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Supplementary designations

The designation suffixes used to identify certain features of SKF double row cylindrical roller bearings are explained in the following.
BPresent standard design with brass cage of double pronged type
BKB + K
CNNormal radial internal clearance; normally 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 two middle quarters of the actual clearance range
P Reduced clearance range corresponding to the upper half of the actual clearance range plus the lower half of the next greater clearance range
The above letters are also used together with the clearance class suffixes C2, C3, C4 and C5
C1Radial internal clearance smaller than C2
C2Radial internal clearance less than Normal
C3Radial internal clearance greater than Normal
C4Radial internal clearance greater than C3
C5Radial internal clearance greater than C4
FRoller-centred machined steel cage of double pronged type
FAOuter ring centred machined steel cage of double pronged type
FBInner ring centred machined steel cage of double pronged type
HA1Case hardened inner and outer rings
HA2Case hardened outer ring
HA4Case hardened rollers, inner and outer rings
HB1Bainite hardened inner and outer rings
HB2Bainite hardened outer ring
HB3Bainite hardened inner ring
KTapered bore, taper 1:12
KTN9K + TN9
K30Tapered bore, taper 1:30
MTwo-piece machined brass cage, roller centred
P4Dimensional and running accuracy to ISO tolerance class 4
P5Dimensional and running accuracy to ISO tolerance class 5
P6Dimensional and running accuracy to ISO tolerance class 6
SPSpecial precision class for machine tool bearings; dimensional accuracy approximately to P5, running accuracy approximately to P4
SPCNSP + CN
SPC2SP + C2
TN9Injection moulded cage of glass fibre reinforced polyamide 66
UPUltra precision class for machine tool bearings; dimensional accuracy approximately to P4, running accuracy better than P4
VE900Preliminary standard design
W33Annular groove and three lubrication holes in outer ring
W33XAnnular groove and six lubrication holes in outer ring
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