Long arm excavator manufacturers for you to analyze the common excavator hydraulic system abnormalities: hydraulic excavator walking motor two main oil pipes (A, B) often burst the main reason is that after the speed change, the valve core of the dual-speed valve failed to return in time, resulting in the oil inlet and return port can not be combined, causing instantaneous high oil hydraulic pressure. At this time:
(1) Increase the spring elasticity of the double-speed valve properly. After relieving the dominant pressure, the valve core can be restored smoothly under the spring elastic force. However, it should be noted that increasing spring elasticity can not simply use the method of growth rate plus gaskets, it is necessary to stop testing with spring elasticity.
(2) Grinding double-speed valve, removing burrs, so that the valve spool can move freely in the valve body, without sticking phenomenon.
(3) Standard operation. For example, the correct operation of shifting during the excavator's walking process is that no matter how fast the excavator changes, it must be stopped first, and then shifted before walking.
2) Walking deviation. When the excavator suffers from running deviation, the following subsection checks can be made under the condition that the technical condition of the walking motor is normal and the crawler tightness is adjusted correctly:
(1) Check the working pressure of walking hydraulic circuit. First check the slow side, start from the combination valve, remove the two tubing on the pressure limiting valve, and plug the outlet with a plug. Remove the two traveling tubing on the other combination valve, start the engine, pull the traveling control handle of the plugged combination valve, check whether the hydraulic pressure can meet the request, and then check whether the A and B holes of the other combination valve (pressure limiting valve) can have oil outflow. If the oil hydraulic pressure is normal, no oil is flowing out from hole A and hole B of another combination valve, then the fault is not in the combination valve; if the oil hydraulic pressure does not reach the normal value, the phenomenon of internal leakage is serious; if the oil is flowing out from hole A and hole B of another combination valve, it is clarified that the two groups of combination valves are in collusion. The only way to make the shuttle valve in collusion is to check the sealing of the shuttle valve or change the shuttle valve.
(2) If the combined valve works normally, the central rotary joint can be inspected according to the order. There are many oil passages at the central rotary joint, which are easy to collude with each other. Inspection methods are: disassemble the A and B tubing of two walking motors, and then block the A and B tubing of one of the hydraulic motors; start the engine, pull the reversing valve of the hydraulic motor blocking the tubing, and check whether the hydraulic pressure is normal (to confirm that the working performance of the two filling valves is perfect); and then check whether the A and B oil holes of the hydraulic motor without blocking can produce oil. If the oil hydraulic pressure is abnormal and no blocked A and B oil holes come out again, that is to say, the oil pipeline of the central rotary joint is not well sealed, and the oil pipelines have colluded with each other, so the sealing parts of the central rotary joint need to be repaired or replaced. The second and fourth oil grooves of the central rotary joint are the A and B oil holes of the left-walking motor, while the third and fifth oil grooves are the A and B oil holes of the right-walking motor. If the second and third oil grooves are in series or the fourth and fifth oil grooves are in series, the excavator will not walk normally.
3) hydraulic cylinder creeping. The main reason why the piston rod of the hydraulic cylinder creeps out is that the seals in the hydraulic cylinder do not match well with the cylinder wall, and the resistance changes greatly from static friction. This phenomenon is usually easy to appear when the hydraulic cylinder is newly assembled. After a period of application, the creeping phenomenon will naturally reduce and disappear. If the creeping phenomenon of hydraulic cylinder still exists after a period of time, it is necessary to check whether the seals are in good condition and assembled correctly.
4) Short-pipe burst of combined valve. In addition to the working pressure of the combination valve exceeding the rule value, the main reason is that the valve core of the speed limit valve is insensitive to movement in the valve body, and there is stuck phenomenon. The working oil coming from shuttle valve can not properly push the speed limit valve, making the return oil not smooth, resulting in the increase of the return oil resistance, causing the instantaneous pressure to rise and the tubing to burst. The trouble can be eliminated by polishing or grinding the speed limiting valve to make the valve core move sensitively.
5) The piston rods of power arm cylinder, bucket rod cylinder and bucket cylinder are only extended and not retracted; the return oil pressure increases, the tubing joint breaks and the engine load increases. In addition to the normal position of the spool, the main reason for the above defects is due to the reverse assembly of shuttle valves. From the analysis of its working principle, it can be seen that according to their different working conditions, the combined valves of the front feeding circuit can respectively draw their respective working pressure oil, push the speed limit valve through shuttle valve opening limit, open the total return oil circuit, and make the whole hydraulic system in normal working state, that is, the valves and all the executing elements can normally enter and return oil. When the edge valve is reversed (the inlet of upper and rear group valves of shuttle valves is mistakenly connected to the outlet of shuttle valves, and the outlet is connected to the inlet of rear group valves), the speed limiting valve in the total return path can not get the working pressure oil from shuttle valves to restrain the spring elasticity of the speed limiting valve, and can not push the speed limiting valve core to the oil return position. At this time, the speed limiting valve core is in the position of closing the total return oil path under the action of spring pressure. Place. The pressure oil output from the hydraulic pump, because there is no circuit, the pressure of each pipeline of the valve group increases abnormally, resulting in tubing fracture. If the reversing valve is pulled under this condition, the hydraulic cylinder without rod chamber has large volume and high pressure, and it can barely push the piston rod into it. Because the total return circuit is not open, the pressure of valve group and tubing is abnormally increased, and the load of diesel engine is increased. Only by properly assembling shuttle valves, the above problems can be mentioned and eliminated.
6）液压泵不能完成合流，挖掘机行走没有快速。在换缶阀位置正确、电磁阀的合流阀无卡滞的状况下，呈现这一毛病的主要缘由是由于6) Hydraulic pump can not complete the confluence, excavator walking is not fast. Under the condition of correct position of the reel valve and no clamping of the confluence valve of the solenoid valve, the main reason for this defect is due to the fact that the position of the reel valve is correct and the confluence valve of the solenoid valve is not clamped.
为您分析常见挖掘机液压系统异常的原因上文已经总结了，东营博诚长臂挖掘机出租公司，建于2003年，自成立以来一直以诚信经营加长臂挖掘机而深受广大新老客户的好评，欢迎来电咨询Long arm excavator manufacturer for your analysis of common excavator hydraulic system abnormal reasons have been summarized above, Dongying Bocheng Long arm excavator rental company, built in 2003, since its inception has been operating long arm excavator in good faith and well received by the majority of new and old customers, welcome to inquire.