4 and the brake plate 5 and effectively lock thereby transferring the frictional forces to the tensioner arm 1 adjusting the rate of taper of the bearing raceway 22 and the mating bearing raceway 23 thus effectively adjusts the rate of application of asymmetric frictional damping applied to the tensioner 21 during wind up the bearing raceway 22 and mating bearing raceway 23 shown in fig2 a in the first embodiment has a relatively shallower slope meaning the rate of change of the position of the bearing 3 changes more slowly than in the case of a shorter arc length bearing raceway 22 and mating bearing raceway 23 shown in the second embodiment in fig2 b the shorter arc length of the second embodiment shown in fig2 b means that for a given displacement of the tensioner arm 1 away from the belt being tensioned the rotating bearing plate 2 and brake bearing plate 4 will separate further than the first embodiment shown in fig2 a the resulting increase in separation increases the frictional damping applied to the tensioner 21 to prevent wind up the total number of bearings 3 and bearing raceways 22 and mating bearing raceways 23 collectively raceways are determined by the length of the raceways the taper of the raceways the size of the bearings 3 the number of bearings 3 is also dictated by the need for the bearing 3 elements to adequately support and separate the rotating bearing plate 2 and the brake bearing plate 4 the smallest number of bearing 3 elements for the design is three and.