The main technical performance of the crane is the maximum lifting weight, the whole machine quality, the full extension length of the boom, the full contraction length of the boom, the maximum lifting height, the minimum working radius, the lifting speed, and so on.
Application of hydraulic system in crane
The hydraulic telescopic arm is the main mode of the crane hydraulic system, the hydraulic system is not a separate working individual, to play the role of the hydraulic system must be fully combined with the power source → control mechanism → mechanism of these three links. The hydraulic pump is the main component of the power source, the control device is mainly composed of the oil pipeline and various valves, and the actuator is mainly the hydraulic motor and the hydraulic cylinder. Only a reasonable combination of these three different mechanisms can effectively stroke the hydraulic circuit with different functions. The hydraulic system of the crane is composed of a lifting mechanism, rotating mechanism, amplitude changing mechanism, telescopic mechanism, and support leg, all hydraulic transmission.
Hydraulic system in the crane application characteristics
Converting the power of the crane through the oil pump can effectively improve the transmission ratio, eliminating the complicated and cumbersome transmission device. The compact structure makes the overall weight of the crane decrease, the performance is enhanced, and the amplitude of the crane can also be better realized and the automatic expansion and contraction can be effectively improved, and the starting characteristics of the engine can be effectively improved, so that the driver has a better rest time. The operation of the components has micromobility, which greatly improves the installation precision and accuracy of the crane and improves the working quality. With hydraulic transmission, the friction in the main structure is reduced, and the parts that need lubrication are reduced, saving time for maintenance and technical preparation.
Stable design of hydraulic lifting system
In the process of starting up the hydraulic system, under normal circumstances, speed regulation is achieved by adjusting the hydraulic pump and the reversing button, which can ensure the normal work of the hydraulic press without accidents. This speed regulation method is simple and reliable, has a wide range of speed regulation, and smooth speed regulation, and can also realize the fine adjustment of the working speed of the lifting mechanism.
To stabilize the performance of the hydraulic system in actual operation and work reasonably, the motor oil supply system of the hydraulic machine is often adjusted during the transmission process. When the lifting range of the lifting system is relatively large, it is necessary to use the motor deceleration function to make appropriate adjustments, generally speaking, the actual operation process will also be used for the gravity-lowering device, that is to say, the clutch is installed between the lifting drum and the drive shaft, and the hydraulic system ensures that the gravity of the empty hook and the load falls. Open the clutch and brake so that the lifting drum and the hydraulic motor free rotation, the empty hook or heavy weight under the action of gravity, at a higher speed down.
The hydraulic transmission is composed of a lifting mechanism, rotating mechanism, amplitude changing mechanism, telescopic mechanism, and support leg. The actuator in the hydraulic transmission system is controlled by the valve, but there will be some gaps between the spool and the valve body of the reversing valve, which will lead to leaks inside the reversing valve, and it is impossible to make the actuator in the non-working condition without external influence. Therefore, it is necessary to use the check valve to control the flow of hydraulic oil, so that the control actuator can be reliably stopped somewhere without external influence.
Circuit design of hydraulic crane
Based on repeated experiments and many years of experience in the industry, the author analyzes the work in the process of the rotary circuit is mainly composed of a hydraulic pump, reversing valve, balance valve, hydraulic clutch, and hydraulic motor. In these processes, the turning loop can play the role of the lifting arm to translate the object. But there's a limited range of movement in this process. The use of a low-speed-speed torque hydraulic motor can eliminate or reduce the deceleration device, so the mechanism is very compact. However, the low-speed torque hydraulic motor cost is high, and the use reliability is not as that high-speed hydraulic motor, coupled with the use of a compact structure, large transmission ratio worm gear transmission, the high-speed hydraulic motor in the rotary mechanism of the crane is widely used. So in general, the slewing mechanism of the crane is designed for the slewing of the high-speed hydraulic motor with a brake.
Introduction to crane hydraulic system
According to the analysis of each circuit and multiple tests, the power source uses a double-gear pump, which is driven by the crane engine through the transfer box on the chassis. The hydraulic pump draws oil from the tank, and the output hydraulic oil is transmitted to each actuator through the manual valve group. In actual operation, the whole system is composed of five working circuits: leg retraction, boom amplitude change, boom expansion, turntable rotation, and lifting, and each part has a certain degree of independence and does not interfere with each other. In this area, the whole system is divided into upper and lower parts, in addition to the hydraulic pump, filter, relief valve, manual valve group, and leg, the rest of the components are all installed in the turntable car part. The fuel tank is mounted on the vehicle and doubles as a counterweight. The upper and lower parts of the oil circuit are connected through the center rotary joint. Therefore, these efforts should be valued.
