For a rolling contact one osculation and a state operation is desirable, in which the drilling torque is in proportion to the extent transferable force a minimum. This is achieved when the distance between torque pole with is as small as possible. This state is reached at a ratio value of | / ab / ln = 0.853 at the Schmiegungswert cos f> = 0.14 and the Drehpolabstand ll \ ab = 0.75. For the rectangular and square surfaces Wernitz Hertz has developed on the basis of calculations by Thomas [8] a similar diagram (see Figure).