During traditional helical gears of parallel axle with external engagement engage, the direction of rotation is converse.

传统的平行轴外啮合斜齿轮在啮合传动过程中，两齿轮的转动方向是相反的。

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According to the relative position of sub-gear axis parallel shaft spur gear drive, bevel gear drive shaft and intersecting cross-axis helical gears.

按齿轮轴线的相对位置分平行轴圆柱齿轮传动、相交轴圆锥齿轮传动和交错轴螺旋齿轮传动。

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