PKB Ball Bearing Nomenclature


PACAMOR KUBAR BEARINGS offers an array of retainer designs and materials, including but not limited to, Crown, Ribbon, heat and moisture resistant Phenolic, and Torlon (polyamide-imide). In addition to selecting the right retainer for your miniature bearing application, dissimilar materials can prevent component micro-welding and extend the life of the bearing.

To this end, we offer standard stainless steel or optional ceramic balls or titanium carbide-coated 440C stainless steel balls(Tic), in our miniature bearing designs.

PACAMOR KUBAR BEARINGS precision miniature bearings are available with up-to ABEC 9 tolerances (as defined by the American Bearing Manufacturers’ Association), with optional flanged-outer rings.


Description of PACAMOR KUBAR BEARINGS part numbering system and methodology, for identifying a PKB part number.

Special Feature Material Type Style Retainer Basic Size Closure
X S F R B 2-5 ZZ
  S (ZZ) R PH 144 Z


Special Feature 

X followed by two numbers = Special feature or change in standard dimension, to basic bearing number.

A = Tapered Outside Diameter (OD)



S = AISI44OC stainless steel



F = Flanged bearing

No Symbol = straight OD

(ZZ) = Open bearing, but with shielded width   



R = Radial Inch

Blank or MM = Metric

AINS = Angular Contact Inner-Relieved, Non-Separable

AIS = Angular Contact Inner-Relieved, Separable

AONS = Angular Contact Outer-Relieved, Non-Separable

AOS = Angular Contact Outer-Relieved, Separable


Retainer Type

Standard retainer could be either one piece crown or two piece ribbon type.

Blank = Pacamor’s standard option

B = Two Piece Ribbon

PH = Phenolic Crown Retainer 

F = Full-Complement (No Retainer)

FU = Full-Complement (Metric Size)

SL = Slug Separators

TO = Teflon Toroids



T = Torlon

*Other machined retainer options available


Basic Size (Bearing Chassis)

See basic bearing numbers listed in our catalog



Z = Single shield LL = Double glass-reinforced Teflon seal
ZZ = Double shield RS = Single rubber seal
Z1 = Shield on flanged side 2RS = Double rubber seal
Z2 = Shield opposite flanged side V = Single non-contact seal
T = Single Teflon seal VV = Double non-contact seal
TT = Double Teflon seal UZ = Single shielded, narrow width bearings
L = Single glass-reinforced Teflon seal  

No designation = open bearing


Ring Feature Alt. Ball Material Radial Play ABEC Tolerance Functional Test Lubrication Coding / Duplex Package
EE CB K25 A5 ST10 L245X ZD P
  TiC K24 A7 EMQ ROY27 DB B


Ring Feature 

EE = Extended inner rings 
NR = Snap ring on bearing OD
Blank = 440c Stainless Steel Balls


Alternate Ball Material

CB = Ceramic (Silicon Nitride) balls

TiC = TiC-coated 440c stainless steel balls


Radial Play 

Symbol K followed by number indicates radial play in tenths of thousands of an inch.


K25 = 0.0002″ to 0.0005″
K58 = 0.0005″ to 0.0008″


ABEC Tolerances 

A1 = ABEC 1
A3 = ABEC 3
A5 = ABEC 5P
A7 = ABEC 7P
A9 = ABEC 9P*

*ABEC9 tolerances are available upon request


Functional Test  

Blank = Pacamor’s standard option

ST followed by number = indicates starting torque in hundreds of MG-MM
E.M.Q. = Electric Motor Quality



Blank = Pacamor’s standard option

See our common lube codes here

LD = Dry bearings (no lubrication)
GP = Indicates grease plate  
BC = Indicates barrier coating  
OP = Oil plate
DIC = Dicronite coating

Alternate lubes/coatings available upon request.



Tolerance 0.0001 Increment Coding (Standard), In 0.000050 Increment Coding, In
Nominal to -0.000050, In 1 A
-0.000050 to -0.000100, In B
-0.000100 to -0.000150, In 2 C
-0.000150 to -0.000200, In D
-0.000200 to -0.000250, In 3 E
-0.000250 to -0.000300, In F
Grade Symbols
Graded Bore and OD ZD XZD
Graded Bore Only ZB XZB
Graded OD Only ZO XZO


Duplex Coding (also known as Duplex Sets or Duplex Pairs)

DB = Back to Back Pairing   — DT = Tandem Pairing
DF = Face to Face Pairing   — DU = Universal Pairing



The following symbols indicate various types available:            

Blank = Vial packaging
P = Individual pill packaging
B symbol = Individual box
M symbol = Individual pack per Mil-197


Contact PKB for more offerings.