(1) Farm tools can not be lifted
When the engine is working, pull the control handle to the lifting position, the suspension rod has no lifting action, and should be checked externally.
1) External inspection: ① hydraulic oil pump transmission mechanism is engaged. ② Whether the oil level height of the hydraulic tank is correct. ③ Whether there is a large amount of hydraulic oil leakage due to the rupture of the tubing and the loosening of the joint. ④ Whether the gap of 10~15mm between the cylinder positioning valve and the positioning baffle is guaranteed. ⑤ Whether the weight of the hanging farm tools exceeds the rated bearing capacity. ⑥ Whether the compression nut of the self-sealing joint is loose, if loose, the closing valve will be closed, and the hydraulic oil will not enter the cylinder from the distributor. In general, external causes can be ruled out immediately after they are found.
2) Analysis and judgment of internal faults. Verify that the external fault is normal, and then check the internal fault. The hydraulic components of the hydraulic system sleeve pump, distributor, cylinder, etc.) are all working in a sealed state, and the fault part cannot be directly observed. It can take the distributor as the center, through changing the different positions of the distribution handle, observe the different phenomena reflected in the distributor and its surroundings, analyze, judge, check in stages, and troubleshoot.
After the engine is running, the distributor control handle is placed in different positions, and the following phenomena will occur. ① After the distributor handle is placed in the "lift" working position, the handle immediately jumps back to the "neutral" position with a sound of "click", and the farm tools cannot be lifted. If the forced handle stays in the "lift" position, and the distributor finds a sharp "rattling" sound (safety valve opening sound), the engine running sound becomes heavy, the load increases significantly, and the oil pipe leading to the lower chamber of the cylinder shakes, this failure indicates that the oil pump and the distributor are working normally, and the oil line leading to the cylinder is blocked. In most cases, the positioning valve is stuck in the closed position or the buffer valve is blocked by dirt. ② After the distributor handle is placed in the "lift" position, the farm tool is not lifted, the handle is not jumped, and the engine load is not changed. This indicates that there is leakage inside the hydraulic system, so that the oil can not establish high pressure, the reason may occur in the oil pump, the distributor, the cylinder needs to be further checked.
First press the positioning valve on the cylinder to block the return oil circuit of pressure drop. Then place the distributor handle in the "pressure drop" position for fixing. Two things can happen. The first case: the distributor makes a sharp "rattle" sound, the engine sounds heavy, and the load increases, which indicates that the oil pump and the distributor work normally, and the cause of the failure occurs in the oil cylinder. The second case: the distributor does not sound and the engine load does not change, which indicates that the fault occurs in the distributor and the oil pump, and the distributor should be checked first and then the oil pump.
Most distributor failures occur at the oil return valve. When the oil return valve is in the open position, it is stuck in the guide sleeve or the cone of the oil return valve and the valve seat are not tightly sealed, so that the oil pumped by the oil pump cannot go to the cylinder and leaks directly from the oil return valve to the tank. In the event of such a failure, a small wooden hammer can be used to gently tap the oil return valve in the distributor to make the oil return valve fall back to the seat due to vibration or remove the oil return valve, so that the valve can move flexibly in the guide sleeve hole and be cleaned and installed with diesel oil. In special cases, the guide sleeve together with the oil return valve must be removed, clean in clean diesel oil and check whether the valve body tail in the guide sleeve is flexible, if there is a stuck phenomenon, apply oil mixing until the valve can move flexibly in the guide sleeve hole, then clean and put back in place.
In the case of normal operation of the oil return valve, if still can not lift, need to check the oil pump. The failure of the oil pump generally occurs at the triangle pressure rubber ring and the self-tightening oil seal of the drive shaft. When the pressure rubber ring is damaged, the high and low pressure oil chamber is connected, resulting in a sudden decline in the working capacity of the oil pump, such as touching the pump shell by hand will feel the temperature is very high, need to replace the new rubber ring. When the self-tightening oil seal is damaged, the working capacity of the oil pump will suddenly decline, and there will be an increase in the engine oil pan oil. When replacing the self-tightening oil seal, the sealing ring on the shaft sleeve should be checked to prevent the early damage of the self-tightening oil seal caused by the aging and failure of the sealing ring.
In addition to the above analysis and judgment, the automatic spring is weakened or broken, and the oil return valve is opened in advance due to the broken safety valve spring
2) Lack of ascension
The lifting capacity is not up to the technical requirements (the lifting force per kilowatt of traction power should not be less than 300N). The reasons are:
1) Gear oil pump is seriously worn. The reason is mainly caused by long-term overload work or hydraulic oil is too dirty.
2) The safety valve pressure is too low or oil leakage. The reasons are: ① improper adjustment pressure; ② The lock nut is loose, causing the safety valve sleeve to loosen; ③ Press the plastic deformation of the spring to reduce the elasticity; ④ Valve and seat wear, strain or dirt stuck. Carefully disassemble the parts of the safety valve. If the parts are damaged or deformed, they must be repaired.
3) The main control valve sleeve is seriously worn. Replace the main control valve sleeve and grind it with the main control valve.
4) The cylinder piston seal ring is damaged. Replace piston seal ring.
5) The sealing rings at both ends of the shaft sleeve are damaged. Replace the seal ring.
6) The sealing ring of the lowering speed regulating valve or cut-off valve is broken. Replace the seal ring.
(3) Slow lifting of farm tools
When the hydraulic system is equipped with different farm tools, the required lifting speed is also different, for the suspension plow, the lifting time from farming to transportation state is not more than 2 seconds for medium and small tractors, and not more than 3 seconds for large tractors. The main reasons for the slow promotion:
1) Intake pipe suction air. This is because the seal between the inlet pipe and the oil pump and the fuel tank is not strict, or the damage of the oil pipe, or the damage of the oil seal of the driving gear will cause the air to enter the oil passage, causing the air and oil to stir into a foam and produce emulsification. After pressure, the volume of gas is reduced, so that the working pressure is reduced, resulting in slow lifting of farm tools. Check the pipe and O-ring carefully, tighten the nut and replace the O-ring if necessary, and weld the hole again if found. If it is found that the working pressure is insufficient, and there is foam in the tank, the air of the hydraulic system should be excluded. Remove method, manipulate the distributor handle, continuously lift several times, and then loosen the upper and lower cavity of the cylinder air discharge screw, and tighten it again after the air is exhausted. The air in the pipeline is generally caused by the loosening of the nut or screw of the pipeline joint, or the aging damage of the O-ring seal and the welding porosity.
2) The oil return valve in the distributor is stuck in the guide sleeve and can not be closed, and the oil from the hydraulic pump flows back to the tank from the oil return valve, making the cylinder pressure too low.
3) The oil temperature of the hydraulic system is too high or too low, and it will also slow the lifting of farm tools. When the temperature is too high, the viscosity of the oil decreases, the leakage increases, and the pressure loss is large. The oil temperature is too low, the viscosity of the oil is large, the oil tank filter is slow, the hydraulic oil flow performance is poor, and it is not easy to flow into the oil pump and suction pipe, and this phenomenon is easy to occur in winter. Therefore, before winter operation, it is necessary to preheat the oil circulation of the hydraulic system itself to keep the oil temperature at the normal working temperature.
4) The hydraulic pump leakage is serious, so that the flow of the oil pump is reduced, resulting in slow lifting of farm tools. This is due to the long-term wear of the oil pump or the failure of the seal ring of the oil pump, causing leakage. If the seal is aged or damaged, replace it with a new seal. If the shaft sleeve and gear pair wear, generally do not repair, need to replace the new pump.
5) The contact between the distributor return oil valve and the seat is poor, so that the seal is not strict, resulting in slow lifting of farm tools. The valve and seat can be cleaned with diesel and put back in place. If the hydraulic oil is too dirty, the hydraulic oil should be replaced.
6) The distributor safety valve pressure is low, open in advance when working, and the hydraulic pressure in the hydraulic system is reduced. Lifting farm tools is slow. Solution: Adjust the opening pressure of the safety valve and replace the spring of the safety valve.
7) The oil filter is blocked. Clean the oil filter, line and hoist housing and replace the hydraulic oil.
8) The hydraulic oil level is too low. Sufficient hydraulic oil should be filled.
(4) Farm implements cannot be kept in transport condition
1) In the state of transport, the hanging farm tools are not overweight, if the piston rod sink more than 8mm within 30 minutes, it may be due to wear at the piston seal or there is greater wear between the slide valve and the hole in the distributor. The distributor control handle can be placed in the lifting position to lift and depress the positioning valve on the cylinder to check. If the settlement stops and shrinks after the positioning valve is depressed, this indicates that the distributor slide valve is worn, and the reverse is the piston seal wear. This fault needs to be repaired and replaced with new products.
2) Oil leakage in the place where the piston rod is connected with the piston in the cylinder will also cause farm tools to not be kept in the transport position. Simply tighten the nut on the piston rod to eliminate this fault.
