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我们使用的一台NK-300汽车起重机曾出现如下事故。当变幅角度为42°时,伸出三节伸缩臂,用卷扬和变幅同时起吊重物时,变幅系统突然不工作。而卷扬、伸缩臂和回转系统均可正常工作。根据该机液压系统图(见附图),测得变幅系统压力为5.2MPa,而正常工作压力应为24MPa。所以,系统不能正常工作的原因是压力不足。系统压力不足的原因可能是:(1)油箱油面过低。(2)泵1发生故障。(3)增压器3发生故障。(4)电磁阀8处于卸荷状态。(5)主溢流阀
The following incident occurred on an NK-300 truck crane we used. When the angle of change is 42°, the three-section telescopic arm is extended, and when the heavy object is hoisted simultaneously with hoisting and varying amplitude, the luffing system suddenly fails to work. The winches, telescopic arms and slewing systems all work properly. According to the diagram of the hydraulic system of the machine (see the attached figure), the pressure of the luffing system is measured as 5.2 MPa, and the normal operating pressure is 24 MPa. Therefore, the reason that the system does not work properly is insufficient pressure. The reason for the lack of system pressure may be: (1) The oil level in the tank is too low. (2) Pump 1 has failed. (3) The turbocharger 3 has failed. (4) The solenoid valve 8 is in an unloaded state. (5) Main relief valve