Exercise 5. Translate into English.
1. Многие экипажи гордятся тем, что могут длительное время эксплуатировать силовую установку своего судна без ремонта.
2. Однако существуют условия, при которых становится невозможным обойтись без посторонней помощи.
3. Часть ремонтных работ выполняется непосредственно на судоремонтном заводе.
4. Многие ремонтные работы, требующие вывода из строя машины, не могут быть выполнены в море.
5. Ремонт двигателя практически ограничивается теми работами, которые можно выполнить в море.
6. Рубашки цилиндров в современных двигателях доставляют много хлопот.
7. Если условия эксплуатации двигателя неправильные, износ некоторых деталей превышает нормальные допуски.
8. Качество используемого топлива является важным фактором в эксплуатации двигателя.
Exercise 6. Read dialogues and reproduce them then make up your own dialogues based on topics given below.
ENGINE DAMAGE
A: Which of the several causes of ignition failures is most likely to occur?
B: Failure of the fuel supply is the most common cause, for the reason that the fuel pump is very sensitive to the presence of air and unless great care has been exercised in cleaning air out of the fuel lines, the pump will not deliver oil to the injection valves. This is especially true after the fuel lines or pumps have been opened up for any reason.
A: How is air cleared out of the fuel lines?
B: Most installations include a by-pass valve in each fuel oil discharge line, adjacent to the injection valve. By opening these valves and operating the hand pumps on the fuel measuring pump, oil is forced through the pump and pipe line out through the by-passes, carrying the air with it. When only oil flows from the by-passes the valves are closed and few strokes given to the hand pumps to force some oil into the injection valves.
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A: How is the compression pressure measured?
B: With the indicator, cutting out one cylinder at a time and indicating that cylinder while the rest of the cylinders operate on fuel or starting air. Both methods should be used in order to determine the difference in compression with hot cylinders and with cold.
A: How is the compression pressure adjusted?
B: By decreasing or increasing the linear clearance between piston and cylinder head. This is usually done by increasing or reducing the thickness of shims under the foot of the connecting rod.
A: What are the principal sources of knocks in the Diesel engine?
B: The large bearings, the valve gear, or the interior of the cylinders. Bearing knocks are caused by too much clearance. Valve gear knocks may be caused by excessive roller clearance, worn or broken rollers, or sticking valve stems. Knocks inside the cylinder are caused by too early injection, valve at low speed, injection air pressure too high, or stuck piston rings.
A: How is the separation of the two halves of the box usually obtained?
B: By placing sheet metal shims between the abutting surfaces.
A: How is bearing usually measured?
B: By placing strips of soft lead wire in the bearing and setting up the bolts. The thickness to which the lead wire is mashed will be equal to the clearance.
A: How is bearing refitted?
B: By scraping surface of the boxes with steel scrapers until all the high spots are removed and even contact is obtained between bearing and boxes.
Comprehensive reading. Read, translate into Russian and discuss the following text.
Shipboard maintenance of machinery
Maintenance problems have recently become more serious, particularly because of the over-complicated designs, delivery delays of spares and unmanned engine room working.
Too much complication in machinery has made repair more difficult worldwide,
Replacement parts
The most efficient and cost effective method of repair is the fitting of proper makers’ replacement parts in-situ by the ships’ engineers but this requires that the correct spare parts are always on the ship at the right time.
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There are many thousands of different parts for the main and auxiliary diesels and hundreds more for each auxiliary machine. It soon becomes impossible to predict, even by computer, which part is going to be required next, so as to ensure its availability on board.
When an urgent request from a ship for spares is received, the problem of availability at makers’ works arises. Delivery times range from days to months. So delivery by air has become commonplace (usual).
When spares become available all that is necessary is an aircraft to deliver them. This may take only a few hours – always assuming the ship’s next destination is known.
Larger parts require special charter flights which take extra time to organize and the cost of transport can amount to many times the value of the part concerned.
Answer the following questions:
1 What is necessary to make repairs by replacement at the right time?
2 Why is it impossible to predict which spare part may be required next?
3 Why is the delivery of spares sometimes delayed?
4 What’s the most common way to deliver spares?
5 What information about the vessel should/must the makers’ works know to deliver the spares as soon as possible?
Lesson 6 . CYLINDER HEADS
Exercise 1. Read and learn the following words and expressions:
Vocabulary notes:
1. сylinder head – крышка цилиндра
2. welding – сварка
3. oxyacetylene – кислородоэтиленовый
4. contraction stress – напряжение при сжатии
5. studding – соединение
6. crank shaft – коленчатый вал
7. hazard – препятствие
8. refinishing – повторная отделка
9. alignment – установка
10. torsional vibration – вибрация вращения
11. flexible – гибкий
12. bearing box – корпус подшипника
13. crosshead – поперечина
14. circumferential crack – кольцевая трещина
15. piston – поршень
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16. substantially – значительно
17. salvage – спасти
18. valve gear – клапанный механизм
Exercise 2. SCANTHE TEXT AND BE READY TO DISCUSS IT.
The head is usually the most complicated casting on the engine, and as such suffers most from heat troubles. The usual head repair is welding of cracks. Both oxyacetylene and electric welding are used, but the former is preferred if the location of the crack will permit its use. If the crack is near the outer edge of the head, where expansion and contraction stresses can be accommodated, gas welding can be used, but if the crack is near the center of the head or surrounded by unsymmetrical masses of metal, as is usually the case, electric welding must be resorted to. To make a successful head repair, electric welding must be done very skillfully and studding employed.
Crank shafts
Breakage of crank shafts in years gone by was accepted as one of the hazards inherent in Diesel-engine operation, but at the present time such breakage is very unusual. Most repair work on crank shafts consists of refinishing pins and bearings that have become scored or worn, or connecting alignment of the shaft in its bearings. Whenever it is necessary to renew a broken shaft, it is found that breakage is due to misalignment of torsional vibration. Wear of main bearings is more rapid in marine engines than in land engines. The more flexible nature of the structure on which the engine rests, as compared to the mass of concrete under the land engine, makes it more difficult to maintain a continuously unbroken oil film between shaft and bearing box.
Torsional vibration is sufficiently well understood that its occurrence can be predicted with accuracy in new engines and steps taken to eliminate it. It is a much less common sourse of trouble than in former years, but it is found occasionally.
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