Plain Bearings

Question 1

Load on a journal bearing

Answer 1

radial

Question 2

Load on a thrust bearing

Answer 2

axial

Question 3

Radial load acting in one direction and on one area of the bearing

Answer 3

stationary load

Question 4

Radial load with loads shift less than 180

Answer 4

oscillating load

Question 5

Radial loads with load shifts more than 180

Answer 5

reciprocating load

Question 6

One piece journal bearing are typically called a

Answer 6

bushing

Question 7

Split bearing that allows bearing to align its bore with sag in the shaft of a heavy rotor. Reduces edge loading

Answer 7

Spherical seat

Question 8

Bushing can handle only radial load except when

Answer 8

used with thrust washer or flanged

Question 9

Advantage of wrapped bushing over solid bushing

Answer 9

fatigue strength

Question 10

Porosity of a Pre lubricated bushing

Answer 10

3-30%

Question 11

Purpose of a circumferential groove

Answer 11

Provides more oil but reduces load by 50%

Question 12

Bearing with an unsteady load at high speed can develop a condition called

Answer 12

oil whirl

Question 13

Oil whirl can be stabilized with these 2 bearing one for heavy use and the other for light use

Answer 13

lobes bearing-light use

tilting pad-heavy use

Question 14

Hydrodynamic vs hydrostatic load capacity

Answer 14

Hydrodynamic higher

Hydrostatic lower

Question 15

Hydrodynamic vs hydrostatic size

Answer 15

dynamic larger

Question 16

Hydrodynamic vs hydrostatic maximum speed

Answer 16

dynamic higher

static lower

Question 17

Hydrodynamic vs hydrostatic minimum speed

Answer 17

dynamic higher

static zero

Question 18

Bearing requiring jacking oil to be up to pressure

Answer 18

Oil lift journal bearing

Question 19

Bushing bored out of a solid piece of bearing material such as lead bronze or teflon

Answer 19

solid bushing

Question 20

Bushing consist of a thin steel shell lined with a soft bearing material such as lead bronze

Answer 20

wrapped bushing

Question 21

bushing often made of rubber, only suitable for very light loads such as on vertical shafts

Answer 21

water lubricated bushings

Question 22

bushings made of porous material soaked with lubricant, only suitable for light loads as oil will evaporate

Answer 22

pre lubricated bushings

Question 23

bushing made of slippery material such as graphite or PTFE, useful in areas where lubrication is impossible due to inaccessibility

Answer 23

dry lubricated bushing

Question 24

material with highest compressive strength

Answer 24

silver

Question 25

material with highest fatigue resistance

Answer 25

silver

Question 26

characteristic- must not seize or weld to journal under rubbing conditions such as during start up. wear can be adhesive

Answer 26

compatibility

Question 27

characteristic- the bearing material should form a good metallurgical bond to the backing material, the bond should not be brittle and should resist breakdown under operation conditions

Answer 27

bondability

Question 28

characteristic- ability to retain a film of lubricant

Answer 28

wettability

Question 29

characteristic- allows the material to yield to misalignment or imperfections in the shaft, it ensures all parts of the bearing carry a share of the load

Answer 29

deformability/ conformability

Question 30

characteristic- the resistance of the bearing material to cracking and flaking

Answer 30

fatigue resistance

Question 31

characteristic- the bearing material must be strong enough to support the shaft loads at maximum operating tempurature

Answer 31

compressive strength

Question 32

bearing use to stabilize shaft in light applications such as turbochargers

Answer 32

lobed

Question 33

bearing use to stabilize shaft in heavy turbine compressors unit

Answer 33

tilting pad style aka pivoted shoe