BEARING DESIGNATIONS AND MEANING

On board our ships BEARINGS are used in almost every machinery.

But what does a Bearing Mean?

"Bearings are a hardened spherical ball that spins between two surfaces and reduces friction".

We are very well aware of the fact that at the time of ordering or at the time of replacing these bearings there is a Specific number designated to them.  This means that every bearing has been designated with a certain set of numbers and alphabets.  Before getting into the Nomenclature lets take a look at different types of bearings.

Different types of Bearings

• NEEDLE BEARINGS

NEEDLE BEARING

• CYLINDRICAL BEARINGS

     

CYLINDRICAL BEARINGS

• SLEEVE BEARINGS

SLEEVE BEARINGS

• SPHERICAL BEARINGS

SPHERICAL BEARINGS

• LINEAR BEARINGS

LINEAR BEARINGS

• ROLLER BEARINGS

ROLLER BEARING

• RADIAL BEARING

RADIAL BEARING

• PILLOW BLOCK BEARINGS

PILLOW BLOCK BEARING

• TRACK RUNNER BEARING

TRACK RUNNER BEARING

• DEEP GROOVE BALL BEARING

DEEP GROOVE BALL BEARING

• ANGULAR CONTACT BALL BEARING

ANGULAR CONTACT BALL BEARING

• THRUST BEARING

SELF ALIGNING ROLLER THRUST BEARING

TILTING PAD THRUST BEARING

• MAGNETIC BEARING

MAGNETIC BEARING

AND THERE ARE MANY OTHER TYPES OF BEARINGS

Now lets find out as to how we can distinguish between so many different types of bearings without even looking at them.

BEARING NOMENCLATURE

Nomenclature depends from manufacturer to manufacturer.  Nomenclature described below is the most common one.

A bearing number has 4 parts to it which includes four numbers and a set of letters.  The first two numbers stand for type and series, the last two numbers designate size and the letters dictate the variation of the bearing.  Lets now take a look at what actually these numbers are and what do they mean:

The first number OR LETTER designates the bearing type.  The first number can be

1 = SELF ALIGNING BALL BEARING

2= SPHERICAL ROLLER BEARING

3= DOUBLE ROW ANGULAR CONTACT BALL BEARING

4= DOUBLE ROW BALL BEARING

5= THRUST BALL BEARING

6= SINGLE ROW DEEP GROOVE BALL BEARING

7= SINGLE ROW ANGULAR CONTACT

8= FELT SEAL ALSO KNOWN AS WIDE CUP BEARING

32= TAPERED ROLLER BEARING

R= INCH NON-METRIC BEARING (i.e bearing dimensions do not comply with metric system)

N= CYLINDRICAL ROLLER BEARING

NN= DOUBLE ROW ROLLER BEARINGS

NA= NEEDLE ROLLER BEARINGS

The second number designates the series or cross section.  It's the ratio of the bore to the width of the bearing, which also controls the OD of the bearing.  The larger the cross section,  the larger the OD of the bearing.  Second number can be

8= EXTRA THIN SECTION

9= VERY THIN SECTION

0= EXTRA LIGHT

1= EXTRA LIGHT THRUST

2= LIGHT

3= MEDIUM

4= HEAVY

The third number is a set of two numbers indicates the bore in mm of the bearings.  All the bearings are designated with metric standards and not inches.  The third number can be

00= 10 mm

01= 12 mm

02= 15 mm

03= 17 mm

For 20-240 mm BEARINGS = LAST 2 DIGITS X 5 = BORE mm

This means if we have the third number as 04 than it would mean that the bore of the bearing is 4x5=20mm or 08 than 8x5=40mm 

The letters indicate the variation.  These vary from manufacturer to manufacturer but the most common ones are as follows

PLAIN= NO SHIELD

TYPE Z= ONE SHIELD (NORMALLY HAVE METAL SHIELDS)

TYPE 2Z= TWO SHIELDS (ONE ON EACH SIDE)

TYPE RS1= ONE SEAL (NORMALLY R INDICATES RUBBER)

TYPE 2RS1= TWO SEAL (RUBBER SEAL ON BOTH SIDES). 

CD= 15 DEGREE CONTACT ANGLE (FOR ANGULAR CONTACT)

ACD= 25 DEGREE CONTACT ANGLE (FOR ANGULAR CONTACT)

V= SINGLE NON CONTACT SEAL

VV= DOUBLE NON CONTACT SEAL

DDU= DOUBLE CONTACT SEALS

N= SNAP RING GROOVE ON OUTER RING

NR= SNAP RING GROOVE ON OUTER RING INCLUDED

M=BRASS CAGE

J= STEEL CAGE

ZBNR= SHIELD AND SNAP RING ON SAME SIDE

ZNJ= SHIELD ON SIDE OPPOSITE SNAP RING GROOVE

ZNRJ= SHIELD ON SIDE OPPOSITE SNAP RING

BLANK= STEEL CAGE

The bearings also have C2, C3, C4 or C5 designation after the bearing number.  This indicates that the internal fit (the inner race to the ball to outer race) is not standard.  Always remember that bearings with these designations need to be replaced with the same designators i.e a C2 bearing is to be replaced with a C2 bearing only.  A C2 bearing is less than standard clearance, while a C3, C4 and C5 are larger than standard.

For further information on bearings and

designations by SKF Click Here 

designations by NSK Click Here or Here

designations by NTN Click Here