Meshing spur gears must have the same diametral pitch.

互相啮合的直齿圆柱齿轮，必须具有相同的径节。

Universal gearbox allows inch, metric, diametral, and module pitch threads without changing gears.

通用变速箱允许英寸，公制，直径，螺距螺纹和模块不改变齿轮。