BS ISO 5287:2021 pdf download.Belt drives — V-belts for the automotive industry — Fatigue test.
6.1.4 Device, through which tension can be applied to the belt: a) in the case of the three-pulley test machine layout, an idler pulley (see Figure 1); b) in the case of the two-pulley test machine layout, a movable pulley (see Figure 2).
6.1.5 Means of determining belt slip, to an accuracy of ± 1 %. The layout of the pulleys and the direction of rotation shall be as shown in Figures 1 and 2. In order to accommodate different lengths of belt, the position of the driving and driven elements, and the position of the idler pulley and its support bracket in the case of the three-pulley test machine, shall be adjustable so that the test layout of the pulleys is attainable for each belt length. So that tension can be satisfactorily applied to the belt, and in order to allow for belt stretch, the idler pulley of the three-pulley test machine and its bearing assembly shall be free to slide, as and when necessary, in its support bracket along the line of application of the tensioning force. In such a case, the line of action of the tensioning force shall bisect the belt layout angle at the idler pulley, shall pass through the axis centre of the idler pulley, and shall lie in the plane through the centre of the groove of the idler pulley (see Figure 1). The two-pulley test machine shall be constructed so that one of the units (driven or driving) can be moved to accommodate belt lengths up to 800 mm (see Figure 2). A method of locking the movable unit in position, with a given tension in the V-belt, shall be provided.
6.2 Test pulleys Test pulleys, which shall comply with the following requirements: be made of steel as defined in ISO 683-1, with a surface hardness of 55 HRC, in accordance with ISO 6508-1, and the pulley groove with a surface roughness such that the arithmetical mean deviation of the evaluated profile, R a , defined by ISO 4287 is lower than 0,8 μm. The characteristics of the test pulleys are given in Figure 3 and Table 1.BS ISO 5287 pdf download.