Oil seals are important components in agricultural machinery and are widely used. The performance and quality of agricultural machinery directly affect the reliability of its use. Some oil seals have a lifespan of up to one year, several months, or even three to five days due to poor sealing and oil leakage, which seriously affects the efficiency of agricultural machinery. This not only increases fuel consumption and production costs, but also pollutes the environment.

1. Working principle of oil seal

(1) In the free state, the inner diameter of the oil seal lip is smaller than the shaft diameter and has a certain interference fit.

(2) After installation, the interference pressure of the oil seal blade and the contraction force of the self tightening spring generate a certain radial pressure on the rotating shaft.

(3) During operation, the oil seal lip forms a sealing contact ring with a width of 0.25-0.50 millimeters under the action of radial pressure. Under the pressure of lubricating oil, the oil seeps into the gap between the oil seal edge and the shaft, forming a very thin layer of oil film. The oil film is subjected to the surface tension of the oil, forming a "crescent surface" on the outer edge of the shaft and oil seal blade to prevent oil leakage and provide a sealing effect.

2. The main factors causing oil seal leakage

Poor sealing of the oil seal is the main factor causing oil leakage. When the shaft wears and forms grooves, even if a new oil seal is replaced, it cannot seal. This is because the contact pressure between the oil seal lip and the shaft decreases, resulting in a small interference fit between the oil seal lip diameter and the shaft diameter after installation. The main reasons for poor sealing are: ① Poor quality of oil seal manufacturing; ② Poor quality of shaft or bearing; ③ Improper use and maintenance; ④ Improper installation; ⑤ The adverse effects caused by improper storage and environmental pollution.

3. Disposal of oil leakage caused by inadequate sealing of oil seals

(1) During installation, if the outer surface roughness of the shaft diameter is low or there are defects such as rust spots, rusting, fuzzing, etc., it should be polished smooth with a fine sandpaper or oilstone; Apply clean engine oil or lubricating grease to the corresponding position of the oil seal lip or shaft diameter. Apply sealant to the outer ring of the oil seal, wrap the keyway on the shaft with hard paper to avoid scratching the lip of the oil seal, and use a special tool to rotate and press the oil seal inward. Do not forcefully hit or punch it. To prevent oil seal deformation or spring breakage and failure; If lip curling, spring detachment, and oil seal misalignment occur, they must be removed and reinstalled. It should be noted that when the shaft diameter is not worn and the oil seal spring has sufficient elasticity, do not tighten the inner spring without authorization.

(2) Oil seals used in agricultural machinery generally work under harsh conditions, with large temperature differences, high levels of dust, and frequent machine vibrations that constantly change the stress conditions of the components. Therefore, it is necessary to regularly inspect, maintain, and upkeep them.

(3) Serious wear of shaft diameter and bearings; Oil seal rubber aging or spring failure should be repaired and corresponding components replaced in a timely manner.

(4) Timely troubleshooting of components or assemblies that generate abnormal heat; Avoid mechanical overspeed and overload operation to prevent the temperature rise of the oil seal lip, rubber aging, and early wear of the lip.

(5) Regularly check the oil level. If there are too many impurities in the oil, such as alloy powder or metal shavings, it is necessary to completely replace the oil with a new one. The brand and quality of the changed oil should meet the requirements of the season.

(6) Temporarily unused oil seals should be properly stored to prevent them from getting stained with oil, dust, or direct sunlight.

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2025 September 1st Week FK Product Recommendation:

Pillow Block:

A pillow block bearing (or plummer block) is a mounting used to support a rotating shaft with the use of bearings and various accessories. The assembly consists of a mounting block which houses a bearing. The block is mounted to a foundation, and a shaft is inserted, allowing the inner part of the bearing/shaft to rotate. The inside of the bearing is typically 0.025 millimetres (0.001 in) larger diameter than the shaft to ensure a tight fit. Set screws, locking collars, or set collars are commonly used to secure the shaft. Housing material for a pillow block is typically made of cast iron or cast steel.

https://www.fk-bearing.com/products/Pillow-Block/698.html

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