Gear reducers are generally used in low-speed, high-torque transmission equipment. They reduce the speed of electric motors, internal combustion engines, or other high-speed power sources by meshing a gear with fewer teeth on the input shaft with a larger gear on the output shaft. Ordinary gear reducers may also have several pairs of gears that work on the same principle to achieve the speed reduction effect. The ratio of the number of teeth on the large gear to the number of teeth on the small gear is the transmission ratio.
Gearbox Classification
A speed reducer is a relatively precise piece of machinery that matches the speed and transmits torque between a prime mover and a driven machine or actuator. Its purpose is to reduce speed and increase torque. There are many types and models of speed reducers, each with different applications.
There are many types of speed reducers, which can be classified according to their transmission type as follows:
1. Gear reducer
2. Worm Gear Reducer
3. Planetary gear reducer
According to the number of transmission stages, reducers can be divided into single-stage and multi-stage reducers;
According to the gear shape, reducers can be divided into cylindrical gear reducers, bevel gear reducers, and bevel-cylindrical gear reducers.
According to the arrangement of the transmission, reducers can be divided into open type, split type and coaxial type.
Gearbox lubricating oil
When selecting grease based on the bearing load of the travel reducer, a grease with a low penetration should be chosen for heavy loads. When operating under high pressure, in addition to low penetration, high oil film strength and extreme pressure performance are also required. When selecting grease based on environmental conditions, calcium-based greases are not easily soluble in water and are suitable for dry environments with low moisture content. When selecting grease based on operating temperature, the main indicators should be dropping point, oxidation stability, and low-temperature performance. The dropping point is generally used to evaluate high-temperature performance; the actual operating temperature of the bearing should be 10-20°C lower than the dropping point . The operating temperature of synthetic greases should be 20-30°C lower than the dropping point .
Different lubricating oils must not be mixed. The positions of the oil level plug, drain plug, and breather are determined by the installation location.
Oil inspection:
1. Disconnect the power supply to prevent electric shock. Wait for the reducer to cool down;
2. Open the drain plug and take an oil sample;
3. Check the oil's viscosity index: If the oil is noticeably cloudy, it is recommended to replace it as soon as possible;
4. For reducers with oil level plugs: check the oil level to see if it is within acceptable limits; install the oil level plug.
Oil level check:
1. Disconnect the power supply to prevent electric shock. Wait for the reducer to cool down;
2. Remove the oil level plug to check if the oil level is full;
3. Install the oil level plug.
Oil change:
After cooling, the oil viscosity increases, making it difficult to drain. The reducer should have its oil changed at operating temperature.
1. Disconnect the power supply to prevent electric shock. Wait for the reducer to cool down until there is no risk of combustion. Note: The reducer should still be warm when changing the oil.
2. Place an oil collection tray under the drain plug;
3. Open the oil level plug, breather, and drain plug;
4. Drain all the oil;
5. Install the drain plug;
6. Inject new oil of the same brand;
7. The oil level should be consistent with the installation location;
8. Check the oil level at the oil level plug;
9. Tighten the oil level plug and breather.
Causes of oil leakage in speed reducer
1. Pressure difference between inside and outside the reducer: During the operation of the reducer, the friction of the moving parts generates heat and is affected by the ambient temperature, causing the reducer temperature to rise. If there is no vent or the vent is blocked, the internal pressure will gradually increase. The higher the internal temperature, the greater the pressure difference with the outside. Under the action of the pressure difference, the lubricating oil will leak out from the gaps.
2. The reducer's structural design is unreasonable.
1 ) The inspection hole cover plate is too thin, and it is easy to deform after tightening the bolts, making the mating surface uneven and causing oil to leak from the contact gap;
2 ) If the castings are not annealed or aged during the manufacturing process of the speed reducer, and internal stress is not eliminated, deformation will inevitably occur, resulting in gaps and leakage.
3 ) There is no oil return groove on the housing, and the lubricating oil accumulates in the shaft seal, end cover, mating surface, etc., and leaks outward from the gap under the action of pressure difference;
4 ) Inadequate shaft seal design. Early reducers often used oil groove and felt ring shaft seal structures. During assembly, the felt was compressed and deformed to seal the gaps at the mating surfaces. If the contact between the journal and the seal was not ideal, the seal would fail quickly due to the poor compensation performance of the felt. Although there were oil return holes in the oil groove, they were easily clogged, making it difficult for the oil return function to be effective.
3. Excessive oil filling: During the operation of the reducer, the oil sump is agitated and the lubricating oil splashes everywhere inside the machine. If too much oil is added, a large amount of lubricating oil will accumulate in the shaft seal, mating surfaces, etc., leading to leakage.
4. Improper maintenance process: During equipment maintenance, oil leakage may also occur due to incomplete cleaning of dirt on the mating surfaces, improper selection of sealant, reversed installation of sealant, or failure to replace sealant in a timely manner.
