Hydraulic tensioner with a molded valve base and cap

摘要

A hydraulic tensioner having a plunger slidably fitted in a mounting cavity in a housing and biased in a protruding direction by a spring and fluid. A variable orifice check valve permits fluid to only flow into, and thereby protrude the plunger, but not out of the mounting cavity is disclosed. The variable orifice check valve is accomplished with a cylindrical compression spring in which the spring coils are normally mutually contacting and which has a top spring cap molded directly to an end of the spring and a bottom spring retainer molded directly to the opposite end of the spring. Such a construction reliably secures the top spring cap and bottom spring retainer to the spring. A mechanical no-return capability is provided to the plunger through an internal ratchet positioned within the mounting cavity and constructed from a cylinder having two helical openings which the plunger engages when the plunger experiences sufficient force to be pushed inwardly.