Lifting and hoisting operations are difficult operations, and cranes are usually used. What should we do if the crane fails? today, Huai'an crane rental We sorted out some common crane failures, analyzed the causes and troubleshooting methods for everyone, and let's get to know!
1、 The crane boom is blocked by foreign matters
Cause analysis:
Check whether the idler gear in the telescopic cylinder is intact. If the idler gear of the telescopic cylinder is normal, check the balance valve of the telescopic cylinder. If the spring in the valve is fatigued and deformed, the telescopic arm will vibrate and make a sound. At this time, replace the spring.
Check the steel wire rope telescopic system, remove the boom and telescopic cable, drive the telescopic boom by the telescopic cylinder alone, and check whether the telescopic boom can expand and contract freely and whether there is shaking or noise. If not, if the boom vibrates or makes noise when installing the expansion cable for expansion test, it may be due to the cable expansion system.
Troubleshooting:
At this time, the length and tension of the telescopic rope or the telescopic rope should be checked, and the nuts fixing the telescopic rope or the telescopic rope of the boom should be adjusted to make it balanced; When checking the lubrication of the expansion wheel or the expansion wheel and the wear of the pulley bushing, timely apply grease or replace the worn bushing. Finally, check whether the boom pulley shaft rotates. If you rotate, you must add a positioning baffle to limit its rotation.
Following the above ideas and methods, if it still fails to work after cleaning the balance valve, removing air, and lubricating the friction surface, it is determined that the cause of the confirmed vibration is caused by the wear of the sliding block and the main pin bushing. After the sliding block is replaced, the boom vibration fault is eliminated.
2、 Automatic sinking of crane boom
Cause analysis: The automatic sinking of the boom, also known as automatic retraction or retraction, is caused by two reasons: one is internal leakage due to loose sealing of the balance valve; The other is that the piston oil seal of the hydraulic cylinder is excessively worn, and the sealing is not tight, resulting in internal leakage.
Troubleshooting:
When troubleshooting, Equipment displacement The manufacturer shall check the balance valve first. The judgment method is to extend the boom, make the manual reversing valve in the middle position, and shut down the engine. Open the hose connection between the balance valve and the change-over valve near the balance valve. If the boom retracts automatically as the boom descends and the hydraulic oil at the hose connector continues to flow out, it is due to the internal leakage of the balance valve caused by poor sealing. Therefore, the balance valve should be removed for maintenance.
When the boom descends, if there is no hydraulic oil flowing out from the hose connector, the internal leakage will be caused by the wear and poor sealing of the hydraulic cylinder piston oil seal, which will cause the boom to fail to retract automatically. After this operation, the fault disappears.
3、 Slight movement of crane expansion joint
Cause analysis:
When the crane runs at a speed of more than 20km/h and brakes, the middle arm section and the top arm section of the telescopic boom will automatically move forward under the inertial action, and the driver will feel that the vibration of getting on the vehicle is great when braking, and there is a sense of instability. There is slight movement. The distance of slight movement of the boom is generally not more than 30mm.
Troubleshooting:
When the piston seals isolating the front and rear chambers in the telescopic cylinder are worn, the oil in the front and rear chambers will slowly seep out from the gap caused by wear. When the crane completes the lifting operation and retracts the telescopic boom, the final action is usually to retract the boom. Therefore, the front chamber (upper chamber) of the hydraulic cylinder forms a high-pressure chamber, and the rear chamber (lower chamber) forms a low-pressure chamber.
After retracting the telescopic boom, if the telescopic cylinder does not work for a long time, the internal leakage will increase until the front chamber pressure decreases. When braking, the middle arm joint and the upper arm joint will move forward slightly under the action of their own inertial force. The more serious the internal leakage, the farther the movement. Generally speaking, the displacement distance is not more than 30mm.
