The XCMG truck-mounted crane slewing balance valve, through precise structural design and advanced control technology, constructs a complete load motion safety control system. Its core mechanism can be summarized into five levels: pressure control, flow regulation, sealing assurance, pilot optimization, and system coordination.
At the pressure control level, the XCMG truck-mounted crane slewing balance valve achieves dynamic balance of the load descent speed through a combination of built-in sequence valves and check valves. When the crane's slewing mechanism descends with a heavy load, the sequence valve of the balance valve generates throttling resistance at the motor's drain port. This resistance balances the force exerted by the load on the motor, thus limiting the descent speed. If the descent speed is accelerated by external interference (such as wind load), the balance valve automatically increases the throttling resistance to prevent overspeeding; conversely, if the load is light and the descent is too slow, it reduces the resistance to ensure smooth operation. This pressure feedback mechanism ensures that the load movement remains within a controllable range.
The flow regulation function is crucial for the XCMG balance valve's safety. It precisely controls the hydraulic oil flow through the coordinated action of the main valve core and the pilot valve core. When the slewing mechanism starts, the pilot valve core responds quickly to the control pressure signal, pushing the main valve core to open to the set position, allowing hydraulic oil to enter the motor at a stable flow rate, avoiding impact loads caused by sudden flow changes. During slewing, if the load changes suddenly (such as the load swinging), the balance valve adjusts the opening of the main valve core to match the flow demand in real time, maintaining a constant slewing speed and preventing the risk of runaway due to inertia.
Optimized sealing performance is directly related to the safety of load movement. The XCMG truck mounted crane slewing balance valve adopts a cone valve sealing structure, forming a line contact seal between the main valve core and the valve seat. Compared with traditional cylindrical surface seals, it has a smaller sealing area and higher contact pressure, effectively preventing high-pressure oil leakage. Furthermore, the balance valve is directly connected to the actuator (hydraulic motor or cylinder). When the oil pipe ruptures or the brake fails, the cone valve seal can instantly lock the oil circuit, preventing the load from falling freely, providing double protection for personnel and equipment.
The application of pilot control technology significantly improves the response speed and stability of the balance valve. XCMG employs a pilot-operated structure, separating the control piston from the pilot valve core to prevent hydraulic forces from interfering with the control signal input. When pilot pressure acts on the pilot valve core, a pressure difference is generated across the main valve core,
pushing it to follow the pilot valve core's movement. This design not only reduces control pressure requirements and energy loss but also minimizes hydraulic interference, resulting in more precise valve core movement and ensuring smooth operation of the slewing mechanism even under rapid load changes.
The safety control of the XCMG truck-mounted crane slewing balance valve is also reflected in its deep integration with the overall system. For example, in the hoisting mechanism, the balance valve and brake form a linkage mechanism: the brake opening pressure is lower than the balance valve's pilot pressure, ensuring the brake actuates before the balance valve, preventing brake pad wear; simultaneously,the balance valve's minimum opening pressure is higher than the system's replenishment pressure, preventing accidental valve core opening due to replenishment. Furthermore, the balance valve's overflow pressure is set to at least 1.3 times the maximum load pressure, allowing excess pressure to be released even under high load conditions, preventing system overload damage.
From an application perspective, the safety control advantages of the XCMG truck-mounted crane slewing balance valve are particularly prominent in complex working conditions. When truck-mounted cranes operate at heights, the slewing mechanism needs frequent starts and stops, and the load inertia is large. The balance valve effectively suppresses impact vibrations during start-up and shutdown by dynamically adjusting the throttling resistance, extending the equipment's service life. In marine engineering applications such as ship cargo winches, the balance valve's anti-pollution design and high sealing performance can withstand the corrosive effects of harsh environments such as salt spray and humidity, ensuring long-term stable operation.
The XCMG truck-mounted crane slewing balance valve constructs a multi-layered, multi-dimensional safety control system through precise pressure and flow control, optimized sealing structure, innovative pilot control, and deep system synergy. This system not only meets the stringent requirements of engineering machinery for load movement safety but also provides a valuable model for industry technological upgrades.
