As a common fault of crawler crane, this paper gives an inventory of the fault analysis and corresponding solutions of crawler crane running deviation.
Case fault description: Right deviation in forward and no deviation in backward. Deviated when filling the door.
The traveling system of crawler crane is mainly composed of mechanical parts (driving wheel, guide wheel, drag chain wheel, support wheel, track) and hydraulic driving part. In line with the principle of easy first and then difficult, the mechanical part is analyzed first.
1. Mechanical part
Mainly check two aspects: (1) whether the two tracks are parallel; (2) whether the center lines of driving wheel, guide wheel, drag chain wheel and support wheel coincide. Any part of these two problems will lead to the phenomenon of walking deviation. But the phenomenon should be that both forward and backward are running off, and the fault is only running deviation when moving forward, so it can be determined that it is not caused by the mechanical part. At this time, it is necessary to analyze the hydraulic part.
From the perspective of walking hydraulic system, any part of motor, brake valve, main valve and control handle will cause walking deviation. According to experience, the order of failure rate from high to low is motor, control handle, main valve and brake valve.
The main fault of the motor is the large internal discharge. If the right side motor has large internal discharge and the volumetric efficiency becomes low, the speed of the right side motor will be lower than that of the left side motor, and this situation will cause both forward and backward to run to the right, so it can be determined that it is not a motor fault.
3. Operating handle
The common faults of the main valve are large leakage in the valve, resulting in large flow loss; or the hydraulic system is not clean, resulting in valve core sticking, valve opening is not complete, and flow is small. Because both forward and backward are completed by the same spool in the main valve, if the leakage in the valve is large, the forward and backward should be deviated. Therefore, it can be judged that the failure possibility of large leakage in the main valve is very small.
4. Brake valve
The common faults of brake valve are large leakage in the valve or valve core action is not in place. If there is a large amount of leakage in the valve, both forward and backward will deviate. If the valve core is blocked by debris or the throttle in the valve is blocked, the valve core action is not in place, the opening of the valve port is small, the amount of hydraulic oil passing through is small, and the deviation will be serious if the pressure and flow loss is large when the throttle is large.
Therefore, a manometer is connected to the oil inlet of the left and right main valves for walking test. It is found that the left and right pressure are the same when the valve is backward. However, if the throttle is small, the pressure difference between the left and right is not large; if the throttle is large, the pressure on the right side is several MPa higher than that on the left side, which indicates that the valve core of the brake valve controlling the forward direction is not in place and the oil flow is not smooth. When the throttle is small, the hydraulic flow is small, the pressure and flow loss is small, and the pressure and flow loss is large when the throttle is large. Therefore, the phenomenon of deviation to the right when moving forward, no deviation in the backward direction, and the phenomenon of deviation when the fuel door is filled.
From the above analysis, there are many reasons for the crawler crane walking fault. When encountering the problem of walking fault, we should analyze it calmly and check it step by step to find out the reason.