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Lubrication system

The document discusses lubrication systems in engines. It describes the purposes of lubrication including reducing friction, sealing, cooling, cleaning, absorbing shock, and absorbing contaminants. It discusses viscosity grades and properties of oil. The key components of a lubrication system are described such as oil pumps, pans, filters, galleries, and the positive crankcase ventilation valve. Finally, it covers gear oil ratings by the American Petroleum Institute.

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LUBRICATION SYSTEM UNIT-4 LUBRICATION SYSTEM EME-505 B.TECH 5TH SEM MECHANICAL ENGINEERING 2013 batch BY VINOD KUMAR YADAV (ASSISTANT PROFESSOR) MECHANICAL ENGG. DEPTT G.L.B.I.T.M GREATER NOIDA
LUBRICATION SYSTEM
Purpose of Lubrication System 1. Lubricate Reduces Friction by creating a thin film(Clearance) between moving parts (Bearings and journals)
Purpose of Lubrication System 2. Seals The oil helps form a gastight seal between piston rings and cylinder walls (Reduces Blow-By) Internal oil leak (blow-by) will result in BLUE SMOKE at the tale pipe.
Purpose of Lubrication System 3. Cleans As it circulates through the engine, the oil picks up metal particles and carbon, and brings them back down to the pan.
Purpose of Lubrication System 4. Cools Picks up heat when moving through the engine and then drops into the cooler oil pan, giving up some of this heat.
Purpose of Lubrication System 5. Absorbs shock When heavy loads are imposed on the bearings, the oil helps to cushion the load. 6. Absorbs Contaminants The additives in oil helps in absorbing the contaminants that enter the lubrication system.
VISCOSITY Viscosity is a measure of oil’s resistance to flow. •A low viscosity oil is thin and flows easily •A high viscosity oil is thick and flows slowly. •As oil heats up it becomes less viscous (Becomes thin)
VISCOSITY •If the oil is too thin(has very low viscosity) it will be forced out from between the moving parts, resulting in rapid wear. •If the oil is too thick(has very high viscosity) it will flow very slowly to engine parts, especially when the engine and the oil are cold, resulting in rapid wear. Viscosity Index is the measure of how much the viscosity of an oil changes with temperature. (20 W) Viscosity number is set by SAE (Society of Automotive Engineers)
VISCOSITY • There are two temperatures used as reference in assigning the numbers to oils -18oC (0oF) and 99oC (210oF) •Single viscosity oils SAE 5W, SAE 10W and SAE 20W (Winter) Are defined in terms of viscosity at -18oC and are oils which render starting in cold climates easy •SAE 20, SAE30, 40, and 50 grades Are defined in terms of viscosity at 99oC and are oils which works satisfactorily in normal and hot climates •Multiple viscosity oils SAE 10W-30. This means that the oil is same as SAE 10W when cold and SAE30 when hot. Plz Note: MARUTI ALTO ENGINE OIL SF (PETROL) SAE 20 W 40 GEAR OILAPI GL- 4
VISCOSITY
Properties of oil •Corrosion and Rust Inhibitor: Displaces water from metal surfaces, to prevent corrosion. •Foaming Resistance: Rotating crankshaft tends to cause bubbles (Foam) in the oil and bubbles in oil will reduce the effectiveness of oil to lubricate. •Synthetic Oils: Made by chemical process and do not necessarily come from petroleum.
Components of lubrication system Oil Pumps Driven by camshaft, crankshaft (Rarely rebuild by an auto technician) •Rotor Pump(Two star shaped rotors pumps the oil) •Gear oil Pump
Oil Pan Stores the oil and helps in cooling the oil Pan gasket splits if over tightened. Components of lubrication system
Pressure Relief Valve to prevent the buildup of high Pressure (Causes the oil filter to bulge, but not a common problem). Good oil pressure is 40-60 psi Components of lubrication system
Oil Pressure Indicator •Light or a Gauge The light turns on or gauge reads low when the pressure drops below 10psi. Common causes of low oil pressure are: •Low oil level •Worn out pump Low oil pressure Safety system will shuts down the car by cutting the ignition System(Spark). •Good oil pressure is 40-60 psi. Components of lubrication system
Oil Filter filters the oil Some particles are too small for the filter Element(paper in the filter ) to trap. Components of lubrication system
Oil Galleries Deliver the oil to top end and returning it To the oil pan. Components of lubrication system
•Pollution prevention •Blow-by back into the intake •Prevent sludge in the engine. Positive Crankcase ventilation (PCV) Valve PCV recycles the blow by gases to the intake manifold from where they are pumped back for next combustion cycle. Not always desirable as it may dilute the A/F mixture ( makes too lean) So blow by gases are recycled when the car is travelling at low speeds or idling When car is idling – air pressure in the inlet manifold is lower than the air pressure in the crankcase, so it sucks the blow bye gases through the PCV and backs into the inlet manifold
Positive Crankcase ventilation (PCV) Valve
SO finally We have come to know the importance of Lubrication system • LUBRICATING • COOLING • CLEANING • SEALING • NOISE REDUCTION CLASSIFICATION OF LUBRICATING SYSTEM 1- WET SUMP LUBRICATION SYSTEM (i) splash lubrication (ii) Pressurized lubrication system 2- DRY SUMP LUBRICATION SYSTEM 3- MIST LUBRICATION SYSTEM
1-WET SUMP LUBRICATION Sump always filled with lubricating oil
WET SUMP LUBRICATION SYSTEM 1-(a) SPLASH SYSTEM Used in small and medium vehicles and four stroke stationary engines with moderate and low bearing load pressures Connecting rod Big end caps – provided with scoops – dip into the oil troughs -Directs oil through holes in caps to big end bearings -Due to splashing action – oil lubricates cylinder walls, crankshaft and other components -Remaining oil return to oil sump -Oil level in trough – maintained by pump via filter
Splash lubrication system
WET SUMP LUBRICATION SYSTEM 1(b) pressure lubrication system OIL form the oil sump is pumped under pressure to the various parts of the engine requiring lubrication . The oil is drawn from the sump through the filter and pumped by means of gear pump. Oil is delivered by pressure pump at pressure ranging from 1.5 bar to 4 bar. The oil under pressure is supplied to main bearings of the crankshaft and camshaft. Holes drilled through the main crankshaft bearing journals, communicate oil to the big end bearing and also small end bearing through holes drilled in the connecting rods. A pressure regulator is provided in the delivery side of the pump to prevent excessive pressure.
PRESSURIZED LUBRICATION SYSTEM
2-DRY SUMP LUBRICATION SYSTEM • Sump does not contain oil and all the oil required for lubrication remains in circulation only. • High speed racing cars and military jeeps uses this type as oil in the wet sump is subjected to large back and forth acceleration system. • An auxiliary tank is used to supply the oil to the main bearings with the help of pump. • The oil is returned back to tray and then returned back to auxiliary tank by scavenging pump, the capacity of which is always 20 to 30 % more than the pressure pump to avoid the flooding of the crank case. • If filter clogged, the pressure relief valve opens and permits oil to flow by passing the filter and supply tank. the oil is then circulated to the bearings from the supply tank
DRY SUMP LUBRICATION
3-MIST LUBRICATION SYSTEM DO YOU REMEMBER THE OLDER 2-S ENGINES IN WHICH WE FREQUENTLY ADD 2T OIL WHILE FUELING ???? Used for 2-s cycle crank charged engines 2 to 3 percent lube oil in fuel tank- Oil and fuel mixture induced via carburetor Fuel is vaporized and oil in the form of mist goes via crankcase into cylinder Some oil pass to the chamber during entry and scavenging and lubricate piston ,piston rings and cylinder walls Problem: oil burns with fuel and emit heavy exhaust and deposits on piston crown, ring grooves and exhaust port Corrosion damage of bearings 5 to 15 percent higher lubricant consumption
GRADES FOR OILS Gear oil is a lubricant made specifically for transmissions, transfer cases, and differentials in automobiles, trucks, and other machinery. It is of a higher viscosity to better protect the gears and usually is associated with a strong sulfur smell. This is necessary since the devices needing this heavy oil do not have pumps for transferring the oil with only a portion of the lowermost gears bathed in an oil sump. This heavy oil can create viscous drag leading to inefficiencies in vehicle operation. Some modern automatic transaxles (integrated transmission and differential) do not use a heavy oil at all but lubricate with the lower viscosity hydraulic fluid, which is available at pressure within the automatic transmission. Most lubricants for manual gearboxes and differentials are hypoid gear oils. These contain EXTREME PRESSURE (EP) ADDITIVES and ANTIWEAR ADDITIVES to cope with the sliding action of hypoid bevel gears. It is extremely important to note that EP additives which contain PHOSPHOROUS/SULFUROUS compounds are corrosive to yellow metals such as the copper and/or brass used in bushings and synchronizers; the GL1 class of gear oils does not contain any EP additives and thus finds use in applications which contain parts made of yellow metals.
GEAR OIL RATING • Gear oils are classified by the AMERICAN PETROLEUM INSTITUTE (API) using GL ratings. • For example, most modern gearboxes require a GL-4 oil, and separate differentials (where fitted) require a GL-5 oil. • It is important that purchasers check the oil against the vehicle manufacturer's specification to ensure it does not contain any aggressive chemicals that may attack yellow metal gear components, such as phosphor bronze. • API viscosity ratings for gear oils are not directly comparable with those for motor oil, and they are thinner than the figures suggest. For example, many modern gearboxes use a 75 W 90 gear oil, which is actually of equivalent viscosity to a 10 W 40 motor oil.
GEAR OIL RATING • Multigrade gear oils are becoming more common; while gear oil does not reach the temperatures of motor oil, it does warm up appreciably as the car is driven, due mostly to shear friction • API(AMERICAN PETROLEUM INSTITUTE) classification subdivides all transmission oils into 6 classes: • API GL-1. Oils for light conditions. They consist of base oils without additives. Sometimes they contain small amounts of ant oxidizing additives, corrosion inhibitors, depressants and antifoam additives. API GL-1 oils are designed for spiral-bevel, worm gears and manual transmissions without synchronizers in trucks and farming machines. • API GL-2. Oils for moderate conditions. They contain anti-wear additives and are designed for worm gears. Recommended for proper lubrication of tractor and farming machine transmissions. • API GL-3. Oils for moderate conditions. Contain up to 2.7% anti-wear additives. Designed for lubricating bevel and other gears of truck transmissions. Not recommended for hypoid gears.
GEAR OIL RATINGS • API GL-4. Oils for various conditions - light to heavy. They contain up to 4.0% effective anti-scuffing additives. Designed for bevel and hypoid gears which have small displacement of axes, the gearboxes of trucks, and axle units. • These oils are standard for synchronized gearboxes, especially in Europe, and may also be recommended for non-synchronized gearboxes of US trucks, tractors and buses and for main and other gears of all vehicles. GL-4 oils may also be used in many limited-slip differentials. • USED IN MARUTI ALTO (LXI) INDIA
GEAR OIL RATINGS • API GL-5. Oils for severe conditions. They contain up to 6.5% effective anti-scuffing additives. The general application of oils in this class are for hypoid gears having significant displacement of axes, generally non limited-slip differentials. • GL-5 is not necessarily backward-compatible in synchro-mesh transmissions which are designed for a GL-4 oil: • GL-5 has a lower coefficient of friction due to the higher concentration of EP additives over GL-4, and thus synchros can not engage as effectively. Also, transmissions which explicitly call for GL-4 oil may have been designed around this lower concentration of EP additives and thus may contain yellow metal parts which GL-5 will corrode. • They are recommended as universal oils to all other units of mechanical transmission (except synchronized gearboxes specifying GL-4). Some GL-5 oils in this class, which have special approval of vehicle manufacturers, can be used in synchronized manual gearboxes.
GEAR OIL RATINGS • API GL-6 is not applied any more as it is considered that class API GL-5 well enough meets the most severe requirements. When API GL- 6 was still in use, it denoted oils for very heavy conditions (high speeds of sliding and significant shock loadings). • They contained up to 10% high performance anti-scuffing additives. • They were designed for hypoid gears with significant displacement of axes. However, in 2011 at least one company offers new polyol ester based API GL-6 oil, mostly for racing applications. • The application is limited to certain types of manual transmissions, but improvements in BSFC of about 5% in standard weather and driving conditions and up to 15-20% in cold extremes (arctic weather conditions) can be expected.