Nov 27, 2018
a. The hydraulic pump is severely worn. The pump leakage is severe at low speed operation; the pump pressure is slightly increased at high speed operation, but the volumetric efficiency is significantly reduced due to wear and internal leakage of the pump, and it is difficult to reach the rated pressure. The long-term operation of the hydraulic pump intensifies the wear and the oil temperature rises, thereby causing the wear of the hydraulic components and the aging and damage of the seal, the loss of the sealing ability, the deterioration of the hydraulic oil, and finally the failure;
b. The selection of hydraulic components is unreasonable. The boom cylinder is 70/40 non-standard series, and the seals are also non-standard parts. The manufacturing cost is high and the seal replacement is inconvenient. The cylinder diameter of the boom cylinder is small, which will inevitably make the system set high pressure;
c. The design of the hydraulic oil pump system is unreasonable. It can be seen from Fig. 1 that the control valve and the full hydraulic steering gear are connected in series with a single pump, the safety valve is set to a pressure of 16 MPa, and the rated working pressure of the hydraulic pump is also 16 MPa. Hydraulic pumps often work under full load or long-time overload (high pressure), and the system has hydraulic shock, long-term oil change, hydraulic oil contamination, and the hydraulic pump wear is aggravated, causing the hydraulic pump casing to burst. Such a fault).