A 3-V kinematic coupling with adjustable vee angles, ranging from 25° to 80° inclination from the base plane, was designed and built to test the limiting coefficient of friction (CoF), which is a measure of the coupling's ability to reach center where all six constraints are engaged. For instance, the vee angles may be optimized by maximizing the limiting CoF to give more margin over the real CoF between contacting surfaces. Although, if the real CoF is too high, that is, higher than the limiting case, the coupling may fail to reach a stable center position. For this experiment, the coupling was configured over a wide-ranging combination of vee angles and several loading conditions for four different surface conditions. The changes in configuration and/or loading condition were made in a logical manner to map out the boundary of incipient sliding between sliding and non-sliding outcomes for a given surface condition. Three of four surface conditions were very clean, either bare 440C stainless steel, thin dense chromium plating, or the same with a proprietary polymer lubricant. The CoF for clean surfaces was too high at about 0.4–0.6 for the coupling to center except for the most favorable sliding direction for which the coupling was being tested. The fourth surface condition was lubricated with vacuum grease and wiped with a clean-room cloth. This lowered the CoF to a point <0.2 where only the least favorable sliding direction could be made non-sliding. An equilibrium equation was developed for this coupling including all the variable parameters under test. Solving it for the limiting CoF for each test configuration successfully resolved the outcomes over the wide-ranging parameter space. This work supports the method used to calculate the limiting CoF and the underlying assumptions that friction forces are directed opposite to local sliding directions and proportional to the contact normal forces.

设计并制造了具有可调V形角度（从底面倾斜25°至80°）的3-V运动型联轴器，以测试极限摩擦系数（CoF），这是衡量联轴器到达中心的能力的度量所有六个约束条件都参与其中。例如，可以通过最大化限制CoF来优化V形角，以在接触表面之间的实际CoF上提供更多的余量。尽管如果实际CoF太高（即高于限制情况），则联轴器可能无法达到稳定的中心位置。对于本实验，在四种不同的表面条件下，将联接器配置在大范围的V形角度和几种载荷条件的组合上。构造和/或加载条件的更改以逻辑方式进行，以绘制出给定表面条件下滑动和非滑动结果之间的初始滑动边界。四个表面条件中的三个非常干净，可以使用裸露的440C不锈钢，薄的致密铬镀层，也可以使用专有的聚合物润滑剂。清洁表面的CoF太高，无法达到中心的联轴器，只有0.4-0.6左右，除了要测试联轴器的最佳滑动方向。第四个表面条件是用真空油脂润滑，并用无尘布擦拭。这将CoF降低到<0.2，仅使最不利的滑动方向变为非滑动。为此耦合开发了一个平衡方程，包括所有待测变量。通过针对每种测试配置的限制CoF求解，可以成功解决广泛参数空间中的结果。这项工作支持用于计算极限CoF的方法，并支持以下假设：摩擦力与局部滑动方向相反，并且与接触法向力成正比。