When visiting the tractor market, both dealers and users have many criticisms about the tractor hydraulic system, reflecting that the hydraulic system has many faults and is prone to failure. The most common hydraulic system failures include oil leakage, automatic settlement, weak lifting, no lifting, gears The pump is broken, the distributor is broken, the multi-way valve is broken, the oil cylinder is broken, etc. Today, I will talk to you about the reasons for the high failure rate of agricultural machinery hydraulic pumps.
The hydraulic suspension system of the tractor is mainly composed of three major components: cylinder, pump, and valve. According to the positional arrangement and combination of the three components of the oil cylinder, gear pump, and distributor, it is generally divided into three categories: split hydraulic system (strong pressure system). ), semi-split hydraulic system, and integral hydraulic system (non-pressure system). At present, the hydraulic lifting system on the domestic high-horsepower tractor mostly adopts the double-cylinder strong pressure type. The main components include a gear pump (double-gear pump), a multi-channel integrated hydraulic valve, two double-acting lifting cylinders, etc. Most of the high-horsepower tractors of foreign brands are non-high-pressure types, and most of them have adopted electronically controlled hydraulic lifting technology, which greatly reduces the driver's operating intensity, and the electronically controlled hydraulic lifting system has good reliability and low failure rate. At present, there are also few domestic high-power tractors. Part of the use of electronically controlled hydraulic technology, but due to factors such as poor cleanliness, high failure rate, high price, and poor reliability of the electronically controlled hydraulic system for domestic tractors, the market promotion of the electronically controlled hydraulic system is difficult, and the common people do not accept it. The user of the tractor with the electronically controlled hydraulic lifting system requires the dealer and the manufacturer to change it back to the extreme case of mechanical operation.
Through market research, we have learned that the main reasons for the high failure rate of the hydraulic system of domestic high-horsepower tractors are as follows:
1. The three components of the cylinder, pump, and valve are of poor quality, poor manufacturing precision, and cheap price. In order to reduce costs, some tractor manufacturers believe that there is no need to use better hydraulic components on tractors, and the accuracy of domestic hydraulic components itself is not high, so the three components of the hydraulic system used on domestic tractors are generally of poor quality. In addition, some manufacturers lack the ability to detect hydraulic components, which makes the lifting cylinder, gear pump, distributor, and multi-way valve indistinguishable, and various failures occur frequently in use.
It is also very strange for manufacturers to judge the quality of these accessories. Most of them are feedbacked through the market failure information after use. Too many failures are not good. In turn, check the quality of the stock parts. Part manufacturers come to analyze, rather than mainly control the quality through incoming inspection, or take the initiative to control the proportion of incoming parts quality. There are too many faults due to poor quality, such as oil leakage at the sealing ring of the piston rod of the lifting cylinder, oil leakage at the limit valve, fracture of the piston rod head, cracking of the base of the lifting cylinder, easy wear at the connecting pin hole of the lifting cylinder, leakage of the gear pump Oil, gear pump casing cracks, gear pump internal leakage, distributor oil leakage, distributor seal leak, automatic settlement, etc.
2. After the "big horse-drawn trolley", the farm implements brought by the tractor are getting larger and larger, but the lifting force of the tractor has not been effectively improved synchronously, which makes the hydraulic system overload and causes frequent failures. For example, in TF series models, originally in 1304, the maximum weight of farm implements was generally less than 1000KG. After TF was upgraded in 2004, the weight of farm implements became larger and larger. Some of the maximum weights were upgraded to about 1400KG and 1500KG. If it is heavier, the required lifting force of the tractor will be larger. According to the physical formula F=PA (F is the thrust of the oil cylinder, in Newton; P is the unit pressure of the pressure oil in the oil cylinder, that is, the pressure, in N/square meter; A is The action area of the oil cylinder, the unit is square meters), the method to increase the thrust of the oil cylinder, one is to increase the action area A of the oil cylinder, and the other is to increase the unit pressure P of the system. Increase the lifting force of the cylinder when the unit pressure P of the system is present; if the area A of the hydraulic cylinder oil pressure is not increased, when a larger lifting force is required, the unit pressure P of the hydraulic system will increase, and the lifting pressure will even exceed The opening pressure of the safety valve set by the original hydraulic system (usually 18±0.5MPa, which is different for each model, in order to increase the lifting force in actual operation, the opening pressure of the safety valve will be further artificially increased, such as adjusting the pressure adjustment bolt to the right Rotate 1/4-1/2 turn and then re-lock), the lifting force of the oil cylinder increases after the unit pressure P of the hydraulic system increases, but the hydraulic system will have many side effects due to the overload pressure, such as the high temperature of the hydraulic system, Easy to leak oil, damaged gear pump, weak lifting, etc. It is suggested that after the horsepower of the tractor increases, the hydraulic lifting system should be improved accordingly to increase the lifting force, and increase the strength of the hydraulic suspension mechanism to meet the matching requirements of agricultural machinery and implements, and avoid various kinds of problems caused by insufficient lifting force and insufficient strength of suspension rods. failure.
3. The quality of the pressure tubing and pressure hose fittings is poor. In actual use, there is often trachoma oil leakage, oil leakage due to poor welding quality, oil leakage due to poor crimping quality at the hose joints, etc. It is recommended that manufacturers strengthen the quality control of oil pipes. Long and unreasonable tubing should be improved and fixed.
4. The assembly quality of the hydraulic system is poor. The O-rings at the oil pipe joints are not assembled properly, the edges are trimmed, the bolts are not tightened, and even the O-rings are missing. The assembly workers of most manufacturers have high mobility. Additional training and important quality control point positions are held by fixed old employees, and assembly quality inspections are strengthened to reduce unnecessary assembly quality problems.
5. The hydraulic system has poor cleanliness. The cleanliness of the hydraulic system of domestic tractors is relatively poor, and the poor cleanliness of the hydraulic system will bring a series of problems. Originally, the accuracy of the domestic distributor and multi-way valve is not high. If the fitting gap is large, there will be leakage, or the dirty things will cushion the valve core to cause leakage, or even cause the valve to become stuck. In addition, poor cleanliness will cause the filter element to be easily blocked. If the hydraulic filter element is not replaced in time, it will cause the hydraulic system to be weak and slow to lift. , Poor cleanliness is a long-standing problem in the hydraulic system. I hope the manufacturer can systematically analyze and consider improving the cleanliness of the hydraulic system and improve reliability of the hydraulic system.
6. Improper use and maintenance by users. The normal use of the hydraulic system requires users to use and maintain it regularly, especially in the case of a high incidence of domestic tractor hydraulic system failures. However, many users take the method of using the hydraulic system as long as it is not replaced. When the tractor is in use, firstly, the hydraulic oil and filter element should be replaced after running-in; secondly, the filter element and hydraulic oil should be replaced regularly, and the hydraulic oil should be checked regularly. Ensure sufficient cleanliness, without secondary pollution of the hydraulic system, and avoid the situation that the more repairs are made, the dirty and the worse the repairs are. Later, we will explain in detail the use and maintenance knowledge and specific operation methods of the tractor.
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