Английский язык. Писарева Л.П. - 40 стр.

                                      Вариант III
                                            Text
                                      Air Starting System

       The method almost universally used for starting engines of more than 200 h.p. is
by admitting air at pressure to the cylinders through timed valves. Air for this purpose
is provided by a compressor which discharges the air to tanks located at any convenient
point in the engine room and counected to the starting valves in the cylinder heads. This
compressor is of two-stage construction because of the lower pressure to be handled. In
some cases the compressor is built into the engine but driven by gears, chains, or v-
belts and in most installations, especially in large engines, it is independently operated,
usually by an electric motor and in some cases by a separate auxiliary engine. Since the
maintenance of an adequate supply of starting air is vitally essential, the air
compressors must be installed in duplicate. If an attached compressor is used a small
independent unit must be provided.
       In order to eliminate the possibility of the compressor’s not being started in time
during extended perfods of manoeuvring, automatic controls should be installed that
will start and stop the compressors in accordance with pressure changes in the air tanks.
There are several methods in use for operating timed starting valves in the cylinder
head. In every case the air main leading from tanks is connected to each starting valve,
but air is turned into these lines only during the times when the valves are in operation.
       In one arrangement the valve are operated by came and levers. Normally the
rollers are held up clear of the cams but, when the sccentric bearings are rotated by the
control gear, which at the same time operates to open the valve that admits air to the
lines leading to the cylinders, the rollers drop onto the cams and the valves open and
close in accordance with their timing.
       In another arrangement the starting valves are spring-loaded valves that open
when air pressure in the valve body exceeds the spring pressure.


                                        Exercises

I. Прочтите и переведите текст письменно.
II. Переведите предложения, обращая внимание на модальные глаголы и их
заменители.

   1. A film of oil should be maintained between any two surfaces having relative
      motion.
   2. Lubrication oil used for cylinders must be applied in small quantities.
   3. Oil used for bearing lubrication an be applied in any desired quantity.
   4. The oil may be returned now to the crankcase for recirculation.
   5. This compressor is to be a two-stage unit because of the lower pressure it is to
      handle.
   6. Worn down rings have to be replaced.

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