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Agriculture Engineering-chptr 3


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Agriculture Engineering-chptr 3

  2. 2. Effects of Improper and Insufficient Lubrication• Carelessness of the operator – time• Poor construction of bearings – lack of maintenance• Failure to provide adequate means of conducting lubricants to the bearings - level Therefore, lubrication is needed because of friction.
  3. 3. Friction• Force that acts between two bodies at their surface of contact to resist the sliding of one body on the other. Friction
  4. 4. Rolling Friction• When one body rolls upon another, the friction is much less than when one body slides upon another. The resistance is called rolling friction Friction Roller
  5. 5. Anti friction bearing• In the form of balls or rollers to diminish the amount of friction. Therefore increase the efficiency of machine
  6. 6. The Present Condition of Friction• Loss of horsepower – decrease 18%• Graduated loss of fuel economy• Frequent oil drains due to degradation• Component wear• Increased emissions• Rising maintenance cost• Rising labor cost
  7. 7. 5 Functions of the Lubricant 1) Friction reduction 2) Seal the cylinders 3) Heat removal 4) Cleanse 5) Absorb shock
  8. 8. Purpose of Lubrication• Helps the engine to run smoothly and last longer• Absorbs and dissipates heat• Helps in the cooling system• Prolongs engine life
  9. 9. 3 basic types of engine lubricating systema. Circulating Splashb. Internal Force Feed and Splashc. Full Internal Force Feed
  10. 10. a) Circulating Splash SystemUsed in small single cylinder air cooled engine A pump supplies oil to a splash pan under the crankshaft As the connecting rod revolve, scoops on the end of rods dip into trough and oil is gravity fed through channels or lines The upper parts of cylinders, pistons and pins are lubricated more by oil mist taken by the oil splash. The mist is created by the rapid movement of the connecting rods
  11. 11. b) Internal Force Feed and Splash– A pump forces oil directly to a main oil gallery in the engine block rather than to a splash pan– From main oil gallery, the oil is force through passages to the main bearings, camshaft bearings, rocker arm shaft, filter and pressure sending unit– The oil escaping from the bearings creates a mist that also lubricates the upper cylinder walls, pistons and pins
  12. 12. c) Full Internal Force Feed System• Preferred in all modern diesel and petrol engines• Pump usually in the form of gear pump – Oil is force not only to the crankshaft – bearings, rocker arm shaft, filter and pressure-sending unit, but also to the piston-pin bearing – Piston pin bearing are lubricated through drilled passages in the connecting rods. The cylinder walls and pistons are lubricated by i) oil escaping from piston-pin bearing ii) or the connecting rod bearings iii) or by oil sprayed by the underside of piston and cylinder wall
  13. 13. How Full Force Feed System WorkOil pump pushes oil through the systemA reserve of oil is stored in the crankcase for circulationthrough the systemAt the oil filter, dirt is taken out of the oil to help it keep cleanOil passages take the oil to engine parts where they providelubrication and cooling and carry away dirt and depositsPressure of the oil is regulated by pressure regulating valveAfter oil moves through the whole system it comes back tothe crankcase reservoir again Pressure gauge tells the operator if engine oil is normal
  14. 14. Major Parts of Lubrication System 1. Oil pump 2. Crankcase 3. Oil cooler (if any) 4. Oil filter 5. Pressure regulating valve 6. Pressure gauge
  15. 15. Criteria of Lubrication1. Keep a protective oil film on moving parts2. Resist high temperatures3. Resist corrosion and rusting4. Prevent ring sticking5. Prevent sludge formation6. Flow easily at low temperature7. Resist foaming8. Resist break down after prolong use
  16. 16. Petrol Lubrication• Is common to small two stroke engines, consist of mixing a small quantity of oil with the petrol• Ratio of oil to petrol vary from 16 parts petrol to 1 part of oil for larger engine to 24:1 for smaller two stroke engines
  17. 17. Maintenance1. Changing Engine Oil prolong using the oil will make the oil dirty and its additives wear out:- • acid formations • sludge • varnish • engine deposits • contaminated oil will make it unfit for continued use that will harm the vital engine parts
  18. 18. 2. Follow the manufacturer’s recommendation on oil and filter changes e.g. 50 hours of working3. When changing oil and filter on any engine, always warm up the engine first. This way the contaminants and foreign materials are mixed with the oil and drained out with it4. After installing the filter and filling the engine with oil, run the engine and check for possible filter leaks5. Keep a maintenance record of all oil and filter changes to be sure of regular engine service
  19. 19. Classification of Oil• Lubrication oil are classified according to their viscosity “thickness” and are given a number which tell us the grade of oil and in some cases the type• Classification is by the Society of Automotive Engineers (SAE) Engine oils are given this number SAE 10; 20; 30; 40 Gear & transmission oil are given this number SAE 50; 70; 90 Power system oil SAE 120; 140
  20. 20. • The lower number indicate low viscosity oil suited to cold climates or engines with many stop and start continually, therefore never reaching proper working temperature.• The higher numbers indicate high viscosity more suited to hot climates, or engines continually running in hot conditions.
  21. 21. Detergent Oil• Oil that contains additives which prevent the formation of carbon and lacquer inside an engine.• Used for lubrication of a diesel engine because when diesel fuel burns in the combustion chamber it produce sediments which stick to the working parts of the engine.• This sediments collect on piston, piston rings and cylinder walls resulting in increased wear.• The additives prevent this from happening by holding in suspension the sticky particles which would settle on the piston.
  22. 22. Multigrade Oil• Oil have special additives which reverse the normal tendency of an oil to thicken when cold and thin out when hot .• They are numbered SAE 10-30 or 20-50 and are called viscostatic or Universal Engine Oil more suited to petrol or propane engines.
  23. 23. Universal Oil• These oil are produced to reduce the number of different types of oil needed to serve all types of tractor and implements, covering engines, transmission, hydraulic system, power steering, etc.• These oil are of a multigrade in nature with suitable additives to combat engine contaminants, gearbox stresses, anti frothing for hydraulic system and power steering
  24. 24. THANK YOU