求翻译：In the present article, the authors are concerned with the ball joint and show the influence of geometry and friction on the secondary moment generated for a non-zero bending angle. Indeed, the main (undesirable) consequence of the torque transmission between two axes is the presence of the secondary moment. With respect to the joint plane containing the input and output shafts, this moment has two components: a component in the joint plane and a component orthogonal to this plane. The latter component having a weak amplitude is cyclic with a six-fold behaviour and identified as the origin of a possible acoustic beat with the F2 engine vibration for an aligned four-stroke four-cylinder engine. This may be the case for a gearbox ratio close to 3.是什么意思？

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