Assignment - Lubrication Flashcards
List the three kinds of friction and provide an example for each one.
a) Sliding: Produced when one surface slides across another.
b) Rolling: Produced when one surface rolling over another.
c) Fluid: Resistance to flow within a fluid.
Which type of friction would produce the greatest heat?
Sliding Friction: offers more resistance that rolling or fluid friction.
What is the definition for viscosity?
Viscosity is a measure of a fluid’s resistance to flow.
How would an increase in viscosity affect the load strength of a lubricant?
It increases the load strength capacity.
How would a decrease in viscosity affect the power consumption of a machine?
The lower the viscosity, the lower the internal power consumption, due to decreased internal friction.
How would an increase in temperature affect viscosity?
As temperature increases, viscosity decreases.
What is the worldwide accepted unit of measurement of oil’s viscosity?
Centistokes (CST)
What does the viscosity index of an oil indicate?
Identifies the amount of change in the viscosity of a lubricant over a temperature range.
How is the pour point of oil determined?
Pour point is the lowest temperature at which an oil is observed to flow.
Why is it important to know the pour point of oil?
The practical importance is that it determines the lowest temperature at which an oil can be used for low temperature start ups. It also determines whether the oil can be pumped at the lowest operating temperature.
What is the flash point of oil and what is its importance?
Flash point is the lowest temperature at which the vapour above an oil will ignite when a flame is passed over it. Flash point indicates the fire or explosion hazard of the lubricant.
List the three stages of lubrication.
a) Full film lubrication
b) Elasto - Hydrodynamic film lubrication
c) Boundary film lubrication
