旧齿标“JB179—60”中周节差△t 的定义是:“齿轮同一圆周上,任意两个周节之差”。作为误差评定,应以最大周节误差作为结论。在新齿标“JB179—83”中,原周节差△t 是以周节偏差△f_(pt),替代的,即:“在分度圆上实际周节与公称周节之差”。显然,△f_(pt)。与△f 在概念上是有区别的。△_t 实际上是一公差值(绝对值),而△f_(pt)是 The old tooth standard “JB179-60” in the week section difference △ t is defined as: “Gear on the same circumference, any two weeks difference.” As the error assessment, should be the maximum error of the week as a conclusion. In the new gear “JB179-83”, the difference Δt p in the original pitch is replaced by Δf pt, ie, “the difference between the actual pitch and the nominal pitch on the indexing circle”. Obviously, △ f_ (pt). And △ f conceptually there is a difference. △ _t is actually a tolerance value (absolute value), and △ f_ (pt) is