1、Jimei university,Lesson 11,Operating troubles and their remedies,Jimei university,Troubles may occur when the engine is running. If the engine does not start on air, it may be due to one or more of the following causes:,Jimei university,starting air pressure(2.53.0MPa) too low, incorrect timing of s

2、tarting air valves, one or more of the starting valves or distributor valves stuck(粘住) in closed position,Jimei university,master valve(主起動(dòng)閥) not actuated, stop valve on air line is closed, or if starting after working on the engine, the turning gear(盤車機(jī)) still engaged.,Jimei university,If the engin

3、e turns too slowly or irregularly on starting air, the possible causes may be,Jimei university,the pistons in starting air distributor sticking, starting valves in cylinder covers defective, faulty timing of the distributor.,Jimei university,The starting air pressure too low may also be another caus

4、e. If the engine does start on air, but combustion does not immediately begin,Jimei university,the cause may be low compression, failure of the fuel pumps to discharge oil into the fuel valves or incorrect timing of fuel pumps.,Jimei university,Failure of fuel injection is usually due to the trouble

5、s in the fuel injection pumps.,Jimei university,However, the injection may be delayed, though the pumps are in good order, if the fuel lines to the injection valves have not been cleared of air.,Jimei university,If there is no fuel injected into the cylinders, the possible causes are fuel gasificati

6、on(汽化) due to excess temperature,Jimei university,pressure before fuel injection pumps too low, fuel too cold, except the troubles in the injection pumps.,Jimei university,Sluggish(行動(dòng)遲緩的) movement of maneuvring gear, incorrect adjustment of maneuvring gear, shut-down devices on engine having operate

7、d,Jimei university,maneuvring air pressure to governor too low, failure in governor may be the case also. These can be indicated by too low fuel pump index.,Jimei university,If the action of the engine indicates that some of the cylinders are not firing, the ones affected may be determined by watch

8、the exhaust temperature.,Jimei university,A common trouble with the fuel pump plungers or fuel valve spindles is oil leakage.,Jimei university,Good strainers and filters should be provided in the fuel oil system and they should be cleaned at intervals(不時(shí)、每隔一段時(shí)間),Jimei university,so as to prevent dir

9、t from getting under a fuel injection pump valve and causing it to leak.,Jimei university,It is not uncommon for the lubricating oil pump suction to be clogged(阻塞) with the dirt left in the crankcase after work has been done on the engine.,Jimei university,Excessive clearances in the main or crankpi

10、n bearings will sometimes be indicated by loss of pressure in the lubricating system before any bearing knock is heard.,Jimei university,The engine may lose power or slow down when running. When this occurs, the first cause possible may be hot bearings and seizures(咬缸) of the pistons in the cylinder

11、s.,Jimei university,Failure of the fuel supply to one or more cylinders may be another cause.,Jimei university,Cracks in the cylinders and cylinder covers may result from(由引起) unequal heating. The cylinder covers should be regularly vented by opening the vent cocks.,Jimei university,Cracks usually r

12、esulting from local overloading are caused by troubles with the fuel pumps or one or more cylinders not firing.,Jimei university,If indicator diagrams(示功圖) are taken at regular intervals, any unequal distribution of load will be easily found out.,Jimei university,Bearing knocks are likely(很可能) to oc

13、cur from bearing wear. Valve gear knocks are more easily located(定位) while the engine is running.,Jimei university,Knocking that occurs between cams and rollers may be caused by troubles such as excessive clearances and worn or broken rollers, or the trouble may be in the valves.,Jimei university,Bl

14、ow-off(噴出、放氣) of the relief valves of the main cylinders during operation indicates that the cams are not properly set, if the blowing off is not due to leakages or slackening(松弛) of the springs.,Jimei university,In such case the cylinder affected should be immediately cut-off and the cause of the t

15、rouble traced(查找、尋跡) by taking indicator diagrams.,Jimei university,Most troubles likely to occur with marine diesel engine can, if located in time, be remedied with no difficulty,Jimei university,and many can be avoided if the engine is maintained with a high sense of responsibility to the people o

16、n the part of(在方面) the motormen(機(jī)工、機(jī)匠) and engineers.,Jimei university,Reading Material,Trouble shooting Faults will develop in prime movers(原動(dòng)機(jī)) of any type or make.,Jimei university,Burmeister Starting failures(see Table 2); Running defects (see Table 3).,Jimei university,Table 1Emergency slow-dow

17、n and shut-down limits Table 2Starting failures Table 3Running defects,Jimei university,B. OPERATION WITH PISTONS AND CONNECTING RODS REMOVED,Jimei university,If some cylinder unit components, such as piston, connecting rod or big end bearing are damaged and cant be repaired, the following can be do

18、ne to make emergency operation possible.,Jimei university,1. Remove the piston, connecting rod and big end bearing of that unit. 2. Cover lubricating oil bore in crank pin.,Jimei university,3. Fit a completely assembled cylinder head without the valve push rods. 4. Disconnect the pilot air pipe to a

19、void starting air to the cylinder head.,Jimei university,5. Set the HP fuel pump out of service by blocking pin.,Jimei university,With one cylinder out of operation exhaust gas temperature of the remaining cylinders should not exceed normal full load temperatures.,Jimei university,If the turbocharge

20、r(s) surges, reduce load further to avoid continuous surging.,Jimei university,Engine operation with a piston and connecting rod removed from one or more cylinders, should be performed only in absolute emergency when no other means are available.,Jimei university,Removal of one or two counterweight(

21、s) may induce vibrations due to unbalance. Please contact Stork-Wartsila Diesel in such a case.,Jimei university,When the engine should be operated with one cylinder out of service, the balance of the engine is disturbed and severe or even dangerous vibrations may occur.,Jimei university,The vibrati

22、on conditions are in practice depending on the type of the installation.,Jimei university,C. INSPECTION OF CRANKSHAFT BEFORE IRON-PLATING(鍍鐵),Jimei university,Since most crankshafts are susceptible to(對(duì).敏感的; 容易受到) progressive fracture, either from repeated bending or from reversed torsional stresses

23、,Jimei university,and fatigue strength(疲勞強(qiáng)度) is greatly dependent upon the surface and radius states of journals and crankpins,Jimei university,the first inspection before iron plating is to check if cracks exist on the worn surface or radius.,Jimei university,Where appropriate, dye penetrants(著色滲透), magna-flux(磁粉探傷) and other testing methods can be used to check for cracks, but sometimes it is still difficult to measure accurately the depth of a crack.,Jimei university,Therefore, in all cases, cracks must be completely ground down before iron-plati