Nomenclature and basic types of SKT seals
Nomenclature
The type and material of the seal vary depending on the working conditions. The same conditions are also used in seal selection and classification. An example to SKT Nomenclature (including material code) is shown below. All dimensions are in metric unit (mm).
| 19,00 x 35,00 x 7,00 : | Nominal dimensions |
| L3L SAG : | Seal type |
| 040671-S : | SKT No (-S : Material code) |
| Nominal dimensions | |
|---|---|
| Shaft diameter | d1 |
| Housing diameter | D |
| Seal width | b |
| Outer diameter | d2 |
Figure 4
Nominal dimensions
There are two unit systems in SKT oil seal:
- Dimensioning of metric seals
- Dimensioning of British unit seals
a. Dimensioning of metric seals
a.a. Seals having three dimensions:
Example: SKT No:040323 Dimension: 30.00 x 45.00 x 8.00
| d1 | x | D | x | b |
|---|---|---|---|---|
| 30.00 | x | 45.00 | x | 8.00 |
| Shaft Diameter. | Housing Diameter. | Total width |
All dimensions are in mm.
a.b. Seals having more than three dimensions :
According to their application some seals have more than three dimensions.
Example: SKT No 047587-Z SPL3LL Dimension: 45.00 x 72.00 - 86.00 x 8.00 - 12.00
| d1 | x | D | - | D' | x | b | - | b' |
|---|---|---|---|---|---|---|---|---|
| 45.00 | x | 72.00 | - | 86.00 | x | 8.00 | - | 12.00 |
| Shaft diameter | Housing diameter | Largest Diameter of the seals | Mounting width | Total width |
All dimensions are in mm.
b. Dimensions converted from British units :
The second dimensions differs in British unit seals.It indicates the outer diameter of the seal.
b.a. Seals having three dimensions:
Example: SKT No: 047472 Type: L1L, Dimension: 69.85 x 92.15 x 14.28
| d1 | x | d2 | x | b |
|---|---|---|---|---|
| 69.85 | x | 92.15 | x | 14.28 |
| Shaft diameter | Seal diameter (second dimension) In order to maintain sufficient interference, housing diameter should be selected accordingly. (Refer to the below tables) |
Total width |
b.b. Seals having more than three dimensions:
Example: SKT no: 410325, Type SPLLKSS, Dimension: 66.67 x 103.34 - 112.69 x 12.7 - 27.78 (outer steel case). Ø 103.34 is outer diameter of this seal and the housing diameter should be Ø 103.21 according to the below table. (Ø 103.34 - 0.13 =) 103.21 mm.
| Outer steel case (L1, SL, SD, etc) | |||
|---|---|---|---|
| Outer diameter (d2) (mm) | Housing diameter Interference (mm) |
Housing diameter tolerances (mm) | |
| ...from | ...to | ||
| 00.00 | 50.93 | -0.13 | +0.03 -0.03 |
| 50.94 | 76.33 | -0.13 | +0.03 -0.03 |
| 76.34 | 127.13 | -0.13 | +0.04 -0.04 |
| 127.14 | 177.95 | -0.15 | +0.04 -0.04 |
| 177.96 | 304.98 | -0.18 | +0.05 -0.05 |
| 304.99 | 508.20 | -0.20 | +0.05 -0.10 |
| 508.21 | 1016.20 | -0.20 | +0.05 -0.15 |
| 1016.20 | 1524.20 | -0.20 | +0.05 -0.25 |
Table 2
| Outer rubber shell seals (L3, L2, etc) | |||
|---|---|---|---|
| Outer diameter (d2) (mm) | Housing diameter Interference (mm) |
Housing diameter tolerances (mm) | |
| ...from | ...to | ||
| 00.00 | 51.00 | -0.20 | +0.03 -0.03 |
| 51.01 | 76.45 | -0.25 | +0.03 -0.03 |
| 76.46 | 127.25 | -0.25 | +0.04 -0.04 |
| 127.26 | 178.10 | -0.31 | +0.04 -0.04 |
| 178.11 | 305.10 | -0.31 | +0.05 -0.05 |
| 305.11 | 508.38 | -0.38 | +0.05 -0.10 |
| 508.39 | 1016.46 | -0.46 | +0.05 -0.15 |
| 1016.47 | 1524.00 | -0.51 | +0.05 -0.25 |
Table 3
Coding description of seal type
| Symbol | Description | Example |
|---|---|---|
| A | No spring groove | SLA |
| B | Application for high pressures | L3B |
| C | Extended lip (1) | L3C |
| C | Outside sealing lip (2) | CL3 |
| D | Leather material | SLD |
| K | Felt material | SLK |
| L | Elastomer material | L1, L3 |
| L | Dust lip (3) | LL3, L3L |
| LL | Double dust lip | L3LL |
| R | Axial dust lip | L5R |
| SAG | Applicable at clock wise rotating shafts | L3SAG |
| SOL | Applicable at counter clock wise rotating shafts | L3SOL |
| SS | Applicable at bi-directional rotating shafts | L3SS |
| SC | Cassette type seal | SC1 |
| SP | Special design (4) | SPL3 |
| T | Corrugated outer surface | L3T |
| X | With double lip | L3X |
(1) If it is at the end of the coding description.
(2) If it is at the beginning of the coding description.
(3)If L comes first the dust lip is retracted. If L comes last at the dust lip protruding.
(4) Special design. Please, apply to SKT for detailed information.
Table 4
For clock wise rotation |
For counter clockwise rotation |
For bi-directional rotation |
Basic types and characteristics
 L1 |
L1 type seal : DIN 3761 type B, outer steel case. |
  L3 L3T |
L3 type seal : DIN 3761 type A, corrugated or flat outer surface, preferred for thermal expansion metarial, split housing, rough surface or eccentric housing bore. |
 L13 |
L13 type seal : Bring together the advantages of L1 and L3 type seal. |
 SL |
SL type seal : DIN 3761 type C, has the properties of L1 while providing higher rigidity. |
 L3L |
L3L seal with dust lip : Used to protect sealing lip from dust and dirt where operating place is open to air. |
 L3LL |
L3LL seal with double dust lip : To protect the seal from environmental effects. |
 |
L3LR radial type with dust lip: Protection function of the dust lips at the radial (R type) and axial directions against high dirt accumulation. |
 L3B |
L3B : Applicable at high pressures (up to 5 bars). |
  L2 L5 |
L2 and L5 type seals are applicable in environments with grease and also as scratchier, viper. |
 D1 |
Leather seal is less sensitive to dimensional and physical imperfections and easier to install. |
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