How to Judge the Front PTO Tractor Failure
"Look, smell, ask and touch" is an important means of traditional Chinese medicine diagnosis in China. Similarly, for front PTO tractor repairmen, borrowing the "look, smell, ask and touch" working method to front PTO tractor fault judgement has a very good effect and is very practical. Let's take a look at the "look, hear, ask and touch" diagnosis method in the fault diagnosis of front PTO tractor hydraulic system.
"Look" is to see and observe the fault phenomenon of the front PTO tractor.
Look at the lifting and lowering, and carefully observe the changes of the lifting and lowering speed of the front PTO tractor lifter lifting agricultural machines and tools and whether they are smooth and stuck. If the lifting is too slow, the load may be too large or the pressure may be low; If the lowering speed is too fast, it is unsafe. Readjust the lowering speed regulating valve; If the agricultural machinery swings too much, the connecting rod may be loose and worn, and the loose and worn parts shall be carefully inspected.
Look at the color. Long time heating will change the appearance color of hydraulic system pipeline and gear pump, mostly yellow. Look at the pipeline, that is, diagnose the fault by looking at the appearance of the pipeline, mainly observe whether there is oil seepage at the front PTO tractor oil pipe joint, whether the oil circuit pipe fittings are deformed and damaged, and whether the control lever is deformed and damaged.
"Smell" is to smell the smell and listen to the sound.
After the front PTO tractor breaks down, one is to smell whether there is abnormal smell, and the other is to listen to whether the sound is abnormal. For example, when the sound of "rattling" is heard after the front PTO tractor is lifted with agricultural machines and tools, it is often the automatic settlement caused by the poor sealing of the distributor safety valve or valve rod;
If there is no obvious "rattle" sound, but the agricultural machinery has slight automatic settlement, which is mostly caused by poor sealing of oil cylinder piston; If there is no obvious "rattle" sound, but there is rapid automatic settlement of agricultural machines and tools, it is mostly caused by poor sealing of distributor check valve;
Large noise is heard near the safety valve, mostly due to excessive pressure and opening of the safety valve for oil unloading. The main causes and treatment methods of this noise are as follows:
(1) The handle does not return to the neutral position after the strong pressure elevator is lifted to the highest position, the safety valve opens and makes noise during oil unloading, so the handle should be quickly returned to the neutral position
(2) When the non forced pressure lifter is lifted to the highest position, the inner lifting arm collides with the shell, the safety valve is opened and the oil unloading makes noise. The lifting height should be quickly reduced and readjusted to ensure that there is a gap of 3-5mm between the inner lifting arm and the shell when it is lifted to the highest position.
"Ask" is to ask about the fault symptoms.
In the fault diagnosis of front PTO tractor hydraulic system, inquiry is that the maintenance personnel ask the driver about the operation status of the front PTO tractor, understand the repair and maintenance of the hydraulic system and the working conditions of hydraulic components, ask the process of the fault, and find out whether the fault is sudden or gradual. Because the operator is familiar with the front PTO tractor performance and is on site when the fault occurs, the information provided is very helpful to the fault analysis. Maintenance personnel usually ask the following questions:
1. When has the front PTO tractor hydraulic system been maintained.
2. Whether the brand of hydraulic oil meets the regulations and whether the dosage is appropriate.
3. Whether a button is pressed by mistake and a program is executed when the fault occurs.
4. Compare the use of hydraulic system before and after the fault in order to analyze the cause of the fault.
5. What are the abnormalities of the front PTO tractor hydraulic system during operation, and whether there are signs such as smoke, peculiar smell, non lifting, weak lifting, falling, abnormal vibration, etc.
Some useful information can often be obtained through inquiry, which is conducive to analyzing the causes of faults according to the working principle of the equipment and repairing them in time.
"Touching" means touching and measuring.
If the temperature of the hydraulic system of the front PTO tractor is too high during normal use, it will cause damage to the hydraulic system of the front PTO tractor. First, it will affect the oil suction capacity and volumetric efficiency of the hydraulic pump; Second, it will cause abnormal operation of the hydraulic system, unstable pressure and speed, and unreliable action; Third, the internal and external leakage of hydraulic components will increase; Fourth, it will accelerate the oxidation and deterioration of oil.
Pay attention to the temperature rise of hydraulic oil at any time during operation. During normal operation, the oil temperature of hydraulic oil and chassis oil shall not exceed 60 ℃, otherwise, stop the front PTO tractor, find out the problem and repair it in time. Without measuring instruments, the temperature rise of the hydraulic system can be judged by finger touch.
Human finger touch is very sensitive and can accurately judge various abnormal temperature rises, with an error of 3-5 ℃. When the temperature is about 40 ℃, it feels like touching a patient with high fever; At about 60 ℃, it feels very hot, but it can endure about 10 seconds; When the temperature is above 80 ℃, the instantaneous touch will feel "numb and hot", and scald can occur if the time is a little longer. Pay attention to safety during "touching" examination! Prevent finger burns! When checking the temperature rise, pay attention to the touch method of the hand. Generally, first touch the surface of the machine quickly with the back of the index finger and middle finger close to the right hand, and then touch it with the finger belly or palm after it is determined that the temperature is not high and will not cause damage to the skin.