4. Mechanical tools

Both in maintenance and in repair of machines all kinds of fitting operations are applied. An important role is played by disassembling and assembling operations. Special instruments are used for performing these operations.

Among the variety of mechanical tools used for disassembling and assembling machine parts and in their repairing are wrenches (Fig. 10). According to their construction and application wrenches may be of different types: single-ended and double-ended nut wrenches, adjustable wrenches, socket wrenches and special wrenches.

Fig. 10. Wrenches:

1-single-ended wrench (a- handle; b- head; c- span);

2- double-ended wrench; 3- adjustable wrench; 4- socket wrench

A nut wrench is used for screwing and unscrewing nuts. It consists of a handle and a head with an opening known as the span.

Adjustable wrenches may be used for unscrewing nuts and bolts of different dimensions.

Socket wrenches are applied in cases when nuts or bolt heads located in recesses are hardly accessible for a nut wrench.

Special wrenches are used for unscrewing and screwing nuts of a definite type.

Wrenches are used by drivers for repairing cars, in locksmith's shops and fitter's shops. Fitters use them to screw different types of machine parts as: washers, bolts, shafts, etc. Plumbers use them to repair pipes, taps, etc. Besides different types of wrenches there are round pliers or needle nose pliers which are widely used by locksmiths, electricians and other specialists for gripping, screwing or cutting off thin metal and wires.

Exercises

I. Use the following words and phrases in sentences of your own:

nut, to screw, to maintain, to unscrew, to assemble, to disassemble, nut wrench, adjustable wrench, socket wrench, to grip, plumber, electrician, fitter

II. Answer the following questions:

l. What operations are applied in maintenance and repair of machines? 2. What instruments are used for disassembling and assembling machine parts? 3. How are wrenches subdivided? 4 What is a nut wrench used for? 5. When are adjustable wrenches applied? 6. In what cases are socket wrenches used? 7. What wrenches are used for screwing and unscrewing nuts? 8. By whom are different wrenches used? 9. What other mechanical tools can be used in repairing?

III. Find in the text nouns for the following verbs:

to maintain, to operate, to construct, to fit, to assemble; to apply

IV. Supply antonyms for the following words:

disassembling, to screw, difficult, single-ended, accessible

V. Supply synonyms for the following words:

to locate, to grip, widely, different, dimensions

VI. State the functions of all the -ed forms and translate the following sentences into Russian:

1. Wrenches used to unscrew and screw nuts are known as adjustable wrenches. 2. Different wrenches are used to screw different types of machine parts, such as washers, bolts and shafts. 3. Locksmiths and fitters use special

instruments depending on the parts of machines to be disassembled and assembled. 4. Nut wrenches may be used for screwing different nuts. 5. Tools called "wrenches" are used for turning bolts and nuts. 6. Tools known as S-wrenches, angle wrenches, etc. are named so according to their shape. 7. The wrenches may also be named from the object on which they are used. 8. Adjustable wrenches are named so because they may be applied for screwing and unscrewing bolts and nuts of different sizes.

VII. Translate the following sentences into English:

1. Обычно механические ключи, используемые при ремонте разнообразных деталей, изготовляются из прочной стали. 2. Кусачки могут применяться для операций, выполняемых слесарями. 3. Торцовый ключ может применяться для завинчивания гаек, расположенных в углублениях. 4. Слесарь часто пользуется инструментами, называемыми разводными ключами. 5. Среди многих инструментов, применяемых электриками, есть круглогубцы.