2Introduction Oil Systems Lubrication is used between 2 sliding surfacesto overcoming friction,and therefore prevent or reduce component wear.The properties demanded from a lubricantvary considerably with the particular application.Lubricant for a bicycle is not suitable for a steam engine;a lubricating oil for any engineshould be of a suitable viscosity for maximum loadsand also retain this viscosityover the full range of engine temperature.
3Oil Systems The ‘Wet Sump’ System Common to most vehicles Engine BlockPumpFilterCommon to most vehiclesOil is stored in the sump and pulled out,through a strainer, by a pump.The oil then passes through a filterto ensure it is clean etc.It then passes into the engine,returning excess oil to the sump.SUMP
4Oil Systems The ‘Dry Sump’ System High Performance/Rally vehicles Engine BlockPumpFilterHigh Performance/Rally vehiclesand AircraftTankOil is stored ina separate tank,but still pulled by pump through a strainer,and passed through a filter into the engine,returning excess oil to the sump.SUMP
5Oil Systems The ‘Dry Sump’ System High Performance/Rally vehicles Engine BlockPumpFilterHigh Performance/Rally vehiclesand AircraftTankScavenge PumpBut the oil is thentaken out of the sumpby a scavenge pump & returned to the tank,hence the name ‘Dry Sump’SUMPThis gives protection against oil loss in cars;and helps maintain correct levels of lubrication in aircraft.
6Oil Distribution Let’s take a closer look here. Oil flowing from the pumpis passed through the filter,and then forced along internal passagewaysto the areas needing lubrication.The oil lubricatesthe ball and roller bearings,gear teeth, piston rings,cylinder walls andother moving parts,then drains to the sump.Let’s takea closer look here.Sump(Oil Tank)PumpFilter
7Oil Distribution Bearing Lubrication A 4 CYLINDER ENGINE CRANKSHAFT The illustration shows the main bearing locations for: -Crankshaft support bearings.Conrod to crankshaft bearings (big-ends) for each piston.The gudgeon pins.In addition (not illustrated) areother bearings required toprovide smooth running ofother componentssuch as the cam shaft,water pump drive shaft,oil pump drive shaft etc.Let’s take a closer look here.FlywheelCon Rod1234GudgeonPinFrontSupport BearingRearSupport BearingsSupportBearingsCrankshaftA 4 CYLINDER ENGINE CRANKSHAFT
8Oil Distribution Bearing Lubrication The illustration shows a cross sectional view of a plain bearing.The plain bearings are made up of two distinct halves,called ‘shell’ bearings,and the big-ends are fixed to prevent rotation in the conrod.Con Rod Big EndShell BearingsCrankshaft
9Oil Distribution Bearing Lubrication The oil is fed into distribution grooves cut in the shells,spreading an even thin film of oilbetween the bearing and crankshaft surfaces.Excess oil is then returned to the sump.Oil SplashCon Rod Big EndShell BearingsOil Distribution GrooveLubricating Oil FilmCrankshaftOil SplashInternalOil Feed
10Oil Distribution Bearing Lubrication Maintaining oil pressure is critical.In most cars a simple indicator light is illuminated.In performance cars and aircraft,a gauge is usual to display actual pressure.To prevent mechanical damageregular servicing is necessary.Oil specification is found invehicle Owner Handbooksand Service Manuals,and aircraft Maintenance Manuals.Engine life in vehicles ismonitored as miles travelled,while in aircraft it is as hoursor cycles flown.FrontSupport BearingRearSupport BearingsSupportBearingsGudgeonPinCon Rod1234
11Oil Pumps Internal Gear Type Pump This pump consists of two gears, one inside the other.The smaller centre gear is the driving gear, powered by the engine.The larger outer gear (‘idler’ gear) is driven by the inner gearvia the meshing of the gear teeth or ‘lobes’.Pump Assembly(end plate removed)Pump BodyDriving GearDriven GearRotating Parts
12Oil Pumps Internal Gear Type Pump The inlet and outlet ports are a known as kidney ports.Fluid is pulled in and forced out through these ports.As the gears rotate,fluid is pulled in and forced out.Pump Assembly(end plate removed)‘Kidney’ PortsPump BodyDriving GearDriven GearKidney PortsYellow = Inlet FlowRed =Outlet FlowRotating Parts
13Fuel Pumps Where are the fuel tanks in most aircraft ? Aircraft fuel tanks are formed by the structure of the wing.Fuel can be transferred from tank to tankto help balance the aircraft in flight.This allows trimming the aircraft efficientlywithout using aerodynamic forceswhich cause drag.
14Fuel Pumps The filler connection is usually underneath the wing and is a self sealing device to prevent spillage.It is also hidden away behind an access hatchto maintain aerodynamic smoothness.Fuel level is measured via a level sensorand indicated on the flight deck by the fuel gauge.The tank is filled from eithera vehicle born bowseror underground storage tanks,as with vehicle filling stations.Filler CapCockpit Fuel GaugeFiller NeckEF1/2FUELBut to get the fuelto the engines,some form ofpump is needed.TankFuel Level SensorFuelPumpTank Cavity
15Mechanical Diaphragm Pump One-wayInlet ValveOne-wayOutlet ValveDiaphragmSpringDriving CamThis is a Positive Displacement pump,which means when the pump stops, flow is prevented.This pump consists of a flexible diaphragm,which is moved up by spring forceand down by an engine driven cam,and two one-way valves.
16Solenoid Diaphragm Pump One-wayInlet ValveOne-wayOutlet ValveDiaphragmMagnetic PlateSolenoid WindingsSwitch MechanismAnother Positive Displacement pump.Consisting of a flexible diaphragm, moved up and downby an electro-magnetic force.In this pump, the piston is moved up and downby a magnetic field generated bythe electrically powered coil underneath.
17Fuel Pumps The Gear Type Pump The Gear Type Pump ‘SPUR’ GEARSBODYThe Gear Type Pumpis the most favoured pump design,because it consists of just a feweasy to produce working parts.Intermeshing straight cut spur gearsrotating in a close fitting body.
18Fuel Pumps The Gear Type Pump As the gears rotate the fluid is carried ‘SPUR’ GEARSFlow ControllerFLOW OUTAs the gears rotate the fluid is carriedbetween the gear teeth.A control valve is set to limitthe absolute pressure in the system,(around 450 psi)to protect against system damage.
19Fuel Pumps The Gear Type Pump Without the flow controller, Pump flow restrictionin the controllercauses pressureto increase‘SPUR’ GEARSFlow ControllerFLOW OUTWithout the flow controller,the pump would provide a flow,but at no pressure.Pressure is only achievedbecause the flow control systemworks on flow restrictionswhich causes the pressure to rise.
20Air Filter Fuel is pumped to the carburettor (which we will examine later).The carburettor controls the mixing of air and atomized fuel,but the air must be filtered to prevent anydamage or blockage in the fuel system or engine.Air FilterCarburettorInletExhaustWe will lookat this areaTankEF1/2FUELFuelPump
21Air Filter A paper based element bonded into a rubberized material, is concertinaed to get the greatest surface area.Air with contaminants passes through the filter,which catches the contaminants and leaves the air cleaner.Filtration rate is in Microns (1 micron = 0.000,001 metre).So a 30 micron filterstops particles of 30 microns or more.Air FilterClean AirFilter of corrugatedpaperDirt trappedby filterAir and Dirt
22Check of Understanding Where would a Dry Sump Oil Systembe most commonly used?Most vehiclesHigh Performance/Rally vehiclesand AircraftOnly in AircraftOnly inHigh Performance/Rally vehicles
23Check of Understanding What differentiates a Dry Sump systemfrom a Wet Sump system?A Diaphragm PumpAn Internal Gear Type PumpA Positive Displacement PumpA Scavenger Pump
24Check of Understanding Bearings in a crankshaftare made up of two distinct parts.What are these called?Dry BearingsRoller BearingsShell BearingsBall Bearings
25Check of Understanding Where would you find the oil specificationsfor an aircraft?The service manualThe maintenance manualThe operating manualThe aircraft log
26Check of Understanding Within an internal gear-type pumpthere are two gears.Which one is driven by the engine?The Idler GearThe Driving GearThe Outer GearThe Driven Gear
27Check of Understanding Which of these pumpshas a flexible diaphragm moved up and downby an electro-magnetic force?A Gear Type PumpA Mechanical Diaphragm PumpA Scavenger PumpA Solenoid Diaphragm Pump
28Check of Understanding Which is the most favoured typeof pump design?Solenoid Diaphragm PumpGear Type PumpMechanical Diaphragm PumpMeshing Gear Pump
29Check of Understanding Without the flow controllerin a gear-type pump,What flow would the pump supply?A flow at no pressureA flow at low pressureA flow at high pressureNo flow at all
30Check of Understanding What is a Micron?11,000,000of a metreof a metre1100,000110,000of a metre11,000of a metre