Материал для подготовки к практическим занятиям (стр. 3 )

1. What does the automobile consist of?

2. What does the power plant include?

3. What does the chassis consist of?

4. The power train carries the power from the engine to the car wheels, doesn’t it?

5. What is the body designed for?

6. What is it necessary to guide the car?

7. Are the brakes the most important mechanisms on the car?

Текст 2

Components of Tractors

Nowadays tractors are widely used in agriculture and in industry. In agriculture tractors are used in such jobs as plowing, planting, cultivating, fertilizing, harvesting, transport works, etc.

In different branches of industry tractors are used as road transport tractors hauling heavy loads. They are also used for different building purposes.

Tractors may be agricultural tractors, road transport tractors and special tractors.

Agricultural tractors are subdivided into: the general tractors designed for hauling agricultural machinery; cultivators designed for specific agricultural jobs; tractors for operation on soft boggy ground.

Road transport tractors are equipped with a load carrying platform.

Special tractors are usually equipped with auxiliary devices. Tractors may belong either to wheeled-type tractors or to track-laying type tractors.

The construction of a tractor includes the following main units:

1. Power unit which includes the engine with all auxiliary devices – a radiator, a fan, a starter device, a fuel tank, a pump, etc.

2. Transmission which consists of a clutch, a speed control unit, universal joints, gearing mechanisms, shafts, steering mechanisms, a final drive, axles.

3. Driver which includes driving, supporting and controlling mechanisms.

4. A steering unit.

5. The tractor frame.

6. Working and auxiliary equipment.

Tractor engines have internal combustion engines as the source of power.

Tractor engines requirements differ considerably from the requirements of the automotive engines. Automotive engines are generally unsuitable for tractors.

1. Tractors are widely used in agriculture and in industry, aren’t they?

2. What jobs are tractors used in agriculture for?

3. How may all tractors be classified?

4. What groups are agricultural tractors subdivided into?

5. What are road transport tractors equipped with?

6. What are special tractors usually equipped with?

7. What type may tractors belong to?

Текст 3

Principal Mechanism of Crawler-Mounted Tractors

The various types of tractors in use today have an almost identical transmission system. They consist of four main groups of mechanisms mounted on the main frame. They are:

1. The power unit, including the engine and all its accessories.

2. The power train, comprising the engine clutch, the propeller shaft, the transmission, the center drive, steering clutches with brakes and the final drive. The power train transmits torque from the engine to tractor tracks.

3. The crawler running gear, including the chain, drive sprockets, the idler, truck wheels and support rollers and a suspension. The suspension connects the tractor frame to the running gear.

4. Controls, consisting of the steering clutch, brakes, and mechanisms controlling fuel feed.

In addition, the tractor carries the hood, the cab and fuel tanks.

Tractors are usually steered by friction clutches mounted on the live axle after the center drive. These clutches, known as steering clutches, consist of a number of friction disks.

The weight of the tractor is transmitted to the ground through support rollers which run on the track. They are connected with the tractor frame by a suspension. The suspension damps shocks when the tractor moves on uneven ground.

Disconnecting one of the steering clutches, partly or completely, reduces the speed of rotation of the corresponding sprocket and its track. And the tractor will turn towards the side of the sprocket lagging behind.

Small-radius turns cannot be made by slowing down one sprocket using the steering clutches. Therefore, the tractor controls include a special device for stopping the free track by means of special brakes, which act upon the driven parts of the steering clutches.

A tractor going down a slope is braked and stopped by using the same brakes applied to both tracks simultaneously.

1. What is the main feature of the various types of tractors in use today?

2. What do crawler-mounted tractors consist of?

3. What mechanisms does the power unit include?

4. What mechanisms does the power train comprise?

5. What is the function of the power train?

6. What mechanisms does the crawler running gear include?

7. What do controls consist of?

VI. Heating and Ventilation

Отопление и вентиляция

Текст 1

Air Conditioning

The term air conditioning has been widely and loosely used, it includes any ventilation system with fan and heater. True air conditioning involves means for warming and humidifying air in winter and for cooling and dehumidifying in summer. Air conditioning is finding an ever widening application in industry. Accurate control of atmospheric conditions is very important for industrial processes. Air conditioning systems vary in complexity and plex systems are finding their application in air conditioning of a multi-storey office block, factory, cinema or theatre.

For many years air has been introduced into buildings after heating, dehumidifying and in some cases, cooling it. And we have called that process ventilation. In recent years much greater stress has been laid on the treatment of air and we call the process air conditioning. Air conditioning systems are divided into three types - winter, summer and complete. Winter air conditioning includes cleaning, heating, humidifying and circulating of air. It is finding its application in offices, auditoriums, schools and residences. Summer air conditioning includes cleaning, cooling, dehumidifying and circulating of air. The people are using summer air conditioning in stores.

Complete air conditioning involves winter and summer functions. It is used in theatres, large department stores. Each type of air conditioning depends upon the climatic conditions.

Developments of the last twenty years have changed our conception of air conditioning. Air conditioning is required for offices, department stores, hospitals, hotels and dwelling houses. But the techniques of air conditioning have not kept pace with the increasing demand. The cost of an air conditioning system influences the cost of the building, as it needs the additional height and floor areas to mount this air conditioning system.

Some efforts have been made to reduce the space occupied by air conditioning systems. But they have not been definitive, except some methods that have been used for many years. Air conditioning is rapidly being adopted in passenger ships and automobiles. Car heaters have been employed for some time. But recently new equipment has been designed to maintain car interiors at a comfortable temperature in summer and winter.

1. What term includes any ventilation system with fan and heater?

2. Air conditioning systems vary in complexity and cost, don’t they?

3. What has much greater stress been laid on in recent years?

4. Where is air conditioning finding application?

5. What does the cost of an air conditioning system influence?

6. Where is air conditioning being adopted?

7. What has new equipment been designed for?

Текст 2

Systems of Heating

The number of different heating systems is almost unlimited. Various systems of heating are being used at the present day. They are: direct, indirect, water heating systems, steam heating systems and so on.

A direct system is that in which the fuel is consumed in the room. It is being used for intermittent heating, or for heating isolated rooms. An indirect system is that in which the fuel is consumed outside the room. In this system the heat is being conveyed to the room by a medium such as steam or hot water. Indirect system is being used for the continuous heating of a number of rooms or large buildings. It begins from one central source and that’s why it is named Central Heating.

Steam heating systems are classified according to the following features: piping arrangement, pressure or vacuum conditions, obtained in operation and method of returning condensate to the boiler. A steam heating system is known as a one-piping and two-pipe system. In one-piping system a single main supplies steam to the heating unit and conveys condensate from it. In two-pipe system each heating unit is being provided with two piping connections. Steam and condensate flow in separate branches. Steam heating systems are classified as high pressure, low pressure (vapour) and vacuum systems. This classification depends on the pressure conditions under which the system is designed to operate. The system is known as a gravity return system. Condensate is returned to the boiler by gravity. All heating units are being elevated above the water line of the boiler.

1. What systems of heating are used at the present day?

2. What heating is the direct system used for?

3. What heating is the indirect system used for?

4. How are steam heating systems classified?

5. What do you know about one-piping system?

6. What do you know about two-pipe system?

7. What can you say about gravity return system?

Текст 3

Modern Heating and Ventilation

Ventilation means the circulation of air without any treatment. Ventilation is used where the cost of air conditioning is not justified. Ventilation may be natural or mechanical. Natural ventilation is due to the action of wind through wall openings and the updraft caused by the difference in temperature between indoors and outdoors. The limiting factors in natural ventilation are usually cold weather conditions and the availability of heat. Buildings with small floor areas are ventilated by natural means. Natural ventilation has the advantage of being cheap to install.

Mechanical or artificial ventilation is used for theatres, factories, large public halls and other buildings with large floor areas. Artificial ventilation may be classified as follows: exhaust ventilation, plenum ventilation and some combination of the above mentioned systems.

Heating and ventilation may be required to provide comfortable conditions for people and for industrial processes. Both are necessary and should be considered together. But the design of each must be treated separately. Heating and ventilation of buildings by electrical methods are finding their application nowadays. These methods have the advantage of being quick in construction. They are suitable for buildings of all sizes and types. Small rooms can be adequately heated with electric fires. Tubular heaters are used for rooms where the temperature must be maintained for long periods. These heaters are usually fixed to the walls near the floor. Not long ago electrically heated panels were developed. On these the heating elements are mounted behind metal panels. The heating of rooms by means of large warmed panels is named panel heating or radiant heating.

Electric heaters play a large part in the air conditioning plants of large buildings. The air enters the building through the ventilation ducts and passes over electric heaters. They raise the temperature of the passing air and give comfort to the people.

1. What does term ventilation mean?

2. What can heating and ventilation be required to provide?

3. Must the design of heating and ventilation be treated separately?

4. What methods of heating and ventilation are widespread?

5. What is the advantage of electric methods?

6. What is used to maintain the temperature for long periods?

7. Electric heaters do not play a large part in the air conditioning plants of large buildings, do they?

VII. Water Supply and Water Disposal

Водоснабжение и водоотведение

Текст 1

Purification

The water industry provides drinking water and wastewater services (including sewage treatment) to households and industry, water purification facility.

In the developing world, 90% of all wastewater still goes untreated into local rivers and streams. The processes generally employed in making water safe for water supply include coagulation, filtration, and disinfection. Water from some sources must be treated also for the removal of color, taste, and odor. Coagulation is commonly effected by adding to the water a salt of aluminum (usually aluminum sulphate) or ferric iron. A precipitate forms and causes a clumping of the bacteria and other foreign particles which then settle out during the several hours of sedimentation. In this way 85% or more of the bacteria and suspended particles can be removed.

Activated carbon is sometimes added before sedimentation to remove tastes and odors. In the process of filtration the water is allowed to pass through layers of fine sand to remove remaining germs and particles. Chlorine is commonly used to destroy harmful bacteria persisting in a municipal water supply after the other treatments. Chlorine dioxide has more recently been found effective as a destroyer of bacteria as well as a means of removing unwanted tastes and odors. Other means of destroying germs include the use of ozone and of ultraviolet light. Some water supplies are aerated, i. e., exposed to the action of air and sunlight either through sprays or by running over coarse gravel; taste and odor are improved and some germs are destroyed.

1. What does the water industry provide?

2. What do the processes generally employed in making water safe for water supply include?

3. What must be treated for the removal of color, taste, and odor?

4. Why is activated carbon added before the sedimentation?

5. What has been found effective as a destroyer of bacteria as well as a means of removing unwanted tastes and odors?

6. What are ozone and ultraviolet light used for?

7. When are taste and odor improved and some germs destroyed?

Текст 2

Water Supply

Water is a common chemical substance that is essential for the survival of all known forms of life. All known forms of life depend on water. Humans require water that does not contain too many impurities.

The distribution of drinking water is done through municipal water systems or as bottled water. Governments in many countries have programs to distribute water to the needy at no charge. Others argue that the market mechanism and free enterprise are best to manage this rare resource and to finance the boring of wells or the construction of dams and reservoirs. Water supply facilities include for example water wells cisterns for rainwater harvesting, water supply network, water purification facilities, water tanks, water towers, water pipes including old aqueducts. Atmospheric water generator is in development. Drinking water is often collected at springs, extracted from artificial borings in the ground, or wells.

Building more wells in adequate places is thus a possible way to produce more water, assuming the aquifers can supply an adequate flow. Other water sources are rainwater and river or lake water. This surface water, however, must be purified for human consumption. This may involve removal of undissolved substances, dissolved substances and harmful microbes. Popular methods are filtering with sand which only removes undissolved material, while chlorination and boiling kill harmful microbes. Distillation does all three functions. More advanced techniques exist, such as reverse osmosis. Desalination of abundant ocean or seawater is a more expensive solution used in coastal arid climates.

1. What is a common chemical substance that is essential for the survival of all known forms of life?

2. How is the distribution of drinking water done?

3. What do water supply facilities include?

4. Building more wells in adequate places is a possible way to produce more water, isn’t it?

5. What must be purified for human consumption?

6. What does filtering with sand remove?

7. Where is desalination of abundant ocean or seawater used?

Текст 3

Sewerage

The problem of protecting natural water resources has grown very pressing for many countries since the beginning of the second half of the 20th century. The development of human society, the growth of civilization and social and technical progress have resulted in the changing of the composition of natural water resources. The rivers, lakes and ground-waters contain today the products of mechanical, chemical and biological pollution.

The waste products that result from the daily activities in a community are of two general types: the liquid waste, known as sewage and the solid wastes, known as refuse. The different wastes are the following: the wastes from lavatories, baths, sinks, and laundry tanks in residences, institutions, and business buildings; wastes from various types of manufacturing or industrial plants, and the surface run-off from storms or street-flushing operations.

Sewage may also be divided according to its source into the following three classes. The sewage from institutions and business buildings is called domestic sewage, sanitary sewage or house sewage; that resulting from manufacturing or industrial processes is known as industrial waste; and that from run-off during storms is called storm sewage. A combination of domestic sewage, industrial waste water is called combined sewage. The removal of all kinds of sewage is usually accomplished by means of sewers. The sewers are placed in the streets below the ground surface. The general process of removing sewage is designated as sewerage and the entire system of sewers including a sewage treatment plant is known as a sewerage system.

In conclusion it should be stressed that with the growth of population many modern treatment systems have been built and much more is still to be done in this field.

1. When has the problem of protecting natural water resources grown?

2. What have resulted in the changing of the composition of natural water resources?

3. The rivers, lakes and ground waters contain today the products of mechanical, chemical and biological pollution, don’t they?

4. What waste products do you know?

5. What is called domestic sewage, sanitary sewage or house sewage?

6. What is known as industrial waste?

7. What is called combined sewage?

VIII. Property Examination and Administration

Экспертиза и управление недвижимостью

Building Materials Строительные материалы

Текст 1

Cement

1. Cement is one of the most essential building materials. When it is mixed with water, cement forms mortar, which hardens, binding various objects, such as bricks or stones, very firmly. It is for this reason that cement is used widely as a binding material in large-scale construction. Cements, except white and coloured, are of grey colour. White or coloured cements can be used where special effects are required.

2. The raw materials used in the manufacture of cement are: chalk, slate, limestone and clay. These substances are heated in a slowly rotating kiln. During the period of their movement through the kiln the clay and the limestone react chemically and the material emerging from the kiln is cement which is then ground and mixed with water.

3. Cement has different properties, most important being the strength of its production. Shrinkage of cement products also the most important property of cements as it is the cause of cracking. This depends on the proportion of cement and the quantity of mixing water. All types of cements shrink during setting and hardening. It is necessary to distinguish between setting and hardening. The term “setting” relates to the stiffening of the mix due to chemical processes; “hardening” is a later and physical-chemical process. Cement starts hardening one hour after the water has been added and the process of hardening lasts for about twenty-eight days.

4. Depending on the kind and composition of the raw materials different types of cement are obtained. The main types of cement are: Ordinary Portland cement, Rapid Hardening Portland cement, White and Coloured Portland cement, Portland Blast - furnace cement and High Alumina cement.

5. The process of manufacture of those cements is rather similar. The usual three stages of producing are: 1. grinding and mixing the raw materials in a form of wet slurry; 2. burning the mixture to hard clinkers; 3. crushing and grinding the clinkers to a very fine powder.

1. What material is formed when cement is mixed with water?

2. What is cement used in construction for?

3. What is the colour of cement?

4. What raw materials are used for producing cement?

5. What properties does cement have?

6. What does the kind of cement depend on?

7. What are the main types of cement?

8. How many stages are there in producing cement?

9. What are they?

Текст 2

Concrete

1. Concrete is an artificial stone. It is made by mixing of cement and water with sand, crushed stone, gravel or other inert material (aggregate). After this mixture is placed in forms, a chemical action takes place and the mass hardens.

2. It is difficult to imagine modern structure without concrete. The most important quality of concrete is its property to be formed into large and strong monolithic units. It should be hard, strong, durable, fire-resistant and economical.

3. Concrete may be divided into two classes: mass or plain concrete and reinforced concrete (ferro-concrete) where it is necessary to introduce steel. Mass or plain concrete dates from very early days. It was employed by the Egyptians, Romans and Greeks in the construction of bridges, roads and town walls. A large part of the Great Chinese Wall (the third century before our era) was also built of concrete. As cement was not known in those times, concrete was made of clay. Mass or plain concrete can be used for almost all building purposes.

4. The idea of strengthening concrete by a network of small iron rods was developed in the 19th century. Ferro-concrete is used in building bridges and arches, dams and dock-walls, for structure under water, for foundations, columns, girders, beams. The main thing about reinforced concrete is the combination of compressive strength of concrete with tensile strength of steel. It is a fire-resistant material and acts as a heat insulator.

5. There is a broad division of concrete types due to aggregates used: a) dense concretes – composed of heavy aggregates (sand, gravel and crushed stone); b) light-weight concretes – composed of light aggregates (blast-furnace slag, coke, breeze, expanded clay, ash). There are “cellular” concretes made by using materials which form gas during the mixing of the concrete. These give a product of very light weight.

6. Builders produce prestressed concrete. It is not a new material. In prestressed concrete steel is not used as reinforcement, but as a means of producing a suitable compressive stress in the concrete. Therefore any beam made of this material is devoid of cracks. Prestressed concrete is used for beams, columns, pipes, storage tanks, etc.

7. Concrete differs not only in its quality but also in the way of working it. So, there are in-situ (or cast-in-place) concrete which can be made in a building site or precast concrete which may be used as the material for making prefabricated units in a factory.

8. Two types of new building materials are produced now: alkali-slag concrete and silica concrete. In alkali-slag concrete cement is replaced by blast-furnace slag and sodium compounds. It is used for irrigation systems, roads, pavements. Silica concrete is light, fire-resistant and acid-proof. It contains no cement whatever. Silica concrete is used in aviation and in under water construction.

1. What materials are used to produce concrete?

2. What are the properties of concrete?

3. What two classes are concrete divided into?

4. What plain concrete is used for?

5. What is the main thing about reinforced concrete?

6. What kinds of concrete are there due to aggregates used?

7. What is prestressed concrete used for?

8. What new two types of concrete are produced?

Текст 3

Bricks and Building Stones

1. A brick is “a building unit”. It can be made of burnt clay, concrete, mortar and other materials; in shape it is a rectangular solid. Bricks are used as walling and facing materials.

2. There exist many kinds of bricks used in construction: common bricks, facing bricks, engineering bricks. They may be used for different mon bricks are used for general purposes. They are cheap, and may vary greatly in strength and durability. Facing bricks are used for facing walls. Their surfaces sometimes are coloured. They should be durable under severe conditions. Engineering bricks should be strong, smooth and hard, highly resistant to changing temperatures. There are hollow bricks and blocks, which are used when it is required to decrease the weight of construction.

3. Natural stones are also widely used in building. Stone has been used as a structural material since the earliest days. Almost all famous buildings of classic times of the medieval and Renaissance periods and of the eighteenth and early nineteenth centuries were erected of stone. The art of making any structure in stone is called stone masonry.

4. The stones which are used for masonry work are as follows: 1. Granite. It is very hard, strong and durable. It is used for basement, column, steps and for facades. Its colour may be grey, yellow, pink and deep red. 2. Sandstone. It is composed of quartz. It is used for steps, sills, etc. It is an excellent material for concrete aggregate. 3. Marble. It is a crystalline stone used for decorative purposes. White and black marbles are used for ornamental decoration.

1. What are the materials for bricks?

2. What is the shape of brick?

3. What are bricks used for?

4. What kinds of bricks are there?

5. What bricks are used for general purposes?

6. What bricks must be durable under severe conditions?

7. What can you say about engineering bricks?

8. What are hollow bricks and blocks used for?

9. What was natural stone used as a structural material for?

10. What is called stone masonry?

11. What is the colour of granite?

12. What stones are used for masonry work?

13. What stone is used for concrete aggregate?

14. What is marble used for?

Текст 4

Timber

1. Timber is the most ancient structural material. It is strong for its weight, it is easily workable. Timber is highly resistant to corrosive chemical attack. Its mechanical properties are good. On the other hand, timber has certain disadvantages. First, it burns and is therefore unsuitable for fireproof buildings. Secondary, it decays.

2. Timber used for building purposes is divided into two groups: softwoods (conifers) and hardwoods (broad-leaved species). Hardwoods are chiefly used for decorative purposes, as paneling, veneering in furniture, and some of them are selected for structural use because of their high strength and durability. Softwoods are mainly used for joinery.

3. In modern construction timber is often used for window and door frames, flooring, fences and gates, unpainted internal woodwork. It may be used for producing different structural elements such as beams, girders, floors.

4. Timber cannot be used immediately it has been felled because of the large amount of moisture which it contains. It must be removed; otherwise the timber will swell, causing a tendency to decay. To decrease moisture timber is dried, and this process of drying timber is called seasoning. There are several methods of seasoning:

a) “natural seasoning”, when timber is dried under natural atmospheric conditions;

b) “kiln seasoning”, when timber is artificially heated;

c) “chemical seasoning”, when timber is treated by special chemicals. When dried, timber changes its size and sometimes its form. Elimination of moisture increases the strength and durability of timber.

1. Is timber a new building material?

2. What are the valuable constructive properties of timber?

3. What disadvantages does timber have?

4. What kinds of timber are used for building purposes?

5. What are hardwoods used for?

6. What are softwoods used for?

7. What structural elements can be produced?

8. How can moisture be removed from timber?

9. What is seasoning?

10. What methods of timber seasoning are there?