In the world of heavy machinery, truck-mounted cranes play a crucial role in various industries, from construction to logistics. These powerful machines are designed to lift and move heavy loads with precision and ease. However, like any complex mechanical system, they are prone to certain common faults that can disrupt their operation and potentially cause delays and additional costs. In this article, we will explore in detail the common faults that may occur in truck-mounted cranes, with a particular focus on the crane component itself.
There are numerous well-known brands in the truck-mounted crane market, including XCMG, SANY, Xinfengong, Hercules, Shimei, Chengli Weilong Changxing, and many others. Each brand offers its own unique features and specifications, but they all share a common core component – the crane. This is the heart of the truck-mounted crane, responsible for the crucial task of lifting goods. Without a properly functioning crane, the entire vehicle becomes virtually useless for its intended purpose.
One of the common issues that can arise with the crane is a malfunctioning oil pump. When the oil pump fails to work, it can bring the lifting operation to a halt. There are several factors that can cause this problem. Firstly, it is essential to check whether the air pressure of the vehicle has reached the required level, typically around 6 to 7 atmospheres. Insufficient air pressure can prevent the power take-off from engaging properly, which in turn affects the operation of the oil pump. Additionally, ensure that the power take-off power switch and solenoid valve are receiving power and functioning correctly. If there is an issue with the electrical supply to these components, it can also lead to the oil pump not working. Another common cause is related to the power take-off air circuit. If this circuit is not properly ventilated, it can prevent the power take-off from engaging fully, resulting in a non-functional oil pump. In many cases, the problem may simply be that the power take-off handle has not been pushed in place completely. This seemingly minor oversight can have a significant impact on the operation of the crane. By ensuring that the power take-off is fully engaged, this issue can often be resolved easily. However, if the problem persists, it could indicate more serious underlying issues. For example, the gear in the power take-off box may be damaged. In such cases, the power take-off needs to be repaired or replaced to restore proper functionality. Another possible cause is damage to the transmission sleeve between the output shaft of the power take-off box and the input shaft of the oil pump. If this transmission sleeve is damaged, it must be replaced to ensure the smooth transfer of power from the power take-off to the oil pump. In the worst-case scenario, if the oil pump itself is burned out, it will need to be replaced entirely.
Another common problem that can occur is an inconsistent speed of the crane. Sometimes, the crane may operate at a normal speed, while at other times, it may slow down or speed up unpredictably. This can be a cause for concern, as it can affect the accuracy and safety of the lifting operation. One possible reason for this issue is an insufficient amount of hydraulic oil in the hydraulic tank. Hydraulic oil is essential for the proper functioning of the crane’s hydraulic system, which controls the movement and speed of the crane. If the oil level is low, it can lead to inconsistent pressure and flow, resulting in fluctuations in the crane’s speed. In such cases, it is necessary to add hydraulic oil in a timely manner to maintain the proper operating level. Another potential cause is a blocked oil filter. Over time, impurities and debris can accumulate in the oil filter, restricting the flow of hydraulic oil. This can cause a decrease in pressure and affect the performance of the crane. Regularly cleaning or replacing the oil filter can help prevent this issue and ensure smooth operation.
The hydraulic system of the truck-mounted crane is also prone to problems related to low pressure and leaks. A low hydraulic pressure can result in a decrease in the lifting capacity of the crane and make it difficult to perform heavy lifts. There are several possible causes for this issue. Firstly, it is essential to thoroughly inspect all pipelines and components of the hydraulic system for any signs of leakage. Leaks can occur at various points, such as connections, seals, or hoses. Any damaged or worn components should be replaced immediately to prevent further loss of pressure. Additionally, the pressure of the relief valve may be adjusted too low. The relief valve is designed to limit the maximum pressure in the system and protect it from overpressure. If the set pressure of the relief valve is too low, it can cause the hydraulic system to operate at a lower pressure than intended. Checking and adjusting the set pressure of the relief valve according to the manufacturer’s specifications can help resolve this issue. In some cases, the relief valve itself may lose its pressure-regulating function due to wear or damage. In such situations, it is necessary to inspect the relief valve and replace any damaged parts. Another possible cause of low hydraulic pressure is a reduced volumetric efficiency of the oil pump. Over time, the internal components of the oil pump can wear out, resulting in a decrease in its pumping capacity. If this occurs, the oil pump will need to be replaced to restore the proper hydraulic pressure.
The luffing cylinder is an important component of the crane that controls the movement of the boom. If the luffing cylinder is weak, it can affect the lifting height and stability of the crane. One common cause of a weak luffing cylinder is damage to the sealing ring. When the sealing ring is damaged, it can lead to increased internal leakage within the cylinder, reducing its lifting force. In such cases, the damaged sealing ring and piston need to be replaced to restore the proper functioning of the luffing cylinder. Another possible cause is damage to the piston or deformation of the cylinder barrel itself. These issues can also result in increased internal leakage and a decrease in the cylinder’s performance. It is essential to carefully inspect the luffing cylinder for any signs of damage or deformation and take appropriate measures to repair or replace the affected components.
The winch is another critical component of the truck-mounted crane, responsible for winding and unwinding the cable to lift and lower the load. If the winch is weak, it can lead to difficulties in lifting heavy loads and potentially pose a safety hazard. One possible reason for a weak winch is a reduced volumetric efficiency of the winch plunger motor. This can be indicated by several symptoms, such as the luffing piston rod being pulled out, the movable arm and outrigger having obvious retraction phenomena, and the lifting hook having a natural descending tendency. In such cases, it is necessary to check the winch motor for any signs of wear or damage. If the motor is found to be faulty, it may need to be replaced. Additionally, the friction brake pads in the winch gearbox can also wear out over time, reducing the braking force and causing the winch to be weak. Replacing the damaged friction brake pads can help restore the proper functioning of the winch. Another possible cause of a weak winch is leakage in the luffing cylinder, telescopic cylinder, or outrigger cylinder. Leakage in these cylinders can lead to a loss of hydraulic pressure and affect the performance of the winch. Inspecting and replacing the sealing parts and piston in the affected cylinders can help resolve this issue. Additionally, the balance valve of the luffing cylinder and telescopic cylinder or the two-way hydraulic lock at the outrigger may be damaged. These components are essential for maintaining the stability and control of the crane during operation. If they are damaged, they need to be replaced or repaired to ensure the safe and proper functioning of the crane.
In conclusion, truck-mounted cranes are complex machines that are subject to various common faults. By understanding these faults and their possible causes, operators and maintenance personnel can take proactive measures to prevent them from occurring and quickly address them when they do. Regular maintenance, inspection, and timely replacement of worn or damaged components are essential for ensuring the reliable and safe operation of truck-mounted cranes. Whether it’s a malfunctioning oil pump, inconsistent crane speed, low hydraulic pressure, or problems with the luffing cylinder or winch, early detection and proper repair can help minimize downtime and keep these important machines working at their best.
