The reason why vertical reducers are more prone to oil leakage and poor lubrication than horizontal reducers is mainly determined by their special vertical installation structure. Under the influence of gravity, the distribution and circulation pattern of lubricating oil has changed significantly, posing higher challenges to seal design and lubrication system.
1. The reason why vertical reducers are more likely to leak oil
1. The bottom output shaft seal faces a huge challenge
Unlike horizontal reducers, the output shaft of vertical reducers needs to pass through the bottom of the box and be exposed to the load below. This high-speed rotating output shaft must use dynamic sealing (such as skeleton oil seal). However, elastic seals are easily worn and aged after long-term operation; once the seal fails, not only will the internal lubricating oil leak out along the shaft, but external moisture or rainwater will also penetrate into the reducer along the shaft, causing oil and water to mix.
2. Increased pressure inside the machine causes leakage
When the reducer is running, friction and heat will increase the temperature inside the machine. If the breathable cap is unreasonably designed or blocked, the pressure inside the machine will gradually increase. Under the action of the internal and external pressure difference, the lubricating oil will be squeezed out from the gaps with the least resistance (such as shaft seals, end covers, joint surfaces, etc.).
3. Gravity intensifies splashing and accumulation
When installed vertically, due to the influence of gravity, lubricating oil splashed by gear agitation is more likely to accumulate toward the bottom. If there is no properly designed oil return groove at the bottom of the box, excess lubricating oil will accumulate in the shaft seal and end cover and leak outward under the action of pressure difference. In addition, excessive refueling can also cause violent splashing of lubricating oil, increasing the risk of leakage.
2. Lubrication structure principle and coping mechanism of vertical reducer
In order to solve the above oil leakage and lubrication problems, modern vertical reducers adopt a variety of targeted technical principles in the lubrication structure and seal design:
1. Forced circulation lubrication system
In large vertical reducers (such as vertical mill reducers), the bottom bearing is usually directly immersed in the oil pool. In order to prevent the lubricating oil inside the cup-shaped bearing sleeve from being unable to be exchanged, resulting in impurity precipitation and high temperature heating, the equipment is usually equipped with an independent oil station and forced circulation device. Through oil guide pipes, annular nozzles or fixing impellers on the power output shaft, the lubricating oil is forced to form pressure in the axial direction and flow to achieve continuous supply and cooling of fresh lubricating oil.
2. Special sealing structure design
Radial double seal and labyrinth seal: By setting an oil retaining plate on the output shaft or using an oil throwing ring, the oil coming from the journal is thrown out and flows directly back to the inside of the box through the oil return hole. This structure can effectively prevent the seal from external impact and extend its service life.
Dry well sealing structure: This is an advanced design that eliminates oil leakage from the source. By lowering the thin oil level, it divides the box into two parts: a thin oil lubrication area and a dry oil (grease) lubrication area. The output gear is placed in the cavity, and combined with the labyrinth-shaped oil sealing ring, it is extremely difficult for liquid to enter the cavity, thus completely solving the oil leakage problem of the output shaft.
3. Application of high adhesion lubricating oil
In view of the fact that lubricating oil is easily lost due to the influence of gravity in vertical installation, special lubricating oil with stronger adhesion needs to be used in oil selection (or lubricating oil additives should be added). This ensures that when the reducer stops running or starts at low speed, the gear oil still adheres to the gear surface to form a protective film, preventing mechanical wear of the upper gear due to lack of oil.
