Abstract: A new type of gear pump for high viscous liquids was designed by introducing the principle of harmonic gear drive into gear pump. The structure and mechanism of radial force balance in the new gear pump were analyzed. It showed that the radial force for the new pump was balanced because the force would not increase with increasing pump pressure. Two higher pressure chambers could discharge flow two times in a period of one revolution, which increased the pumping efficiency and stability in pressure.

Key words: radial force, high viscosity, harmonic style gear pump