2nd ICAI 2022

International Conference on Automotive Industry 2022

Mladá Boleslav, Czech Republic

The degree of influence of the contact pattern is clearly visible from the figure between the 0° and 90° sleeve positions. The difference between the 90°, 180° and 270° sleeve angular positions is not significant. Exactly what caused this phenomenon (whether deviations in the spacing of the synchronous gearing, clearance between the sliding sleeve and the synchromesh body, misalignment of the synchromesh body on the shaft, or something else) is the subject of further research. 3.4 Effect of rolling elements (needles) of the needle bearing Another factor that could affect the size, position and shape of the contact pattern is the needle bearings on which the change gears are usually mounted (Figure 14). Needle diameter tolerances, along with shaft and change gear diameter tolerances, together form a chain that determines the amount of radial clearance. In fact, the length of the needle is a factor that will also affect the potential amount of change gear slope. Its length is always less than the length of the bearing cage, which is considered as the design width of the needle bearing. However, the functional length is smaller and it is the length of the needle. The shape of the edge, or the size of the radius of the needle end, is also an important factor for change gear slope.

Figure 14: Schematic representation of the effect of the needle on change gear slope

Source: Škoda Auto, a.s., internal materials The exact extent of the influence of the shape, length, orientation, and number of needles on the contact ratios in the gearing is currently not fully mapped and will be subject to further verification. However, it is already apparent that the internal design of the needle bearing affects the contact pattern. As the number of needles in a bearing of the same geometric dimensions increases, the bearing bandwidth increases (Figure 15). And as the length of the needles in the bearing increases, while maintaining the number of needles, the bearing band also increases (Figure 16).

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