Shaft torsional rigidity is checking calculation of shaft torsional deformation at work, is to use per metre shaft torsional Angle measurement. Shaft torsional deformation will affect the performance of the machine and working accuracy, such as internal combustion engine camshaft torsion Angle is too big, can affect the correct valve opening and closing time. Gantry crane motion mechanism of the shaft torsional Angle will affect the synchronicity of driving wheels, Danger to occur torsional vibration of shaft and the control system of the shaft, needs to have larger torsional rigidity.