Sealing System Leakage Analysis - Seal

 

Contaminants Packed in the Seal Area

Probable Causes	Actions or Countermeasures
Failure of auxiliary lip	Look for cut or damaged auxiliary lip. Look for auxiliary lip worn excessively.

 

Below is an example of contamination cause by the failure of the auxiliary lip.

 

 

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Paint Spray on Seal Lip

Probable Causes	Actions or Countermeasures
Lack of paint mask.	Review painting procedures and recommend a mask.
Service or in-field paint procedure.	Issue a service bulletin to prevent paint over-spray or specify a mask.

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Check for Seal Cocking

Probable Causes	Actions or Countermeasures
Seal installation.	Use proper installation tool. Check installation force to insure complete installation.
Insufficient or improper bore chamfer.	Provide proper amount and lead in angle for chamfer.
Excessive seal interference with rubber OD seal.	Check bore ID and seal OD for proper dimensions.

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Check for Proper Installation and Orientation Relative to Assembly

Probable Causes	Actions or Countermeasures
Backward installation caused by lack of proper installation tool or visual aid.	Provide foolproof installation tool and/or aide to identify proper orientation.
Improper axial location of seal.	Provide proper installation tool.
Improper axial position of shaft.	Provide proper installation tool and visual aide for proper position

Below is an illustration of a seal improperly installed backwards.

 

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Check for OD Leakage

Probable Causes	Actions or Countermeasures
Oversized bore/undersized seal.	Check bore and seal diameters at removal.
Damaged housing.	Check upon removal.
Damaged seal.	Check for OD damage upon removal.
Differential thermal expansion (Al or Mg housing).	Calculate fit at maximum temperature.

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Check for Case Deformation (Dishing or Damage)

Probable Causes	Actions or Countermeasures
Dented heel face caused by hammer installation.	Provide proper installation tool.
Dished heel face caused by improper installation tool.	Provide proper installation tool.

 

Below is an example of case damage most likely caused during installation.

 

 

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