What Are TC Series Double Lip Shaft Seals Used For?

The duty of TC Series Double Lip Shaft Seals is sealing the point where a shaft leaves a housing — keeping the lubricant in and dirt, water and dust out of the bearing behind it. A spring-loaded elastomer lip runs on the shaft surface, and it is the shaft finish and the elastomer compound, not the seal body, that decide how long it lasts. The sections that follow cover the sectors that specify them, how to state the designation, clearance, sealing, cage and fit on an order, how to mount them, and the known limits of the type. Dimensions are to DIN 3760 / ISO 6194-1. This series is catalogued from 22 mm to 125 mm bore; the full table of boundary dimensions is further down the page.

Typical Applications for TC Series Double Lip Shaft Seals

The machine positions and sectors where this type is specified:

• Agricultural and mobile equipment: axial V-ring seals flicking mud and water away from the housing entry before it reaches the lip.
• Maintenance and repair (MRO): replacing a failed bearing where the original designation, clearance group and sealing have to be matched exactly.
• OEM machine building: designed-in shaft support on new equipment, specified from the load, speed and envelope at the design stage.
• Bearing housings and gearboxes: sealing the shaft exit so the lubricant stays in the housing and contamination stays out of the bearing.
• Bearing housings and pedestals: sealing the shaft exit of a plummer block or a pillow block so the grease stays in and washdown water stays out.

How to Specify TC Series Double Lip Shaft Seals for Your Application

• Bore: Start from the bore the shaft or housing gives you — this series is catalogued from 22 mm to 125 mm — then check the outer diameter and width against the space available. The boundary dimensions are fixed by the standard, so they are the same from any manufacturer; the load ratings and limiting speeds are not, and belong to the specific bearing being supplied.
• Elastomer and lip: State the shaft diameter, housing bore, width, lip arrangement (single lip, dust lip) and elastomer. The elastomer sets the temperature and chemical limits, and it is the field most often missing from an order.
• Dimensions and type: State the shaft diameter, the housing bore and the width, and the seal type — single lip, double lip with a dust lip, or an axial V-ring that runs against a face rather than in a bore.
• Elastomer: The elastomer sets the temperature range, the chemical compatibility and the permissible surface speed. It is the field most often left off an order, and the one that most often explains a seal that failed early.
• Designation and suffixes: State the complete designation including every suffix. The base number gives the type and the boundary dimensions; the suffixes carry the sealing, the cage, the clearance group, the tolerance class and any special execution — and two bearings whose base numbers match but whose suffixes differ are not interchangeable.
• Clearance and tolerance: State the running clearance or fit class the assembly requires, together with the tolerances of the mating parts that produce it. For this type the clearance is created by the parts around the bearing rather than being built into it, which is precisely why it has to be written down.
• Seal or shield: State open, shielded (ZZ, 2Z) or sealed (2RS, 2RZ). A shield is non-contacting: it excludes coarse contamination and costs nothing in speed. A contact seal excludes fine dust and water and retains grease, but it rubs — it adds drag, raises the running temperature and lowers the permissible speed. Sealed bearings are also greased for life and cannot be relubricated.
• Cage: not applicable: This part has no cage and no rolling elements to separate, so the equivalent decision is the sliding material or liner. That is stated above, and it plays the same role: it is what sets the temperature limit and the lubrication requirement.
• Shaft and housing fit: Specify the seat tolerances, not just the bearing. The rule is that the ring which rotates relative to the load direction takes the interference fit: for a rotating inner ring under normal radial load the shaft seat is typically k5 or k6 with the housing bore H7, and where the outer ring rotates the interference moves to the housing (N7 or P7) with a clearance fit (g6) on the shaft. Heavier loads and hollow shafts move the fits tighter. A correctly chosen bearing in the wrong fit fails anyway — too loose and the ring creeps and frets its seat, too tight and the interference consumes the internal clearance and the bearing runs preloaded.
• Standard: Boundary dimensions are to DIN 3760 / ISO 6194-1. Quoting the standard on the order guarantees the mounting dimensions are interchangeable between suppliers — it does not standardize load ratings, limiting speeds or internal design, which remain manufacturer-specific.

Mounting & Assembly Practice

• Fit with the lip facing the medium being retained — a seal fitted backward leaks from the first hour and looks perfectly installed.
• Never pull a lip over an unchamfered shaft end, a keyway or a thread. Use a fitting sleeve; a lip nicked during assembly leaks immediately.
• Press on the outer case with a flat tool over its full diameter, square to the bore. A cocked seal distorts the case and the lip runs eccentric.
• Inspect the shaft at the seal track. A groove worn by the previous seal is a leak path: repair it with a thin-wall sleeve or move the new seal axially along the shaft.

Common Selection Mistakes with TC Series Double Lip Shaft Seals

• Choosing the seal on dimensions alone and leaving the elastomer to the supplier, then finding an NBR lip hardened by an operating temperature that required FKM.
• Fitting a new seal onto a shaft with a worn running track, which leaks regardless of the seal.
• Running a lip seal dry. The lip is lubricated by a controlled film of the medium it retains; a seal that runs dry burns its contact band within minutes.
• Sizing this bearing from the boundary dimensions alone. Load ratings and limiting speeds are manufacturer-specific for this series and are deliberately not published here — take them from the catalog of the bearing actually being supplied and calculate the life against them.

Where TC Series Double Lip Shaft Seals Are Not the Right Choice

• Not a substitute for a bearing seal where the bearing itself needs protecting — the shaft seal guards the housing exit.
• A shaft seal carries no bearing load and locates nothing. It seals a shaft exit and nothing else.
• Not for a rough, soft or damaged shaft surface — the shaft is half of the sealing interface and its finish and hardness are part of the specification.
• Not for pressure, unless a pressure-rated design is specified: an ordinary radial lip seal is designed for approximately atmospheric pressure behind it.
• Not for surface speeds above the rating of the elastomer, where the frictional heat in the contact band destroys the lip.