Patent ID: 8267821

Claim:
A mechanical tensioner for a tension element drive of an internal combustion engine, comprising: a pulley arm with a tension pulley adapted to contact the tension element drive at a distal end and a mounting bore at a proximal end; a mounting base that is adapted to be fixedly attached to the engine; an outer hub fixed to the mounting base that extends along a pivot axis having a flange, the pulley arm is pivotably mounted to the mounting base about the pivot axis, and the flange is located on a side of the pulley arm away from the mounting base to retain the pulley arm; a spring that functions in compression and torsion located about the pivot axis on the mounting base, with one end connected to the pulley arm and the other end attached to the mounting base, the spring provides torsion between the pulley arm and the mounting base to maintain tension on the tension element, and is compressed between the pulley arm and a surface of the mounting base to transmit an axial force between the pulley arm and the outer hub; and a shaped bush which functions at least as a damping element is located in a space between the outer hub and the pulley arm, an outer surface of the outer hub, the bush and at least a portion of the bore in the pulley arm have a tractrix pseudosphere shape to provide increased life and reduced wear.