Created on:2021-10-22 10:31

Railway engineering equipment_ Maintenance of car dumper -- improvement of hydraulic system

Railway engineering equipment_ Maintenance of car dumper -- improvement of hydraulic system

(1) Overview

Car dumper is used to dump coal, ore and other goods in vehicles. It is advanced in design, realizes the operation automation of the whole machine, and has high unloading efficiency (25 vehicles can be dumped per hour on average). It is mainly used in thermal power plants, steel mills, ports and wharfs.

During the overturning unloading process of the dumper, the vehicle is driven by the hydraulic system. The leaning hydraulic cylinder and the rolling hydraulic cylinder drive one leaning plate and four rolling beams respectively and are fixed on the track of the dumper. In order to prevent the vehicle from derailing and falling off the track, it is required that the vehicle must be reliably fixed on the dumper track, and in order to protect the vehicle from being damaged by too much external force, the Ministry of Railways has also formulated a standard, which stipulates that the clamping force acting on the vehicle shall not exceed the allowable range of the standard. Therefore, the working pressure of the parking and pressing hydraulic cylinders should be adjusted as small as possible. As long as the parking plate and pressing beam can be driven into contact with the vehicle, and then the parking and pressing hydraulic cylinders can be locked, the vehicle can be fixed during turnover. However, there is still a problem. Each vehicle is loaded with about 50t goods, and the dead weight of the goods compresses and deforms the bogie spring of the vehicle. When the vehicle turns over to a certain angle with the dumper, the goods in the vehicle begin to be unloaded continuously, and the pressure on the compressed spring decreases with the reduction of the goods, Therefore, it is necessary to restore the deformation upward and drive the whole vehicle to have an upward trend. If the hydraulic cylinder of the car dumper is always locked to fix the vehicle, when all the goods are unloaded, the clamping force of the car dumper beam for the vehicle is equal to the dead weight of the goods carried by the vehicle (about 50t) to balance the spring force. Such a large clamping force must exceed the allowable range of the standard, which seriously affects the service life of the vehicle. In order to solve this problem, the hydraulic schematic diagram of the pressing part of the car dumper is designed as shown in Figure G.

(2) Analysis on hydraulic principle of car dumper pressing part

The pressure oil is supplied from the oil port P, the electromagnet yh1 of 5 is powered on, the control pressure oil enters the oil port X of the control cover plate of the cartridge valve 7, and the cartridge valve is closed. At the same time, the oil port Z1 of the control cover plate of the cartridge valve 6 is connected with the oil drain port L, and the cartridge valve is opened. In this way, the pressure oil can enter the rod chamber and rodless chamber of the hydraulic cylinder from the oil ports a and B respectively. The piston rod 1 extends under the differential action. The rolling hydraulic cylinder drives the rolling beam to clamp the vehicle. After the rolling beam touches the upper end of the vehicle, the pressure in the circuit begins to rise. When the setting value of the pressure relay 8 is reached, the pressure relay sends a signal. If other rollover conditions have been met, The car dumper starts to turn over. When the goods in the vehicle are gradually unloaded, the force of the spring to push the piston rod 1 upward due to the recovery of deformation also increases, the pressure in the rodless chamber of the hydraulic cylinder also increases gradually, and the pressure oil in the rodless chamber acts on the piston rod 2. When the pressure rises to the setting value of the cartridge sequence valve 10, the sequence valve is opened, and the hydraulic oil in the rodless chamber of the piston rod 2 flows out of the oil port C through the sequence valve, In this way, the piston rod 2 moves upward for a certain distance, and the corresponding piston rod 1 moves upward with the pressing beam for the same stroke. The whole vehicle rises upward, the spring recovers a certain deformation, and the force acting on the vehicle is reduced. Moreover, the hydraulic oil flowing out of port c enters the rod cavity of the hydraulic cylinder through port a through one-way valve 1 and one-way throttle valve 9, just to supplement the oil required after the upward action of piston rod 1.

After unloading all the goods, the dumper turns back to the original position, the electromagnet yh2 of the electromagnetic directional valve 5 is powered on, the control pressure oil enters the oil port Z1 of the control cover plate of the cartridge valve 6, and the cartridge valve is closed. At the same time, the oil port X of the control cover plate of the cartridge valve 7 is connected with the oil drain port L, the cartridge valve is opened, and the rodless chamber of the hydraulic cylinder is connected with the oil return port t. The pressure oil enters the rod cavity of the hydraulic cylinder from the oil port a, the piston rod 1 retracts, the pressing beam is loosened, and the pressure oil enters from the oil port C to push the piston rod 2 back to its original position. In this way, the pressing hydraulic cylinder completes a complete action cycle and is ready for the next cycle.

The pressing part adopts a special double piston rod type pressing hydraulic cylinder. The whole process of eliminating spring force is mainly realized inside the hydraulic cylinder through the movement of piston rod 1 and piston rod 2, and the maximum movable stroke of piston rod 2 can be set as the maximum compression deformation of vehicle bogie spring, Avoid the vehicle derailment or falling off the track caused by too large loosening of piston rod 1 with the rolling beam due to too large movement of piston rod 2. In addition, the valve group of the integrated hydraulic control valve is directly installed on the press hydraulic cylinder, and the connecting pipeline between the hydraulic cylinder and the valve group is omitted to avoid the problem that the press hydraulic cylinder does not maintain pressure due to pipeline leakage. In addition, the cartridge valve is selected as the control valve to form a differential circuit during clamping action, which improves the clamping speed of the hydraulic cylinder under the same system flow. In addition, the cartridge valve also has the advantages of fast opening and closing speed, good sealing, less leakage, reliable operation, not easy to jam and easy integration.

(3) Summary

The hydraulic system of car dumper is the key part of the whole unloading equipment. The above pressing principle successfully solves the complex problem that the clamping force increases beyond the standard due to the unloading of goods during the turnover process, and ensures that the vehicle is safely and reliably fixed on the track during the turnover process without derailment and falling off the track.

Home    Article    Railway engineering equipment_ Maintenance of car dumper -- improvement of hydraulic system