1, failure phenomenon and the reasons for maintenance from the following three reasons to find fault, and improve the system: (1) Check the boom cylinder internal leakage situation. The easiest way is to raise the boom, to see if a significant free fall. If the whereabouts of the obvious would be demolished cylinder inspection, seals should be replaced if worn. (2) Check the control valve. First rinse valve, check valve for wear, such as wear and tear should be replaced. Valve remained unchanged after the installation, and then check the control valve spool wear, the gap is generally use limit 0.06mm, badly worn should be replaced. (3) measuring the pressure of the hydraulic pump. If the pressure is low, then make adjustments, plus the pressure is still not be set up, then pump heavy wear. In general, the resulting load can not raise the boom was mainly due to: a. Pump badly worn. At low speed pump serious leak; high-speed operation, the pump pressure has increased slightly, but due to pump wear and internal leaks, volumetric efficiency decreased significantly, it is difficult to reach the rated pressure. Exacerbated by long working pump wear, temperature rise, and the resulting hydraulic components wear and aging seals, damage, loss of sealing capability, hydraulic oil deterioration, leading to malfunction. b. hydraulic component selection is unreasonable. Specification of the boom cylinders 70/40 Non-standard series, the seal is also standard parts, manufacturing cost and inconvenience of replacing the seal. Boom cylinder bore small, is bound to make the system set pressure is high. 2, improvements and effects (l) improved hydraulic system design. After much argument, and finally the use of advanced priority valve with load sensing hydraulic steering gear form, shown in Figure 2. The new system in accordance with steering requirements to assign priority traffic, regardless of load size, low speed steering wheel can ensure adequate supply, all the rest can be used to supply the working unit circuit, thereby eliminating the shift caused by excessive power supply circuit losses, improve system efficiency and reduce the hydraulic pressure of work. (2) optimization of the boom cylinders and hydraulic modeling, reduce system operating pressure. By optimizing the calculation, the boom cylinder standard series 80/4. Pump displacement by a 10ml / r increased to 14ml / r, the system set pressure 14MPa, meet the boom cylinder lifting force and speed requirements. (3) It should also be noted in the course of the proper use and maintenance of loaders regularly add or replace hydraulic oil, hydraulic oil to maintain the cleanliness and strengthen routine inspection and maintenance. [Company name] Tengzhou Machine Co., Ltd. Heng Noda】 【Sales Manager Mr. Sun Sales Hotline】 【0632-5168661 [Business Phone] 13356372661 [Main products] small hydraulic machine column hydraulic single column hydraulic machine gantry arm hydraulic machine hydraulic machine hydraulic machine Four small 200t hydraulic machine hydraulic machine column hydraulic gantry hydraulic single column hydraulic press machine [Company website] http://www.hengnuoda.com/ http://www.youyaji1.com [Address] Tengzhou City Economic Development Zone Industrial Park South