1. Jimei university Lesson 8 Text Lubrication system

2. Jimei university Duties of a lubricant trouble free life( 无故障使用寿命 ) The successful operation of any engine or machine and its trouble free life( 无故障使用寿命 ) depends on effective lubrication which involves the formation and maintenance of a lubricating oil film between the moving parts.

3. Jimei university The marine diesel engine is no exception and considerable thought has gone into the problem of the lubrication of its many parts with their widely varying operating conditions.

4. Jimei university neutralize( 中和 ) In addition to providing lubricating films, oils used in marine diesel engines have to remove heat from oil cooled pistons, neutralize( 中和 ) acidic products of combustion,

5. Jimei university oxidation( 氧化 ) wear detritus( 磨屑 ) cleanse hot moving parts of carbonaceous deposits, resist oxidation( 氧化 ) and wash away wear detritus( 磨屑 ).

6. Jimei university kept pace with( 与 … 同步 ) The development of oils has kept pace with( 与 … 同步 ) the increasing demands made by the steady rise in powers produced by modern marine diesels.

7. Jimei university The selection of an oil from the commercially available range depends to a great extent on the operating conditions, the design of the engine and the type of fuel to be burned.

8. Jimei university Large marine diesel engines of crosshead construction generally have two systems of lubrication:

9. Jimei university a total loss system( 全损系统 ) a total loss system( 全损系统 ) feeding the cylinders and a circulating system lubricating the running gear and cooling the pistons.

10. Jimei university CYLINDER LUBRICATION Temperatures in the cylinder are naturally high, though only the cylinder combustion space and piston crown are subjected to actual flame temperatures.

11. Jimei university The piston rings exert a varying pressure on the liner walls under conditions involving rapidly changing speed and reversal of direction of motion.

12. Jimei university quills( 注油针 ) Oil is supplied to the cylinder liner wall and the piston rings by means of mechanical lubricators giving a carefully controlled oil feed, through injectors or quills( 注油针 ),

13. Jimei university impinges( 射到 ) piston ring belt and in some designs it is timed so that the oil impinges( 射到 ) only on the piston ring belt, thus ensuring the most efficient lubrication.

14. Jimei university Cylinder liner Piston Piston ring Quill Jimei university belt

15. Jimei university Injector Hydraulic motor Camshaft Gear pump Lubrication oil Jimei university

16. The films of oil between the rings and the liner and between the rings and the grooves in the piston are not only essential for lubrication but also play an important part in achieving a gas seal.

17. Jimei university In carrying out these duties the oil is exposed to contamination by products of combustion.

18. Jimei university residual fuels Some of these are acidic, particularly if residual fuels are being used and can cause corrosive conditions which promote heavy rates of wear.

19. Jimei university lacquer( 漆膜 ) Also, lacquer( 漆膜 ) and carbonaceous deposits form in the ring belt which interfere with the correct operation of the rings.

20. Jimei university formulated( 配制 )impart( 给 予 ) alkalinity( 碱性 ) detergency( 去垢能力 ) To counteract these undesirable effects cylinder oils usually contain additives formulated( 配制 ) to impart( 给 予 ) a high degree of alkalinity( 碱性 ) and detergency( 去垢能力 ).

21. Jimei university The alkalinity neutralizes the acid conditions and the detergency cleanses the rings and grooves.

22. Jimei university CRANKCASE LUBRICATION Operating conditions in the crank chamber are very different from those in the cylinder and it is the need for the oil to perform its functions over a very long period, which determines the properties required in the lubricant.

23. Jimei university The following features are essential for crank chamber oils:

24. Jimei university rupture( 破裂 ) 1. They must have good lubricating properties and be able to resist rupture( 破裂 ) of the film separating the moving parts in order to ensure minimum friction losses.

25. Jimei university 2. They must be able to remove heat from a bearing and to do so the viscosity should be high enough at operating temperatures to assist film maintenance.

26. Jimei university 3. They must be capable of removing heat from oil cooled pistons and in doing so must have the highest possible degree of resistance to oxidation and other effects of heat.

27. Jimei university deterioration( 变质、恶化 ) The use of a poor quality oil can lead to rapid deterioration( 变质、恶化 ) of its properties with the resultant formation of deposits in the piston crown

28. Jimei university which in turn results in a considerable reduction in heat transfer with subsequent overheating and thermal cracking.

29. Jimei university articulated pipe ( 铰接管 ) The cooling oil is usually supplied to the pistons by means of telescopic pipes 、 articulated pipe ( 铰接管 ) connected to the crossheads and passages in the piston rods.

30. Jimei university To ensure a constant supply of clean and temperature controlled oil to the engine requires the provision of a great deal of auxiliary equipment such as pumps, filters, centrifuges, coolers, drain and storage tanks etc.

31. Jimei university READING MATERIAL A. LUBRICATION The lubrication system of an engine provides a supply of lubricating oil to the various moving parts in an engine.

32. Jimei university cleaner Its main function is to enable the formation of a film of oil between the moving parts, which reduces friction and wear. The lubricating oil is also used as a cleaner and in some engines as a coolant.

33. Jimei university drain tank( 循环油柜 ) Lubricating oil for an engine is stored in the bottom of the crankcase, known as the sump, or in a drain tank( 循环油柜 ) located beneath the engine.

34. Jimei university The oil is drawn from this tank through a strainer, one of a pair of pumps, into one of a pair of fine filters.

35. Jimei university It is then passed through a cooler before entering the engine and being distributed to the various branch pipes.

36. Jimei university The branch pipe for a particular cylinder may feed the main bearing, for instance.

37. Jimei university gudgeon pin( 十字头销 ) Some of this oil will pass along a drilled passage in the crankshaft to the connecting rod bottom end bearing and then up a drilled passage in the connecting rod to the gudgeon pin( 十字头销 ) or crosshead bearing.

38. Jimei university An alarm at the end of the distribution pipe ensures that adequate pressure is maintained by the pump.

39. Jimei university Pumps and fine filters are arranged in duplicate with one as standby. The fine filters will be arranged so that one can be cleaned while the other is operating.

40. Jimei university - read-out After use in the engine the lubricating oil drains back to the sump or drain tank for re- use. A level gauge gives a local read-out of the drains tank contents.

41. Jimei university A centrifuge is arranged for cleaning the lubricating oil in the system and clean oil can be provided from a storage tank.

42. Jimei university The oil cooler is circulated by sea water, which is at a lower pressure than the oil. As a result any leak in the cooler will mean a loss of oil and not contamination of the oil by sea water.

43. Jimei university CYLINDER LUBRICATION Large slow speed engines are provided with a separated lubrication system for the cylinder liners.

44. Jimei university Oil is injected between the liner and the piston by mechanical lubricators which supply their individual cylinder.

45. Jimei university A special type of oil is used which is not recovered. In addition to lubricating, it assists in forming a gas seal and contains additives which clean the cylinder liner.

46. Jimei university A. DIFFICULTY WITH THE CYLINDER LUBRICATING SYSTEM Possible causes may be: (a) The non-return valve for the lubricating stud is defective. (b) The cylinder lubricator or its drive is defective.

47. Jimei university (c) Lubricating oil pipes or pipe connections are defective. (d) Lubricating oil pipes, or cylinder lubricating studs, are defective. (e) The cylinder lubricators need replenishing. (f) There is air in the piping.