四、特性曲线在内啮合齿轮副的界限线图上,除了界限线外,还列入下列特性曲线: (ⅰ)ε=1.2的线; (ⅱ)两齿轮齿顶厚S_a=0.25m的线; (ⅲ)两齿轮齿根的滑动系数最大值相等的线η′=η″,滑动系数相等而绝对值最小(针对给定的变位系数差x_d=x_2-x_1)的条件式为 Fourth, the characteristic curve In the internal gear mesh limit line graph, in addition to the limit line, but also included the following characteristic curve: (i) ε = 1.2 line; (ii) two gear tooth thickness S_a = 0.25m line ; (Iii) Line η ’= η "where the maximum sliding coefficient of the two gear roots is equal, and the condition that the sliding coefficients are equal but the absolute value is minimum (for a given displacement coefficient difference x_d = x_2-x_1) is