UBC Bearings of America Limited. basic BEARING knowledge.

UBC Bearings of America Limited

basicBEARINGknowledge

What is a Bearing Used for?

Designed to:

Reduce friction

Carry loads

Guide moving parts

Rolling and Sliding Friction

µ

µ

Component parts of a ball bearing

Seal Rolling elements Inner ringOuter ring Cage Seal

Shields Low-friction seals Seals

-Z and -2Z -RZ and -2RZ -RS and -2RS

Contaminantexclusion

Silentrunning

Greaseretention

SpeedcapabilityS

eal a

nd

Sh

ield

Var

iati

ons

Application Shield Seal

Need 2Z 2RZ 2RS

Low friction +++ ++(+) –torque

High speed +++ ++(+) –ability

Grease + ++ +++retention

Dust + ++ +++exclusion

Water – – +exclusion

Low/high Depends on: Depends on:operatingtemperature Grease – Grease

– Rubber mix

+++ Excellent ++ Good + Fair – Poor

Characteristics of Different Seals

Storage Requirements

Roller and Ball Raceway Contact

Axial and Radial load capability

Axial load

Radial loadCombined load

Fa

Fr

Roller Types

Spherical roller(asymmetrical)

Taper roller

Spherical roller(symmetrical)

Needle roller

Cylindrical roller

Ball

Ball and Roller Bearing Ranges

Deep groove

Ball bearings Roller bearings+Angularcontact

Self-aligning Cylindrical Taper Spherical

Load Capabilities

Load carrying capacityis expressed as the basicdynamic load rating

Ball Bearing Capabilities

Deep groove Angular contact Self-aligning

Radial load Axial load Speed Accommodates

carrying capacity carrying capacity capability misalignment

Function of the Cage

Prevent immediate contact betweenrolling elements to minimize frictionand heat generation

Guide the rolling elements

Provide space for lubricant

Retain the rolling elements when bearings of separable designare mounted or dismounted

Cage Variants

Nylon cage Steel cage Solid brass cage

Nylon Cages

+ Lightweight

+ High elasticity

+ Good sliding properties

+ Good marginallubrication properties

– Operating temperature< +120 °C

Steel Cages

+ Lightweight

+ High strength

+ High vibration andacceleration resistance

– Sensitive topoor lubrication

+ No operatingtemperature limit

Solid Brass Cages

+ Very high strength

+Suitable for very highspeed in connectionwith circulating oil

– Relatively (very) expensive

+ Very high vibration andacceleration resistance

Internal Clearances

Radialclearance

Axialclearance

The bearing internal clearance is definedas the total distance through which onebearing ring can be moved relative to the other under zero measuring load.

Why Internal clearance?

• In order to fit a bearing tightly on a shaft, it is necessary that the shaft is slightly larger than the bore of the inner ring. When the bearing is mounted, the inner ring will be expanded and consequently the space available for the rolling elements will be reduced. The reduction in space available for rolling elements when the bearing is mounted is accommodated by the internal clearance.

Why Internal clearance?

• Steel will expand with increased temperature. In operation, the temperature of the various parts of a bearing will not remain uniform and resulting in varying degrees of expansion which is compensated by the internal clearance.

Internal Radial Clearance

Clearance range

C1 Clearance less than C2

C2 Clearance less than Normal

C3 Clearance greater than Normal

C4 Clearance greater than C3

C5 Clearance greater than C4

COLD

WARM

Reducedradial

clearance

Expansion

Compression

The internal clearance required is dependent upon the mounting fit and the operating conditions. In case of doubt, a bearing with greater internal clearance shall always be selected.

Effect of Internal Preload and Clearance on Bearing Life

Relative basic rating life L10, %

Preloading Clearance

Correct Fits

Tolerance range for bearings manufactured to ISO

Operating conditions

Available space Misalignment

Speed Life

Load/Direction

Bearing Selection Factors

International Organization forStandardization

ISOISO

ISO Standards

Diameter Series

Relationship: Diameter and Width Series

Diameter Series

Width Series Height Series

Dimension Series

Width Series

Dia

met

er S

erie

s

Bore diameter Written as Example

Below 10 mm

3

.

.

9

3

.

.

9

623

.

.

629

10 – 17 mm

10

12

15

17

00

01

02

03

6200

6201

6202

6203

20 – 480 mm

20

25

.

.

480

04

05

.

.

96

6204

6205

.

.

61896

Above 500 mm 710 /710 241/710

Bore designation system

How the Designation System Works

Bearing types

Radial bearings, width (B, T) Thrust bearing, height (H)

Outside diameter (D)

Bearing size d/5

(30 mm bore diameter)

Tapered Bore Suffixes

Suffix K

Suffix K30

Taper 1:12

Taper 1:30

Dee

p g

roov

e b

all b

eari

ng

Sel

f-al

ign

ing

bal

l bea

rin

g

Pla

ne

thru

st b

all b

eari

ng

An

gula

r co

nta

ct b

all b

eari

ng

Sp

her

ical

rol

ler

bea

rin

g

Tap

er r

olle

r b

eari

ng

Cyl

ind

rica

l rol

ler

bea

rin

g

THE END