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2ed Year Millwright theory a > Plane Bearings > Flashcards

Flashcards in Plane Bearings Deck (18):
0

What are the two main functions of journal bearings

To support radio load
To hold a journal in location accurately

1

What must be done before starting up to ensure there's no damage to oil lift bearing

Checking oil must be brought up to pressure

2

How do you check the contact area of a bearing

By lightly coating the journal with Prussian blue and rotating it inside

3

What are two advantages of measuring bearings with clearance with plastigage instead of lift check

Plastigage provides a more accurate measurement of clearance
Plastigage reveals changers clearance along to Bearing

4

What is a plain bearing

Plain bearings have no rolling elements

5

What are the 2 main purpose of a Journal bearing

To hold journal and it's required location
To support the intended radial load

6

What is a wrapped bushing

It consists of a thin steel shell lined with a soft bearing material such as lead or bronze

7

What is a Hydrodynamic bearings

They are designed to develop full film lubricant when the journal is up to operating speed a.k.a. oil wedge

8

what is a hydrostatic bearing

Hydrostatic bearings are found on equipment that operate too slow to form a Hydrodynamic film
Hydrostatic bearings depend on external pumps to provide pressurized film of lubricant to support the loaded shaft

9

What is compressive strength

The bearing material must be strong enough to support the shaft loads at maximum operating temperature

10

Fatigue resistance

Fatigue resistance is the resistance of the bearings material to crack and flake

11

High embeddability

High embeddability allows abrasive contaminants to become embedded in the material without failing

12

Deformability

Deformability allows the material to yield to misalignment or imperfections in the shaft such as change in diameter it ensures all parts of the bearing carry the the load

13

Wetability

Is the ability to retain a film of lubricant

14

Compatibility

Must not seize or weld to the journal under rubbing conditions such as start up

15

What are the two main types of plain bearings

Journal bearing
Thrust bearing

16

Hydrodynamic bearing suitable for low speeds Why or why not

No because it would not develop an oil wedge

17

What is the reason for crush and spread on connecting rod inserts

To ensure the insert is tightly sealed it to the rod Bores