Results show that there can be four situations for meshing boundary line on the tooth surface of wheel, namely, inexistence of boundary line, a unique line, two lines and two coincident lines.

• 分析表明；蜗轮齿面上啮合界限线的分布情况有4种:不存在啮合界限线；有一条啮合界限线；有两条啮合界限线；以及两条啮合界限线完全重合.