Sealing Excellence, Securing Industry

CFKS Gearbox Sealing NBR Rubber EC Oil Seal 52*7 Hydraulic End Cover Seal

The CFKS 52*7 NBR EC Oil Seal is a heavy-duty, static boundary component engineered explicitly for large industrial gearboxes and hydraulic end covers. By fully encapsulating a rigid carbon steel skeleton within a durable elastomeric NBR jacket, this premium bore plug provides an impenetrable, interference-fit barrier. It permanently seals open housing bores, preventing catastrophic loss of internal gear lubricants while actively excluding environmental contamination.

  • Absolute Static Sealing: The fully rubberized 52mm outer diameter naturally compensates for housing bore imperfections and thermal expansion.

  • Deep 7mm Axial Stability: The extended 7mm width provides maximum surface area contact, preventing the plug from twisting or backing out under internal gearbox pressure spikes.

  • Corrosion-Proof Exterior: The continuous NBR coating completely isolates the internal metal reinforcement, eliminating the risk of galvanic corrosion between the plug and the cast-iron transmission casing.

Find your sealing solution with CFKS — contact us for a quote.

Brand Name CFKS OEM  Accpetable
Material NBR FKM Silicone  Features  wear resistance
Dimensions Customized Certificate  ISO9001/TS16949
Type EC Cap Seal  Packing 1 pc per bag

 

The mechanical integrity of this massive end cap relies on a precisely calculated radial interference fit combined with its substantial axial profile. The internal metal skeleton provides the structural rigidity necessary to prevent the 52mm cap from buckling or dishing. Simultaneously, the NBR rubber coating compresses firmly against the housing bore. Because rubber behaves as an incompressible fluid when confined, this compression forces the elastomer into the microscopic machining grooves of the housing, creating an absolute static lock. The generous 7mm width provides exceptional frictional hold, drastically increasing the plug’s resistance to internal casing pressure and high-frequency gear vibration.

This advanced formulation is explicitly engineered to handle continuous exposure to standard mineral-based gear oils, hydraulic fluids, and synthetic transmission lubricants at operating temperatures up to 100°C. The thick rubber jacket acts as a permanent vibration dampener, ensuring the plug remains firmly seated over millions of machine cycles, while also providing complete immunity against external atmospheric rusting in harsh factory or outdoor environments.

Striking the center of the 52*7mm cap will cause the internal metal skeleton to “dish” or cave inward. This deformation instantly pulls the outer diameter away from the bore wall, completely destroying the radial interference fit and guaranteeing a static oil leak. Technicians must use a flat, heavy-duty installation mandrel that distributes force perfectly across the extreme outer edge of the seal. Furthermore, wiping a very light film of system-compatible gear oil on the rubber OD prior to installation prevents the elastomer from binding, rolling, or tearing against the housing chamfer during the press-fit operation.

Frequently Asked Questions (FAQ)

Why does my CFKS oil seal fail prematurely? Common causes and prevention tips2025-06-26T15:44:39+08:00

Premature oil seal failure can result from improper installation, poor shaft finish, incorrect material selection, or excessive pressure. To prevent this, ensure the shaft surface is smooth and within tolerance, use correct tools during installation, and choose seals made from materials compatible with your media and temperature.

How to correctly install a CFKS industrial oil seal to avoid leakage2025-06-26T16:04:32+08:00

Always clean the shaft and bore before installation. Use appropriate seal drivers to avoid deformation. Lubricate the lip before fitting to reduce friction during the first rotation. Ensure the seal is seated evenly and not tilted to avoid leaks.

What to do when your CFKS hydraulic seal is leaking under pressure2025-05-20T16:33:14+08:00

Check if the pressure exceeds the seal’s rated limit. Examine for wear, hardening, or improper installation. Replace the seal if damaged, and consider upgrading to a high-pressure CFKS seal variant. Also, verify that the housing and shaft are properly aligned.

How to choose the right CFKS oil seal for extreme operating environments2025-05-20T16:34:39+08:00

For high temperatures, aggressive chemicals, or abrasive environments, choose CFKS seals made of FKM, PTFE, or high-performance elastomers. Consider using seals with protective dust lips or metal casing. Our team can recommend the best fit for your application.

CFKS Seal Manufacturing Co., Ltd.
https://cfksseals.com/
 Email: cfksnacy@gmail.com  Mobile/WhatsApp/Wechat: (86) 188-3097-5917
EC End Cap Oil Seal Size List
TypeSIZE
EC End Cap Oil SealEC8*4
EC End Cap Oil SealEC10*4
EC End Cap Oil SealEC11*7
EC End Cap Oil SealEC12*4
EC End Cap Oil SealEC12*5
EC End Cap Oil SealEC14*4
EC End Cap Oil SealEC15*4
EC End Cap Oil SealEC15*5
EC End Cap Oil SealEC16*4
EC End Cap Oil SealEC16*5
EC End Cap Oil SealEC16*6
EC End Cap Oil SealEC18*4
EC End Cap Oil SealEC20*4
EC End Cap Oil SealEC20*5
EC End Cap Oil SealEC20*6
EC End Cap Oil SealEC20*7
EC End Cap Oil SealEC22*4
EC End Cap Oil SealEC22*4
EC End Cap Oil SealEC22*5
EC End Cap Oil SealEC22*5
EC End Cap Oil SealEC22*7
EC End Cap Oil SealEC23*4
EC End Cap Oil SealEC24*5
EC End Cap Oil SealEC24*5
EC End Cap Oil SealEC24*7
EC End Cap Oil SealEC24*7
EC End Cap Oil SealEC25*5
EC End Cap Oil SealEC25*6
EC End Cap Oil SealEC25*7
EC End Cap Oil SealEC25*7
EC End Cap Oil SealEC25*8
EC End Cap Oil SealEC26*4
EC End Cap Oil SealEC26*5
EC End Cap Oil SealEC26*6
EC End Cap Oil SealEC26*6
EC End Cap Oil SealEC26*7
EC End Cap Oil SealEC26*8
EC End Cap Oil SealEC27*5
EC End Cap Oil SealEC27*5
EC End Cap Oil SealEC28*4
EC End Cap Oil SealEC28*5
EC End Cap Oil SealEC28*5
EC End Cap Oil SealEC28*6
EC End Cap Oil SealEC28*7
EC End Cap Oil SealEC28*8

 

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