Gear pumps are generally used in the work environment is not clean construction machinery and precision of the general machine tools, and the pressure is not too high and the flow of hydraulic systems. Gear pump advantages: 1) simple structure, better technology, lower cost. 2) compared with other types of pumps of the same flow, compact structure, small size. 3) Self-priming performance is good. Self-priming is reliably achieved at high and low speeds even under manual conditions. 4) speed range. Due to the pump drive parts and gears are basically balanced, at high speeds will not produce greater inertia. 5) The dirt in the oil has a bad influence on the work and is not easy to kill. Gear pump shortcomings: 1) lower working pressure. Gear pump gears, shafts and bearings on the pressure imbalance, radial load, limiting its pressure increase. Gear pump is mainly used in low pressure system. 2) lower volumetric efficiency. This is due to the large leakage of gear pump end face. 3) large flow pulsation, causing pressure pulsations, so that pipes, valves and other vibration, noise. Gear pump common cause of failure and troubleshooting methods do not hit the oil or insufficient oil pressure and mention the pressure is not high 1. Motor steering error 2. Suction pipe or filter clogged 3. Axial or radial clearance is too large 4. Leakage of all connections caused by air mixed 5. Oil viscosity is too high or oil temperature rise too high Correct the motor steering 2. Dredge the pipeline, clean the filter to remove the blockage, replace the new oil 3. Repair replacement parts 4. Tighten the screws on the joints to prevent leakage and prevent air from mixing in 5. Oil should be selected according to temperature changes