Hydraulic oil is the hydraulic medium used in hydraulic systems that utilize liquid pressure energy. It plays the roles of energy transmission, anti-wear, system lubrication, anti-corrosion, anti-rust, cooling, etc. in the hydraulic system. For hydraulic oil, it should first meet the requirements of the hydraulic device on the liquid viscosity at the working temperature and the starting temperature. Since the viscosity change of the lubricating oil is directly related to the hydraulic action, transmission efficiency and transmission accuracy, the viscosity-temperature performance of the oil is also required. And shear stability should meet the various demands put forward by different uses. There are many kinds of hydraulic oils, and the classification methods are different. For a long time, it is customary to classify them by use, and some are classified by oil type, chemical composition or flammability. These classification methods only reflect the income of oil products, but they are not systematic, and it is difficult to understand the relationship and development of oil products. Biodegradable hydraulic oil is developed to meet environmental protection requirements and control environmental pollution. There are mainly vegetable base oils and synthetic vinegar. Vegetable oils are the main development direction of environmentally friendly lubricants due to their natural biodegradability, excellent lubricating properties, and viscosity-temperature properties, as well as abundant resources and relatively low prices. This kind of hydraulic oil has no official product hydraulic oil in our country. However, there are many abroad, such as Ruianbo in the United States, which are formulated from vegetable oil base oils and can eventually degrade. Biodegradable hydraulic oil is an anti-wear hydraulic oil with excellent performance, which is specially formulated to meet the requirements of various hydraulic equipment. These products extend oil/filter life and provide maximum equipment protection, reducing maintenance and product disposal expenses. This series of products is jointly developed with major equipment manufacturers, which can meet the strict requirements of high hydraulic pressure and high output pumps in the precision hydraulic system of the device, and can also cope with other components of the hydraulic system, such as low-clearance servo valves and high-precision CNC machine tools, etc. strict requirements. This series of products widely meet the most stringent performance requirements of various hydraulic system and component manufacturers designed with multi-metallurgical technology, and a single product has outstanding performance characteristics.

The hydraulic systems of automobiles and construction machinery use hydraulic oil as the working medium. The flow rate of the oil in this type of hydraulic system is low and the pressure is high, so it is called hydrostatic transmission. The quality of hydraulic oil will greatly affect the reliability and service life of the hydraulic system. Generally, the quality requirements for hydraulic oil are as follows: 1) Appropriate viscosity and good viscosity-temperature performance to ensure accurate and sensitive power transmission under the condition of changing working temperature, and to ensure the normal lubrication of hydraulic components. 2) It has good rust resistance and oxidation stability, and is not easy to oxidize and deteriorate under high temperature and high pressure conditions, and has a long service life. 3) It has good anti-foaming properties, so that the foam produced by the oil is easy to disappear under the working condition of continuous mechanical stirring, so that the power transmission is stable and the accelerated oxidation of the hydraulic oil is avoided.

The HH, HL, HM, HR, HG, HV, and HS hydraulic oils in the GB/T7631.2-2003 classification are all mineral oil-type hydraulic oils. There are many types of this type of oil, and the usage accounts for about 10% of the total hydraulic oil. More than 85%, the hydraulic oil commonly used in the hydraulic system of automobiles and construction machinery also belongs to this type. HH type HH hydraulic oil is a mineral oil without any additives. Although this oil has been included in the classification, it is not used in hydraulic systems. Because this oil has poor stability and is easy to foam, it has a short service life in hydraulic equipment. HL type Specification: HL hydraulic oil is made of neutral base oil with high refining depth, plus anti-oxidation and anti-rust additives. HL hydraulic oil can be divided into six grades of 15, 22, 32, 46, 68, and 100 according to the kinematic viscosity at 40°C. Application: HL hydraulic oil is mainly used for lubricating bearing housings, low-pressure circulation systems or similar mechanical equipment circulation systems of various machine tools where there is no special requirement for lubricating oil and the ambient temperature is above 0°C. Its service life can be more than double that of mechanical oil. This product has good rubber sealing adaptability, and its maximum service temperature is 80°C. Quality requirements: (1) Suitable viscosity and good viscosity-temperature performance. It is required that the viscosity of the oil is less affected by temperature changes, that is, temperature changes will not affect the normal operation of the hydraulic system. (2) It has good rust resistance and oxidation stability. (3) It has ideal air release value, anti-foaming property, water separation and rubber sealing adaptability. Precautions (l) Before use, the original hydraulic oil tank should be thoroughly cleaned to remove residual oil, waste oil and sediment, etc., and avoid mixing it with other oil products. (2) This product is not suitable for special machine tools with harsh working conditions and high lubrication requirements. For gear transmissions, hydraulic systems and guide rails that require high oil quality, medium and heavy-duty gear oils, anti-wear hydraulic oils or HG hydraulic oils should be used. Precautions for use: (1) Before use, the original hydraulic oil tank should be thoroughly cleaned to remove residual oil, waste oil and sediment, etc., and avoid mixing it with other oil products. (2) This product is not suitable for special machine tools with harsh working conditions and high lubrication requirements. For gear transmissions, hydraulic systems and guide rails that require high oil quality, medium and heavy-duty gear oils, anti-wear hydraulic oils or HG hydraulic oils should be used. (3) This oil replaces mechanical oil for the lubrication of the circulation system of general-purpose machine tools and other similar mechanical equipment. It has significant economic benefits, can extend the oil change cycle, and saves lubricating oil by 1/3-1/2 on average.

Select the type of hydraulic oil according to the working environment and working conditions. When selecting the hydraulic oil used in hydraulic equipment, you should comprehensively consider and judge from several aspects such as working pressure, temperature, working environment, hydraulic system and component structure and material, and economy. . Environmental factors include: above ground, underground, indoor, outdoor, coastal, cold area, high temperature, open flame. Operating conditions: pump type, pressure, temperature, material, sealing material, running time. Oil properties: physical and chemical properties. Economy: use time, oil change period, price. work pressure Mainly put forward requirements on the lubricity of hydraulic oil, that is, anti-wear property. The hydraulic components of the high-pressure system, especially the friction pair in the boundary lubrication state in the hydraulic pump, due to the increase of positive pressure and high speed, the friction and wear conditions are relatively harsh, so it is necessary to choose HM oil with excellent lubricity, that is, anti-wear performance and extreme pressure performance. . Select hydraulic oil according to the working pressure of the hydraulic system and oil pump. For pressure <8MPa, use L-HH, L-HL (for vane pump, use L-HM), for pressure 8-16MPa, use L-HL, L-HM, L-HV, for pressure >16MPa use L-HM, L-HV hydraulic oil. The working pressure of the hydraulic system is generally marked by the rated or maximum pressure of the main oil pump. Operating temperature It refers to the temperature of the hydraulic oil in the hydraulic system when it is working. It mainly puts forward requirements on the viscosity temperature and thermal stability of the hydraulic oil. For the working temperature of -10-90°C, use L-HH, L-HL, L-HM hydraulic oil, Use L-HV and L-HS for temperatures lower than -10°C, and high-quality L-HM, L-HV, and L-HS for working temperatures >90°C. The general relationship between the ambient temperature and the operating temperature is: the hydraulic equipment is in the workshop, and the normal working temperature is 15-25°C higher than the ambient temperature; the hydraulic equipment is outside the temperate zone, and the temperature is 25-38°C; under the tropical outdoor sunshine, the temperature is 40-50°C higher . type selection ① According to the form and material of the friction pair According to the form of the friction pair and its material. The vane of the vane pump and the stator surface are in contact with the oil and are easily worn during movement. The steel-steel friction pair material is suitable for L-HM anti-wear with ZDDP (zinc dialkyldithiophosphate) as the anti-wear agent. Hydraulic oil; the friction form and movement form of the cylinder, oil distribution plate, and piston of the plunger pump are also suitable for using HM anti-wear hydraulic oil, but there are bronze parts in the plunger pump, which will cause corrosion and wear due to the action of this material part and ZDDP Therefore, the plunger pump with bronze parts cannot use HM anti-wear hydraulic oil with ZDDP as additive. At the same time, the selection of hydraulic oil should also consider its compatibility with the sealing material in the hydraulic system. Generally, vane pumps can use zinc-containing anti-wear hydraulic oil, and plunger pumps should use ashless oil. For hydraulic systems where the pressure of the vane pump is higher than 15MPa, the pressure of the plunger pump is higher than 30MPa, and two types of pumps exist at the same time, the oil that meets the Denison HF-0 specification should be selected. ②Gear pumps, vane pumps and plunger pumps are the main types of pumps in hydraulic systems. The order of the lubricity of hydraulic oil on the anti-friction effect of the three major pumps is vane pump>piston pump>gear pump. Therefore, it is better to use HM oil regardless of the pressure of the hydraulic system where the vane pump is the main oil pump. The higher the accuracy of the hydraulic system, the higher the cleanliness of the selected hydraulic oil is required. For example, the closed-loop hydraulic system with electro-hydraulic servo valve requires the hydraulic oil of CNC machine tools. These two oils can be used with high-grade HM and HV hydraulic oil respectively. replace. The test shows that the three types of pumps require the order of hydraulic oil cleanliness to be that the plunger pump is higher than the gear pump and the vane pump, and the order of the extreme pressure performance is that the gear pump is higher than the plunger pump and the vane pump.

1. Definition of hydraulic transmission Hydraulic transmission uses oil as the medium to transmit the power of the engine, instead of the traditional clutch and gearbox. Specifically: the rotation of the engine drives the transmission oil through a device similar to a water pump, and the transmission oil drives a device similar to a water turbine to rotate, thus transmitting the power of the engine to the transmission shaft. The advantage of this transmission method is that it is smooth and can be easily changed. But because fluid movement consumes energy, the fuel consumption of hydraulic transmission is higher than that of mechanical transmission. Second, the advantages of using hydraulic transmission 1. Compared with other types of transmission devices, the hydraulic transmission device is small in size and light in weight under the same power condition, so the inertia is small and the action is sensitive, and it can realize frequent starting and reversing. 2. It is easy to realize stepless speed regulation, and the speed regulation range is large. 3. It is easy to realize overload protection, and it is generally equipped with a safety valve to prevent overload. Runs smoothly and absorbs shock and vibration easily. 4. The hydraulic transmission can be transmitted in various directions, and it is easy to realize reciprocating transmission. Due to its small size and high power transmission, complex motion forms can be transmitted in a small space. These characteristics make hydraulic transmission widely used in combined machine tools and automatic lines. 5. It is easy to operate and easy to realize automation, especially when it forms an electro-hydraulic composite system with an electrical control system, the above advantages are more obvious. 6. The hydraulic components are easy to standardize, serialize and generalize, and are easy to promote and use. 3. Disadvantages of using hydraulic transmission 1. Due to the inevitable leakage of the working fluid, the slight compressibility of the oil, and the elastic deformation of the pipeline, hydraulic transmission is not suitable for transmission systems with strict transmission requirements. 2. It requires a high level of manufacturing technology. Use and maintenance must also have a high technical level. 3. When the oil temperature and load change greatly, it is not easy to maintain the stability of the load movement speed. Oil contamination has a significant impact on the performance of hydraulic systems. 4. The flow of oil in the pipeline will cause pressure loss. When the pipeline is long, the pressure loss will be greater and the power transfer efficiency will decrease. Therefore, hydraulic transmission is not suitable for long-distance transmission.

A hydraulic component that provides pressurized fluid for hydraulic transmission and is a type of pump. Its function is to convert the mechanical energy of the power machine (such as electric motor and internal combustion engine, etc.) into the pressure energy of the liquid. There are many factors that affect the service life of hydraulic pumps. In addition to the design and manufacturing factors of the pump itself, it is also related to the selection of some components related to the use of the pump (such as couplings, oil filters, etc.), and the operation during the test run. The working principle of a hydraulic pump is that movement brings about a change in the volume of the pump chamber, thereby compressing the fluid so that the fluid has pressure energy. The necessary condition is that the pump chamber has a sealed volume change. Types of commonly used hydraulic pumps: 1. According to whether the flow can be adjusted, it can be divided into: variable pump and quantitative pump. The output flow can be adjusted according to the needs is called the variable pump, the flow can not be adjusted called the quantitative pump. 2. According to the pump structure commonly used in the hydraulic system, it is divided into three types: gear pump, vane pump and plunger pump. Gear pump: Smaller in size, simpler in structure, less strict on oil cleanliness, and cheaper in price; but the pump shaft is subjected to unbalanced forces, causing serious wear and leakage. Vane pump: divided into double-acting vane pump and single-acting vane pump. This kind of pump has uniform flow, stable operation, low noise, higher operating pressure and volumetric efficiency than gear pumps, and more complex structure than gear pumps. Piston pump: high volumetric efficiency, small leakage, can work under high pressure, and is mostly used in high-power hydraulic systems; but the structure is complex, the requirements for materials and processing precision are high, the price is expensive, and the cleanliness of the oil is high. Generally, the plunger pump is used when the gear pump and the vane pump cannot meet the requirements. There are also some other forms of hydraulic pumps, such as screw pumps, etc., but their applications are not as common as the above three.