6.8 Bearings

Question 1

What is a bearing?

Answer 1

A machine element that constrains relative motion.

Question 2

What are the two major groups of bearings?

Answer 2

Plain bearings and rolling element bearings.

Question 3

What two characteristics does a good bearing have?

Answer 3

Made of strong material
Held in position with close tolerances.

Question 4

What forces are the bearing subjected too in rotating parts?

Answer 4

Axial/ thrust loads
Radial/ journal loads

Question 5

In a bearing where do the axial loads act?

Answer 5

Along the supported shaft

Question 6

In a bearing where do the journal loads act?

Answer 6

Right angles to the shaft

Question 7

What are some examples of suitable bearing materials?

Answer 7

Copper
Lead tin
Cast iron
Synthetics

Question 8

What do dry powdered bearings contain?

Answer 8

Fluid or solid lubricants in their pores.

Question 9

How are synthetic bearings lubed?

Answer 9

With water

Question 10

Where are plain bearings used?

Answer 10

Used in mainly light applications and motion continuous

Question 11

Due to the frequent maintenance, what has now largely replaced plain bearings?

Answer 11

Anti friction bearings

Question 12

What is a pivot bearing or axial bearings?

Answer 12

Designed for pivot journals which are designed to accept forces in a longitudinal direction.

Question 13

What are the advantages of rolling element bearings over plain bearings?

Answer 13

-Low starting friction
-Can carry heavy loads
-Suitable for reversing or oscillating movements
-Run cooler than plain bearings

Question 14

What are the five types of anti-friction bearing?

Answer 14

Tapered
Needle
Ball
Spherical
Cylindrical

Question 15

What are the raceways and rolling elements manufactured from?

Answer 15

Chromium Steel and Chromium Nickel Steel

Question 16

What are the cages usually made from?

Answer 16

Brass or steel plate

Question 17

How can ball bearings be self aligning?

Answer 17

If the races are machined internally or externally.

Question 18

Where might you find needle bearings?

Answer 18

Planetary gear bearings in light duty epicyclic hub reduction units.

Question 19

What does the self aligning feature of a spherical roller bearing allow?

Answer 19

Minor angular displacement between shaft and housing to be accommodated.

Question 20

What is the main benefit of tapered roller bearings?

Answer 20

Lower price when comparing the calculated fatigue life.

Question 21

If radial loading is expected what must be mounted alongside the thrust bearing?

Answer 21

Normal bearing