Abstract: Reasonable use of lubricating oil can reduce the occurrence of faults and extend the service life of machinery. The performance characteristics of lubricating oil, gear oil, and lubricating grease for agricultural machinery were emphasized, providing reference for the correct selection of lubricating oil.
Keywords: Agricultural machinery; Lubricating oil; use
The lubricating oils used in agricultural machinery include engine lubricating oil, gear oil, and lubricating grease. Reasonably using lubricating oil to provide good lubrication for agricultural machinery can reduce wear, improve the performance of machinery, reduce the occurrence of faults, and extend the service life of machinery.
1. Engine lubricating oil
The power engines of agricultural machinery are mainly diesel and gasoline engines. Diesel engines have advantages such as high thermal efficiency, good fuel economy, reliable operation, and good fire safety. Combine harvesters, tractors, agricultural trucks, etc. are all powered by diesel engines. The characteristics of gasoline engines are lightweight, good low-temperature starting performance, and smooth operation. They are mostly used in rice transplanters and plant protection machinery. Engine lubricating oil is divided into two types: gasoline engine oil and diesel engine oil.
1.1 Engine requirements for lubricating oil
When the engine is working, there must be friction between the relative motion surfaces of the transmission components, such as the crankshaft and main bearings, piston rings, and cylinder walls. The friction on the metal surface not only increases the internal power consumption of the engine, but also causes rapid wear on the working surface of the parts. The large amount of heat generated by friction will cause the piston to melt. In order to ensure the normal operation of the engine, it is necessary to have a good lubrication and cooling system. The lubrication system lubricates the surfaces of relatively moving parts, creating a layer of oil film between the metal surfaces to reduce frictional resistance, reduce power loss, reduce component wear, and extend engine service life. The lubrication of engine components by lubricating oil can be divided into three types: fluid lubrication, boundary lubrication, and extreme pressure lubrication.
(1) Fluid lubrication. The two moving solid surfaces are completely separated by the lubricating oil film, and the resistance to movement comes from the internal friction of the lubricating oil. The magnitude of the friction force is only related to the viscosity of the oil.
(2) Boundary lubrication. As the load increases, the motion speed of the two objects decreases or the viscosity of the lubricating oil decreases, and the oil film between the friction surfaces becomes thinner. When the thickness of the oil film is roughly equal to the height of the convex and concave surfaces of the solid, local contact occurs between the two solid surfaces, and friction increases, resulting in wear, which is called boundary lubrication.
(3) Extreme pressure lubrication. As working conditions deteriorate, the degree of possible rupture of the lubricating oil film increases. Under extreme pressure lubrication conditions, if there are no anti extreme pressure additives in the lubricating oil, it can cause friction surface abrasion and friction melting.
1.2 Application scope of engine lubricating oil
(1) Gasoline engine lubricating oil is mainly used in gasoline engines and medium to low speed diesel engines. There are four grades of single stage gasoline engine lubricating oil produced in China: HQ6, HQ8, HQ10, and HQl5 (the number represents the viscosity of the oil), which are determined according to the season when selecting. The 6th gasoline engine lubricating oil is suitable for winter, the 8th is suitable for severe winter season, the 10th is suitable for summer, and the 15th is suitable for gasoline engines and medium to low-speed diesel engines operating at high temperatures.
(2) Diesel engine lubricating oil is mainly used on high-speed diesel engines. The main difference from gasoline engine lubricating oil is the addition of multifunctional additives, which have good antioxidant performance. The traditional single stage diesel engine lubricating oil has three grades: HC-8, HC-11, and HC-l4, and the selection should also be determined according to the season. The 8th is suitable for winter, the 1st is suitable for summer, and the 14th is suitable for high-speed diesel engines operating at high temperatures. In addition, diesel engines can also choose engine oil grades based on the material of the bearing shells. If the diesel engine bearings are made of copper alloy, choose engine oil No. 8 or No. 11 in winter and spring, and engine oil No. 11 or No. 14 in summer and autumn. If the diesel engine bearing shells are made of bus alloy, use No. 6 gasoline engine oil in winter and spring, and No. 10 or No. 15 gasoline engine oil in summer and autumn. In recent years, lubricant production enterprises have produced QC, QD, QE, and QF multi-stage diesel engine lubricants in accordance with the world's general standards.
2. Gear oil
Gear oil is divided into two types: general gear oil and hyperbolic gear oil. General gear oil is commonly used for lubrication of gears in automotive, tractor transmissions, and Z-final drive devices. The performance requirements for gear oil are: good oil properties, good viscosity and temperature, good low-temperature fluidity, good thermal oxidation stability, high compressive and wear resistance, and good corrosion resistance. According to the national standard GB7631.7-89, domestic automotive gear oil is divided into three levels: CLC, CLD, and CLE. CLC (GL-3) is a common vehicle gear oil; CLD (GL-4) is a medium load vehicle gear oil; CLE (GL-5) is a heavy-duty vehicle gear shaft.
A mechanical transmission is composed of spur and helical gears, and its meshing tooth surfaces are in line contact, which can form fluid lubrication (under light load conditions) or elastic fluid lubrication (under heavy load conditions). However, the meshing tooth surfaces of the drive axle spiral reduction gear are not as prone to oil wedges as transmission gears, while the meshing tooth surfaces of the hypoid gear are difficult to form fluid lubrication or elastic fluid lubrication film due to lateral sliding, and are basically in a boundary lubrication state under heavy load conditions. Therefore, the viscosity of gear oil plays a major role in the friction of mechanical transmissions, while the friction of spiral bevel gear reducers and hypoid gears mainly depends on the chemical properties of the gear oil. So, for mechanical transmissions and drive axle main reducers, it is better to use different gear shafts.
During the use of gear oil, it is strictly prohibited to add diesel or other substances to the gear oil for dilution, and do not bake the rear axle or transmission due to the impact on winter starting, to avoid serious deterioration of the gear oil. If this situation occurs, low-viscosity multi-stage gear oil should be used instead.
3 Lubricating grease
3.1 Performance characteristics of lubricating grease
Lubricating grease is commonly known as butter. In use, it has different characteristics from lubricating oil, with strong pressure resistance. Different additives are added in different parts to form a strong lubricating film to withstand greater pressure; Has good buffering performance, such as lubricating grease at the steering knuckle main pin, thrust bearing, hub bearing, transmission shaft, etc. of tractors, which plays a buffering role and can be used to reduce mechanical vibration; It has good sealing and protective properties, preventing the invasion of moisture, dust, impurities, and corrosive substances, keeping the friction surface clean and not corroded; It also has good viscosity and temperature properties, that is, the viscosity of lubricating grease does not change significantly with temperature; It also has the characteristics of water resistance and resistance to loss.
3.2 Scope of application of lubricating grease
Lubricating grease is commonly used on bearings. Lubricating grease for bearings can reduce friction and wear, dissipate heat, and keep the surface of running parts free of dirt and corrosion. Maintenance free bearings, such as clutch release bearings, have already been lubricated during the manufacturing process. Do not clean sealed maintenance free bearings and do not inject lubricating grease into maintenance free bearings again.
There are four types of lubricating greases: calcium based, sodium based, calcium sodium based, and lithium based. Agricultural machinery commonly uses No. 2 and No. 3 calcium based butter. Tractor clutch bearings, generator bearings, motor bearings and other parts with high operating temperatures are commonly lubricated with No. 3 sodium based grease.
2024 July 2nd Week VAFEM Product Recommendation:
Agricultural machinery requires better seals for contaminated conditions, provisions for misalignment, and economical mountings for shafts and housings. VAFEM offers bearings for disc harrows, planters, mowers, rakes, all types of balers, tillage, seeding and forage harvester equipment, combines, cotton pickers/stripers, and other agricultural equipment like silo unloaders and grain elevators.
We also offer a complete line of insert ball bearings, shaft mounted with either tapered adapters or locking collar or set screws. Our proven seal designs include low torque shields to heavy-duty triple lip seals. Disc harrow bearings are also available with either round, square, or hexagonal bores. All bearings are available with or without re-lubrication holes.
https://www.vafem.com/products/Agricultural-Bearings/775.html
2024-07-12