MACHINERY LUBRICATION- INDIA NOVEMBER-DECEMBER 2019 | Page 26

IN THE TRENCHES
amount of information on the machine.
The bearing type and operational data
may be listed on metal plates commonly
referred to as “tags.” Although these are
more readily found on equipment like
pillow-block bearings and electric motors,
some pumps, gearboxes and compressors
may also have them. A shorthand code
usually indicates which bearing is being
identified on the tag. This typically is listed
as drive end (DE), non-drive end (NDE) or
opposite drive end (ODE).
You may also see inboard and outboard
bearing or input and output. This refers
to a bearing supporting a shaft through
the piece of equipment. The motor’s drive
end is the side that the shaft is coupled to
the component. The back or fan side is
denoted as the non-drive end. Thus, the
side closest to the motor or coupling is the
drive or inboard side, while the other is the
non-drive or outboard side.
Decoding
Bearing Numbers
After the equipment tag has been located
and the bearing numbers uncovered, you
will see a series of numbers and letters. This
code is the key to unlocking which type
of bearing is in use within the machine.
Depending on the manufacturer, the
machine’s age and the country in which it
was made, the code may be displayed in
different formats.
Perhaps the most widely used system is
employed by SKF bearings. It utilizes
a numeric code for the bearing’s basic
designation. This will contain many
of the details you are most concerned
about, including the roller type, size and
configuration. A series of letters or numbers
will also designate unique features, such
as the use of shields or seals and if there
are special clearances for this particular
component. All of this information can be a
goldmine when developing a reliability
initiative, as each bearing will behave
differently and may require different
maintenance activities.
24 | November - December 2019 |
000
AAA
OO
AAAA
Bore Type Width & OD Cage Shields or Seals & Modifications
Code Space
No. Common
Symbols Description
Bore 1, 2, 3 17 or 105 Inside diameter of bearing in milli­
meters; refer to bearing catalog
Type 1, 2, 3 BC Ball bearing, single row, radial,
non-filling slot
BL Ball bearing, single row, radial, filling
slot
BD Ball bearing, double row, radial,
non-filling slot
BF Ball bearing, double row, radial, filling
slot
00 6000 series bearing
02 6200 series bearing
03 6300 series bearing
04 6400 series bearing
X Manufacturer a standard bearing cage
P Metal shield permanently fastened
S Contact seal permanently fastened
G Snap ring groove on OD with snap ring
3 Internal clearance greater than
standard
Width & OD
Cage Shields
or Seals
Modification
1, 2
1, 2, 3
Internal Fit
Up
1
0
Internal
Fit Up
AFBMA Code System for Bearings
An example of a bearing number in this
format would be 6203ZZ. This designation
indicates that the bearing is a single-row,
deep-groove ball bearing that is for light
duty with a 17-millimeter bore and shielded
on both sides.
The next designation is known as the
Anti-Friction Bearing Manufacturers
Association (AFBMA) code system. It
has similar components in that it utilizes
an alphanumeric system to indicate the
bearing’s dimensions and configurations.
The code starts with the bearing’s bore,
which is followed by the type, width, outside
diameter and any modifications, such as
seals or shields. In this nomenclature, the
bearing from the previous example would
be denoted as 17BC02PP.
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Both of these systems, along with a host
of others, can be cross-­referenced against
each other. Published tables are available
to assist you in looking up the details for
each system. Your spare-parts vendor can
help you check this information as well. It
generally will be most important to identify
these numbers when you are performing
calculations for greasing or vibration
data. They also can be useful when your
equipment needs to be repaired and you
want to replace a bearing with the same
style or type.
Guidelines for Rebuilds
and Repairs
Depending on the type of equipment, you
may choose to perform rebuilds in-house.
This can offer better control over which