5. Переведите на английский язык.

1. Имеется много типов тракторов__________________________________________

______________________________________________________________________ 2. В стенках цилиндров имеются отверстия или окна_________________________

______________________________________________________________________ 3. Имеется три основных такта двигателя____________________________________

______________________________________________________________________ 4. В этой статье имеется три схемы________________________________________

______________________________________________________________________

5. Для руководства ремонтом двигателей имеются специальные учебники_______

_____________________________________________________________________________________________________________________________________________

6. Имеется несколько классификаций двигателей____________________________

___________________________________________________________________

6. Прочтите и переведите текст в.

The 2 – stroke Engine

A type of engine known as a 2-stroke engine is often used to provide power for small machines used on farms or in horticultural work. Some makes of tractors are powered by these engines but the majority of modern tractors use the 4-stroke engine.

The construction of the engine is different to that of a 4-stroke engine in that valves are not normally fitted. Instead, there are openings or ports in the walls of the cylinder. There are three of these openings which are known as the inlet port, transfer port and exhaust port respectively. Figure below shows the positions of these ports. The piston is usually of the type known as a deflector piston. The crankcase is gas-tight.

The situation shown in the picture is that the piston is almost at the top of the compression stroke compressing fuel mixture above it, and from this point the operating cycle can be followed.

When the piston moves up on the compression stroke a partial vacuum is created in the crankcase and fuel air mixture rushes in through the inlet port. Therefore compression and induction have taken place during one upward movement of the piston.

When the piston is at the top of the compression stroke a spark takes place across the points of the plug and fuel mixture ignites immediately. The fuel mixture burns, expands and forces down the piston, thus the power stroke is produced.

As the piston moves down on the power stroke it uncovers the exhaust port (see picture) and the exhaust gases which are still exerting pressure on the piston escape through the port and out to the atmosphere. Downward movement of the piston also partially compresses the fuel mixture in the crankcase and when the transfer port is uncovered at about the same time as the exhaust port the mixture is transferred from the crankcase to the cylinder. During this one downward movement of the piston, which is the second stroke, power and exhaust have taken place. The cycle then starts again.