Lubrication System Flashcards
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
to minimize the effect of the dynamic loads transmitted from the rotating assembly to the bearing housings, squeze film type bearings are sed
Bearings
is to vent excessive pressure in the bearing chambers so the pressure differential between the bearing chambers and the lubrication system is maintained and the oil jets maintain the proper spray pattern
Vent system
prevents supply oil from seeping through oil pump elements and high-pressure Lines after shutdown. oil could accumulate in the accessory gearbox, compressor rear housing, and conbustíon chamber.
Check valves
one of the funtion of the oil is to cool the engine
Oil cooler
removes the oil from the breather air
Deioler
attract and hold any ferrous metal particles. First, any metal articles that are attracted to the detector are prevented fron circulating in the engine and causing additional wear. Second, the collection of metal particles on a chip detector provide aluable information when troubles shooting engine problems
Magnetic chip detector
- type of detector is unique because it can discriminate between Small wear-particles, which are considered nonfailure related, and Larger particles, which can be an indication of impending failure
Electric pulsed chip detector
allow you to monitor the effectiveness of a given lubrication system,
oil pressure gauge
The reason for this is that oil viscosity varies enough among commonly used oils to produce several hundred grades when using Saybolt values
Engine oil grading system
-straight mineral oil
-ashless dispersant oil
-multi-viscosity oil
-synthetic oils
Types of oils
(MIL-L-6082E)that has no additives many years, the principle type of oil used in aircraft. Although straight mineral oil is an effective lubricant, it does have some linitations.
Straight mineral oil
The most conmonly used oil in reciprocating engines is ashless- dispersant, or AD Dil that conforms to MIL-L-22851ID. It does not have the carbon forming restrictions of straight mineral oil nor does it forn ash deposits like detergent oils.
Ashless-Dispersant Oil
they provide adequate lubrication over a wider temperature range. This allows multi-viscosity oil to flow more quickly in cold weather and keep from thinning in hot weather.
Multi viscosity oil
have multi-viscosity properties due to their chemical composition and are similar to automotive grades SAE-5 to SAE-2O. They are a blend of chemical additives and certain DÍesters, which are synthesízed extracts of mineral, vegetable, and aninal oils.
Synthetic oils
(hypoid lubricants)- are specially formulated to provide protectíon under high loads. A hypoid lubricant contains additives that bond to metal surfaces to reduce friction under high pressures or high rubbing velocities
Extreme pressure lubricants
The Lubrication Systems on a turbine engine supplies oil to moving parts within the engine which are subjected to friction and heating. ln most cases, pressure lubrication is used to Lubricate all the necessary components within a turbine engine.
Turbine Engine Lubrication
carbon depasits formed from oil míst and vapor contact with hot engine surfaces
Vapor phase deposits
provides for heavy Loads 0n the bearing system of turbine engine
Load carrying ability
minimum formation of sludge deposits duringng severt operation
Cleanliness
resistance to physical or chemical change resulting from oxidation.
bulk stability
most turbine oil is compatible with other oils that meet the same military specifications.
Compatibility
essntial for the life of egines with carbon seals that Lubricant properties prevent wear of the carbon at the carbon seal face.
Seal wear
although the dry-sump systems use an oil tank that contains most of the oil supply, a small sunp is sually lncluded on the engine to hold a small supply of oil
Oil Tank
