Lubrication System Flashcards
(47 cards)
Propertles and characteristics of Lubricating oils Vary with the oil type.
Engine Lubricating oils
The requirements of lubricating oil are to:
Lubricate
Cool
clean
Prevent Corrosion
Resist oxidation at high temperatures
Possess suitable visoosity at all operating temperatures
able to use low viscosity oil due to the absence of Reciprocating parts.
Turbojet engines -
requires slightly higher viscosity oil, due to the heavily Loaded propeller reduction gears and the need for a high- Pressure oil supply to operate pitch control mechanisms.
The turbo-propeller engine
often considered to be the Life blood an engine. without it, the friction and wear produced between moving parts would cause an engine to wear at a very rapid rate.
Lubricating oil
a flim of Lubrication oil is placed between the moving parts
Reduce friction
oil absorbs some of the heat produced by conbustion as it circulates through the engine. The pistons and cylinder walls are especially dependent on lubricating oil for cooling
Absorbs heat
oil also exhibits excellent wetting characterístics because the oil film has an ability to evenly coat metal surfaceses.
Seals
helps reduce some of the impact force between a crankshaft and its connectíng rods
Cushion
As the oil circulates, it picks up foriegn particles such as dirt, dust, carbon, and small amounts of water. These particles are held in Suspension by the oil and carried to a filter where they are trapped and removed.
Cleans
The oil film which coats internal engine parts acts as a barrier, preventing Oxygen and moisture from reaching the metal surface and causing it to corrode.
Protects Against corrosion
The amount of oil consumed depends on factors such as engine rpm engine temperature operating clearances, and lubricant characteristics.
Oil consumption
the perfect engine oil is thin enough to circulate freely, yet heavy enough to stay in place and maintain a reasonable film strength.
Oil Properties
One of the most important properties of an oil is viscosity, which is a measure of an oil’s resistance to flow. An oil that flows slowly is Viscous, or has a high viscosíty. On the other hand, oil that flows freely has a low viscosity. most inportant properties of an oil is viscosity, which is a measure of an oil’s resistance to flow.
Viscosity
oil viscosity is measured
Saybolt universal Viscosimeter
determined by the amount of light that passes through an oil sample in a glass container when placed in front of a light of known intensity.
Color
The color test is conducted with a device known
ASTM union colorimeter
The color is then conspared to an
ASTM color chart.
temperature at which paraffin wax and other solids normally held in a solution of oil begin to solidify and separate into tíny crystals.
Cloud Point
represents the lowest temperature at which the oil can flow or oil property which determines a given oil’s ability to lubricate at Low operating tenperatures.
Pour Point
An oil’s flash point is the temperature at which it begins to enit ignitable vapors. As temperature increases beyond the flash point, the oil’s fire point is reached and sufficient pors are enitted to support a flame. A typical lubricating oil has a fire point approxímately 50 to 6o°C higher than the fash point.
Flash Point and Fire Point
a given amount of oil is place in stainless steel receptacle and heated to a controlled temperature until it evaporates.
Carbon residue test.
is an extension ofa carbon residue test requires the carbon residue to be burned until only ash remains. The amount of ash remaining is then expressed as a percentage by weight of the carbon residue.
Ash test
a fixed nozzle that provides a relatively consistent oil flow to the main bearings at all engine speeds.
Oil jets
