Patent ID: 6863631

Claim:
A tensioner for a power transmission belt that operates on an endless path and that utilizes asymmetric motion control, the tensioner comprising: an arm comprising a belt engaging section and a drum section; a support member for securing the tensioner relative to the belt, the arm pivoting about the support member; a spring that urges the arm to pivot about the support member in a first direction and urges the belt engaging section against the belt with a force to tension the belt, wherein the spring is a flat, spiral wound spring and wherein the support member comprises a housing for the spring; a stator inside the drum section of the arm forming arcuate spaces, the arcuate spaces being circumferentially spaced around the stator between the stator and the drum section; and arcuate shaped wedges located in the arcuate spaces, wherein the spring resists the tension force of the belt via the belt engaging section with a first force during a first operating state, and the spring and the wedges resist the tension force of the belt with a second force that is greater than the first force during a second operating state.