Sealing Excellence, Securing Industry

CFKS Industrial Transmission NBR Rubber End Cap 11*7 Gearbox End Cover Seal

The CFKS 11×7 NBR Industrial Transmission End Cap is a highly specialized static boundary component designed to securely close off auxiliary shaft bores in compact gearboxes and power transmission systems. By fully encapsulating a rigid internal carbon steel skeleton within a durable elastomeric jacket, this deep-profile bore plug provides a leak-proof, interference-fit barrier. It permanently prevents internal gear lubricants from escaping while actively excluding abrasive industrial contaminants from breaching the housing.

  • Absolute Static Sealing: The fully rubberized outer diameter (OD) naturally compensates for minor housing bore machining imperfections and thermal expansion.

  • Deep 7mm Axial Stability: The extended 7mm width prevents the plug from canting, twisting, or backing out under internal gearbox pressure spikes.

  • Corrosion-Proof Exterior: The NBR coating completely isolates the internal metal reinforcement, eliminating the risk of galvanic corrosion between the plug and the 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 cap relies on precisely calculated radial interference combined with its deep axial profile. The internal metal skeleton provides the structural rigidity necessary to prevent the cap from buckling, while the NBR rubber coating compresses against the 11mm housing bore. Because rubber behaves as an incompressible fluid when confined, this compression forces the elastomer into the microscopic machining grooves of the cast iron or aluminum housing, creating an absolute static lock. The generous 7mm width provides significant surface area contact, drastically increasing the plug’s resistance to internal casing pressure and high-frequency gear vibration.

Industrial gearboxes utilize heavy-weight gear oils (such as ISO VG 220 or 320) that generate significant heat and internal splashing under load. To guarantee long-term fluid retention, our end caps are injection-molded utilizing a specialized, high-density Nitrile Butadiene Rubber (NBR) matrix.

Striking the center of the 11*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 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 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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