20) provided on a fitting yoke (7) on the side of the proximal end of the inner tube and an oiling conduit unit (11; 24, 25) for connecting the oiling port unit (10; 20) and the hose mounting portion (8c; 23) of the partition unit.

Abstract: A coupling device in which a shaft or pipe is coupled to a boss member in which balls, disposed in radial holes in the boss, engage a groove on the shaft or pipe. A set ring slidable on the boss selectively forces engagement of the balls with the groove. The set ring is biased in both direction toward the apertures. The bias can be provided by one or two spring rings engaging two oppositely inclined surfaces on either the boss or the set ring or by a coil spring set between two spring supports that are each moved by both the boss and the set ring.

Abstract: A removable coupling device comprising a boss member with a central axial hole and radial holes opening into the axial holes containing locking balls which engage with a circumferential set groove of a shaft inserted into the axial hole. The boss member has inclined surfaces sloping radially inwardly and away from the apertures. An axially movable set ring selectively forces the balls, into the holes and has a spring ring engaged with a groove of the set ring and radially inwardly presses the inclined surface so that the set ring automatically returns to the position in which the balls lock the shaft.