German LEMO seals LEMO models LEMO prices

LEMO seals are the customary term for general seals, simply referring to lubricating oil seals. They are mechanical components used to seal grease (oil is the most common liquid in transmission systems, and also refers to general liquids), isolating lubricated parts from output parts in transmission components to prevent lubricating oil leakage. Seals used for static sealing and dynamic sealing (generally reciprocating motion) are called oil seals. The representative form of oil seals is the TC oil seal, which is a double-lip oil seal with a self-tightening spring fully covered by rubber. The term oil seal generally refers to this type of tc skeleton oil seal.

LEMO seal classification

Oil seals are generally divided into monolithic and assembled types. Assembled types allow free combination of the skeleton and lip material, generally used for special oil seals. Based on sealing function, characteristics, structural type, operating state, and sealing mechanism, oil seals can be categorized into various forms and names. However, conventionally, rotating shaft lip seals are called oil seals, while seals for static and dynamic (generally reciprocating) applications are called seals. The representative form of oil seals is the TC oil seal, which is a double-lip oil seal with a self-tightening spring fully covered by rubber. The term oil seal generally refers to this type of tc skeleton oil seal.

LEMO seal materials

Common materials for oil seals include: Nitrile rubber, Fluorine rubber, Silicone rubber, Acrylate rubber, Polyurethane, Polytetrafluoroethylene, etc. 1) Nitrile rubber (NBR): It has good heat and wear resistance, resistant to various lubricating oils, greases, and oil-gas mixtures. Applicable temperature range: -30~120 degrees Celsius. However, it cannot be used in phosphate ester hydraulic oils or gear oils containing extreme pressure additives. It performs stably in gasoline and low aniline point mineral oils. 2) Polyacrylate rubber (ACM): Superior oil and heat resistance, wear resistance, ozone resistance, and UV radiation resistance. Especially resistant to lubricating oils, gear oils, motor oils, engine oils, and petroleum-based hydraulic oils containing extreme pressure agents. Suitable for working temperatures in the range of -30~150 degrees Celsius. 3) Fluorine rubber: Resistant to aging, heat, and oil. Suitable for almost all lubricating oils, fuel oils, and gasoline. It does not harden easily in oils containing extreme pressure additives. However, it has poor cold resistance and high-temperature wear resistance, and significant permanent compression deformation. Suitable for temperatures between -20~250 degrees Celsius. 4) Silicone rubber: Outstanding high and low-temperature resistance. Can be used long-term at 150 degrees Celsius without performance change; can be used continuously at 200 for 10000h. Maintains its unique elasticity, ozone resistance, and weather resistance in the working temperature range of -70~260. 5) Polytetrafluoroethylene (PTFE): Outstanding chemical stability, thermal stability, friction reduction, and self-lubrication. Its decomposition temperature is above 400. Therefore, it can work normally in the temperature range of -200~300 degrees Celsius. Except for free fluorine and alkali metals, it has excellent corrosion resistance to chemicals, solvents, hydroxides, and acids. Nitrile rubber and fluorine rubber are widely used oil seal materials. The former is low-cost, but the latter offers significant improvements in temperature resistance and sealing, though at a higher cost. It still retains some negative commonalities of ordinary rubber materials, such as poor wear resistance, short service life, and high sensitivity to shaft eccentricity, making leakage relatively common. PTFE oil seals are high-tech products and represent the future direction of oil seal development [2]. When selecting oil seal materials, compatibility with the working medium, adaptability to the working temperature range, and the lip's ability to follow the rotating shaft at high speeds must be considered. Generally, the lip temperature of an oil seal is 20~50℃ higher than the working medium temperature, which should be noted during material selection. The working range of an oil seal depends on the material: Nitrile rubber (NBR) is -40~120℃, Acrylic rubber (ACM) is -30~180℃, and Fluorine rubber (FPM) is -25~300℃.

LEMO seal troubleshooting

1) Main factors causing oil seal leakage: Poor sealing of the oil seal is the primary factor causing leakage. When the shaft wears and forms grooves, even replacing it with a new oil seal fails to achieve sealing because the contact pressure between the oil seal lip and the shaft decreases, resulting in an insufficient interference fit between the oil seal lip diameter and the shaft diameter after installation. Taking the crankshaft oil seal of the S195 diesel engine as an example, the main reasons for poor sealing are analyzed as follows: (1) Poor manufacturing quality of the oil seal; (2) Poor quality of the shaft or bearing; (3) Improper use and maintenance; (4) Improper installation; (5) Improper storage, leading to adverse effects from environmental contamination. 2) Countermeasures for leakage due to poor oil seal sealing: Acquire basic knowledge to identify counterfeit and inferior products, and purchase high-quality, standard-compliant oil seals. During installation, if the outer surface roughness of the shaft diameter is low, or if there are defects such as rust spots, corrosion, or burrs, polish it smooth with fine sandpaper or an oil stone; apply clean engine oil or lubricating grease to the oil seal lip or the corresponding position on the shaft diameter. Apply sealant to the outer ring of the oil seal, wrap the keyway area on the shaft with hard paper to avoid scratching the oil seal lip, and use special tools to rotate and press the oil seal inward. Never hammer or force it in, to prevent deformation of the oil seal or breakage of the spring, which would cause failure; if lip flipping, spring detachment, or oil seal skewing occurs, it must be removed and reinstalled. Note: Do not arbitrarily tighten the inner spring when the shaft diameter is not worn and the oil seal spring tension is sufficient. Oil seals used in machinery generally operate under harsh conditions, with large ambient temperature differences, abundant dust, and frequent vibration causing constantly changing stress on components; therefore, frequent inspection, maintenance, and upkeep are required. If the shaft diameter and bearing are severely worn, or if the oil seal rubber is aged or the spring has failed, repair and replace the corresponding parts promptly. Troubleshoot abnormal heating in components or assemblies immediately; avoid overspeeding and overloading the machinery to prevent increased temperature at the oil seal lip, rubber aging, and premature lip wear. Regularly check the engine oil level; if there are excessive impurities in the engine oil, such as alloy powder or metal iron filings, completely replace it with new engine oil. The brand and quality of the replacement engine oil must meet seasonal requirements. It is recommended to add Metraley Super Sealant & Lubricant to the engine oil. It is an excellent gearbox additive that forms an inert material film on components, which can reduce oil seal leakage, extend the service life of oil seal gears, and reduce gearbox noise. The use of this Metraley super sealant lubricant will not contaminate the oil or cause deterioration.

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