Lubrications Flashcards
3 kinds of friction
Fluid
Sliding
Rolling
What is a lubricant
A substance that reduces friction
What is full film lubrication
Is Thick enough to completely seperate the surfaces with a continuous film
What is elasto hydrodynamic film lubrication
Completely separates two surfaces
- anti friction bearing
- type of full film
What is a boundary film
Does not completely seperate the surfaces
Form at low speeds
What is viscosity
A measurement of fluid friction
-Fluids that flow easily like water have low viscosity
-fluids that flow very slow such as tar have a high viscosity
What affect viscosity
Temperature
Pressure
Speed
Units of viscosity
Centistoke
SUS or SSU
What is 1 centistoke
1 sqaure millimetre/second
What does SUS stand for
Saybolt universal second
Viscosity in centistoke is measured at what temperatures
40 deg Celsius
The SUS viscosity is measured at what temperature
100 deg Celsius
What is absolute viscosity
Measure in centipoises and a direct measurement of the force of resistance to flow in a fluid
What is viscosity index
Is a number that identifies the amount of change in viscosity of a lubricant over a temp range
What is four point
Lowest temperature at which an oil is observed to flow
How is pour point determined
3 degrees C above the temp at which the oil shows no movement
- widely used as a low temp flow indicator
What is flash point
Lowest temp at which the vapour above an oil ignites when a flame is passed over
How are low temp engine grades indicated
By a W
Indicate cold weather starting ability
How are high temp engine grades indicated
No letter after the number = rated for high temp engine grades
Types of oils
Petroleum based
Paraffin based
Naphtha based
Synthetic
What is oxidation inhibitors
Additives in the oil that work to inhibit or slow down the process of oxidation
lubrication systems
Bottle lubrication
Wick feed oilers
Drip feed lubrication
Ring or chain oilers
Pressure lubrication
Air activated lubrication
