
In a hydraulic tensioner, a deairing valve unit, for releasing air mixed with oil in the high pressure oil chamber of the tensioner, comprises a check ball, a retainer, which envelops the check ball, but allows the check ball to move freely between an inflow end and an outflow end of a retainer passage, and a cylindrical ball seat press-fit into to a recess formed in a front end of the retainer. The deairing valve unit communicates with an exhaust vent formed in the front end of the plunger. A b...











