A. Be heavily worn of hydraulic pumps. The pump leakage is serious at low speed. At high speed, the pump pressure is slightly increased. Due to pump wear and internal leakage, the volumetric efficiency decreases significantly and it is difficult to reach the rated pressure. The long working time of hydraulic pump aggravates wear and oil temperature rise, which causes hydraulic component wear and seal aging, damage, loss of sealing ability, deterioration of hydraulic oil, which finallyleads to failure.

B. Unreasonable selection of hydraulic components. The movable arm oil cylinder is 70/40 non-standard series, and the sealing parts are also non-standard parts. The manufacturing cost is high and the sealing parts are difficult to replace. Movable arm oil cylinder bore is small, will certainly make the system adjust the pressure high.

C. Unreasonable design of hydraulic system. The operating valve and the full hydraulic steering are in series of single pump. The pressure of the relief valve is set at 16MPa, and the rated working pressure of the hydraulic pump is also 16MPa. The hydraulic pump often works under full load or long time overloading (high pressure), and the system has hydraulic impact, and it does not change oil for a long time, which can cause the hydraulic oil is polluted and aggravates the hydraulic pump wear, causeing the hydraulic pump shell to burst.