Tensioner for a chain or belt

摘要

A chain or belt tensioner comprises a plunger displaceable in a housing between retracted and extended positions. A stop ring between the plunger and housing frictionally contacts a smooth surface of the housing. A recess in the plunger has a tapered face for engagement with a bevelled surface of the stop ring. Inward movement of the plunger causes the tapered face to engage the stop ring and to force it to deform outwardly to a wedging position in which the stop ring is wedged between the tapered face and the surface thus preventing further inward movement of the plunger. The recess has a second face that engages the stop ring when the plunger moves out of the housing so as to slide it over the surface. The invention provides for a stop mechanism that enables retraction of the plunger to be prevented at an infinite number of positions.