Patent ID: 6878082

Claim:
A hydraulic tensioner for applying tension to a chain comprising: a housing having a bore open at one end; a hollow plunger with an outer circumference slidably received in the bore of the housing, having an inner space defining a fluid chamber with the bore and an axially extending groove formed as part of the outer circumference of the plunger; a first biasing member biasing the plunger in a protruding direction; a rack member formed with rack teeth, slidably supported in the axially extending groove, such that the rack member has a longitudinal length less than an axial length of the groove; and a ratchet member, sliding in a ratchet holes, having an axis extending in an inclined direction and intersecting an axis of the plunger, the ratchet member having a cylindrical head portion with an outer circumferential edge portion at its distal end, such that the outer circumferential edge portion of the cylindrical head portion engages the rack teeth, the engagement of the outer circumferential edge portion of the ratchet member with the rack teeth permitting travel of the plunger in a protruding direction but blocking retraction of the plunger in a backward direction; a second biasing member biasing the ratchet member in an engaging direction of the rack teeth with the distal end of the cylindrical head portion.