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Designation system

The designations of most SKF rolling bearings follow a system that may consist of a basic designation with or without one or more prefixes and/or suffixes (→ Basic bearing designation system).
An example and the applicable options for double row cylindrical roller bearings are given below.
Basic bearing designation system
NNU 41/1000 K30M/W33whereNNU 41/1000 =
K30 =
M =
W33 =
In addition to their designation, double row cylindrical roller bearings are also identified by the design variant/features (→ product table). Some of these features may not be part of the bearing designation, but are always part of the design variant/features (→ Variants/features).
Test Designation 1Prefixes (n.a.)

Test Designation 2Basic designation
Listed in table 1 or drawing number identification

Catalogue image - Test Designation 3Suffixes - Internal design
A, B, CDeviating or modified internal design

Test Designation 4Suffixes - External design (seals, snap ring groove etc.)
GHelical groove in inner ring bore
KTapered bore, taper 1:12
K30Tapered bore, taper 1:30

Catalogue image - Test Designation 5Suffixes - Cage design
F
Machined steel cage, roller centred
MMachined brass cage, roller centred

Catalogue image - Test Designation 6.1Suffixes - Materials, heat treatment
HA1Case-hardened inner and outer rings
HA4Case-hardened inner and outer rings and rollers
HA5Case-hardened rollers
HB1Bainite-hardened inner and outer rings

Test Designation 6.2Suffixes - Accuracy, clearance, preload, quiet running
CNNormal radial internal clearance; only used together with an additional letter that identifies a reduced or displaced clearance range
  • H = Reduced clearance range corresponding to the upper half of the actual clearance range
  • L = Reduced clearance range corresponding to the lower half of the actual clearance range
  • M = Reduced clearance range corresponding to the middle half of the actual clearance range
  • P = Displaced clearance range comprising the upper half of the actual clearance range plus the lower half of the next larger clearance range
The above letters are also used together with the clearance classes C2, C3, C4 and C5, e.g. C2H
C2Radial internal clearance smaller than Normal
C3Radial internal clearance greater than Normal
C4Radial internal clearance greater than C3
C5Radial internal clearance greater than C4

Catalogue image - Test Designation 6.3Suffixes - Bearing sets, matched bearings
DRSet of two matched bearings
TRSet of three matched bearings
QRSet of four matched bearings

Test Designation 6.4Suffixes - Stabilization
S1Bearing rings heat stabilized for operating temperatures ≤ 200 °C (390 °F)
S2Bearing rings heat stabilized for operating temperatures ≤ 250 °C (480 °F)

Test Designation 6.5Suffixes - Lubrication
W20Lubrication holes in the outer ring
W33(X)Annular groove and lubrication holes in the outer ring

Test Designation 6.6Suffixes - Other variants (n.a.)
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