Product Description
Teflon® PTFE (Lip code: T) has excellent dry running capabilities but comes with important caveats as well.
Low coefficient of friction.
Excellent chemical resistance.
Resistant to oxygenated hydrocarbon blends.
PTFE has poor abrasion resistance to dirty environments.
There is high thermal expansion with PTFE.
Due to the delicate nature of Teflon, care must be taken when handling the seal as PTFE has unforgiving "memory" and will retain deformation of the sealing surface if banged, nicked, creased or folded during installation.
It must be noted that although fluoropolymers such as FKM and PTFE are classed as resistant to high temperatures, they will thermally degrade on exposure to extreme temperatures (FKM @ 316°C/600°F) and (PTFE @ 371°C/700°F) and emit hazardous fumes containing hydrofluoric acid (HF).
In the unlikely event of such a high temperature incident, allow the components in question to cool, douse with limewater (Calcium hydroxide solution), and handle with PVC gloves until neutral pH confirmed, then discard.Many of Nationals metal cased seals are offered with Redi-Coat® rubberized coating which is applied over the seals bare metal case and helps fill in any minor bore imperfections upon installing the new seal.Please note that not all product images are representative of the item being shown but are similar in appearance. Please refer to the seals technical specifications sheet provided in the image carousel for absolute confirmation before ordering.Follow this link for access to Timken's interactive, multi-vehicle, bearing & seal application database.
Follow this link to access Timken's National oil seal & competitor's interchange.
Timken Metric Oil Seal Catalog
National 7707 Inch Oil Seal Catalog & Interchange
Shaft size
Shaft size 2.875"
Seal outer diameter 3.755"
Seal width 0.500"
Seal type & style PDW (Double lip)
Lip material T (Teflon®)
Case material Redicoat® on metal case
Temperature range -73°C to 232°C (-100°F to 450°F)
Spring retained No
Seal series 40000
Notable feature Clockwise spiral lip design
Denoted measurement Inch
Shown in catalog Yes