如图所示的一种活动顶尖结构,在生产中使用时发现有较高精度,达到了设计的预定要求——径向跳动在6微米以内。此结构采用了两个相当于Ⅱ级的向心球轴承10、12,并使它们的位置尽可能远离;另外又用了两个锁紧螺母9和大螺帽2来消除所有三个轴承的间隙, A top-of-the-range structure, as shown, is found to have higher accuracy when used in production and meets the design requirements of the design - a radial runout of less than 6 microns. This configuration uses two radial ball bearings 10, 12 corresponding to class II, with their position as far as possible; in addition two locknuts 9 and a large nut 2 are used to eliminate all three bearings gap,