![<?echo $_SERVER['SERVER_NAME'];?>](/template/twentyseventeen/skin/images/header.jpg)
**I. Introduction**
The traditional hydraulic system of cranes typically uses valve control, where the flow rate is regulated by adjusting the opening of a multi-way valve to control the speed of the actuator. This method often leads to energy loss and excessive heat generation in the system.
To address these issues, modern crane systems now employ pump-controlled hydraulic technology. This approach ensures better coordination between the engine and the hydraulic system, allowing for more efficient use of engine power, reducing unnecessary energy consumption, and enabling smooth, stepless speed regulation for various mechanisms.
This advanced system offers excellent stability, significantly reducing hydraulic shocks and protecting both the system and its components. As a result, the lifespan of hydraulic parts is extended, and the overall safety, reliability, and efficiency of the crane are greatly improved. The system integrates electrical control with hydraulic functions, making it a truly intelligent machine. It also features a retractable mechanism with an electrically controlled single-cylinder latch function.
**II. Overview**
The system utilizes electro-hydraulic proportional pilot control to adjust the displacement of the actuator, thereby changing the movement speed. The system consists of a closed-loop rotary circuit, along with open circuits for the main and auxiliary oil lines.
The swing oil circuit employs a swash-plate variable displacement piston pump connected to a fixed-displacement motor in a closed loop. The pump’s outlet is connected to the motor’s inlet, while the motor’s outlet connects back to the pump’s inlet, forming a self-contained loop without the need for valves. By adjusting the swash plate angle, the pump controls the direction and flow of pressure oil, which in turn adjusts the rotational speed and direction of the motor. This setup ensures smooth rotation and good mobility.
The main oil circuits include lifting, luffing, and telescoping functions. The main pump is a dual axial-variable pump that allows independent control to meet different working conditions. The constant power curve depends not only on the pump's own setting but also on the load from other pumps. With power regulators and load limiters, the system can manage the pump’s displacement based on working pressure, preventing overloads and ensuring safe operation.
The entire system is controlled through an electro-hydraulic proportional pilot system, where the pump’s displacement is regulated by pilot oil pressure. A proportional relief valve adjusts the pressure according to the current input from the remote control handle, allowing for precise control of the pump’s output. This enables smooth and continuous speed adjustment, improving overall performance and operator control.
**III. Function Description**
1. **Swing Circuit**
The swing mechanism is crucial for the crane’s handling performance, efficiency, and structural integrity. In addition to using on-demand pump control, the system ensures stable rotation with good start-up and buffering performance. The closed-loop swing circuit eliminates the need for valves, and the pump’s swash plate angle is adjusted to control flow and direction. A charge pump and filter help maintain optimal pump performance, while a buffer valve ensures smooth operation.
A free-wheeling solenoid valve is included to prevent boom damage during heavy lifting. When activated, it allows the boom to float under gravity, reducing stress on the structure.
Key advantages of the swing system include smooth start/stop control, wide speed range, and three-speed control options, enhancing operator precision and control.
2. **Main and Auxiliary Lifting Circuits**
The main and auxiliary lifting mechanisms feature fixed-displacement motors with built-in safety valves to protect against overload. The system uses a proportional relief valve to control the pump’s displacement, ensuring safe and controlled lifting or lowering. The lifting balance valves prevent stalling and ensure steady descent, improving safety.
An optional quick connector allows for easy switching between the main and auxiliary lifting functions.
3. **Luffing Circuit**
The luffing system uses a gravity reduction principle to control the descent speed of the boom. A proportional valve, directly controlled by the pilot handle, regulates the speed of the luffing cylinder. If the cylinder force increases beyond a set limit, the balance valve compensates automatically, ensuring stable and safe operations.
4. **Telescopic Circuit**
The telescopic system features a single-cylinder design with a bolt-expansion mechanism. The telescoping sequence can be manually controlled or pre-set for automatic operation. The system uses a multi-way reversing valve to regulate the extension and retraction of the boom, ensuring smooth and secure movement. A balancing valve on the telescopic cylinder rod enhances stability during retraction.
5. **Auxiliary Oil Circuit**
The auxiliary circuit includes the pilot control, counterweight, and cooling systems. The pilot oil pressure is maintained at 3 MPa to power the proportional relief valve and control the main directional valve. The cooling system automatically activates when the oil temperature rises, using a temperature sensor to trigger the fan motor for effective heat dissipation.
Thermoforming Blister Packaging Machine
Thermoforming Blister Packaging Machine, Medical Products Packaging Machine, Paper-plastic Packaging Machine, Blister Packaging Machine in Thermoforming
ZHUCHENG YIKANG FOOD PACKING MACHINERY CO., LTD. , https://www.yikangmachinery.com