Английский язык: Сборник текстов и упражнений для студентов специальности "Эксплуатация судовых энергетических установок". Писарева Л.П. - 4 стр.

                                      SECTION I
                            INTERNAL COMBUSTION ENGINES



                                            Lesson 1
                                Essential parts of a Diesel Engine

       The diesel engine in its main features is composed of the following parts:
       Bedplate (engine frame) and crankcase. These two parts make a supporting structure to
hold the cylinders, crankshaft and main bearings in firm relation to each other. The crankcase
(mostly steel) serves as oil sump for the forced lubrication system.
       Cylinders are of cast iron. They are clamped to the frame by means of long through-bolts
which transmit the combustion pressure in the cylinders direct to the frame without causing
tensile stresses. The cylinders are provided with large removable inspection doors through
which the cooling water spaces may be inspected and cleaned.
       Cylinder covers (heads) close the top end of the cylinders.
       Cylinder liners. The liner is a comparatively thin cylinder, flanged at the upper end and
slightly thickened at its lower end in the way of the packing grooves. The bore is carefully fi-
nished to ensure perfect roundness and uniform diameter. The finish is given by boring, grind-
ing or reaming, but of these three methods the first is most generally used. For high grade work
it is general practice to finish the interior surfaces of diesel engine liners by grinding, followed
by honing. The outside surface of the liner is rough turned.
       Owing to the fact that the maximum pressure, occurs at the top of the liner and the minimum
at the lower end of the stroke the thickness usually tapers toward the bottom to about one-half that
at the top. In the 4-cycle liners it is frequently necessary to make recess at the top to provide clear-
ance for the inlet and exhaust valves, which can be placed close enough together in the head to
clear the liner. The holes for admission of the lubricating oil are placed at the height that will coin-
cide with the second piston ring from the top when the piston is at the end of the down stroke.
       Piston and piston rings. The piston is made of steel, cast iron or special alloy which is
highly resistant to heat stresses. The piston has a long life. According to size, the piston is pro-
vided with piston rings to produce compression and scraper rings to prevent lubricating oil
from penetrating into the combustion chamber, where it would burn and deposit coke. The cor-
rect function of the scraper rings contributes to the low lubricating oil consumption.
       Connecting rods. The connecting rod is made of steel. The connecting rod connects the
piston to the crank on the crankshaft. It transmits force in either direction from the piston to the
crank on the crankshaft.
       The crankshaft is made of forged steel. It has bored ducts conveying the forced lubrica-
tion oil to all bearings.
       Valves serve to admit the air and to discharge the spent or exhaust gases.
       The camshaft is of steel and is driven from the crankshaft through gear wheels. The bear-
ings are roller and ball bearings. The cams are of case hardened steel. The camshaft drives the
fuel pumps, one for each cylinder.
       The flywheel is a heavy wheel fastened to the crankshaft. Its purpose is to keep the en-
gine running smoothly from the time of one power stroke to the next power stroke.
       Large-size diesels are often double acting. Then there is included with the above a cross-
head and a piston rod.

                                             Vocabulary

      to be composed of=to consist of                   состоять из
      bedplate                                          фундаментальная рама

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