US Patent 8157682 Tensioner

A tensioner comprising a base having a shaft, a pivot arm engaged with the shaft, a pulley journalled to the pivot arm, an arcuate damping member frictionally engaged with a pivot arm inner surface, a torsion spring having a first end engaged with the pivot arm, the torsion spring having a second end bearing upon the damping member so that upon loading of the torsion spring in the unwinding direction the damping member is compressed between the second end of the torsion spring and the base thereby causing a normal force to be imparted upon the pivot arm by said damping member.