R23 Double Lip and TB Metal Cased Oil Seal Applications and Differences

If you’ve spent time around rotating equipment, you already know—an oil
seal’s condition can make or break uptime. Once oil leaks out or grit makes
its way in, you’re no longer talking about “minor maintenance”; you’re
looking at a chain reaction that can take down bearings, gears, and even the
entire drive system. Choosing the right seal type isn’t theory—it’s
survival.

Two designs you’ll bump into again and again on the shop floor are the R23
double-lip seal and the TB metal-case seal. Both work, both are proven—but
they’re not interchangeable.

Spotting the Difference

A R23 seal is easy to pick out. Picture a steel case buried under a rubber
coating, the outside pressed snug into the housing bore. Inside, a spring-
energized main lip rides the shaft, keeping the oil where it should be. Just
ahead of it sits a slimmer “dust lip,” almost like a miniature squeegee,
whose only job is to block dirt and grit. That rubber-clad outer diameter also
helps when the bore is a little rough or slightly out of round—the kind of
thing you see in older gearboxes or hastily machined housings.

The TB seal feels more rigid in the hand. It’s all metal on the outside, with
the elastomer bonded inside where the lips are formed. The main lip still has
its spring, and the dust lip is separate, but here the rigid shell gives it
better dimensional stability. That’s why it’s often the choice for big-
diameter shafts or machinery that sees higher mechanical loads.

Materials and What They Can Handle

Both designs can be ordered in the usual range of elastomers. NBR will do fine
for most mineral oils at moderate temperatures. FKM is what you reach for when
heat and aggressive media are in play. ACM holds up well in automatic
transmissions that run hot. For weather resistance or high-pressure duty, EPDM
or HNBR come into their own.

For the case, R23 versions usually stick with carbon steel under that rubber
jacket. TB types may move to stainless when corrosion is on the table—think
marine drives or outdoor wind turbines.

Where They Shine

Head-to-head, the R23’s dust-lip arrangement gives it an edge in dirty
environments—agriculture, sawmills, places where airborne dust is the norm.
The TB wins when rigidity counts, like in large gearboxes, propulsion shafts,
or any setup where the bore alignment is spot-on and the seal OD must hold
shape under stress.

Installers know the R23 is more forgiving if the bore finish isn’t perfect.
The TB, on the other hand, expects precision—sloppy fits will cost you.

Industry Sightings

You’ll see R23s in pumps, small motors, farm equipment, home appliances, and
plenty of hydraulic systems. TBs are more at home in heavy industry—steel
mills, marine propulsion, big construction drivetrains, and wind turbine main
shafts.

Choosing Between Them

Most engineers start with the shaft and bore size, then check the environment:
Is there dust? Is there moisture? Are we fighting chemicals? Temperature range,
shaft speed, and any pressure differential all play in.

For example, that wind turbine main shaft—with its large diameter, outdoor
exposure, and dust risk—might get a TB in stainless steel for rigidity and
corrosion resistance. A combine harvester’s drive shaft? The R23’s double-lip
dust barrier will keep mud and grit out season after season.

There’s no “better” in R23 vs. TB—only the right choice for the conditions.
Knowing their quirks and strengths is how you keep machines running longer and
with fewer surprises. And if you want backup in that decision, our team can
walk you through it—drawing not just from catalogs, but from years of real-
world fixes that worked when the clock was ticking.

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