BS ISO 5287:2021 pdf – Belt drives — V-belts for the automotive industry — Fatigue test.
1 Scope This document specifies a fatigue test for the quality control of V-belts (sections AV 10, AV 10X, AV 13, AV 13X, AV 17 and AV 17X) intended for driving the auxiliaries of internal combustion engines used for automotive purposes. NOTE The dimensional characteristics of these belts and of the corresponding pulleys are the subject of ISO 2790. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 683-1, Heat-treatable steels, alloy steels and free-cutting steels — Part 1: Non-alloy steels for quenching and tempering ISO 2790, Belt drives — V-belts for the automotive industry and corresponding pulleys — Dimensions ISO 4287, Geometrical Product Specifications (GPS) — Surface texture: Profile method — Terms, definitions and surface texture parameters ISO 6508-1, Metallic materials — Rockwell hardness test — Part 1: Test method 3? Terms? and? definitions No terms and definitions are listed in this document. ISO and IEC maintain terminological databases for use in standardization at the following addresses: — ISO Online browsing platform: available at https://www.iso.org/obp — IEC Electropedia: available at https://www.electropedia.org/
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.
8.2 Procedure 8.2.1 Preparation 22.214.171.124 Three-pulley test machine After mounting the belt on the pulleys, apply the specified belt tensioning force (see 8.1) to the idler pulley while the idler pulley support bracket is moved in its slide, bring the drive up to the specified rotational frequency (see 8.1). Then apply the relevant load to the driven pulley as quickly as possible. Run the drive under these conditions for 5 min ± 15 s, not including the starting and stopping time. Stop the machine and leave it to stand for at least 10 min. Then turn the drive manually for several revolutions of the belt and, by means of a dial indicator mounted in contact with the idler pulley support bracket, note the maximum limits of travel of the idler pulley. Immediately lock the idler pulley support bracket in the position midway between the two limits of travel. 126.96.36.199 Two-pulley test machine Use the same procedure as in 188.8.131.52 with the movable unit taking the place of the idler pulley support. 8.2.2 Test Restart the machine, bring the drive up to the specified rotational frequency, apply the test load to the driven pulley and measure the slip between the driving and driven pulleys. The drive shall run continuously under these conditions until either the belt fails or the additional slip, g, exceeds the slip measured initially, by 4 %.