3306 Industrial Engines – Lip Type Seals

Lip type seals are used to seal the bearing supported sealing journals and the contact surfaces in an oil compartment.

Sealing Journal Storage

Best storage practice for sealing journals

Acceptable storage practice for sealing journals

Sealing journals should be stored with a sealing journal cap and in conformance with the storage and shelf life as per Contamination Control Guidelines, PEBJ0002, “Caterpillar Dealer Contamination Control Compliance Guide”. A cap provides protection to the critical areas of the sealing journal. The use of a cap reduces the risk of damage and contamination to the part.

Bore Storage

Bores should be stored in a manner that will reduce contamination and risk damage to the inside of the bore. Storage should also conform to Contamination Control Guidelines, PEBJ0002, “Caterpillar Dealer Contamination Control Compliance Guide”.

Handling of the Seal

Proper handling of lip seal

Many seals are pre-lubricated. Do not remove the lubrication on pre-lubricated seals.

Lip seals should only be handled on the outer edge. To avoid contamination, the sealing surface should not be touched. Refer to Illustration 6 for proper handling.

Many seals come with a polytetrafluoroethylene (PTFE) coating on the seal. Do not remove the coating or damage the coating in any way. Handle with proper and adequate care.

Note: PTFE is more commonly referred to as Teflon from Dupont.

Handling of Mating Components

Lip seals are sensitive to the quality of the mating components. Mating component surfaces should be checked for the presence of defects that would compromise sealing, and not be used if such defects are found. These defects include:


Nicks/Large scratches

Contamination such as: paint, metal shavings (for example: machining chips) and dirt

Liquid contamination (grease, and so on.)

Other debris

Poor surface finish or porosity

Visual Out-of-Roundness

Clean cardboard or plastic separators are recommended to prevent damage during the transportation and storage of finish-mating components.

Mating components should be handled in such a way to reduce the risk of damage or contamination.

Assembly Aids

Refer to the D & A manual for instruction in the use of any assembly aids.

The fluid being sealed is the proper lubricant for use with lip seals and the mating components of lip seals.

It will not be necessary to obtain an assembly aid to remove supplier-applied sealant build-up if proper tooling care and contamination control techniques are followed.

Assembly Tooling

Types of Lip Seal Tooling

When installing lip-type seals, it is important that proper tooling and tooling care need to be followed.

Refer to the respective D & A manual for the tooling used to install the lip-type seal.

Tooling – Care

Before using the tooling check the tool for damage. Tools with damage such as nicks, gouges, missing material, or deformation must be replaced immediately.

Tools should be cleaned daily to remove contamination. If contamination is present, use a clean lint-free wipe to remove the debris. To maintain cleanliness and prevent tool damage, storage fixtures should be cleaned as a part of daily 5S activities.

Note: 5S activities refer to Caterpillar Production System (CPS) For Dealers related to “Sort, Set, Shine, Standardize, and Sustain”.

For more details refer to:

Referencehttps://dealer.cat.com/cda/files/2498665/7/030%20R_Module %2017%205S_Visual%20Workplace%20v3.ppt

Do not use a chemical remover to remove supplier-applied sealant build-up from the seal tooling. Various chemicals can deteriorate the coatings on the lip-seals.

Refer to “Loctite Maintenance and Solutions Heavy Equipment Guide for Cat Dealers” to determine which chemical removers can be used.

Cleaned tooling should be stored in ergonomically designed designated areas that prevent damage to the tools.

Tooling – Inspection

All tooling should be inspected before use for damage. An improperly maintained tool can cause seal damage and increase the risk of leaking due to improper seating of the seal. Tools with damage such as sharp edges, nicks, burrs, “mushroomed” driver heads (applicable to lip seal drivers), should be reconditioned or replaced prior to further use.

Tooling – Storage

To help protect the seal tooling from damage, it is important that proper lip-seal tooling storage needs to be provided. Placing seal tooling on a metal surface can severely damage the tool due to metal-to-metal contact.

Seal tooling should be stored on a soft, forgiving surface such as nylon, HDPE, and so on.

Do not store tools in a basket to avoid the damage to the tools critical. Proper storage facilities must be provided to all workstations to reduce risk of damage to tool.

Regular inspection of the storage surface and/or racks is required and shall accompany the maintenance schedule for the seal tooling.

Properly label tooling to reduce risk of misuse or misplacement.

Tooling – Maintenance & Damage Reporting

All seal-specific tooling should be placed on a routine maintenance schedule similar to the torque-tooling schedule.

A formal reporting process shall be established at every dealer to report damaged tooling.

To reduce the risk of downtime and use of an unapproved tool due to tooling damage, replacement tooling shall be in inventory and available for immediate use. Damaged tools should be replaced immediately since using a damaged tool increases the risk of seal damage or leaks.

Preassembly Inspection Of Critical Components

Complete a 1-second inspection for seal and mating components for damage and contamination. A 1-second inspection is a quick visual inspection of the part and mating component to determine if damage is present to either part prior to assembly.

Lip Type Seals – Assembly

Seal Lubrication Application

Use an eyedropper or spray bottle for lubrication of the seals. Apply a thin film of lubricant to the designated seal surfaces. Do not use bristle brushes, foam pads, or cotton swab type applicators, as these will contaminate surfaces of the seal.

For elastomeric seals the sealing lip and sealing journal should be lubricated using the fluid to be sealed. Do not over-lubricate. Over-lubrication may cause oil/grease to drip or wash down after assembly, which may give the appearance of a leaking seal.

Note: PTFE seals are intended for dry installation. Do not lubricate the sealing lip and the journal. Common applications for these seals are in crankshafts and water pumps. Refer to appropriate engineering drawing for material specification.

Lubrication Location

For elastomeric seals the sealing lip and sealing journal should be lubricated using the fluid to be sealed.

For rubber outside diameter seals, also lubricate the outside diameter.

For metal outside diameter seals, do not lubricate the outside diameter.

Note: Do not remove grease from pre-greased seals.

Sealant Use

Some applications may require the use of sealant, commonly referred to as Loctite. Apply sealant to bore directly, if required.

Refer to “Loctite Maintenance and Solutions Heavy Equipment Guide for Cat Dealers” for a list of acceptable sealants part numbers and the application for use.

Also refer to “Doing it Right Loctite User Guide” for the best application of adhesives and sealants.


Do not apply sealant directly to seal.

Do not use sealant with rubber outer diameter seals.

When assembled, the shaft and seal must be lubricated with the lubricant being sealed. In water/glycol applications, glycerin is an appropriate substitute.

Note: PTFE seals MUST BE INSTALLED DRY for proper wear-in.

Assembly Tooling Use

Do not bottom the installation tool on housings with as-cast surfaces.

Use the correct seal assembly tool as specified on the Assembly Work Order.

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