All SY10 SY11 SY21 SY22 tandem internal gear pumps integrate two pump cores of different displacements in series. All adopt involute straight tooth structure and quenched alloy grinding tooth surface, equipped with built-in automatic axial and radial dual clearance compensation. Independent oil supply for high and low pressure circuits with flexible flow matching delivers low pulsation and quiet operation. Four series cover full working conditions including standard, medium large flow, high pressure heavy duty and ultra high pressure high flow. Widely applied in injection molding equipment, CNC machine tools and multi-circuit hydraulic stations. The compact integrated design saves installation space and reduces overall supporting cost.