Maintenance of tractor in winter

In order to prolong the service life of the tractor and keep it in good technical condition, we must try to prevent and reduce the occurrence of faults. In addition to adhering to the maintenance in accordance with the provisions of the operation manual, the maintenance in the slack season in winter is one of the important measures to prevent tractor failure.
Standard for good technical condition
1. All parts are complete, adjusted correctly and lubricated well. 2. No oil leakage, water leakage and air leakage. 3. The engine output power, fuel consumption and speed meet the specified requirements. 4. The engine is easy to start, sensitive speed regulation and stable speed. 5. The exhaust pipe smoke exhaust is normal, without oil spots, carbon particles, etc. 6. There is no abnormal noise during tractor operation. 7. During full load operation, the water temperature, oil temperature and oil pressure are within the normal range. All moving friction parts shall be free from overheating. 8. The clutch, gearbox, steering, braking and other mechanisms work normally. 9. Electrical equipment works normally without leakage. 10. The auxiliary devices and hydraulic system work reliably and operate flexibly without abnormality.
If the tractor deviates from the above requirements during use, it indicates that its technical state has deteriorated; When the tractor cannot work normally or cannot work, it indicates that its technical state has further deteriorated, which is also called fault.
Causes and analysis of faults
1. Improper operation. Failure to operate in strict accordance with the operating procedures will cause damage to parts and components, resulting in failure. 2. Poor maintenance. Untimely maintenance or improper maintenance will cause rapid wear and damage of parts and cause faults. 3. Improper assembly and adjustment. Improper assembly and adjustment of components or parts will make them unable to work normally. 4. Manufacturing defects. During the use of the tractor, its technical state will gradually deteriorate, and its power, economy, reliability and operation efficiency will also be reduced, or even fail. After the tractor breaks down, some abnormal phenomena will occur, which are called fault signs.
The main manifestations of fault signs are:
One is abnormal function. Complete or partial loss of function of mechanism or parts and components. Such as failure to start, difficult operation, etc.
Second, the temperature is abnormal. The engine or some components are overheated. For example, the water temperature and oil temperature are too high.
Third, abnormal sound. Such as cylinder knocking, shooting, scraping, etc.
Fourth, the appearance is abnormal. Such as blue smoke, black smoke, dim light, deformation and displacement of parts, oil leakage, etc.
Fifth, the smell is abnormal. Such as the smell of burning oil, the smell of burnt friction plate and the smell of rubber after wire burning.
Fault inspection and analysis method
Common inspection and analysis methods include:
1. Partial stop method. The method of intermittently stopping the work of a component or system and comparing the changes of fault signs before and after to judge the fault location and cause. 2. Cross comparison method. The method of replacing suspected faulty parts with parts in normal technical state. 3. Heuristics. The method of changing the technical state of local scope and observing the change of fault signs to judge the cause of fault. 4. Auscultation. This method is used to judge abnormal sound.
How to repair
Make a comprehensive appraisal of the technical status of the tractor to determine whether it needs to be sent for repair. If it is necessary to send for repair, the agricultural machinery maintenance point with repair capacity shall be selected for repair. When sending the tractor for repair, the repair category shall be determined according to the use of the tractor and the results of joint inspection by both parties, the integrity and general technical status of the tractor shall be filled in the handover form for repair, and a maintenance contract can be signed if necessary.
Tractor repair is divided into overhaul and minor repair.
(1) Overhaul. It's a periodic repair. During overhaul, the tractor shall be fully inspected and the parts with wear reaching the limit shall be thoroughly repaired or replaced. The overhauled tractor shall meet or approach the technical performance index of the new vehicle. (2) Minor repair. It is a partial repair. It is mainly used to repair the parts and parts of the tractor with rapid wear, so as to balance the uneven wear between tractor parts, so that the tractor can work normally for an overhaul cycle after one or two minor repairs between two major overhauls. During minor repair of the tractor, it is mainly to comprehensively inspect and repair the engine, locally inspect, adjust and repair the transmission system and walking system according to their technical status, and replace some vulnerable parts.
External cleaning of the whole machine
The tractor to be repaired shall be cleaned externally at the working place with external cleaning conditions. The steps of external cleaning are as follows:
(1) Drain the lubricating oil (engine oil pan, transmission, rear axle, hydraulic system, etc.). Replace with clean diesel oil for rotary washing, and then discharge the diesel oil. (2) Drain the diesel oil in the fuel system and the cooling water of the cooling system. (3) Remove all electrical equipment from the tractor. (4) Flush the outside of the tractor with water.
Disassembly and assembly of complete machine
The tractor is composed of thousands of parts and many components. It has complex structure, accurate processing, tight cooperation and high technical requirements. Therefore, the disassembly and assembly of tractor is a very important link in the repair work. Correct disassembly is conducive to the smooth progress of repair work and is an important premise to ensure the repair quality of tractor.
1. Disassembly of complete machine
(1) General rules of tractor disassembly. The assembly shall be disassembled as a whole, the assembly shall be disassembled into components, and then the components shall be disassembled into parts; From accessories to main parts, from outer layer to inner layer. However, due to the different characteristics of the upper structure of various tractors, the disassembly procedures may be different. Therefore, in order to disassemble correctly, the maintenance personnel must first understand the structure of the tractor. (2) Precautions for tractor disassembly. During disassembly, the following points must be noted:
① Don't dismantle it if you can. What should be dismantled must be dismantled. If it can be concluded that the parts and components meet the technical requirements through inspection without disassembly, it is not necessary to disassemble them. For example, the oil pump does not need to be disassembled if its pressure and oil supply at a certain speed meet the technical requirements through assembly test on the oil pump test bench. If it is difficult to judge the technical status without disassembly, or it is considered to be faulty after preliminary inspection, it must be disassembled for further inspection or repair. ② During disassembly, appropriate disassembly tools shall be used to avoid hard hitting and knocking, so as to avoid damage or deformation of parts. ③ During disassembly, various parts and components shall be checked and marked, and stored by category. If there is no mark, mark the non working surface of the part to maintain the original matching relationship. In order to facilitate assembly, the disassembled parts shall be classified and placed according to the size, precision and assembly relationship of the parts. (3) When disassembling the bolt connector, first distinguish the positive and negative directions of the thread, and select the appropriate disassembly tool before disassembly. For the removal of rusted nuts. It shall be soaked in kerosene, knocked with a hammer and screwed out gradually by repeated tightening. For the removal of broken bolts. It can be disassembled by drilling holes on the bolts, tapping back threads or welding nuts on the bolts.
In addition to the disassembly method of a single bolt, the bolt group shall also be disassembled by symmetrically loosening each bolt by 1 ~ 2 buckles diagonally in the reverse order of assembly, and then disassembled one by one to prevent parts from deformation and damage (such as the disassembly of cylinder head bolt group). When removing the bolt assembly, it should also be noted that the bolts at the difficult parts should be loosened or removed first (such as the bolts near the back of the general oil pan).
The key to the disassembly of interference fit parts is to use special disassembly tools to prevent damage by hand hammer. When removing the interference fitting, first check whether there are supplementary positioning devices such as pins and circlips, then select the correct force application position, apply force evenly, and remove the parts.
Riveted parts are generally not removed during repair. Only remove if replacement is necessary. The rivets are generally removed with a drill during disassembly, but attention shall be paid to prevent damage to the part body.
2. Assembly of complete machine
(1) Preparation before assembly. The cleaning and inspection of parts, as well as the check of part number and assembly mark. At the same time, pay attention to apply lubricating oil to the relatively moving parts before installation. (2) Assembly of connectors. The common connections of tractors include bolt, riveting, interference fit, conical surface, key connection and so on. In addition to meeting the technical requirements, the assembly of these connectors shall be clean and free of burrs.
For bolt connection, lock plate, spring pad, cotter pin and stop wire must also be used reasonably.
Bolts and nuts for important connections (such as main bearing bolts and connecting rod bolts) shall not be interchanged as far as possible during installation, and the bolts shall be kept clean and fit with the joint surface.
For the assembly of bolt group, the force shall be applied evenly and tightened in a certain order. One strand shall be tightened step by step in the middle and diagonal (such as the tightening of cylinder head bolts). Important bolts (such as connecting rod bolts, main bearing bolts and cylinder head bolts) must be screwed to the specified torque distance with a torque wrench.
Cleaning of parts
The cleaning of parts is an important part of repair work. The cleaning method and effect of parts directly affect the accuracy of part identification, repair cost and service life of the repaired machine.
The common dirt of parts is greasy, carbon deposit and scale. To remove the above dirt, different methods shall be used for parts with different materials and different accuracy to clean the dirt without damaging the part body.
1. Oil crisp cleaning
When cleaning steel or cast iron parts, generally use water melt with 10% caustic soda and 0.2% emulsifier (such as soap, water glass, etc.), heat it to above 90 ℃, and boil and wash the parts for 30 minutes. In order to improve the cleaning effect, frequently stir the solution. In order to avoid the corrosive effect of alkali on metal, the boiled and washed parts shall be cleaned of saponification with a cloth or brush after removal. Finally, wash it with hot water at 60 ~ 80 ℃ and dry it by itself. The parts with small holes shall be dried with compressed air.
Aluminum alloy parts shall be cleaned with weak alkali solution, and the solution shall be aqueous solution of caustic soda 1% and emulsifier 0.4%.
Rubber and leather parts shall not be cleaned in alkaline or acidic solution. If necessary, they can be cleaned with alcohol.
Precision parts (such as plunger, oil outlet valve, injector needle valve and other precision coupling parts and bearings) should be cleaned with diesel, kerosene or gasoline rather than boiled with alkaline water. In addition, attention shall be paid to the pairing of precision coupling parts, which shall not be interchanged.
2. Removal of carbon deposits
Most of the carbon deposits accumulate on the cylinder head, piston, valve and injector. The carbon deposit is firmly combined with the part surface. It is usually removed by mechanical and chemical methods.
(1) Remove carbon deposits mechanically. This method is to make a special metal brush or scraper according to the shape of the removed part, and scrape off the carbon deposit with a brush or scraper. This method is simple, but it is difficult to remove the carbon deposit, and affects the surface roughness of the parts, resulting in scratches on the surface of the parts. (2) Remove carbon deposits chemically. This method is to keep the parts in the chemical solution for a certain time to soften the carbon deposit and remove it.
For steel and cast iron parts, the following chemical solution formula (kg of chemical added to 100 kg of water) can be used:
Formula 1: caustic soda 2.5, sodium carbonate 3.3, sodium silicate 0.15, soap 0.8. Formula 2: caustic soda 10, potassium dichromate 0.5.
The heating temperature of the solution is 80 ~ 95 ℃, and the soaking time of parts is about 2 ~ 3 hours.
For aluminum alloy parts, the following chemical solution formula can be adopted (kg of chemical substance added to 100 kg of water):
Formula 1: sodium carbonate 1.85, soap 1.0, sodium silicate 0.85. Formula 2: sodium carbonate 1.0, soap 1.0, potassium dichromate 0.5.
The heating temperature of the solution is 80 ~ 95 ℃, and the soaking time of parts is about 2 ~ 3 hours.
Soak the parts for the specified time by the above chemical method, then take out the parts, wipe the carbon deposit with a brush or cotton thread, and finally wash and dry them with hot water (add 0.1 ~ 2.3% potassium heavy lead acid in the water).
3. Scale removal
The main components of scale are calcium sulfate, calcium carbonate and calcium silicate. Some contain one ingredient, while others have several ingredients at the same time.
Scale containing more calcium carbonate and calcium sulfate can be cleaned with 8 ~ 10% hydrochloric acid solution. In order to prevent parts from being corroded by hydrochloric acid, atropine can be used as corrosion inhibitor. The addition amount of corrosion inhibitor is 3 ~ 4G per liter. The solution temperature is 50 ~ 60 ℃, and the cleaning time is about 1 hour. After treatment with hydrochloric acid solution, it shall be cleaned with aqueous solution added with potassium heavy lead acid (5g per liter of water), or 5% caustic soda aqueous solution shall be injected into the cleaned parts to neutralize the residual hydrochloric acid solution. Then rinse with clean water until it is clean.
Scale containing more calcium silicate shall be cleaned with 2 ~ 3% caustic soda solution. During cleaning, the temperature of the solution is 30 ℃, the soaking time is 8 ~ 10 hours, and then rinse with clean water.