Autotensioner

An autotensioner comprising a fixed shaft, a pulley support supported on said fixed shaft so as to be pivotable around said fixed shaft, a pulley supported on said pulley support, a tension imparting means for pivoting said pulley support in such a direction as to impart tension to a belt, one of said pulley support and said fixed shaft having a cylindrical portion arranged coaxially with the other, the other being formed with cam surfaces at such a position that wedge-shaped spaces are defined between said cam surfaces and said cylindrical portion, said wedge-shaped spaces being narrower in a direction in which said pulley support pivots to slacken the belt, friction members each mounted in said respective wedge-shaped spaces and having a shape substantially complementary to the shape of said wedge-shaped spaces, and spring members each mounted in said respective wedge-shaped spaces for biasing said friction members into the narrower area of said each wedge-shaped space.