1. What type of lubricating oil is used for different speed reducers?
1. Under normal circumstances, horizontal cycloidal reducers use oil bath lubrication, and the oil level should be maintained in the middle of the sight glass. In harsh working conditions and high ambient temperature, circulating lubrication can be used.
2. Cycloidal pinwheel reducers are generally lubricated with 40# or 50# mechanical oil at normal temperature. In order to improve the performance of the reducer and extend its service life, it is recommended to use 70# or 90# extreme pressure gear oil. When working under high and low temperature conditions, the lubricating oil should also be reconsidered.
3. "If domestic reducer manufacturers can achieve 100% sealing, it is still recommended to use oil lubrication, because most companies have not yet solved the sealing problem. Therefore, under normal circumstances, 0# and 00# greases are recommended for RV reducers . 00# is recommended for better sealing and 0# for poorer sealing. If it is a harmonic reducer, 1# or 2# is recommended . "
4. Gearboxes operating under heavy loads place more stringent demands on lubricants. This requires lubricants to possess excellent extreme pressure resistance and anti-wear properties. Lubricants containing specially formulated EP additives and anti-wear additives can better meet the lubrication requirements of gearboxes under heavy loads.
5. For vertically installed planetary cycloidal pinwheel reducers, it is crucial to prevent the oil pump from cutting off to avoid damage to the reducer components.
6. To add oil, simply unscrew the vent cap on the top of the machine base. To drain oil, unscrew the drain plug at the bottom of the machine base to release the contaminated oil. This reducer is shipped without internal lubricating oil.
7. The choice between lubricating oil and grease must be determined based on the transmission structure design and operating conditions of the reducer. Factors such as gear geometry, material, circumferential speed / sliding speed, load ( torque / tooth surface pressure ) , energy consumption, operating temperature, tooth surface heat dissipation, and sealing condition must be considered. Appropriate lubricant not only provides long-term lubrication protection for the reducer but also helps reduce wear, lower noise, improve accuracy and reliability, and extend the service life of components.
8. The first time the gearbox is filled , the oil should be changed after 100 hours of operation. After flushing out any dirty oil, continuous operation can continue. The oil should be changed every six months, using an 8- hour workday. If working conditions are harsh, the oil change interval can be shortened. Practice has shown that frequent cleaning and oil changes (e.g., every 3-6 months) are crucial for extending the gearbox's lifespan. Therefore, lubricating oil should be replenished frequently during use. During long-term use, the gearbox should be cleaned regularly to reduce wear. Gearbox cleaning and maintenance machines utilize the gearbox's original oil supply and drainage system and filtered old oil to clean the gearbox, quickly filter waste oil, and add new oil, helping to solve wear and other problems.
II. Performance Characteristics of Gearbox Lubricating Oil
1. It has good wear resistance.
Anti-wear properties refer to the ability of gearbox lubricating oil to form and maintain an oil film on the friction surfaces between moving parts, preventing metal-to-metal contact and reducing wear. The anti-wear properties of gearbox lubricating oil mainly depend on its oiliness and extreme pressure properties.
Oiliness refers to the ability of gear oil to adhere to the friction surfaces of parts, forming an oil film to reduce wear. Generally, when we say gear oil has good oiliness, we mean it has strong adsorption capacity, which improves its anti-wear properties.
Extreme pressure performance refers to the ability to prevent damage such as sintering and adhesion to friction surfaces under extremely high pressure lubrication conditions where the oil film is prone to rupture. It is also called load-carrying capacity.
2. Viscosity and viscosity-temperature properties
The lubricating oil for the speed reducer must have suitable viscosity and good viscosity-temperature properties.
Generally speaking, high-viscosity lubricating oil is beneficial for preventing damage to machine parts and reducing noise, while low-viscosity lubricating oil is better in terms of transmission efficiency, cooling effect and oil transfer properties.
While gearbox lubricating oil doesn't experience the same significant temperature fluctuations as engine oil, it still requires good viscosity-temperature properties due to the high pressure on the gear surfaces, especially in cold regions. Otherwise, it will lead to accelerated wear and increased oil consumption.
3. Oxidation stability
When the gearbox lubricating oil is agitated by the gear movement and comes into constant contact with oxygen, various oxides are formed under the catalytic action of metals. This increases the viscosity of the lubricating oil, darkens its color, raises its acid value, increases the amount of sediment, and causes corrosion of machine parts. Consequently, the anti-foaming and anti-oxidation properties of the lubricating oil deteriorate, making it necessary to replace the lubricating oil.
Lubricating oils with good oxidation stability have a longer service life. Therefore, antioxidants are usually added to lubricating oils to improve their oxidation stability.
4. Resistance and corrosion resistance
Rust prevention refers to the ability of gearbox lubricating oil to prevent metal from rusting. Corrosion prevention refers to the ability of gear oil to prevent metal from corroding.
Rusting of metal parts is mainly caused by the presence of oxygen and water in the lubricating oil. Corrosion, on the other hand, is caused by acidic substances and sulfides in the oil. Anti-corrosion additives are usually added to gearbox lubricating oil to improve this.
5. Anti-foaming properties
The lubricating oil in a speed reducer generates many small bubbles due to the vigorous agitation caused by gear movement. If these small bubbles disappear quickly, they do not affect the operation. However, if they form stable foam that persists and emulsifies, they will overflow onto the gear surfaces, damaging the lubricating oil film and accelerating wear.
III. Principles for Selecting Lubricating Oil for Gear Reducers
The primary factor in selecting gear reducer lubricating oil is viscosity. Viscosity is a very important physicochemical property of gear oil, and the gear meshing speed is the main indicator for selecting viscosity. A suitable gear reducer oil viscosity can reduce internal friction, thereby greatly reducing gear surface wear, transmission noise, and vibration.
The viscosity of gearbox lubricating oil is mainly achieved through base oil and viscosity index improvers. A good viscosity index improver not only requires high viscosity-increasing capacity and good shear stability, but also good low-temperature performance and thermal oxidation stability. Viscosity index improvers with poor shear stability cause the main chain of the polymer to break down under shear stress, reducing the molecular weight and thinning the oil, thus affecting wear and oil consumption. For lubricating oils of the same viscosity grade, if unrefined base oils and inferior viscosity index improvers are used, although a certain viscosity standard can be achieved through blending, the viscosity-temperature characteristics and shear stability will be poor, and the expected service life will not be reached. Therefore, for low-speed, heavy-load cement gearboxes, such lubricating oils should be avoided as much as possible; instead, high-quality lubricating oils should be selected because their base oils and viscosity index improvers are of better quality.
The higher the viscosity of gear oil, the stronger its protective ability against various types of damage to the gear teeth, thus reducing wear on the reducer. However, excessively high viscosity makes it difficult for abrasive particles to settle, reducing the lubricating oil's flushing effect and heat absorption/cooling effect on the gear teeth, leading to poor lubrication. Simultaneously, abrasive particles suspended in the oil can enter the meshing area, easily causing abrasive wear. Furthermore, excessive viscosity increases transmission resistance, gear surface temperature, and power consumption. Generally, increasing the viscosity by one grade increases energy consumption by approximately 1 % -5 %, and the oil's stability and demulsibility decrease. However, higher viscosity offers significant benefits in reducing noise and preventing oil leaks. Additionally, equipment with uneven loads, frequent starts, and operation in high-temperature environments should use slightly higher viscosity oils. In conclusion, reducers should use high-grade lubricating oils with appropriate viscosity. For large gear reducers with low speed and heavy load, extreme pressure heavy-duty gear oil with high viscosity should be selected as much as possible. This is because it has better extreme pressure anti-wear properties, thermal oxidation stability, corrosion and rust prevention, and excellent demulsification properties than medium-duty gear oil. This makes it easier to form a chemical film on the meshing surface of the gears, thereby protecting the gear tooth surface and minimizing the wear of the gear reducer.
IV. Precautions for using gearbox lubricating oil
1. The occurrence of oil leakage in a speed reducer is mainly related to three factors: First, the viscosity of the oil, which is related to the viscosity required by the speed reducer; second, the sealing process of the speed reducer, that is, the lip design of the sealing ring, including the material of the rubber, whether it is customized or standard, and whether it is suitable for the application conditions; third, whether the oil and the sealing ring are compatible. Some materials, such as NBR , are compatible with mineral oil and PAO , while polyethylene glycol oil is incompatible with PAG . Incompatibility can easily cause the rubber to crack.
2. If the oil content in the grease is too low, the thickener content will be too high, resulting in poor lubrication. Because the wave generator and RV wheel have some backflow during operation, excessive thickener will affect the oil's fluidity. Poor fluidity makes it difficult for the oil to return to the friction point. If it cannot return to the friction point, localized heat will be generated in the reducer, leading to wear. The lubricant in the affected area will become ineffective and turn black, causing a series of problems such as abrasive wear. Using oil for lubrication can carry away the localized high temperature and wash away the basic particles at the friction point.
3. For gear reducer systems with centralized thin oil lubrication, due to the strict requirements on the temperature of the lubricating oil or oil tank, coolers or cooling coils are typically used for cooling. Although gear oil is required to have good anti-emulsification properties, the presence of a significant amount of water in the oil can easily cause emulsification. When gear oil containing extreme pressure anti-wear agents emulsifies, the additives are hydrolyzed or precipitated, losing their original properties and producing harmful substances, causing the gear oil to rapidly deteriorate and lose its performance. Ribang New Energy reminds everyone that emulsified oil should never be used. For water-cooled lubrication systems, it is crucial to prevent water leakage to avoid unnecessary damage to the reducer.
4. For reducer systems using pumps for circulating lubrication, pay attention to the pump pressure differential and clean the filter screen promptly. If the pump pressure differential is large within a short period, or the frequency of filter screen cleaning increases significantly, and there is a noticeable increase in sludge and metal wear on the filter screen, it indicates that the lubricating oil is not in good condition. Besides issues with materials and design, this could be due to an inappropriate selection of lubricating oil: firstly, the viscosity may not be suitable; secondly, a higher-grade gear oil could be used for heavy-duty applications instead of medium-duty applications, which would significantly improve performance.
5. It is crucial to avoid mixing new oil with old oil, or adding high-viscosity oil to achieve a desired viscosity despite a decrease in viscosity. While this may provide some short-term benefits, it will significantly reduce the oil's performance, worsen lubrication, increase wear, and ultimately shorten equipment lifespan. Furthermore, mixing different main components may cause additives to "clash," negating each other's effects and potentially leading to disastrous consequences for the equipment.
6. Regarding the oil change cycle, theoretically, a shorter oil change interval can better reduce friction loss and extend the service life of the equipment, while also providing a necessary condition for ensuring its normal operation. However, from an economic perspective, oil should be used more accurately and effectively. Whether to change the oil and when to change it should not only follow the specified oil change interval but also consider factors such as the equipment's operating time and utilization rate, so as to maximize the use of the oil.
7. Regularly monitor the oil temperature, vibration, and noise levels of the equipment using lubrication. Deterioration in lubrication conditions causing damage to the gear surfaces can directly lead to a significant increase in vibration and noise.
