Английский язык: Сборник текстов и упражнений для студентов специальности "Эксплуатация судовых энергетических установок". Писарева Л.П. - 45 стр.

                                      SECTION III.
                                   TEXTS FOR READING

      Read and translate the following texts to get some more information about engine de-
signs of different makers. Do all exercises. Learn the vocabulary.




                                       Lesson 18
                    Burmeister and Wain Engines. General Information

      The present B. and W. marine engines are all exhaust turbo charged, the power output of
which is one- third more than that of the corresponding normally aspirated engines for the
same number of revolutions per minute. The reduction of fuel consumption with a turbo
charged engine is of 3 per cent.
      The engine is a single- acting, two- stroke cycle, exhaust poppet- valve type and finds a
wide application all over the world. The design is a true crosshead engine, i.e. one in which the
crankcase is completely separated from the cylinder. Scavenging air enters the cylinder through a
row of ports located in the lower part of the liner. The scavenge air is given a swirling motion.
The exhaust gases are expelled through the poppet valve centrally arranged in the cylinder cover.
      The structural components of the engine type consist of the bedplate, «A» frame and sca-
venging air receiver. These together form a rigid longitudinal girder which supports the cylind-
er units. For engines of cast iron construction, vertical mild steel through- bolts are provided.
They extend from the top of the cooling water jackets to the bottom of the bed plate cross gird-
ers. The crankshaft may be fully- built or semi- built depending on the number of cylinders and
torsional vibration characteristics of the system. The main bearing steel shells are lined with
white metal, the bearing keeps are of cast steel. The connecting rod bottom-end top-end bear-
ings, also the cross- head shoes, are of cast steel lined with white metal. There are two cam-
shafts. One operates the fuel injection pumps, the other actuates the exhaust valves through
cams, rollers, roller guides, push rods and rockers.
      A fuel injection pump is provided for each cylinder and it's cam- operated through a roll-
er and roller guide from a camshaft.
      The cylinder covers are made of chrome – molybdenum cast steel and are bolted to the
cooling water jackets. The liners are of very simple design made of alloy cast iron. Two fuel
valves, a starting valve, a safety and exhaust valves are arranged in the cylinder cover. The cy-
linder covers, c. liners and exhaust valves are fresh water cooled. The pistons are of a simple
design with crowns of chrome- molybdenum cast steel and skirts of cast iron. The pistons are
oil- cooled from the forced lubrication system. The B. and W. turborchavging system for two-
stroke cycle engines is a flunctuating pressure system.


                                           Exercises

     I. Answer the questions.
     1. What is the power output of the pressure- charged engines?
     2. What are the main particulars of the B. and W. design?
     3. In what way are the cylinders scavenged?
     4. How is the fuel injection pump operated?
     5. What material are the cylinder covers made of?
     6. What valves are arranged in the cylinder cover?
     7. What pistons are used in the engine?

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