6.8- Bearings

Question 1

Describe a plain bearing.

Answer 1

Load carrying cylindrical inserts, made from hard wearing materials.

Question 2

What are the common uses for plain bearings?

Answer 2

Where the loads are light and the motion is continuous.

Question 3

In view of frequent maintenance of plain bearings what are they now being replaced with?

Answer 3

Anti-friction bearings.

Question 4

What are bearings used to support?

Answer 4

Journals of shafts and axles.

Question 5

What are bearings used to support journals at right angles called?

Answer 5

Journal bearings or roller bearings.

Question 6

Bearings for pivot journals which accept longitudinal direction are known as what?

Answer 6

Pivot bearings or axial bearings.

Question 7

The journal of a sliding bearing operates in what?

Answer 7

Bearing box, bushing or bearing body.

Question 8

What does the amount of bearing play depend on?

Answer 8

The demands of the bearing and the lubricant.

Question 9

What are sliding bearings resistant too?

Answer 9

Push forces, operating with little noise.

Question 10

What are two disadvantages of sliding bearings?

Answer 10

High starting resistance and high maintenance.

Question 11

What are the bearing loads commonly experienced?

Answer 11

Radial and thrust.

Question 12

What are the 5 basic types of anti-friction bearing?

Answer 12

Tapered
Needle
Ball
Spherical
Cylindrical.

Question 13

What does an anti-friction bearing consist of?

Answer 13

Outer and inner raceway
Rolling element
Rolling element cage.

Question 14

What are the raceways and rolling elements made from?

Answer 14

Chromium steel or Chromium Nickel Steel.

Question 15

What contact do ball bearings have?

Answer 15

Point- this means all the stress is concentrated on one point.

Question 16

What is the most popular ball bearing and what loads can it take?

Answer 16

Deep groove ball bearing and light radial loads only.

Question 17

What is the most common use for cylindrical roller bearings?

Answer 17

Non-locating positions where it is necessary to deal with thermal expansion.

Question 18

What does the self-aligning feature of spherical roller bearings allow?

Answer 18

Minor angular displacements between the shaft and housing to be accommodated.

Question 19

Why must the cage around spherical roller bearings be robust?

Answer 19

To counteract the roller skewing effect which increases inertia.

Question 20

Why is a tapered roller bearing the best?

Answer 20

Because it has all the benefits of the other types and many more of its own.

Question 21

What materials are suitable for bearings? (6 examples)

Answer 21

Copper tin alloys
copper tin zinc alloys
lead tin alloys
cast iron
dry powdered metals
synthetics

Question 22

What’s a benefit of using dry powdered metals such as graphite for bearings?

Answer 22

They contain fluid or solid lubricants in their pores.

Question 23

What are synthetic bearings lubricated with?

Answer 23

Water, it also acts as a coolant.

Question 24

How does an air bearing work?

Answer 24

It utilizes a thin film of air to provide a zero friction load bearing.