lubrication Flashcards
3 types of friction
sliding
rolling
fluid
which of the 3 friction has the most friction
sliding
which of the 3 friction has the least friction
fluid
what is the property of reducing friction
lubricity
type of lubricant film is thick enough to completely seperate the surface with a continuous film
full film lubricant
extremely high pressure causes viscosity to (icrease/decrease)
increase
type of full film lubricant , film completely separates two surfaces however the two surfaces are loaded to the extent that deformation takes place in the loaded area
elasto hydrodynamic film lubricant
type of lubricant film does not completely separate so some of the asperities touch
boundary film lubricant
type of lubricant film
forms at low speeds
forms when the visocosity of the lubricant is too low to support the load
forms if there is not enough lubricant
boundary film lubricant
type of lubricant film
offers least friction resistant
eliminates wear on the moving surfaces
generates the least amount of heat
full film lubricant
what happens to support area of a bearing as clearance increases
support area decreases
whats happens to support area of a bearing as clearance decreases
support area increases
thickness of hydrodynamic film is affected by the 3
speed
viscosity
load pressure
3 facts that affect viscosity
temperature
pressure
speed
water has a high/low viscosity
low
tar has a high/low viscosity
high
viscosity is measured iin
centistoke and SUS (saybolt universal seconds)
tempurature increase =viscosity
decrease
pressure increase = viscosity
increase
shear increase is also know as
surface speed increase
absolute viscosity is measured in
centipoises
the term for direct measurement of the force of resistance to flow in a fluid
absolute viscosity
a number that identifies the amount of change in the viscosity of a lubricant over a temperature range
viscosity index
the lowest temperature at which an oil is observed to flow
pour point
the lowest temperature at which the vapour above an oil ignites when a flame is passed over it
flash point
oil engine grade indicted by a W
low temperature engine grade
10W-30 is an example of what engine grade
multigrade
oil derived from base stock produced at the refineries
petroleum based
oil with high wax content
paraffin base
oil used as base oil in cold temperature
naphtha base
what percent of oil do additives make up
22%
oil oxidization rate doubles for every 8 degrees above what degree
55 degrees celsius
oil inhibitor reacts with metal
chemical
oil inhibitor attracted to metal surfaces
physical
stiffness of grease is known as
consistancy
4 types of oil lubrication systems
bottle lubrication
wick feed
drip feed
ring or chain oilers
