Hydraulic auto-tensioner

A hydraulic auto-tensioner comprising a cylinder containing hydraulic oil, a rod inserted in the cylinder, a return spring biasing the rod and the cylinder in a direction in which the rod protrudes from the cylinder, a hydraulic damper mechanism mounted in the cylinder and configured to dampen a pushing force that tends to axially push the rod into the cylinder against the force of the return spring, and first and second coupling piece assemblies,

• wherein the first coupling piece assembly includes a coupling piece mounted to a closed bottom end of the cylinder and the second coupling piece assembly includes a coupling piece mounted on a top end portion of the rod which protrudes from the cylinder, each of the coupling pieces being formed with a mounting hole and having first and second axial end surfaces,
• wherein each of the first and second coupling piece assemblies further comprises a support ring inserted in the mounting hole, and a bush inserted in the support ring, wherein one and the other of a radially outer surface of the support ring and a radially inner surface of the mounting hole are a curved surface and cylindrical surface, respectively, whereby the support ring is alignable, wherein the support ring has a first radially outwardly extending flange at a first end portion of the support ring and the bush has a second radially outwardly extending flange at a second end portion of the bush which is axially opposite to the first end of the support ring such that first and second axial gaps are defined between the first radially outwardly extending flange and the first axial end surface of the coupling piece and between the second radially extending flange and the second axial end surface of the coupling piece, respectively, and
• wherein each of the first and second coupling piece assemblies further includes a coupling arrangement configured to engage both the support ring and the bush when the bush is inserted into the support ring, thereby preventing axial separation of the support ring and the bush from each other.