How to adjust the hydraulic system of the loader if there are many problems?

Q: What should I do if the boom operation is normal, but the bucket flips slowly, weakly, or has no movement?

Answer: In the hydraulic system of the homework equipment, if only the boom is working normally, the turning bucket will flip slowly, have no action or be powerless. According to the principle of hydraulic operation and the measured system pressure of 16Mpa, it can be seen that the boom lifting is normal, which indicates that the working pump and main safety valve are working normally, and the supplied pressure is met. At the same time, it also indicates that there are no problems with the pump inlet pipeline, oil filter, and oil tank oil quantity and quality. At this moment, all that is needed is to inspect the rotary slide valve, the double effect safety valve of the rotary chamber, the rotary cylinder, the oil pipe of the rotary section, and its seals.

The diagnosis and cleaning methods for hydraulic transmission problems are similar, and the treatment methods for the same rotary bucket and boom parts are also basically the same. Therefore, the treatment can be carried out according to the method of problem one. Another thing to note is that double effect safety valves are installed on the large and small chambers of the rotary bucket oil cylinder, which have overload maintenance and oil replenishment effects, and also control the pressure of the two chambers. The slow, weak, or unresponsive operation of the rotary bucket is still related to the low control pressure of the two double effect safety valves, which is also a common problem. Therefore, it is also important to inspect the double effect safety valves.

Check and adjust the pressure of the small chamber safety valve of the rotary bucket oil cylinder: Connect a 20Mpa range pressure gauge to the pressure measuring point at the oil pipe joint, raise the boom to a horizontal position, idle the engine, operate the rotary bucket valve stem to make the rotary bucket tilt forward to the maximum position, and the rotary bucket slide valve returns to the neutral position; Then operate the slide valve to raise the boom. At this moment, the pressure gauge reading should be 12Mpa. If there are differences in parameters, roll the pressure regulating screw, twist in the pressure to increase, and twist out the pressure to decrease. This method can also eliminate the problem of automatic bucket retraction during shovel loading operations.

Check and adjust the pressure of the safety valve in the large chamber of the rotary bucket oil cylinder: It is necessary for the pressure in the large chamber to be higher than the system pressure, and the standard pressure is 18Mpa. Connect a 25Mpa range pressure gauge to the pressure measuring point at the oil pipe joint. The pressure of the main safety valve can be adjusted to 18Mpa first, and then the large chamber of the rotary bucket cylinder can be loaded. At this moment, the pressure gauge reading should be at 18Mpa. If there are differences in parameters, the pressure regulating screw should be rolled and twisted in to increase the pressure and out to decrease the pressure. It is necessary to pay attention to the reliability and pressure safety of the joints of each oil pipe when increasing the pressure in this method.

If the pressure regulation does not work, it is possible that the double effect safety valve does not work. Disassemble the double effect safety valve and check the gap between the valve hole and the valve stem. The standard value is 0.01-0.02mm, and the limit is 0.035mm. Check that the tension spring pressure should be greater than 660N.