1) Try to make the radial pressure force uniform and consistent with the leakage pressure law, so that the bearing surface of the bushing is pressed evenly, so that the bushing wear is small and uniform.2) Make the packing in the packing sealing structure have compensating capacity, enough lubricity and elasticity.3) The axial tightness of the sealed packing must be evenly distributed. In view of the above analysis, the new packing seal structure should be a packing seal structure that can automatically change the sealing force according to the change in pressure of the sealing medium. The structure of the modified packing seal is shown in the figure