Timing belt tensioner with a backstop device with controlled one-way mechanism

A tensioner for an endless belt comprising

• a stationary structure,
• a pivotal structure mounted on said stationary structure for pivotal movement in forward and return directions about a pivotal axis,
• pulley rotatably carried by the pivotal structure for rotational movement about a rotational axis that is parallel to the pivotal axis,
• a spring acting between said stationary and pivotal structures to bias the pivotal structure to pivot in the forward direction, thereby causing movement of the pulley into belt-tensioning relation to a belt with which the pulley is rollingly engaged,
• a one-way device including a backstop disposed on a movable structure movable relative to both said stationary structure and said pivotal structure, said one-way device preventing movement of said movable structure relative to said stationary structure in a first direction corresponding to the return direction of said pivotal structure to thereby enable said backstop to limit movement of said pivotal structure in the return direction, said one-way device being constructed and arranged such that, responsive to said pivotal structure moving in said forward direction, said movable structure moves in a second direction corresponding to said forward direction of said pivotal structure so as to progressively move said backstop in said forward direction relative to said stationery structure in accordance with the movement of said pivotal structure, and
• a damper operatively connected to said one-way device, said damper being constructed and arranged to restrict movement of said movable structure in said second direction caused by sudden, short-time vibratory movements or dynamic vibrations in cold conditions.