General classification of machines
Unit 1
Grammar:Tenses;
Emphatic construction
Text A
GENERAL CLASSIFICATION OF MACHINES
Machines employed for construction and road making can be classified according to their purpose as follows:
1. Transporting facilities: crawlers and wheel –mounted tractors, trucks, general and special-purpose trailers and semi-trailers.
2. Materials handling equipment: winches, cranes, hoists, conveyors, air-operated equipment, loading and unloading machines.
3. Machines for earthwork: bulldozers, scrapers, elevating graders, towed graders, revolving shovels, hydraulic equipment and compactors.
4. Machines for preparing and placing concrete mixes: mixers, vibrators and vacuum plants.
5. Machines for laying stabilized pavements: bitumen storage equipment, machines for preparing asphalt-concrete mixes, for placing and compacting asphalt-concrete, machines manufacturing reinforced concrete products, machines placing reinforced concrete slabs, etc.
All of the above machines can be classified by the working process (continuous action or intermittent action), the prime mover (driven by electric motors or by internal combustion engines), mobility(stationary or mobile).
All machines are also characterized by definite parameters. Thus, the main parameter of a power shovel or a scraper is the capacity of the bucket, for cranes the main parameter is the maximum load-lifting capacity, for a bulldozer – the pulling effort, etc.
Among the main parameters of a machine there are capacity, weight, engine, power, overall dimensions, working and travelling speeds, etc.
For most machines per hour capacity is determined by the volume or weight of scooped material.
Active Vocabulary:
facility - оборудование, приспособление
purpose - цель, назначение
trailer - прицеп
equip - оборудовать
winch - лебедка, ворот
hoist - подъемник
earthwork - земляные работы
scraper - скрепер
elevate - поднимать
revolving shovel - ковш, вращающаяся лопата
compactor - уплотнитель
continuous - непрерывный
intermittent - периодический, циклический
prime mover - пусковой (основной) двигатель
pendant - навесной
self-powered - самоходный
mobile - подвижный, перемещаемый
capacity - емкость, производительность, мощность
pull - тянуть, тащить
dimension - размер
determine - определять
scoop - ковш, вычерпывать
Exercise 1.Answer the following questions:
1. How can the machines be classified according to their purpose?
2. What equipment is applied for handling materials?
3. What types of machines for earthwork do you know?
4. What machines are used for preparing and placing concrete mixes?
5. What is the main parameter for a power shovel?
6. How can cranes be characterized?
7. What are the important parameters of a machine?
8. How is the per hour capacity of a machine determined?
2. Exercise Define the tense of the predicates and translate the following sentences:
1. Tractors are mounted either on crawlers or on wheels.
2. Machines have been employed for construction purposes since early times.
3. We need different machines.
4. They have been testing the new transporting facility for a month.
5. Special purpose trucks were used to deliver building materials.
6. Before they installed modern hoisting equipment, simple winches had been
used.
7. The builders are using vibrators to compact concrete mix.
8. Concrete slabs will be placed with a tower crane.
9. They will replace old conveyor system next month.
10. The new asphalt pavement will have been laid by the end of the week.
Exercise 3.Translate the following sentences paying attention to the Emphatic Construction:
1. It is an electric motor that is used to drive most machines in modern shops.
2. It was steam that first began to move machines.
3. It is the construction site where most of the cranes are used.
4. It will be in June when the development plan is carried out.
5. It is a mechanic engineer who designs new machines for our industry.
Exercise 4.Translate the text without a dictionary:
Text B
POWER MACHINES
If one looked around a machine shop, he could see two types of machines: driven machines and driving or power machines.
Power machines are connected with driven machines by several methods. In the older workshops, belts and pulleys were much used but they are gradually disappearing. It is an electric motor that is used to drive most machines in modern workshops. Power is transmitted to the motor from the electric generators by means of insulated electric cables. Power may also come from a steam or gasoline engine.
Selection of power for a given operation is one of the first problems that must be solved in planning a new construction job. Whether the power is built into the machine, as in a tractor, or must be supplied separately, as with a pile driver, it is necessary to know what the manufacture’s rating of power is in terms of performance. Too much power means spending too much money. Too little power means that the job cannot be performed. Moreover, as machine wears with time and use, power may be lost or wasted. A knowledge of fundamentals of power finds application during operation as well as in planning.
Power may be defined as the rate of producing work. Its most commonly employed unit of measurement is the horsepower. The equivalent of 1 hp is 33,000 ft-lb per minute or 746 watts (w).
Notes:
connect - соединять
gradually - постепенно
disappear - исчезать
insulate - изолировать
Unit 2
Grammar: Participles;
Absolute Participle Construction
Text A
MECHANICAL HANDLING
At present plants, factories and building sites are equipped with various mechanisms and machinery that do the job of loading and unloading, lifting and positioning materials in place.
Depending on its purpose materials handling equipment consists of the following three main groups:
1. Hoisting equipment: winches, jacks, hoists and cranes for intermittent operation.
2. Conveying equipment: intermittently acting (rope-and-bucket) and continuously acting conveyors (belt, bucket, screw, vibration type, etc.), cableways, air-operated equipment.
3. Loading equipment for intermittent and continuous operation. Load handling equipment includes rail-mounted cranes, fork lift trucks and mobile cranes.
Loads are now handled at greater speeds and at smaller costs, possible damage has been brought to the minimum. Most materials loaded and unloaded are palletized. Pallets are handled by fork lift trucks. Fork lift machines are used in ever increasing numbers to carry loads. Loads that cannot be palletized are handled by cranes.
The lifting appliances include stationary and mobile cranes. Much work is done by quay cranes. In the last few years, quay cranes have been greatly improved.
Although quay cranes have become larger and more efficient it is the mobile cranes and particularly the fork lift trucks that revolutionized the handling methods. The fork lift truck is now used to lift, convey and stack loads.
Mechanization of handling materials ensures growth of speed of loading and unloading operations.
Active Vocabulary:
position - положение, место
jack - домкрат
rope - веревка, канат
cableway - канатная дорога
fork lift truck - погрузчик с вилочным захватом
pallet - поддон
palletize - пакетировать
quay crane - портальный кран
stack - складывать, складировать
appliance - приспособление, прибор
ensure - обеспечивать, гарантировать
Exercise 1.Answer the following questions:
1. What are factories and building plants equipped with now?
2. What kind of work do various mechanisms perform?
3. How many groups of materials handling equipment are there?
4. What machines does hoisting equipment include?
5. What kinds of conveying equipment do you know?
6. What machines does load handling equipment include?
7. How are most materials handled?
8. What machines are pallets handled by?
9. What loads are handled by cranes?
Exercise 2.Define the functions of Participles and translate the following sentences:
1. There are driven machines and driving or power machines.
2. Palletized loads can be handled by cranes.
3. Machines are used to actuate the operating members employed to change
properties, condition, shape or position of the material being handled.
4. Operating the crane the mechanic should be attentive.
5. The first bulldozers were adapted from farm tractors.
6. The conveyor system is positioned as required.
7. During the 20-th century diesel-powered rollers were gradually replacing their
steam-powered counterparts.
8. Initial compaction is done using pneumatic-tyred rollers.
9. Self-powered rollers have replaced horse-drawn ones.
Exercise 3.Translate the following sentences, paying attention to Absolute Participle Construction:
1. The engineer testing a new type of the bridge crane, the builders helped him.
2. Prefabricated flooring is widely used, cranes being employed to lift concrete
slabs.
3. The oil being of high quality, the lubrication will be efficient.
4. Conveyors being driven by electric power, a motor is the main part of the
equipment.
5. All machines have some energy loss, that energy being converted into useless
heat due to friction.
6. The lifting appliances include stationary and mobile cranes, some of them being
mounted on rubber-tyred wheels.
7. Cranes lifting great weights are usually operated by two motors, one motor
giving the lifting power and the other moving the crane itself.
8. The structure being very high, the builders used giant cranes.
Exercise 4.Translate the text without a dictionary:
Text B
LOAD HANDLING DEVICES
Loads are lifted by means of simple solid hooks. To handle small loads (up to 3 tons in weight) a hook may be attached directly to the free end of the rope.
Overhead travelling cranes employ multiple pulley systems in which two ropes run onto a drum symmetrically reducing thus the swinging of the load carried by a travelling crane.
Jacks, winches and hoists are widely used as hoisting equipment.
A jack is the simplest load lifting appliance for raising a load to a small height. There are mechanical and hydraulic jacks, the latter ones have the advantage of easy operation and high capacity.
Winches are widespread in the construction industry and are available in variety of designs.
A hoist is a simple suspension type mechanism of small size. It is used mainly for assembling machines. There are hand-operated and electric hoists. They can handle from 0.25 to 10 tons of load. The height to which the hook of a travelling electric hoist can be raised ranges from 6 to 18 metres, the travelling speed being 20 m/min.
Notes:
solid - твердый, сплошной
multiple - многократный, многочисленный
drum - барабан, цилиндр
swing - качать(-ся), колебать(-ся)
Unit 3
Grammar: Conditional Clauses;
Polysemantic Words
Text A
BULLDOZERS
The first bulldozers were adapted from farm tractors. Their versatility in soft ground for logging and road building led directly to their becoming the tank in World War I.
In 1923, a young farmer named James Cummings and a draftsman named J. Earl McLeod made the first designs for a bulldozer. A replica is on display at the city park in Morrowville, Kansas where the two built the first bulldozer.
By the 1920s, tracked vehicles became common, particularly the Caterpillar 60. To dig canals, raise earth dams, and do other earthmoving jobs, these tractors were equipped with a large thick metal plate in front. This metal plate (it got its curved shape later) is called a "blade". The blade peels layers of soil and pushes it forward as the tractor advances. Several specialized blades have been developed: blades for high volume loads such as coal, rakes to remove only larger boulders, or blades with razor sharp edges to cut tree stumps. In some early models the driver sat on top in the open without a cabin. These attachments, home built or by small equipment manufacturers of attachments for wheeled and crawler tractors and trucks, appeared by 1929. Widespread acceptance of the bull-grader does not seem to appear before the mid-1930s. It had become the preferred excavation machine for large and small contractors by the 1940s, by which time the term "bulldozer" referred to the entire machine and not just the attachment.
Over the years, bulldozers got bigger and more powerful to meet the demand for equipment suited for ever larger earthworks. Firms like Caterpillar, Komatsu, Fiat-Allis, John Deere, International Harvester, Case, Liebherr, Terex and JCB manufactured large tracked-type earthmoving machines.
Bulldozers grew more complex as time passed. Important improvements include more powerful engines, more reliable drive trains, better tracks, raised cabins, and hydraulic (instead of early models' cable operated) arms that enable more precise manipulation of the blade and automated controls. As an option, bulldozers can be equipped with rear ripper claw(s) to loosen rocky soils or to break up pavement (roads). A more recent innovation is outfitting of bulldozers with GPS technology, such as manufactured by Topcon Positioning Systems, Inc., Trimble Inc, or Mikrofyn for precise grade control.
The best known maker of bulldozers is probably Caterpillar which earned its reputation for making durable reliable machines. There are however other manufacturers of bulldozers for instance Fiat, Komatsu or Allis Chalmers. Although these machines began as modified farm tractors, they became the mainstay for big civil construction projects, and found their way into use by military construction units world-wide. Their best known model is the Caterpillar D9.
Active Vocabulary:
adapt - адаптировать, приспосабливать
tracked vehicle - гусеничное транспортное средство
raise - поднимать
shape - форма
layer - слой
soil - почва, земля
forward - вперед
volume - объем
cut - резать, срезать
acceptance - принятие
contractor - подрядчик
meet the demands - отвечать требованиям
suit - подходить, соответствовать
reliable - надежный
precise - точный
option - выбор
pavement - тротуар, мощеная дорога
durable - прочный, долговечный
Exercise 1.Answer the following questions:
1. When were the first bulldozer designs made?
2. What were those machines equipped with to do earthmoving jobs?
3. What specialized blades have been developed?
4. What bulldozer manufactures do you know?
5. What do bulldozer improvements include?
6. Why is Caterpillar the best known maker of bulldozers?
Exercise 2.Translate the following sentences, paying attention to the Conditional Clauses:
1. If bulldozers had not become bigger and more powerful they wouldn’t be able to
do large earth work.
2. Machines are used provided there are heavy and numerous operations.
3. If one uses bulldozers with GPS technology, grade control will be more precise.
4. People had not been able to build modern houses unless they had created
powerful machines.
5 If the machine were more versatile, it would be more useful.
6. This crane could be used provided its lifting capacity was larger.
7. They wouldn’t have used this tractor unless it had suited their needs.
8. Had they more modern equipment, their work would be more efficient.
Exercise 3.Translate the following sentences, paying attention to the underlined words:
1. The machine provided with a powerful engine will give much energy for work.
2. The friction force is directly proportional to the speed provided the latter is not
too high.
3. Bulldozers are very versatile provided they are used with numerous attachments.
4. If a tractor is equipped with a blade it can peel layers of soil and push it forward.
5. It is always necessary to determine if the stress is not too high for a given
structure.
6. The work is more efficient if the building site is provided with all necessary
equipment.
8. The builders wanted to know if the equipment would be delivered to the site in
time.
Exercise 4.Translate the text without a dictionary:
Text B
ROAD ROLLERS
The first road rollers were horse-drawn, and were probably just borrowed farm implements.
Since the effectiveness of a roller depends to a large extent on its weight, self-powered vehicles replaced horse-drawn rollers from the mid 1800s. The first such vehicles were steam rollers. Double-cylinder designs were preferred. Single-cylinder steam rollers were uncommon and unpopular, as the power impulses from the steam engine would produce slight waves in the road. Some road companies in the United States used steamrollers through the 1950s, and in the UK, some remained in commercial service until the early 1970s.
As internal combustion engine technology improved during the 20th century, kerosene-, gasoline- (petrol), and diesel-powered rollers gradually replaced their steam-powered counterparts. The first internal-combustion powered road rollers were very similar to the steam rollers they replaced. They used similar mechanisms to transmit power from the engine to the wheels, typically large, exposed spur gears. Some companies did not like to employ them as the engines of the era were typically difficult to start, particularly the kerosene-powered ones.
In fact, all road rollers in commercial use now use diesel power.
Initial compaction of the substrate is done using a pneumatic-tyred roller, with two rows (front and back) of pneumatic tyres. The flexibility of the tyres, with a certain amount of vertical movement of the wheels, enables the roller to operate effectively on uneven ground.
Notes:
borrow - заимствовать
implement - инструмент, прибор
slight - легкий
counterpart - копия, двойник
spur gear - цилиндрическая шестерня
Unit 4
Grammar: Gerund;
Ing-forms
Text A
DUMP TRUCK
A dump truck is a truck used for transporting loose material (such as sand or gravel) for construction. A typical dump truck is equipped with a hydraulically operated open-box bed hinged at the rear, the front of which can be lifted up to allow the contents to be emptied on the ground behind the truck at the site of delivery.
The dump truck was first made in Saint John, New Brunswick when Robert T. Mawhinney attached a dump box to a flat bed truck in 1920. The lifting device was a winch attached to a cable that ran over a sheave (pulley) mounted on a mast behind the cab. The cable was connected to the lower front end of the wooden dump box which was attached by a pivot at the back of the truck frame. The operator turned a crank to raise and lower the box. Today, virtually all dump trucks operate by hydraulics and they come in a variety of configurations each designed to accomplish a specific task in the construction material supply chain.
A standard dump truck is a full truck chassis with a dump body mounted to the frame. The dump body is raised by a hydraulic ram mounted between the truck cab (traction unit) and the dump body (semi-trailer).
A standard dump truck has one front axle, and one or more rear axles which typically have dual wheels on each side. The largest of the standard dump trucks has seven axles. The rear two axles are powered and the front axle is the steering axle. The intermediate axles are present to support the weight over the length of the chassis and sometimes to provide additional braking power. The short wheelbase of a standard dump truck makes it more maneuverable than the higher capacity semi-trailer dump trucks.
An articulated dump truck has a hinge between the cab and the dump box. Steering is accomplished via hydraulic rams that pivot the entire cab. This vehicle is highly adaptable to rough terrain.
A transfer dump is a standard dump truck which pulls a separate trailer which can also be loaded with aggregate (gravel, sand, asphalt, clinker, snow, wood chips, etc.). Transfer dump trucks typically haul between 26 and 27 tons of aggregate per load.
A semi bottom dump is a 3-axle tractor pulling a 2-axle trailer with a clam shell type dump gate in the bottom of the trailer. The key advantage of a semi bottom dump is its ability to lay material in a row. In addition, a semi bottom dump is maneuverable in reverse.
Double and triple bottom dumps consist of a 2-axle tractor pulling one single-axle semi-trailer and an additional full trailer (or two full trailers in the case of triples). These dump trucks allow the driver to lay material in rows without leaving the cab or stopping the truck. The main disadvantage is the difficulty in backing double and triple units.
A side dump truck has hydraulic rams which tilt the dump body onto its side, spilling the material to either the left or right side of the trailer. The key advantages of the side dump are that it allows rapid unloading and can carry more weight.
Dump trucks are normally built for some amount of off-road or construction site driving; as the driver is protected by the chassis and height of the driver's seat, bumpers are either placed high or omitted for added ground clearance.
Another safety consideration is levelling of the truck before unloading. If the truck is not parked on a relatively horizontal ground, the sudden change of weight and balance due to lifting of the skip and dumping of the material can cause the truck to slide, or even - in some light dump trucks - to turn over.
Active Vocabulary:
bed - дно
hinge - прикреплять на петле; висеть, вращаться на петле
sheave - шкив, блок
mast - мачта
pivot - точка вращения, ось; вращаться
supply - снабжать, доставлять
chassis - шасси, рама, ходовая часть
ram - подъемник, силовой цилиндр
intermediate - промежуточный
provide - обеспечивать, снабжать
braking power - сила торможения
maneuverable - маневренный
articulated - шарнирный
via - через
clam-shell - грейфер
spill - рассыпать
ground clearance - клиренс
safety безопасность
Exercise 1.Answer the following questions:
1. What is a dump truck used for?
2. What is a dump truck equipped with?
3. When was the first dump truck made?
4. How is the dump truck body raised?
5. What are the advantages of a bottom dump?
6. How does a side dump truck empty its body?
7. How is the driver protected?
8. Why is levelling of the truck before unloading necessary?
Exercise 2.Define the functions of Gerund and translate the following sentences:
1. A dump truck is used for transporting loose materials.
2. Steering is accomplished via hydraulic rams.
3. Double and triple bottom dumps allow laying the material without driver’s leaving the cab or stopping the truck.
4. The main disadvantage is the difficulty in backing double and triple units.
5. Another safety consideration is levelling of the truck before unloading.
6. A side dump truck allows rapid unloading.
7. Engineers have various devices for testing building materials.
8. A more recent innovation is outfitting bulldozers with GPS technology.
9. Earthmoving is an important part of every road building.
10. Specialized blades allow using a bulldozer for high volume loads.
Exercise 3.Translate the following sentences, paying attention to ing-forms (define the part of speech and function):
1. Wide tracks help to distribute the vehicle’s weight over a large area, thus
preventing it from sinking in sandy or muddy ground.
2. Cranes are used for the construction of tall buildings.
3. The first mechanical power was supplied by steam engines, the earliest steam
crane being introduced in the 19-th century.
4. Loader tractors were created by removing the blade and substituting a large
volume bucket, thus making it useful for scooping up earth and loading it into
trucks.
5. Modifications to the original bulldozer include making it smaller.
6. At present, most equipment uses hydraulics as a primary source of transferring
power.
7. The use of heavy equipment has a long interesting history.
8. A bulldozer is used to push large quantities of material during construction
work.
9. Light transportation of building materials, digging holes, breaking asphalt and
paving roads are some of the jobs accomplished by backhoe loaders.
10. Potentially flying goods must be covered to prevent loose materials from flying
outside the bed while the truck is moving.
Exercise 4.Translate the text without a dictionary:
Text B
SPECIALIZED DUMP TRUCKS
Dump trucks speed up unloading operations and require the services of only few helpers.
Dump trucks have proved highly efficient when large quantities of bulk load have to be conveyed over short distances, a feature typical of any construction site.
Dump trucks are always emptied by means of hydraulic hoists. Hydraulic hoists may be provided with one or two cylinders arranged, as a rule, under the body. The cylinders may be arranged vertically, horizontally or in an inclined plane. The cylinders may raise the body directly or through lever type system.
When the trucks follow in a continuous stream, side dumping allows the use of trailers or semi-trailers with self-dumping bodies. Side dumpers are discharged by telescopic hydraulic cylinders.
Telescopic cylinders are also very convenient in three-side dumpers.
Dump trucks are designed with special bodies. Practical experience shows that all-metal bodies with the rear open are most durable.
Notes:
bulk - объемный
prove - доказывать, оказываться
arrange - приводить в порядок, располагать
inclined - наклонный
discharge - разгружать
Unit 5
Grammar:Degrees of Comparison;
Functions of “one” and “that”
Text A
CRANE
A crane is a lifting machine equipped with a winder, wire ropes or chains and sheaves that can be used both to lift and lower materials and to move them horizontally. It uses one or more simple machines to create mechanical advantage and thus move loads beyond the normal capability of a human. Cranes are commonly employed in the transport industry for the loading and unloading of weights; in the construction industry for the movement of materials; and in the manufacturing industry for the assembling of heavy equipment.
It is a very old construction equipment and one of the most useful on the building site.
The first cranes were invented by the ancient Greeks and were powered by men or animals, such as donkeys. These cranes were used for the construction of tall buildings. Larger cranes were later developed, employing the use of treadwheels*, permitting the lifting of heavier weights. In the High Middle Ages, harbour cranes were introduced to load and unload ships and assist with their construction – some were built into stone towers for extra strength and stability. The earliest cranes were constructed from wood, but cast iron and steel replaced it with the coming of the Industrial Revolution.
For many centuries, power was supplied by the physical force of men or animals, although hoists in watermills and windmills could be driven by the harnessed natural power. The first 'mechanical' power was provided by steam engines, the earliest steam crane being introduced in the 18th or 19th century, with many remaining in use well into the late 20th century. Modern cranes usually use internal combustion engines or electric motors and hydraulic systems to provide a much greater lifting capability than was previously possible, although manual cranes are still used where the provision of power would be uneconomic.
Cranes exist in an enormous variety of forms – each adapted to a specific use. Sizes range from the smallest jib cranes, used inside workshops, to the tallest tower cranes, used for constructing high buildings.
In using cranes we concentrate building operations on a single site, increase the speed of construction and save the building costs.
Modern cranes are used for many purposes. Most of them are convertible. Versatility is added to the crane by different attachments and devices to be hooked to the end of the hoist line to handle materials. These devices are: buckets for loose bulk material and concrete, hooks and grapples for lumber, pipes and drums.
*treadwheel – a large wheel powered by animals or men walking on a circular belt or climbing steps
Active Vocabulary:
permit - позволять, разрешать
heavy - тяжелый
assist - помогать
strength - прочность, сила
stability - стабильность, устойчивость
wood - древесина
cast iron - чугун
steel - сталь
provision - снабжение, обеспечение
exist - существовать
variety - разнообразие
range - ряд, диапазон; колебаться в пределах
single - один, одиночный
increase - увеличивать, возрастать
save - экономить
convertible - обратимый, изменяемый
concrete - бетон
grapple - захват
Exercise 1.Answer the following questions:
1. How were the first cranes powered?
2. What materials were the cranes made of?
3. What power sources for cranes do you know?
4. Why are different crane attachments and devices used?
5. What type of engine do modern cranes usually have?
6. What can be done using cranes?
Exercise 2.Translate the following sentences, paying attention to Degrees of Comparison:
1. In older machine shops, belts and pulleys were much used.
2. Loads are now handled at greater speeds and at smaller costs.
3. Most materials loaded and unloaded are palletized.
4. Quay cranes have become larger and more efficient.
5. A crane is one of the most useful devices on the building site.
6. Lifting appliances include stationary and mobile cranes from the smallest to the
largest lifts.
7. Bulldozers grew more complex.
8. Important improvements include more powerful engine and more reliable drive
train.
9. The most recent innovation is GPS technology.
10. The best known maker of bulldozers is probably Caterpillar.
11. The largest of the standard dump trucks has seven axles.
12. The output energy is in practice slightly less than the input energy.
Exercise 3.Define the functions of “one” and “that” and translate the following sentences:
1. A standard dump truck has one front axle.
2. The first internal-combustion powered road rollers were very similar to the
steam-powered ones that they replaced.
3. One can lift heavy loads by means of different types of cranes.
4. That lifting operations with the old crane are uneconomical is taken into
consideration.
5. The speed of operation of new cranes should be higher than that of old ones.
6. The simple machine that was used in old times for lifting weights was an
inclined plane.
7. All of those machines are useful.
8. We know that we always lose some useful energy when machines are used.
Exercise 4.Translate the text with a dictionary in written form:
Text B
CRANES IN ANCIENT GREECE
The crane for lifting heavy loads was invented by the ancient Greeks in the late 6th century BC. The archaeological record shows that no later than about 515 BC distinctive cuttings for lifting tongs begin to appear on stone blocks of Greek temples. Since these holes point at the use of a lifting device, and since they are to be found either above the center of gravity of the block, or in pairs at the equal distance from a point over the center of gravity, they are regarded by archaeologists as the positive evidence required for the existence of the crane.
The introduction of the winch and pulley hoist soon led to a widespread replacement of ramps as the main means of vertical motion. For the next two hundred years, Greek building sites witnessed a sharp drop in the weights handled, as the new lifting technique made the use of several smaller stones more practical than of fewer larger ones. In contrast to the archaic period with its tendency to ever-increasing block sizes, Greek temples of the classical age like the Parthenon invariably featured stone blocks weighing less than 15-20 tons. Also, the practice of erecting large monolithic columns was practically abandoned in favour of using several column drums.
Although the exact circumstances of the shift from the ramp to the crane technology remain unclear, it has been argued that the unstable social and political conditions of Greece were more suitable to the employment of small, professional construction teams than of large groups of unskilled workers, making the crane more preferable to the Greek cities than the more labour-intensive ramp which had been the norm in the autocratic societies of Egypt or Assyria.
The first literary evidence for the existence of the compound pulley system appears in the Mechanical Problems attributed to Aristotle (384-322 BC), but perhaps composed at a slightly later date. Around the same time, block sizes at Greek temples began to match their archaic predecessors again, indicating that the more sophisticated compound pulley must have found its way to Greek construction sites by then.
Unit 6
Grammar:Modal Verbs;
Polysemantic Words
Text A
CRANES DESIGN
There are two major considerations that are taken into account in the design of cranes. The first is that the crane must be able to lift a load of a specified weight and the second is that the crane must remain stable and not tip over when the load is lifted and moved to another position.
Cranes illustrate the use of one or more simple machines to create mechanical advantage.
The lever. A balance crane contains a horizontal beam (the lever) pivoted about a point called the fulcrum. The principle of the lever allows a heavy load attached to the shorter end of the beam to be lifted by a smaller force applied in the opposite direction to the longer end of the beam. The ratio of the load's weight to the applied force is equal to the ratio of the lengths of the longer arm and the shorter arm, and is called the mechanical advantage.
The pulley. A jib crane contains a tilted strut (the jib) that supports a fixed pulley block. Cables are wrapped multiple times round the fixed block and round another block attached to the load. When the free end of the cable is pulled by hand or by a winding machine, the pulley system delivers a force to the load that is equal to the applied force multiplied by the number of lengths of cable passing between the two blocks. This number is the mechanical advantage.
The hydraulic cylinder. This can be used directly to lift the load or indirectly to move the jib or beam that carries another lifting device.
Cranes, like all machines, obey the principle of conservation of energy. This means that the energy delivered to the load cannot exceed the energy put into the machine. For example, if a pulley system multiplies the applied force by ten, then the load moves only one tenth as far as the applied force. Since energy is proportional to force multiplied by distance, the output energy is kept roughly equal to the input energy (in practice slightly less, because some energy is lost to friction and other inefficiencies).
Cranes can mount several utensils to be able to pick up several objects.
Cranes can be controlled by remote control from the ground.
In order for a crane to be stable, the sum of all moments about any point such as the base of the crane must equate to zero. In practice, the magnitude of load that is permitted to be lifted (called the "rated load") is some value less than the load that will cause the crane to tip.
Active Vocabulary:
consideration - рассмотрение, соображение
account - счет, расчет
remain - оставаться
stable - стабильный, устойчивый
tip - наклонять(-ся), опрокидывать(-ся)
create - создавать
beam - балка
point - точка
opposite - противоположный
equal - равный
strut - стойка, подпорка
support - поддерживать
fix - укреплять, устанавливать
wind - наматывать, поднимать при помощи лебедки
conservation - сохранение
exceed - превышать
remote control - дистанционный контроль
value - значение, величина
cause - быть причиной, вызывать
Exercise 1.Answer the following questions:
1. What considerations are taken into account in the design of cranes?
2. What kinds of simple machines does the use of cranes illustrate?
3. What does the principle of the lever allow to do?
4. How does the pulley system increase the applied force?
5. What does the principle of energy conservation mean?
6. How can cranes be controlled from the ground?
7. How is the crane stability provided?
Exercise 2.Translate the following sentences, paying attention to Modal Verbs:
1. The crane must be able to lift a load of specified weight and must remain stable.
2. The hydraulic cylinder can be used directly to lift the load or indirectly to move
the jib.
3. The energy delivered to the load cannot exceed the energy put into the machine.
4. Cranes can mount several utensils to be able to pick up several objects.
5. In order for a crane to be stable, the sum of all moments about any point must be
equal to zero.
6. The front assembly of a loader may be a removable attachment or permanently
mounted.
7. Backhoe loaders are to be used in urban engineering and small construction
projects.
8. Agricultural implements may be towed behind or mounted on the tractor, and
the tractor may also provide a source of power.
9. The outriggers have to be retracted when the vehicle needs to change its
position.
10. For larger projects, a tracked excavator should be used.
Exercise 3.Translate the following sentences, paying attention to the underlined words:
1. As an option, bulldozers can be equipped with ripper claws.
2. Bulldozers grew more complex as time passed.
3. Bulldozers are very powerful tractors and have excellent ground hold, as their
main tasks are to push or drag things.
4. Superdumps can be rated as high as 80,000 pounds.
5. Because of their large volume buckets loader tractors are very useful.
6. A bulldozer can push soil because it has a blade.
7. Backhoe loaders can be used for a wide variety of tasks.
8. For many years loaders have been further modified.
9. Hydraulic arms (instead of cable operated) are preferred for they enable more
precise manipulation.
10. Steam cranes have been used since the 18-th century.
11. Since the effectiveness of a roller depends on its weight self-propelled vehicles
replaced horse-drawn rollers.
12. Widespread use of the bull-graders does not seem to appear before the mid-
1930s.
13. The cranes had been constructed from wood before cast iron and steel replaced
it.
Exercise 4.Translate the text without a dictionary:
Text B
ROMAN CRANES
The Romans adopted the Greek crane and developed it further. We are relatively well informed about their lifting techniques thanks to rather lengthy accounts by the engineers Vitruvius and Heron of Alexandria . There are also two surviving beliefs of Roman treadwheel cranes offering pictorial evidence, with the Haterii tombstone from the late first century AD being particularly detailed.
The simplest Roman crane, the Trispastos, consisted of a single-beam jib, a winch, a rope, and a block containing three pulleys. Having thus a mechanical advantage of 3:1, it has been calculated that a single man working the winch could raise 150 kg (3 pulleys x 50 kg = 150), assuming that 50 kg represent the maximum effort a man can exert over a longer time period. Heavier crane types featured five pulleys (Pentaspastos) or, in case of the largest one, a set of three by five pulleys (Polyspastos) and came with two, three or four masts, depending on the maximum load. The Polyspastos, when worked by four men at both sides of the winch, could already lift 3000 kg (3 ropes x 5 pulleys x 4 men x 50 kg = 3000 kg). In case the winch was replaced by a treadwheel, the maximum load even doubled to 6000 kg at only half the crew, since the treadwheel possesses a much bigger mechanical advantage due to its larger diameter. This meant that, in comparison to the construction of the Egyptian Pyramids, where about 50 men were needed to move a 2.5 ton stone block up the ramp (50 kg per person), the lifting capability of the Roman Polyspastos proved to be 60 times higher (3000 kg per person).
However, numerous Roman buildings which feature much heavier stone blocks than those handled by the Polyspastos indicate that the overall lifting capability of the Romans went far beyond that of any single crane.
Roman engineers accomplished lifting extraordinary weights by two measures: First, a lifting tower was set up, whose four masts were arranged in the shape of a quadrangle with parallel sides with the column in the middle of the structure. Second, a multitude of capstans were placed on the ground around the tower, for, although having a lower leverage ratio than treadwheels, capstans could be set up in higher numbers and run by more men (and, moreover, by draught animals).
Notes:
adopt - заимствовать
assume - предполагать, допускать
effort - усилия
exert - напрягать(силы), осуществлять
crew - бригада
ramp - скат, наклонная плоскость
capstan - кабестан, ворот
Unit 7
Grammar: Infinitive;
Polysemantic Words
Text A
TYPES OF CRANES ( PART I)
Different types of cranes are used for maintenance work, recovery operations and weight loading.
Mobile Crane
The most basic type of a mobile crane consists of a steel truss or telescopic boom mounted on a mobile platform, which may be a rail, wheeled (including "truck" carriers) or caterpillar tracks. The boom is hinged at the bottom, and can be raised and lowered by cables or by hydraulic cylinders. A hook is suspended from the top of the boom by wire rope and sheaves. The wire ropes are operated by whatever prime movers the designers have available, operating through a variety of transmissions. Steam engines, electric motors and internal combustion engines (IC) have all been used. Older cranes' transmissions tended to be clutches. The operational advantages of this arrangement can now be achieved by electronic control of hydrostatic drives, which for size and other considerations is becoming standard. Some examples of this type of crane can be converted to a demolition crane by adding a demolition ball, or to an earthmover by adding a clamshell bucket or a dragline and scoop, although design details can limit their effectiveness.
To increase the horizontal reach of the hoist, the boom may be extended by adding a jib to the top. The jib can be fixed or, in more complex cranes, luffing (that is, able to be raised and lowered).
Telescopic Crane
A telescopic crane has a boom that consists of a number of tubes fitted one inside the other. A hydraulic or other powered mechanism extends or retracts the tubes to increase or decrease the total length of the boom. These types of booms are often used for short term construction projects. The relative compactness of telescopic booms makes them adaptable for many mobile applications.
Tower Crane
The tower crane is a modern form of a balance crane. Fixed to the ground (or "jacked up" and supported by the structure as the structure is being built), tower cranes often give the best combination of height and lifting capacity and are used in the construction of tall buildings. To save space and to provide stability the vertical part of the crane is often mounted on large beams, braced onto the completed structure, being lifted from one floor to the next as the structure grows. The jib (colloquially, the 'boom') and counter-jib are mounted to the turntable, where the slewing bearing and slewing machinery are located. The counter-jib carries a counterweight of concrete blocks, and the jib suspends the load from the trolley. The hoist motor and transmissions are located on the mechanical deck on the counter-jib, while the trolley motor is located on the jib. The crane operator either sits in a cabin at the top of the tower or (rarely seen) controls the crane by radio remote control from the ground. In the first case the operator's cabin is most usually located at the top of the tower attached to the turntable, but can be mounted on the jib, or partway down the tower. The lifting hook is operated by using electric motors to manipulate wire rope cables through a system of sheaves.
In order to hook and unhook the loads, the operator works in conjunction with a signaller (known as a 'rigger'). They are most often in radio contact, and always use hand signals. The rigger directs the schedule of lifts for the crane, and is responsible for the safety of the rigging and loads.
A tower crane is usually assembled by a telescopic jib crane of greater reach. In the case of tower cranes that have risen while constructing very tall skyscrapers, a smaller crane (or derrick) will be lifted to the roof of the completed tower to dismantle the tower crane afterwards. A self-assembling tower crane lifts itself off the ground using jacks, allowing the next section of the tower to be inserted at ground level. It is often claimed that a large fraction of the tower cranes in the world are in use in Dubai.
Active Vocabulary:
maintenance - эксплуатация, уход, текущий ремонт
recovery - восстановление
truss - ферма, связь
wire rope - проволочный канат
dragline - дреглайн, скребковый экскаватор
luffing - перемещение по горизонтали, изменение вылета
стрелы
decrease - уменьшать
space - пространство, место
turntable - поворотный круг
boom - стрела, укосина
slew - поворачивать(-ся), вращать(-ся)
counterweight - противовес
trolley - тележка, вагонетка, контактный ролик
schedule - расписание, график, режим
responsible - ответственный
rigger - такелажник
derrick - деррик-кран
insert - вставлять
claim - утверждать, заявлять, требовать
Exercise 1.Answer the following questions:
1. What does the most basic type of a crane consist of?
2. How can the boom be raised and lowered?
3. What power installations have been used in cranes?
4. How can the horizontal reach of the hoist be extended?
5. What features of a telescopic crane do you know?
6. What crane is used in the construction of tall buildings?
7. How does the crane operator control the crane?
8. How is a tower crane dismantled?
Exercise 2.Translate the following sentences, paying attention to the Infinitive:
1. A crane must not tip over when the load is lifted.
2. The lever allows a heavy load to be lifted by a smaller force.
3. The main tasks of bulldozers are to push or drag things.
4. Bulldozers have been further modified to evolve into new machines.
5. A large fraction of the tower cranes in the world is claimed to be used in Dubai.
6. In order to hook and unhook the loads the operator works together with a
signaller.
7. The crane’s ability to lift heavy weights is useful for installing large pieces.
8. The Caterpillar 9 can easily tow tanks that weigh more than 70 tons.
9. Sometimes a bulldozer is used to push another piece of earthmoving equipment
known as a scraper.
10. Subcompact tractors help to perform minor excavation projects.
11. To deliver a high tractive effort at slow speeds is the main design characteristic
of a tractor.
12. The crane to lift heavy loads was invented by ancient Greeks.
Exercise 3.Translate the following sentences, paying attention to the underlined words:
1. Some buckets have a retractable bottom.
2. The operator of a truck crane drives the truck and operates the crane at the same
time.
3. In some cases conveyors are installed in a vertical position.
4. All cranes have mostly the same principle attachments.
5. Both vehicles are off-road haul trucks.
6. Both the Liebherr T28B and the Caterpillar 797B have the same payloads of 400
tons.
7. Like the larger agricultural tractors a CUT (Compact Utility Tractor) will have a
four wheel drive.
8. Some companies did not like to employ road rollers as the engines of the time
were difficult to start.
Exercise 4.Translate the text with a dictionary in written form:
Text B
CRANES IN MIDDLE AGES
During the High Middle Ages, the treadwheel crane was reintroduced on a large scale after the technology had fallen into disuse in western Europe. The earliest reference to a treadwheel reappears in archival literature in France about 1225.
Generally, vertical transportation was done safer and cheaper by cranes than by customary methods. Newly introduced machines like treadwheels or wheelbarrows did not completely replace more labour-intensive methods like ladders, hods and handbarrows. Rather, old and new machinery continued to coexist on medieval construction sites and harbours.
The exact process by which the treadwheel crane was reintroduced is not recorded, although its return to construction sites has undoubtedly to be viewed in close connection with the simultaneous rise of Gothic architecture. The reappearance of the treadwheel crane may have resulted from a technological development of the windlass from which the treadwheel structurally and mechanically evolved.
The medieval treadwheel was a large wooden wheel turning around a central shaft with a treadway wide enough for two workers walking side by side. While the earlier 'compass-arm' wheel had spokes directly driven into the central shaft, the more advanced 'clasp-arm' type featured arms arranged as chords to the wheel rim, giving the possibility of using a thinner shaft and providing thus a greater mechanical advantage.
Contrary to a popularly held belief, cranes on medieval building sites were neither placed on the extremely lightweight scaffolding used at the time nor on the thin walls of the Gothic churches which were incapable of supporting the weight of both hoisting machine and load. Rather, cranes were placed in the initial stages of construction on the ground, often within the building. When a new floor was completed, and massive tie beams of the roof connected the walls, the crane was dismantled and reassembled on the roof beams from where it was moved from bay to bay during construction of the vaults. Thus, the crane ‘grew’ and ‘wandered’ with the building with the result that today all extant construction cranes in England are found in church towers above the vaulting and below the roof, where they remained after building construction for bringing material for repairs aloft.
Less frequently, medieval cranes were mounted on the outside of walls with the stand of the machine secured to putlogs.
In contrast to modern cranes, medieval cranes and hoists - much like their counterparts in Greece and Rome- were primarily capable of a vertical lift, and not used to move loads for a considerable distance horizontally as well. Slewing cranes which allowed a rotation of the load and were thus particularly suited for dockside work appeared as early as 1340. While ashlar blocks were directly lifted by sling, lewis or devil's clamp, other objects were placed before in containers like pallets, baskets, wooden boxes or barrels.
It is noteworthy that medieval cranes rarely featured ratchets or brakes to forestall the load from running backward. This curious absence is explained by the high friction force exercised by medieval treadwheels which normally prevented the wheel from accelerating beyond control.
Notes:
barrow - тачка, тележка
hod - приспособление для подноски на спине кирпича или
раствора
windlass - лебедка, ворот
extant - сохранившийся
aloft - наверх, наверху
putlog - палец строительных лесов
ashlar - тесаный камень
ratchet - храповик, храповый механизм
Unit 8
Grammar: Functions of “to be” and “to have”
Polysemantic and Auxiliary Words
Text A
TYPES OF CRANES (PART II)
Giant Cantilever Crane
The "hammerhead" or giant cantilever crane is a fixed-jib crane consisting of a steel-braced tower on which revolves a large, horizontal, double cantilever; the forward part of this cantilever or jib carries the lifting trolley, the jib is extended backwards in order to form a support for the machinery and counter-balancing weight. In addition to the motions of lifting and revolving, there is provided a so-called "racking" motion, by which the lifting trolley, with the load suspended, can be moved in and out along the jib without altering the level of the load. Such horizontal movement of the load is a marked feature of later crane design. These cranes are generally constructed in large sizes, up to 350 tons.
Truck Crane
A crane mounted on a truck carrier provides the mobility for this type of crane.
Generally, these cranes are designed to be able to travel on streets and highways, eliminating the need for special equipment to transport a crane to the jobsite. When working on the jobsite, outriggers are extended horizontally from the chassis then down vertically to level and stabilize the crane while stationary and hoisting. Many truck cranes possess limited slow-travelling capability (just a few miles per hour) while suspending a load. Great care must be taken not to swing the load sideways from the direction of travel, as most of the anti-tipping stability then lies in the strength and stiffness of the chassis suspension. Most cranes of this type also have moving counterweights for stabilization beyond that of the outriggers. Loads suspended directly over the rear remain more stable, as most of the weight of the truck crane itself then acts as a counterweight to the load. Factory-calculated charts (or electronic safeguards) are used by the crane operator to determine the maximum safe loads for stationary (outriggered) work as well as loads and travelling speeds.
Rough Terrain Crane
A crane mounted on an undercarriage with four rubber tires that is designed for pick-and-carry operations and for off-road and "rough terrain" applications. Outriggers that extend horizontally and vertically are used to level and stabilize the crane for hoisting.
These telescopic cranes are single-engine machines where the same engine is used for powering the undercarriage as is used for powering the crane, similar to a crawler crane. However, in a rough terrain crane, the engine is usually mounted in the undercarriage rather than in the upper, like the crawler crane. It is a mobile crane which has the necessary equipment to travel with high speed on public roads/highways and on the job site in rough terrain with all wheels and crab steering.
Crawler crane
A crawler is a crane mounted on an undercarriage with a set of tracks (also called crawlers) that provide for the stability and mobility of the crane. Crawler cranes have both advantages and disadvantages depending on their intended use. The main advantage of a crawler is that it can move on site and perform lifts remaining stable on its tracks with no outriggers. In addition, a crawler crane is capable of travelling with a load. The main disadvantage of crawler cranes is that they are very heavy, and cannot easily be moved from one job site to the next without significant expense. Typically, a large crawler must be disassembled and moved by trucks, rail cars or ships to be transported to its next location. Crawler cranes range in lifting capacity from about 40 tons to 3500 tons.
Active Vocabulary:
cantilever crane - кран-консоль, кран-укосина
extend - тянуть(-ся), вытягивать(-ся)
rack - перемещать при помощи зубчатой рейки
alter - изменять, переделывать
level - уровень
feature - особенность, характерная черта
eliminate - исключать, устранять
outrigger - аутригер, выносная опора
swing - качаться, колебаться
stiffness - жесткость
undercarriage - ходовая часть, шасси
off-road - внедорожный
depend on - зависеть от
intend - намереваться, предназначать
set up -
significant - важный
Exercise 1.Answer the following questions:
1. What does a cantilever crane consist of?
2. What motion can a cantilever crane perform in addition to the lifting and
revolving motions?
3. Where are truck cranes able to travel?
4. How is stability of a track crane provided?
5. What is the main feature of a rough terrain crane undercarriage?
6. What is the main advantage of a crawler crane?
7. How can a crawler crane be moved from one job site to another?
Exercise 2.Translate the following sentences, paying attention to the verbs “to be” and “to have”:
1. A giant cantilever crane is a fixed-jib crane.
2. The jib is extended backwards in order to form a support.
3. Outriggers are to be used to level and stabilize the crane.
4. The operator’s cabin is most usually at the top of the tower.
5. When a truck crane is working on the job site, outriggers are extended
horizontally from the chassis.
6. There are different types of a running gear.
7. Great care has to be taken not to swing the load.
8. Most truck cranes have moving counterweights.
9. In recent years, small compact tractors from the manufacturers such as Kubota
have become very popular.
Exercise 3.Translate the following sentences, paying attention to the underlined words:
1. Heavy bulldozers are mainly employed to level the ground to prepare it for
construction.
2. It was the steam engine that provided the first mechanical power.
3. It has been calculated that a single man working the winch could raise 150kg.
4. Due toits small size and versatility, a backhoe loader i