Introduction of all-terrain crane pump hydraulic
**Introduction to the Pump Control Hydraulic System of Large Tonnage All-Terrain Cranes**
First, Foreword
Crane hydraulic systems are typically valve-controlled, where the flow rate is regulated by adjusting the opening of a multi-way valve. This method controls the speed of the actuators but often leads to energy loss and excessive heat generation in the system. To address these issues, modern cranes employ pump-controlled hydraulic systems. These systems ensure better coordination between the engine and the hydraulic components, allowing for more efficient use of engine power, reducing unnecessary energy consumption, and enabling smooth, stepless control of the crane’s operations.
The system features excellent damping characteristics, significantly reducing hydraulic shocks and protecting the hydraulic components, which extends their service life and enhances the safety, reliability, and efficiency of the crane. The integration of electronic control allows for seamless interaction between mechanical, electrical, and hydraulic systems, making the crane more intelligent. Additionally, the system includes a retractable mechanism that enables single-cylinder plug functionality.
Second, Overview
The system uses electro-hydraulic proportional pilot control to adjust the displacement of the actuator, thereby regulating the movement speed. It consists of a closed-loop rotation circuit, an open main oil circuit, and an auxiliary oil circuit. The swing oil circuit employs a swash-plate variable displacement piston pump combined with a closed-loop fixed motor circuit. The pump's outlet connects to the motor's inlet, while the motor's outlet returns to the pump's inlet, forming a closed loop without the need for valves. By adjusting the angle of the variable pump, the flow and direction of the pressure oil can be controlled, which changes the rotational speed and direction of the motor. This results in smooth and stable rotation. A charge pump and charge device are also included to improve pump performance and prevent cavitation.
The main oil circuits include lifting, luffing, and telescoping lines. The main pump is an axial-variable dual pump, capable of independent variable control to meet different operational needs. The constant power curve depends not only on the pump's set point but also on the load conditions of other pumps. Power regulators and load limiters ensure that the pump displacement remains within safe limits, preventing overload. If overloaded, the proportional relief valve adjusts the pressure, reversing the dual pump to reduce flow and increase power absorption.
The entire system utilizes advanced electro-hydraulic proportional pilot control technology. The pump displacement is controlled by pilot oil pressure, which is adjusted via a proportional relief valve. The greater the displacement of the remote control handle, the higher the current output, leading to increased pump displacement and faster actuator movement. Conversely, smaller displacements result in slower movement. Operators control the direction of each actuator through the main valve and adjust the speed by changing the pilot handle's position. Pressure control allows for continuous adjustment of the dual pump's displacement, ensuring smooth and precise operation across a wide range of speeds.
Third, Function Introduction
1. **Swing Oil Circuit**
The swing mechanism is crucial for the crane's handling performance, operational efficiency, and structural stability. In addition to using on-demand pump control, the system incorporates a fixed motor drive to ensure stable rotation and good start-up performance. The closed-loop swing circuit eliminates the need for valves, with the pump’s swashplate angle controlling the flow and direction of the pressure oil. A charge pump and filter are included to enhance performance and protect the system. A buffer valve ensures smooth operation, and a free-wheeling solenoid valve prevents boom damage during heavy lifting by allowing the boom to float under its own weight.
Advantages of the swing system include smooth start/stop control, a wide speed curve, and three-speed adjustment options, improving operator control accuracy.
2. **Main and Auxiliary Lifting Oil Circuits**
The main and auxiliary lifting mechanisms use fixed motors with built-in safety valves to protect against overloads. The system uses a proportional relief valve to control the main pump's displacement, ensuring safe lifting and lowering operations. When the pilot handle is neutral, the brake is engaged, locking the winch in place. Lifting balance valves prevent stalling during descent, ensuring a steady and safe lowering process.
3. **Luffing Oil Circuit**
The luffing system uses a gravity reduction principle and a proportional valve controlled by the pilot handle. When the cylinder force reaches a set value, the balance valve compensates for pressure, slowing the cylinder down to maintain boom stability during luffing operations.
4. **Telescopic Oil Circuit**
The telescopic system features five main booms driven by a single cylinder. The extension and retraction can be manually or automatically controlled. A counterbalance valve ensures stability during retraction, and a dual-loop design prevents damage from valve failure.
5. **Auxiliary Oil Circuit**
The auxiliary system includes a pilot control circuit, counterweight circuit, and cooling system. The pilot oil pressure is maintained at 3 MPa to control the proportional relief valve and main directional valve. An automatic cooling system activates when the oil temperature rises, using a load-sensing gear pump to drive the fan and dissipate heat. If the temperature is low, the system operates in a low-pressure return mode to conserve energy.
Easter Egg Gift Box,Candy Packaging Iron Box,Easter Eggs Tin Box,Egg Shape Gift Box
Dongguan Tielangtou Hardware Products Co., Ltd , https://www.tinboxtlt.com