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As the most important category of construction machinery lifting products, truck cranes also have many important features in the development of hydraulic systems. China Road Machinery Network specially introduces you to the current situation and trends of truck crane hydraulic systems.
1. Lifting hydraulic system
For cranes, the lifting action is the most frequent action. At present, the most commonly used lifting hydraulic systems are fixed pumps, fixed or variable motor open hydraulic systems. However, modern construction puts forward new requirements for lifting systems: energy saving, high efficiency, reliability, and good micro-movement and stability. In order to adapt to these new requirements, the previous quantitative pumps will gradually be replaced by advanced and reliable constant power variable pumps with load feedback and pressure cutoff. The previous quantitative motors or hydraulic control variable motors will also be replaced by electronically controlled variable motors. This system will effectively achieve the effects of light load high speed, heavy load low speed and energy saving.
2. Luffing hydraulic system
The development trend of the luffing hydraulic system is also embodied in energy saving and high efficiency. At present, the most advanced one is to make full use of the gravitational potential energy of the boom and heavy objects when the luffing is descending to realize the gravity lowering, and the lowering speed is steplessly controlled by the pilot handle. Smooth and without impact.
3. Telescopic hydraulic system
For telescopic hydraulic systems with telescopic arms below five sections, synchronous or sequential plus synchronous telescopic methods are generally adopted in China. When two-stage oil cylinders are used, the upper and lower oil cylinders realize internal communication, generally using a cartridge type balance valve; for those with five sections The hydraulic system of the above telescopic boom adopts a single-cylinder bolt telescopic mechanism. This telescopic mechanism is light in weight and can greatly improve the lifting performance of the crane. It can effectively control the weight of the whole machine. It adopts the oil of multiple oil ports and multiple balance valves. Way to improve the efficiency of expansion and contraction.
4. Rotary hydraulic system
Slewing is also a frequently used action of cranes, but relatively speaking, the power required for slewing is the least, so the highest requirements of the slewing system are: smooth slewing, no side load in lifting operations; the development trend of slewing system is through small motors and large transmission ratios To achieve smooth operation, the automatic centering function of the lifting weight is realized by setting up a rotary buffer valve and a free sliding function, thereby effectively preventing the generation of side load.
5. Manipulation and control system
Mechanical control is the simplest and most widely used control method for truck cranes. The hydraulic proportional control system has also been widely used in our factory and is quite mature. The operating performance has been greatly improved; however, the most promising one is Electric proportional control system, with the help of computer technology and programmable technology, truck cranes will develop towards intelligence.
In addition, the hydraulic system also shows obvious development trends in the following aspects:
1. The use of international matching, and the use of international matching for hydraulic components with high system requirements, such as pumps, valves, motors, etc., can improve product reliability. In addition, mature, large-quantity and low-cost components used abroad are also widely used in China use.
2. The card sleeve type connector is adopted. Because the card sleeve type connector has strong advantages in the control system pollution and leakage prevention, the use of the card sleeve type connector can greatly reduce the failure rate and the early feedback rate.
3. Design speed divisions in the system. Due to the different requirements of different construction projects, the requirements for the crane's various operating speeds are also different. The speed division technology has also emerged as the times require. Design different speed gears to suit different working conditions. Requirements.
4. Extensive use of highly integrated and modular valve groups can simplify pipelines, effectively reduce liquid groups, improve efficiency, and are easy to maintain.
5. Deep penetration into the field of computer technology, truck cranes will develop in the direction of wireless remote control technology, remote diagnosis service technology, black box self-protection technology, etc. In order to realize the functions of the whole machine, hydraulic technology and computer technology will penetrate each other and develop together.