German HKS seals HKS models HKS prices

HKS seals are a typical representation of oil seals; the term "oil seal" generally refers to skeleton oil seals. The function of an oil seal is typically to isolate components requiring lubrication within transmission parts from the external environment, preventing lubricating oil leakage. The skeleton acts like rebar in concrete components, providing reinforcement and enabling the oil seal to maintain its shape and tension. Based on structural form, they can be divided into single-lip skeleton oil seals and double-lip skeleton oil seals. The secondary lip of a double-lip skeleton oil seal serves as a dust shield, preventing external dust, impurities, etc., from entering the machine interior. Based on skeleton type, they can be divided into inner-covered skeleton oil seals, exposed skeleton oil seals, and assembled oil seals. Based on operating conditions, they can be divided into rotating skeleton oil seals and reciprocating skeleton oil seals. Used in locations such as gasoline engine crankshafts, diesel engine crankshafts, gearboxes, differentials, shock absorbers, engines, and axles.

HKS Seal Classification

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

HKS Seal Materials

Common materials for oil seals include: Nitrile rubber, Fluorocarbon rubber, Silicone rubber, Acrylate rubber, Polyurethane, Polytetrafluoroethylene, etc. 1) Nitrile rubber (NBR): It has good heat resistance and wear resistance, resists various lubricating oils, greases, oil-gas mixtures, etc. 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 operation in the -30~150 degrees Celsius range. 3) Fluorocarbon 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 set. Suitable for temperatures -20~250 degrees Celsius. 4) Silicone rubber: Features 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 within the working temperature range of -70~260. 5) Polytetrafluoroethylene: Features outstanding chemical stability, thermal stability, friction reduction, and self-lubrication. Its decomposition temperature is above 400. Therefore, it can operate normally within 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 fluorocarbon rubber are widely used oil seal materials. The former is low-cost, but the latter offers significant improvements in temperature resistance and sealing performance, though at a higher cost. It still retains certain negative commonalities of ordinary rubber materials, such as poor wear resistance, short service life, and high sensitivity to shaft eccentricity, so leakage phenomena remain relatively common. PTFE oil seals are high-tech products and represent the future direction of oil seal development [2]. When selecting oil seal materials, one must consider the material's compatibility with the working medium, adaptability to the working temperature range, and the lip's ability to follow the rotating shaft during high-speed rotation. Generally, the lip temperature of an oil seal during operation is 20~50℃ higher than the working medium temperature, which should be noted when selecting materials. The operating range of an oil seal depends on the material used: Nitrile rubber (NBR) is -40~120℃, Acrylic rubber (ACM) is -30~180℃, and Fluorocarbon rubber (FPM) is -25~300℃.

HKS 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 may not achieve proper sealing. This is due to reduced contact pressure between the oil seal lip and the shaft, resulting in 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 knowledge to identify counterfeit and inferior products, and purchase high-quality, standard-compliant oil seals. During installation, if the outer surface of the shaft diameter has low roughness or 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. 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 conditions on components. Therefore, frequent inspection, maintenance, and servicing 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 Metraile 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 Metraile super sealant lubricant will not contaminate or degrade the oil.

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