The groove includes a macro groove (151) and at least one micro groove (152) located within the macro groove.

The inner groove is formed in the outer groove.

A groove is defined in the shaft cam, the groove comprising a groove upper surface.

Intersecting the concentric groove is a longitudinal groove (50).

The outer annular groove (22) and the inner annular groove (23) are in communication via the diversion groove (21).

The rolling groove opening of one latter rolling groove faces the rolling groove bottom of one preceding rolling groove.

The transitional groove (5) can be an annular groove.

The clamping groove (103) is buckled in the sunk groove (407).

The transitional groove (5) can be an annular groove.

In each steep groove (7) is formed a tilt groove bottom (8) where the groove depth gradually increases from the center main groove (3) toward a first side-main-groove (5).

The guide groove comprises at least a first administration groove, and a second administration groove continuously provided from the first administration groove.

The clip (119) is disposed in the lower groove and the housing groove (129) in the first stage; and in the upper groove and the housing groove in the second stage.

Also, that end (11b) of the fine groove (11) which is on the groove bottom side does not open in a groove bottom (1b) of the main groove (1), and the end (11b) is located closest to the groove bottom.

The vent step groove (53a) is connected to the communication groove (45).

The outer annular groove (22) is in communication with the inner annular groove (23) via the flow diversion groove (21).