Why does the Boom of the Truck-Mounted Crane Shake during Operation?

The boom, being one of the crucial components of the truck-mounted crane, has a direct influence on the lifting capacity of the entire crane. When the boom is fully extended or reaches its highest position during upward luffing, and subsequently, retraction or downward luffing operations are carried out, the boom tends to shake. This phenomenon often leads to instability of the lifted goods, making them difficult to control and posing a significant safety hazard. It is therefore essential to promptly identify the cause and address it without delay.

If there is an overly large amount of friction during the process of extending and retracting the boom, it can cause sudden fluctuations in the system pressure. This can result in hydraulic shock, which in turn leads to shaking during the extension and retraction of the boom. In cases where the boom slider is severely worn, the boom will tilt downward during extension and retraction, increasing the likelihood of shaking. Moreover, the greater the resistance during extension and retraction, the more pronounced the shaking of the boom becomes.

Let’s delve deeper into this aspect. The boom slider acts as a crucial interface between the boom and the supporting structure. When it is worn beyond the specified limit, it not only affects the smooth movement of the boom but also alters the force distribution, causing imbalances and increased stress on certain areas. This can lead to erratic movement and shaking.

Solution: Replace the slider if its wear exceeds the specified value. Adjust the gap between the boom and the slider to align with the prescribed limit. When adjusting the slider gap without a load, aim for an appropriate upward deflection value after extending the boom. This compensates for the downward deflection that occurs when the boom is under load, minimizing the chances of shaking during extension and retraction.

For example, if the slider gap is too large, the boom might have excessive play, causing instability and shaking. Conversely, if the gap is too small, it can increase friction and resistance, also contributing to the shaking issue.

A loose telescopic wire rope of the boom can be a contributing factor to the shaking of the boom. By removing the telescopic wire rope and relying solely on the telescopic cylinder to drive the telescopic boom, one can observe if the boom extends and retracts freely and without shaking. If there is no shaking in this scenario, conducting a telescopic test after reinstalling the wire rope can help determine if the wire rope was the cause of the shaking.

The telescopic wire rope plays a significant role in ensuring the synchronized and stable movement of the boom. When it is loose, it can lead to uneven forces and inconsistent movement, resulting in shaking.

Solution: Firstly, carefully inspect the length and tension of the telescopic boom wire rope to ensure they meet the specified requirements. Subsequently, examine the condition of the extension and retraction pulleys and the wear of the pulley bushings. If necessary, apply grease to reduce friction or replace the pulley bushings that are excessively worn.

For instance, a wire rope that is too long or too short can affect the tension and alignment, causing instability and shaking. Similarly, worn pulleys or bushings can increase resistance and cause uneven movement.

A low liquid level in the hydraulic oil tank or a leakage in the hydraulic circuit can allow air to enter the hydraulic circuit. Once air infiltrates the hydraulic circuit, it increases the elasticity of the oil and reduces the stiffness of the hydraulic transmission. As a result, the telescopic cylinder experiences shock and crawling phenomena, thereby causing the boom to shake during extension and retraction.

The presence of air in the hydraulic system disrupts the smooth flow and pressure transmission of the hydraulic fluid. This can lead to inconsistent and erratic movement of the cylinder, which is directly reflected in the shaking of the boom.

Solution: Identify the precise fault point where the air is entering the hydraulic circuit. Carry out necessary repairs to seal the leak and subsequently expel the air from the hydraulic circuit. This might involve bleeding the system or using specialized equipment to remove the trapped air.

To guarantee smooth boom extension and retraction and prevent load shock, a balance valve is installed in the telescopic circuit. This valve consists of a one-way valve and a relief valve. The relief valve core is equipped with a damping hole. Once this damping hole becomes blocked, the balance valve loses its functionality, resulting in the boom shaking during extension and retraction.

The balance valve plays a crucial role in regulating the flow and pressure within the hydraulic system to ensure stable and controlled movement of the boom. A blocked damping hole disrupts this regulation, causing imbalances and shaking.

Solution: Disassemble the balance valve, thoroughly clean it, and unclog the damping hole. Ensure that all components of the valve are free from debris and in proper working condition before reassembling.

It is of utmost importance to pay close attention to any shaking of the boom of the truck-mounted crane. During the operation of the crane, remain vigilant. If a problem is identified, address it promptly and without hesitation. Any delay in resolving the issue can easily lead to accidents and potentially cause significant damage and harm.

In conclusion, understanding the causes of boom shaking and implementing the appropriate solutions is essential for the safe and efficient operation of the truck-mounted crane. Regular maintenance, inspections, and prompt action upon detecting any abnormalities are key to preventing problems and ensuring the reliable performance of the crane.