The hydraulic system efficiency of a construction machine depends mainly on the volumetric efficiency of the hydraulic pump. When the volumetric efficiency drops to 72%, routine maintenance, replacement of bearings and aged seals are required. Replacement or repair of the friction pair beyond the mating clearance is required Its performance has been restored. In this paper, direct-axis swash plate piston pump-based, describes its use. 1. Hydraulic pump oil supply form Direct-axis swash plate piston pump is divided into two types of self-suction type oil pressure type. Most of the pressure supply type hydraulic pump with air pressure tank, there are hydraulic pump itself with a charge pump to the hydraulic pump inlet to provide pressure oil. Self-priming oil pump self-priming oil capacity, no external oil supply. By hydraulic pressure oil tank, each time you start the machine, you must wait for the hydraulic pressure box to reach the use of air pressure before operating machinery. If the pressure of the hydraulic tank is low, it will cause the pull-off phenomenon in the hydraulic pump and the slippery whip, which will cause abnormal wear of the return plate and the pressure plate in the pump body. The use of charge pump piston pump, use 3000h, the operator needs to check the plunger pump 1-2 times a day to check the hydraulic pump running sound is normal. If you find the hydraulic cylinder speed or boring car, you should disassemble the charge pump check, check the edge of the impeller scratches, internal gear pump clearance is too large. For self-priming piston pumps, the fluid in the hydraulic tank should not be lower than the lower limit of the oil standard, and a sufficient amount of hydraulic oil should be maintained. The higher the cleanliness of the hydraulic fluid, the longer the life of the hydraulic pump. 2. The most important component of the hydraulic pump piston pump bearing is the bearing, if the bearing appears clearance, you can not guarantee the hydraulic pump within the three pairs of normal friction pair, but also will destroy the hydrostatic friction of the friction oil film thickness, Decrease the life of plunger pump bearings. According to information provided by the hydraulic pump manufacturer, bearing the average service life of 10000h, more than this value will need to replace the new port. Demolition of the bearings, there is no professional testing equipment can not detect the bearing clearance, only visual inspection, such as the roller surface scratches or discoloration, it must be replaced. In the replacement of bearings, bearings should pay attention to the original letters and models, most of the piston pump bearing load capacity of large bearings, it is best to buy the original manufacturer, the original specifications of the product, if the replacement of another brand, should consult the bearing experience Staff look-up table swap, the purpose is to maintain the bearing accuracy level and load capacity.