Tribology and Lubrication: Master Friction, Wear, and Lubrication for Machine Design

Question 1

In which lubrication regime does a continuous fluid film completely separate contacting surfaces, preventing direct contact?

Accepted Answer

Hydrodynamic lubrication

Answer

Boundary lubrication

Answer

Mixed lubrication

Answer

Elastohydrodynamic lubrication

Question 2

Which of the following is not a primary function of lubrication?

Accepted Answer

Increasing surface roughness

Answer

Reducing friction

Answer

Dissipating heat

Answer

Preventing wear

Question 3

In hydrodynamic lubrication, the film thickness between the contacting surfaces is primarily determined by:

Accepted Answer

The viscosity of the lubricant

Answer

The load applied

Answer

The speed of the surfaces

Answer

The surface roughness

Question 4

Which of the following types of wear is characterized by material removal due to the formation and breakage of junctions between the contacting surfaces?

Accepted Answer

Adhesive wear

Answer

Abrasive wear

Answer

Fretting wear

Answer

Rolling contact fatigue

Question 5

Which of the following is an example of a boundary lubricant?

Accepted Answer

Molybdenum disulfide

Answer

Mineral oil

Answer

Water

Answer

Air

Question 6

In hydrodynamic lubrication, a thin layer of what separates the contacting surfaces?

Accepted Answer

Fluid

Answer

Grease

Answer

Solid film

Answer

Gas

Question 7

The primary function of a lubricant in machine design is to:

Accepted Answer

Reduce friction and wear

Answer

Control temperature

Answer

Prevent corrosion

Answer

Enhance aesthetics

Question 8

Which property of a lubricant is essential for effective boundary lubrication?

Accepted Answer

Oiliness

Answer

Viscosity

Answer

Pressure resistance

Answer

Thermal conductivity

Question 9

The key difference between hydrodynamic and hydrostatic lubrication lies in the:

Accepted Answer

Pressure generation mechanism

Answer

Fluid film thickness

Answer

Contact type

Answer

Lubricant type

Question 10

Which type of wear occurs due to repeated sliding motion under high contact stresses?

Accepted Answer

Surface fatigue wear

Answer

Adhesive wear

Answer

Abrasive wear

Answer

Erosive wear

Question 11

When selecting a lubricant, which factor is NOT typically considered?

Accepted Answer

Personal preference

Answer

Operating temperature

Answer

Load conditions

Answer

Surface finish

Question 12

In selecting a lubricant for a mechanical system, which factor is typically NOT a primary consideration?

Accepted Answer

Cost of the lubricant

Answer

Operating temperature

Answer

Load and speed of the system

Answer

Environmental conditions

Question 13

For applications involving high radial loads, moderate speeds, and potential shock loading, which bearing design is most suitable?

Accepted Answer

Roller bearing

Answer

Ball bearing

Answer

Plain bearing

Answer

Hydrodynamic bearing

Question 14

The primary purpose of lubrication in machine design is to:

Accepted Answer

Reduce friction and wear

Answer

Enhance heat transfer

Answer

Prevent corrosion

Question 15

Which of the following describes boundary lubrication?

Accepted Answer

When a thin film of lubricant separates the surfaces, with some asperity contact.

Answer

When a thick film of lubricant completely separates the surfaces

Answer

When surfaces are in direct contact without any lubricant

Question 16

The Stribeck curve is primarily used to:

Accepted Answer

Predict the behavior of a bearing under varying operating conditions

Answer

Calculate the viscosity of a lubricant

Answer

Determine the surface roughness of a component

Question 17

A major advantage of solid lubricants is that they:

Accepted Answer

Can operate in extreme conditions where liquid lubricants fail

Answer

Are always more cost-effective than liquid lubricants

Answer

Provide a higher coefficient of friction

Question 18

A common failure mode for lubricated bearings is:

Accepted Answer

Wear

Answer

Overheating

Answer

Corrosion

Answer

Electrical failure

Question 19

The primary function of a lubricant filter is to:

Accepted Answer

Remove contaminants from the lubricating oil

Answer

Reduce the temperature of the oil

Answer

Increase the viscosity of the oil

Answer

Monitor the oil level

Question 20

Which instrument is typically used to determine the viscosity of a lubricant?

Accepted Answer

Viscometer

Answer

Spectrometer

Answer

Rheometer

Answer

Microscope

Question 21

The main advantage of hydrodynamic lubrication is:

Accepted Answer

Prevents direct contact between surfaces by supporting the load on a fluid film

Answer

Reduces friction by providing a solid surface coating

Answer

Enhances heat dissipation from the contact area