YCB series circular arc gear oil pump is applied to handle non-corrosive, non-solid particles and fiber-free lubricating oil or liquids with similar properties to lubricating oil. The machine adopts a double arc sine curve tooth shape, whose outstanding advantage is that there is no relative sliding of the tooth profile surface during gear meshing compared with involute gears. It gets rid of the traditional design, making the gear pump enter a new field in design, production and use. This machinei s characterized by smooth operation, no trapped liquid phenomenon, low noise, long life, high efficiency, etc.