Grammar: The Past Participle

Examples:

1. The heat energy developed by fuel increases the gas temperature and pressure.

2. The fuel is ignited by the compressed air.

Grammar exercises

I. Find in the text all sentences with Past Participles.

II. Connect the two given sentences into one using the Past Participle:

Model: Fuel generates heat energy. The heat energy is used to increase the temperature of the gas and to produce outside work.

Fuel generates heat energy used to increase the temperature of the gas and to produce outside work.

1. A diesel engine uses fuel. Fuel is injected into the cylinder in a finely divided state.

2. Combustion takes place at such a high rate that the piston doesn't move during such combustion. Such combustion is obtained when the piston is at the top center.

3. The advantage of this method of fuel combustion is a high thermal efficiency. High thermal efficiency is received during combustion at constant volume.

4. A two-stroke engine has a blower. A blower is used for obtaining scavenge air.

5. The necessary amount of air is supplied into the cylinder by a special device. This device is called a supercharger.

6. The piston pushes out the gases through the exhaust valve. The exhaust valve is opened when the piston is at the bottom centre.

7. The advantage of the combustion at constant pressure is smooth running and a more even torque. Torque is produced by an engine.

III. Insert Present or Past Participle of the verbs given in brackets:

1. All the heat energy ... by the fuel goes into an increase of the gas temperature and pressure. (to develop)

2. The fuel is burned so that the pressure ... at the end of the compression stroke is maintained during the greater part of the combustion event. (to attain)

3. The advantage of combustion at constant pressure is a smooth running engine ... a more even torque of an engine. (to produce)

4. There are four working strokes ... two complete revolutions of the crankshaft. (to occupy)

5. A ... engine develops 20 per cent more power than an ordinary diesel of the same type. (to supercharge)

6. The necessary amount of air is supplied into the cylinder by a special device ... a supercharger. (to call)

Unit VIII

Text

Lubrication

The aim of lubrication is to make the rubbing surfaces operate with as little friction as possible and so reduce wear to a minimum and obtain the maximum power out of the burnt fuel. Good lubrication is one of the main factors for satisfactory engine work.

Every moving part must be lubricated to ensure a lasting oil film which prevents metal-to-metal contact. There are three general methods of lubrication:

1. Mechanical force feed lubrication;

2. Circulating lubrication;

3. Splash lubrication.

During mechanical force feed lubrication oil is delivered to all points from one or more mechanical lubricator units. The number of individual pumps in each unit is determined by the number of points to be lubricated. At each feed point there is a check valve preventing oil from draining or blowing back.

The second method of lubrication may be divided into lubrication by gravity and by pressure circulation. Gravity lubrication is seldom used in modern engines. At present all engines are lubricated by pressure circulation method. Pressure delivers oil to all bearings and gears or chain-drivers. From the main bearing the oil passes through holes in the crankshaft to the connecting rod bearings and through the connecting rod to the wrist pin or crosshead.

During the splash lubrication method the crankcase is filled with oil. The rotating cranks dip into the oil and spray it over bearings and cylinder walls. Valves and other parts are lubricated by hand oiling, but cylinders are sometimes oiled by mechanical lubrication.

Words

aim, n цель, назначение

friction, n трение

rubbing surfaces трущиеся поверхности

reduce, v уменьшать

wear, n,v износ, изнашивать

satisfactory, adj удовлетворительный

prevent, v предотвращать

lubrication, n смазка

ensure, v обеспечивать

film, n пленка

lasting film прочная пленка

metal-to-metal contact сухое трение

mechanical force feed lubrication механическая смазка под

давлением

circulating lubrication циркуляционная смазка

splash lubrication смазка разбрызгиванием

unit, n установка, агрегат

determine, v определять

check valve контрольный, запорный, обратный клапан

drain, v спускать, осушать

blow back втягивать

divide, v делить, подразделять

lubrication by gravity смазка самотеком

gear, n зубчатая передача, шестерня

chain-driver, n цепная передача, привод

wrist pin, n поршневой палец

crosshead, n крейцкопф

dip, v погружать

crankcase, n картер