Abstract: Based on the distribution features of a gear pump’s flow field， the asymmetric pressure distribution in the master-slave gear cavity was analyzed. Taking a certain type high-pressure gear pump as the research object， the relationship between the radial clearance and the deflection of gear shaft was analyzed. The nonlinear differential equation of pressure in the transition zone was established. Comparing the corresponding position pressures of both master and slave gear side cavities， it could be concluded that the pressure distribution of a gear pump’s master-slave gear cavity is asymmetric. The experimental data showed that the corresponding point pressure value between the experimental and theoretical error is less than 5.0%. The master and slave pressure difference is 4.17MPa in the transition zone， and the pressure difference is 1.55MPa at the end of high-pressure groove under the rated conditions. This study provides a theoretical basis on the asymmetric analysis of pressure distribution in the high-pressure gear pump’s gear cavity and on the calculation of floating end plates’ overturning torque.

Key words: gear pump, gear shaft, asymmetry, end plate, overturning torque