Plain Bearings

Front 1

Two parts of a journal bearing

Back 1

* Bearing

* Journal

Front 2

What two loads can a journal bearing carry

Back 2

1. Radial

2. Axial thrust

Front 3

Fluid lubrication in a journal bearing depends mainly on

Back 3

* Viscosity of lubricant

* Adhesion to the surfaces of the journal bearing

Front 4

Best method to provide lubricating film to friction bearings not fed under constant pressure

Back 4

Oil grooves

Front 5

In a hydrostatic journal bearing the oil groove is best located in what sector

Back 5

The loaded sector

Front 6

Hydrostatic journal bearings

Back 6

* Are supplied under pressure externally

* Recommended for minimal speeds, heavy loads at start up and frequent stops and starts

Front 7

Plain thrust bearing

Back 7

* Transfers thrust loads from shaft to frame

* Absorbs shaft loads

Front 8

Two ways to find bearing clearance in thrust loads

Back 8

1. Feeler gauges

2. Dial gauge bump test

Front 9

Tilting pad thrust bearing

Back 9

* Vertical or horizontal

* High or low speed

* Can absorb moderate misalignment

Front 10

What keeps tilting pad surfaces separated from shaft collar

Back 10

Oil wedge

Front 11

Type of bearing used as positioning device

Back 11

Thrust bearing

Front 12

Pivoted shoe journal bearing

Back 12

* Supports radial loads

* Uses shoes positioned by cylindrical groves in retaining ring

Front 13

Poor resistance to scoring in journal bearings is called

Back 13

Adhesive wear

Front 14

Ability of journal bearing to absorb contaminants within itself

Back 14

Embedebility

Front 15

Ability of a bearing material to flow slightly under load

Back 15

Conformability

Front 16

Seizures of journal bearings usually occur due to

Back 16

* Localized hot spots

* poor thermal conductivity

* poor fit

Front 17

Bronze bearing material that can absorb oil

Back 17

Sintered 3% - 30%

Front 18

Self lubricating bearing material

Back 18

Teflon

Front 19

What do you do before pouring melted babbitt

Back 19

Heat the bearing shell

Front 20

Tinning process

Back 20

Applying a coat of 50-50 solder to bearing shell so Babbitt will stick

Front 21

Journal bearings need what on the edges for good oil distribution

Back 21

Chamfers

Front 22

Functions of journal bearings

Back 22

* Hold journal in required location

* Support intended radial load

Front 23

Types of radial loads

Back 23

* Stationary

* oscillating

* Reciprocating

Front 24

Reciprocating load

Back 24

Load shifts 180 degrees from one side to the other

Front 25

Stationary load

Back 25

Load generally in one area and one direction

Front 26

Types of plain radial bearings

Back 26

* Thin shell split

* thick wall split spherical seat

* Thick wall plain seat

* Bushings

Front 27

Thin wall split bearing

Back 27

* Flexible

* Thin overlay on steel backing

* Seated in strong housing with accurate bore

* High load capacity

* More compact housing

* Inexpensive and quick to change

* Can be oversize and undersized

* Consistent quality

* Wide range of materials

Front 28

Thick wall split bearings

Back 28

* Not as common

* Not flexable

* Expensive

* Plain seat or spherical

Front 29

Bushings

Back 29

* Axial or radial with shoulder

* Load and speed comparable to split of same size

* Available in various nominal sizes

Front 30

Wrapped bushing

Back 30

* Steel shell with soft bearing material

* High fatigue strength

* Pre finished sizes

* Oversized before install

Front 31

Solid bushings

Back 31

* Can be non standard sizes

* Can accommodate deep grooves

* Not as high fatigue strength as wrapped

* Must be reamed after install

Front 32

Pre lubricated bushing types

Back 32

Porous, soaked in lubricant

* Can hold 30% of volume in oil or 3% for higher load

* Or with pockets-sintered-oilite

* Poor heat distribution

* Good for start stops

* Pre lubed for mainly light loads

Front 33

Dry lubed bushings

Back 33

* Can run dry or wet

* Solid or lined

* Large range of liner materials to suit various loads, speeds, temps or chemicals

Front 34

Hydrodynamic bearings

Back 34

* Depends on rotation to drag oil into loaded area

* Can be split or a bushing

* Oil inlet in unloaded sector

* Load supported by full oil film at operating speeds but not below minimum speed

Front 35

Types of Hydrodynamic bearing

Back 35

* Steady one direction loads

* Reciprocating loads

* Oscillating loads

* Slow speeds

Front 36

Oil whirl

Back 36

* Created at high speeds with unsteady load

* Causes shaft whip

* Stabilized with lobes or tilting pads

Front 37

Hydrodynamic bearing applications

Back 37

* Turbines

* Gear boxes

* Engines

* Compressors

Front 38

Hydrostatic bearings

Back 38

* Supported by pressure film supplied by external pump

* No minimum speed

* Can be split or bushings

* Shaft position and stability can be accurately controlled

* Full film on start up

Front 39

Compressive strength

Back 39

Ability to support the shaft loads at maximum operating temperature

Front 40

Fatigue resistance

Back 40

Resistance to cracking and flaking

Front 41

High embedebility

Back 41

Ability to absorb contaminants without failing

Front 42

Deformability

(Conformability)

Back 42

Ability to yield to misalignment or imperfections in shaft

Front 43

Wetability

Back 43

Ability to retain a film of lubricant

Front 44

Good thermal conductivity

Back 44

Allows rapid transfer of heat

Front 45

Good corrosion resistance

Back 45

Resistance to corrosion from acids in oxidized oil

Front 46

Bondability

Back 46

Bonds metallurgicaly to backing

Front 47

Comparability

Back 47

Resistance to welding to shaft under rubbing condition

Front 48

Oscillating load

Back 48

Shifts through an arc less than 180 degrees back and forth

Front 49

What metal is not used in babbitt

Back 49

Zinc

Front 50

Synthetic friction bearing material is used to reduce

Back 50

Sliding friction