Truck-mounted cranes will encounter various issues, both major and minor, after prolonged usage. Today, I will share with you the four common fault problems and their maintenance methods for truck-mounted cranes.
The truck-mounted crane does not operate, and the lifting capacity diminishes, evidently failing to meet the specified requirements.
Fault phenomena:
The oil pump is non-functional. Firstly, verify if the vehicle’s air pressure is 6/7 bars, whether the power take-off power switch and solenoid valve are energized, and if the power take-off air circuit is ventilated. Many instances arise because the power take-off handle is not pushed fully in place. Simply pushing the power take-off handle to the correct position can solve the issue; Another cause could be damage to the gears within the power take-off box, which is more cumbersome and requires an overhaul of the power take-off box; The transmission sleeve between the output shaft of the power take-off box and the input shaft of the oil pump is damaged and must be replaced; If the oil pump is burned out, it needs to be replaced.
He oil pump is functioning, but the speed of the crane is sometimes slow and sometimes fast. The oil level in the fuel tank is insufficient, and hydraulic oil needs to be added completely; The oil filter is clogged and requires cleaning.
Imagine a situation where the crane is in the middle of a critical lifting operation, but suddenly stops working due to an issue with the oil pump. This not only delays the work but also poses safety risks.
The pressure of the hydraulic system is too low. There is a leakage within the system. Inspect all pipes and components and implement measures to stop the leakage; The pressure of the relief valve is set too low. Examine the set pressure of the relief valve (The specified set pressure of the relief valve is 14 Mpa (for 2-3 ton cranes) / 17.5 Mpa (for 5-8 ton cranes). Overadjustment is not permitted). If the relief valve loses its pressure regulating function, the relief valve should be overhauled and the damaged components replaced; The volumetric efficiency of the oil pump decreases, and the oil pump needs to be replaced.
A low-pressure hydraulic system can lead to weak lifting force and inaccurate positioning, affecting the crane’s performance and potentially causing safety hazards.
The luffing cylinder is weak. The damaged sealing ring inside the luffing cylinder leads to increased internal leakage. Replace the damaged seals and pistons; The piston inside the luffing cylinder is damaged or the cylinder barrel of the luffing cylinder is deformed, causing significant internal leakage. Check for cylinder barrel deformation.
Weak luffing cylinders can compromise the crane’s ability to lift and position loads accurately, especially in complex lifting scenarios.
The winch is weak. The volumetric efficiency of the winch plunger oil motor decreases. Replace the winch plunger oil and motor. After the goods are lifted, they noticeably drop naturally (more than 2mm/min). It can be clearly observed that the luffing piston rod is pulled out, the movable arm and outrigger have obvious retraction, and the lifting hook has a natural drop. There is internal leakage in the luffing cylinder, telescopic cylinder, and outrigger cylinder. Replace the damaged seals and pistons; The balance valve of the luffing cylinder and telescopic cylinder is damaged. Replace or overhaul the balance valve; The two-way hydraulic lock at the outrigger is damaged. Replace or overhaul the two-way hydraulic lock; The volumetric efficiency of the winch motor decreases, and the friction brake pads inside the winch gearbox are damaged. Replace the friction brake pads and the motor.
A weak winch can result in unstable lifting and potential load drops, posing significant risks to both the equipment and the surrounding environment.
Now, let’s explore some additional common faults and their maintenance considerations:
One common issue is the malfunction of the control valves. If the control valves are sticky or not responding accurately, it can lead to erratic crane movements. Regular inspection and cleaning of the control valves, along with checking for worn or damaged valve components, can help prevent such problems.
The crane’s boom structure may also develop faults over time. Cracks or deformations in the boom can occur due to excessive stress or fatigue. Regular visual inspections and non-destructive testing methods can help detect such issues early. In case of significant damage, repairs or replacement of the boom section might be necessary.
Hydraulic hose leaks are another frequent problem. Hoses can deteriorate due to age, exposure to harsh conditions, or excessive pressure. Regularly checking hoses for signs of wear, cracks, or bulges and replacing them promptly can prevent hydraulic fluid leaks and system failures.
The electrical system of the crane can also experience faults, such as faulty sensors, wiring issues, or problems with the control panel. Regular electrical system checks, including testing of sensors and ensuring proper wiring connections, are essential for smooth crane operation.
When it comes to maintenance, it’s not just about addressing faults when they occur but also implementing a preventive maintenance schedule. This includes regular fluid changes, lubrication of moving parts, and inspection of critical components according to the manufacturer’s recommendations.
In addition, operator training is crucial. Operators who are familiar with the proper operation and maintenance procedures of the crane can often identify potential issues early and take appropriate actions to prevent major breakdowns.
Finally, keeping detailed maintenance records can provide valuable insights into the crane’s performance over time, helping to predict and prevent future faults and ensuring the longevity and reliability of the truck-mounted crane.
In conclusion, understanding and addressing the common faults of truck-mounted cranes, along with implementing a comprehensive maintenance strategy, is essential for ensuring the safe and efficient operation of these important pieces of equipment.
