German Knoll seals, Knoll models, Knoll prices

Knoll seals are the customary term for general seals; simply put, they seal lubricating oil. They are mechanical components used to seal grease (oil is the most common liquid in transmission systems, and the term also refers to general liquids), isolating lubricated parts in the transmission from output parts 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 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 generally refers to this type of tc skeleton oil seal.

Function of Knoll seals

Prevent high-pressure liquid from leaking out of the pump and prevent air from entering the pump. Although the shaft seal occupies a small position in the pump, the normal operation of the pump is closely related to the shaft seal. If the shaft seal is improperly selected, it will not only require frequent maintenance during operation and cause significant loss of the conveyed liquid, but may also cause fire, explosion, and poisoning accidents due to the leakage of flammable, explosive, and toxic liquids, with unimaginable consequences. Therefore, the shaft seal structure must be reasonably selected to ensure the safe operation of the pump. 1) Since the pressure inside the cylinder is not equal to the external atmospheric pressure, steam inside the cylinder or air outside the cylinder will inevitably leak out or in along the radial gap between the main shaft and the cylinder, causing working fluid loss, worsening the operating environment, and heating the journal or allowing steam to enter the bearing chamber, causing deterioration of oil quality. Air leakage also destroys the vacuum, thereby increasing the pumping load, which reduces unit efficiency. For this reason, shaft seals are installed where the rotor passes through both ends of the cylinder; this type of shaft seal is called an end shaft seal, abbreviated as shaft seal. High-pressure shaft seals are used to prevent steam from leaking out of the cylinder, and low-pressure shaft seals are used to prevent air from leaking into the cylinder. 2) During turbine operation, a portion of steam inevitably leaks from the shaft end to the atmosphere, causing loss of working fluid and heat, and also affecting the working environment of the turbogenerator. If adjustment is improper and steam leakage is excessive, it will cause the temperature of bearings near the shaft seal to rise or water to enter the bearing oil. For this reason, shaft seal heaters are installed in various units to recover and utilize the shaft seal steam leakage from the turbine. 3) Prevent steam inside the cylinder and valve stem leakage from leaking outward, polluting the turbine room environment and bearing lubricating oil quality. Prevent high-temperature steam from flowing over the turbine main shaft during normal unit operation, causing it to heat up and thus causing bearing overheating. Prevent air from leaking into the vacuum part of the cylinder. Ensure condenser vacuum effect and degree during unit startup. Recover shaft seal and valve stem leakage to reduce working fluid and energy loss. 4) During turbine tripping shutdown and the entire hot shutdown process where the condenser needs to maintain vacuum, prevent air from leaking into the turbine, accelerating internal cooling of the turbine and causing main shaft bending.

Knoll seal replacement steps

1) Remove the main pulley (belt drive) and remove the key pin; 2) Use a pin puller to remove the locating pins of the shaft seal end cover; 3) Remove the fixing screws of the shaft seal end cover; 4) Use a circular external puller to remove the shaft sleeve (if no puller is available, cut a groove on the shaft sleeve with a cutting machine and knock it off with a chisel; note: block sand with something to prevent it from getting into the screw rod); 5) Remove the old shaft seal; 6) Clean the end cover shaft seal and bearing positions, then clean with 755; 7) Apply 638 adhesive to the shaft seal installation position, then carefully install the shaft seal; note: do not damage the rubber lip; you can apply some oil or high-temperature grease to the rubber surface of the shaft seal; 8) After cleaning the shaft sleeve position, reinstall and fix the end cover securely (you can wrap a layer of thick glossy paper around the shaft to prevent the shaft seal lip from accidentally touching the keyway during end cover installation); 9) Clean the new shaft sleeve and installation position, apply fixing adhesive 638 to the inner circle of the shaft sleeve. Cold fit: use a force bar to evenly knock the shaft sleeve in; pad the outside of the new shaft sleeve with an outer ring of the same size to knock it in to avoid damaging the shaft sleeve. Hot fit: clean the inside of the shaft sleeve thoroughly, ensuring no oil. Apply a ring of 638 adhesive to the shaft journal before the shaft seal, heat the shaft sleeve to 110 degrees, and install it. (Note: Push the shaft sleeve to the edge of the shaft seal, pause briefly. Wait for the temperature to drop before pushing it to the shaft seal position; 10) Install the pulley or coupling, correct parallelism or centerline, and manually reverse the machine head to allow lubricating oil to return to the front bearing and shaft seal.

Knoll 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 insufficient interference 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 them 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, 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 environmental 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 ages or the spring fails, 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 Metra 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 Metra super sealant lubricant will not contaminate the oil or cause deterioration.

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