Lubrication Flashcards
What are some negative effects of friction
Causes wear
generates waste heat
is resistant to movement increasing power consumption
Friction resistance movement what is the lubricants main job
To reduce resistance
Positive effects of friction
Provides traction between rolling elements
promotes accurate tracking in bearing raceways
provides a means of starting stopping and acceleration
Three types of friction
Sliding
rolling
fluid
What is sliding friction
Produce when one surface slides across another
What is rolling friction
Movement of one surface rolling over another
What is fluid friction
Resistance to flow within the fluid
How does a lubricant reduce friction
Separates the moving surfaces with a film that has less friction that a moving surface
What are four functions of a lubricant
Protect against corrosion
carry away heat
carry away contaminants
help seal
What is a full film lubrication
Think enough to completely separate the surfaces within a continuous film
What is the last elasto-hydrodynamic film lubrication
Completely separates two surfaces and is therefore a type of fulfillment lubrication
How is a boundary film formed
Low speeds
Viscosity is too low to support the load
Not enough lube
How is an oil wedge created
Uses the rotation of the shaft to form an oil wedge that forces a full film of fluid into the loaded area
What is viscosity
Measurement of fluid friction
Fluids that have low viscosity, flow easy
Does viscosity effect film strength
Yes
Three factors that affect viscosity
Temperature
pressure
speed
What is pour point
Lowest temperature at which an oil is observed to flow
What are centistokes
Unit of viscosity that has been excepted by industry worldwide
Viscosity index is a number that
Identifies the amount of change in the viscosity of a lubricant over a temperature range
What is it called when a vapor above an oil will ignite when a flame is passed over it
Flash point
How is a low temperature engine grade indicated
With a “W”
Oils without a “W” are for what season
Summer
What is the purpose of a multigrade engine oil
To accommodate the start up in conditions that are both hot and cold
Where are naptha based oil’s mainly used
North America
Between Paraffin and naptha what has a very high wax content
Paraffin
What based oil’s do not wear out
Petroleum based
What are problems are synthetic oils developed to solve
To solve lubricating problems.
Is there wax in synthetic oil’s
No
What are additives
Chemicals that are added to the base oil to enhance the performance of the oil under specific operating conditions
What percentage do additives make up of oil
22%
What do you rust and corrosion inhibitors avoid
Costly maintenance and repair fees
Two types of corrosion
Rusting and acid attack
Extreme pressure additive protect against what
Welding of surface asperities when metal to metal contact occurs.
Common types of solid additives
Graphite
molybdenum
Teflon
How far up the lowest rolling element in an oil bath should the oil be
1/3 to 1/2 way up the lowest rolling element
What does a bottle oiler rely on to lubricate
Vibrations
What does a wick feed oiler rely on
Capillary action or attraction
Drop feed oiler relies on what to lubricate
Gravity
How does a ring or chain oiler work
Hangs from the shaft and dips into an oil bath and transfers oil onto the shaft to flow into the bearing
How does a pressure lubrication system work
A pump delivers the oil onto the shaft which flows on to the bearings
Two types of air activated lubrication systems
Oil mist and the air oil system
What applications is a blocked lubricator used for
Large stationary engines and reciprocating compressors
What is it called when oil is circulated through The machines bearings and back through the filters on the lubrication console to remove any contaminants that are in the system
Oil line flushing
Greece is a liquid lubricant mixed with what
Thickener
List three properties of a multipurpose grease
Wide temperature range
water resistant
Mechanically stable in high speed bearings
Is a lower number of grease going to be thicker or thinner
Thinner
What are the two methods of applying grease
Single point and centralized
Single point Greece message don’t need any what?
Pumps
Metering
Valves
