The Reasons for the Failure of Tractor Hydraulic Lifting System

The hydraulic lifting system of a tractor is mainly composed of a gear pump, a lifting cylinder, a distributor (multi-way valve) and a connecting oil pressure hose. The main function of the gear pump is to provide high oil pressure for the hydraulic system, and the main function of the lifting cylinder is for farm tools ascending or descending, the main function of the distributor is to control the direction of the pressure oil flow.

 

Tractors often have hydraulic system failures in use. The hydraulic lifting system is the system with the highest failure rate on the tractor. According to statistics, the failure rate of the hydraulic lifting system of the medium-sized tractor in 2018 reached 24.84%, and the failure rate of the hydraulic lifting system of the large tractor reached 49.58%. On average, at least one of the two high-horsepower tractors has experienced hydraulic lifting problems. The failure rate of the hydraulic lifting system of high-horsepower tractors is exactly twice that of medium-sized tractors. This shows that as tractor horsepower increases, the reliability of the hydraulic lifting system is getting worse.

 

According to statistics, the failures of the hydraulic lifting system of large tractors accounted for 19.0% of all tractor failures in 2018, ranking first among all systems.

 

Among the failures of the hydraulic lifting system of medium and large tractors in 2018, the failure of weak lifting power is very prominent. Next, we will analyze the common failure causes of the hydraulic lifting system.

 

1. The agricultural machinery is too heavy, or it does not match the tractor, or the connecting hole of the pull-down rod and the lift rod is used improperly.

If the new vehicle is equipped with agricultural machinery and the lifting is weak, first you should consider whether the agricultural machinery is too heavy and the agricultural machinery does not match the tractor. If other tractors of the same model are also equipped with this type of agricultural machinery, and the lifting is normal, it’s the tractor’s hydraulic lifting problem. If other tractors of the same model cannot be lifted, it is caused by a mismatch between the tractor and the agricultural machinery or the agricultural machinery is too heavy. If it is an agricultural machinery that has been used for a period of time, and it is used to be able to lift normally, but now it is weak to lift, it must be the problem of the tractor itself. There is also a possibility that the hole connecting the pull-down rod and the lifting rod is wrong. Some tractors have two holes for the pull-down rod to connect with the lifting rod. If you use the front hole to connect, the lifting force of the tractor will be smaller. If the rear hole is connected, the lifting force will be larger, which is mainly caused by the change of the length of the moment arm, so when supporting heavier agricultural tools, the lifting rod should be connected to the hole behind the down rod.

 

 

2. The hydraulic oil filter is clogged and the lifting is weak. 

The clogging of the hydraulic oil pressure filter is also a common failure of the hydraulic system. The cause of the clogging is poor cleanliness of the hydraulic oil, long time no oil change, deterioration of the hydraulic oil, etc. At this time, the fuel water separator filter should be cleaned and replaced.

 

 

3. The tractor's lifting hydraulic oil is insufficient and the oil path has oil leakage.

First, check whether there is oil leakage in the hydraulic oil path and whether the hydraulic oil is sufficient. If there is oil leakage or insufficient oil, supplement the hydraulic oil to the specified oil level, check and eliminate the oil leakage. You can find it on the oil pressure indicator.

 

 

4. The hydraulic oil model of the tractor is not suitable.

For example, the hydraulic oil added to the tractor has poor low temperature resistance. When the temperature is low in winter, the oil viscosity is high, the hydraulic oil filter is slow to filter, and the oil throughput is insufficient. At this time, add hydraulic oil that meets the requirements of the tractor manual.

 

 

5. The hydraulic pipeline takes in air, that is, the air is sucked in from the oil suction path.

If the suction path of the lifting system is not tightly sealed and suck in air, it will mix the air and oil to form a foam and produce emulsification. The air is easily compressed and the volume becomes smaller, resulting in lower lifting pressure and weak lifting. If it is found that the tractor is unable to lift agricultural tools and there is foam in the hydraulic oil tank, carefully check the tightness of the pipeline and remove the air from the hydraulic system, and tighten the oil pressure switch.

 

6. It may be caused by low pressure of the distributor or the safety valve.

When the tractor is lifting agricultural tools, the safety valve is opened in advance due to the low pressure, and the hydraulic oil pressure in the hydraulic lifting system is reduced, resulting in weak lifting. At this time, the opening pressure of the safety valve should be adjusted.

 

 

7. The oil temperature of the hydraulic system is too high and the lifting is weak.

If the temperature of the hydraulic lifting system is too high, the viscosity of the lifting hydraulic oil will decrease, and the leakage in the hydraulic system will increase, resulting in a large pressure loss and weak lifting. So we should pay attention to the pointer on the tractor oil pressure gauge.

 

 

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