This text analyzes the source producing the error of the radial load force of calibration test for the fatigue testing machine, introduces the evaluation method of the uncertain degree of the test result, calculates out the total uncertain degree of the radial load force.

It has been shown that incremental method is accurate solution for radial loading.

This reduction of the bearing center distance will lead to create additional radial pressures between teeth of meshing gears, thus make the gearing operate under the condition for both profile surfaces of the tooth to engage.

The principle of loading axially on rotating assembly using hollow hydraulic cylinder, as well as the structure and design of hollow hydraulic cylinder are introduced.