NCB-type internal gear pump gear is the use of gear meshing principle, the internal and external gear pitch circle close to one side, the other side is covered by the pump "crescent" separated because of the high viscosity medium can be widely used in all walks of life, but In the actual travel there will be problems. The following analysis of these problems and solutions to make the following: NCB internal gear pump may occur failures and causes: First, the flow is small (lack of suction) reasons: 1, the suction pipe air leaks; 2, the suction pipe is not immersed Liquid; 3, the suction port diameter is small; 4, the end gap is too large; 5, the pump shaft speed is slow; 6, e filter obstruction 7, the pump has worn Second, the flow instability reasons: There is air leakage or lack of liquid; 2, the liquid vaporization Third, the pump noise causes: 1, the current is too large; 2, liquid viscosity; 3, the speed is too high; 4, the outlet pressure is higher than the rated value; Insufficient; 6, packing gland pressed too tight 7, the unit loose.