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CRANES
Cranes are suitable for an enormous variety of jobs, and are available in many types and a wide range of capacities. Practically almost all modern dock and wharf cranes are driven by electricity or hydraulically operated. Capacity depends entirely upon the nature of the goods to be handled, but for the ordinary mixed cargo a capacity of 3—5 tons per lift has been found most convenient.
With specially heavy classes of goods higher-powered cranes are, of course, required and this can be met by having available floating cranes of 10 to 100 tons capacity, which can be brought to the ship or quay where such special loads are required to be handled.
In other cases, high capacity can be provided, but this generally involves moving the ship when a heavy load has to be handled. Should a ship be lying at the quay where the heavy lift crane is situated, the crane is not available for any other ship unless both are moved.
During recent 30 years there has been an enormous increase in the numbers and in scope of application to modern industry, of heavy lift mobile cranes. This is partly due, no doubt, to the advent of the diesel engine and its ready adaptability to electric transmission, coupled with the fact that no fuel is consumed during periods of slackness.
Remarkable strides have been made within the last 30 years in the design of electric cranes. With moderate lifts, goods can be handled at fairly high speeds.
DEVELOPMENT OF THE QUAY CRANE
It is interesting to trace very briefly the development of the quay crane, which is quite in a class by itself among a great variety of cranes and lifting appliances. Its prototype was a very crude affair, consisting of little more than a winch and a fixed jib. Progress in crane design was slow before the advent of steam- propelled vessels, because in the old sailing ship days, time was not a factor of importance, and there was no call for expeditious methods of loading and unloading. Manual labour was considered quite sufficient for all quayside requirements.
In the year 1864 hydraulic power was applied to quay cranes. This gave a considerable impetus to quay crane design, and led to a very extensive increase in the cranage equipment of docks and harbours. Then, in the last decade of the nineteenth century, the electric crane appeared. It cannot be said that the hydraulic crane has been altogether displaced. It is still regarded as a most useful appliance. For slow heavy uniform lifts, it presents advantages of no inconsiderable value.
In the lighter, rapid and variable class of work associated with the handling of merchandise, the electric crane is able to function more economically and efficiently.
The principal development in quay cranes design has been in reference to the jib.
Perhaps the most striking feature of the modern quay crane is the luffing motion of the jib, by which it is able to move inwards and outwards in a straight line, as contrasted with the radial action of a fixed jib. This arrangement has been devised for the purpose of avoiding contact with ship's gears, rigging and other obstructions, when working in a restricted areas. But the luffing action of the jib, as at first introduced, entailed a lifting of the load suspended from the jib, due to the raising of the jib head during the inward movement.
This lifting was not only superfluous in action, but it was w asteful of power, and consequently uneconomical. Various expedients were attempted to counteract the effect, and some very ingenious designs have been put forward.
QUAY CRANE REQUIREMENTS
There are certain essential points to be specified in the design of a quay crane. These may be briefly discussed as follows:
Capacity. The average draft, or parcel, of goods from a ship's hold does not exceed 1—2 tons.
A large number of quay cranes, however, have maximum capacities as high as 5 tons. Even in the case of an electric crane, where the consumption of current is exactly proportional to the load lifted, it has to be borne in mind that the more powerful the crane, the greater the initial outlay, and, if much in excess of requirements, there will be a corresponding unremunerative investment of capital. Moreover, the additional power capacity involves additional structural weight which has to be moved whenever the crane is slewed.
Motions and Motors. The motions required in a quay crane are four in number: (1) Travelling along the quay; (2) Hoisting and lowering the load; (3) Slewing the jib, and (4) Luffing the jib.
All these motions are provided by separate motors, which work independently.
It is possible, of course, to work all these motions by a single motor, and it can be done quite satisfactorily, but the multiple motor system is more common, being, on the whole, more reliable, and also more speedy, as the time taken to change gears and clutches is saved.
Speed. The ideal motor speeds are those which correspond with the rate of goods handling at the point of feeding and at the point of distribution. The depth of the hold governs the requirements to some extent, and the speed should be greater for a deep ocean liner than for the shallower coasting vessels or inland waterway craft.
WORDS AND PHRASES
enormous [i'no:mas] огромный
range [гешёз] диапазон
hydraulically [hai'drorlikoli] гидравлически
this can be met by having available floating cranes этого можно добиться, имея в наличии плавучие краны
involve [in'volv] повлечь за собой
advent ['aedvant] появление
diesel engine ['di:zal 'end3in] дизель
transmission передача
to consume [kan'sju:m] потреблять
slackness зд. бездействие
to make strides делать успехи
moderate ['modarit] средний, умеренный
quay crane портовыйкран, береговой кран
briefly кратко
which is quite in a class by itself among a great variety of cranes and lifting appliances который занимает особое место среди весьма разнообразных кранов и подъемных приспособлений
crudeaffairзд. несовершенное устройство
fixed jib стационарная стрела
expeditious [/ekspi'dijss] быстрый, скорый
impetus ['impitas] толчок
carnage equipment крановое оборудование
uniform ['ju:nib:m] однообразный
of no inconsiderable value немалойважности
merchandise ['ma:tjandaiz] товары
efficiently производительно, продуктивно
inreferenceв отношении
to luff'перемещаться по горизонтали
to devise [di'vaiz] изобретать
obstruction [ob'strAkJn] препятствие
to entail fm'teil] влечьзасобой
to suspend [sas'pend] подвешивать
superfluous [sju/pa-.fluas] излишний
expedient [iks'pi.'diant] средство
ingenious [in'd3i:njas] остроумный
to put forward предлагать
to specify ['spesifai] точно определять, устанавливать
draft зд. партия
consumption [kan'sAmpJn] потребление, расход
the more powerful the crane, the greater the initial outlay чем
больше мощность крана, тем выше первоначальные издержки
unremunerative ['Anri'mjuinarativ] невыгодный investmentкапиталовложение
to slew поворачивать
multiple состоящий из нескольких единиц
I. Answer the following questions:
1. What lifting appliances do you know?
2. What is a floating crane used for?
3. What mechanical apparatus do loading and unloading?
4. What is the average speed of a modern 5-ton mobile crane?
5. Have you ever operated a crane?
6. What does the capacity of a crane depend on?
7. What average crane capacity is required for the ordinary mixed cargo?
8. In what cases are high-capacity cranes provided?
9. Have you ever seen a floating crane?
10. What is the maximum capacity of the floating crane?
11. What cranes are called quay cranes?
12. What cranes are called mobile cranes?
13. What is the most striking feature of the modern quay crane?
14. What motions are required in the quay crane?
15. How are these motions provided?
16. Is it possible to work all the motions of the crane by a single motor?
17. What is the maximum working load of the quay crane?
18. What is the average luffing speed of the quay crane?
19. What are some of the advantages of cranes driven by electricity?
20. What are quay crane requirements?
II. Analyse the following sentences:
1. This type of crane is known to be suitable for dealing with medium loads.
2. Progress in recent years in port and harbour design and in equipment is indicated by the existing activities at many ports, and an increased use of mechanical appliances is evident.
III. (a) Form nouns from the following adjectives and translate them into Russian:
effective, hard, active, cool, compressive, wide, strong, long, deep.
(b) Form nouns from the following verbs and translate them into Russian:
cool, connect, compress, elongate, produce, admit, seize, require, situate, move, apply, design, consume, hoist, render, equip, operate, lift, apply, consider, function, arrange, introduce, correspond, travel, slew, satisfy, distribute, govern.
.
IV. Translate the following sentences into English:
' 1. Простейшие подъемные устройства применялись более чем 2000 лет до нашей эры. 2. В Древней Греции применялись устройства, являющиеся прототипом простейшего подъемного крана. 3. В конце XX в. появился электрический привод, который быстро вытесняет другие виды приводов. 4. Для питания электродвигателя применяется постоянный и переменный ток. 5. В Одесском порту много береговых кранов. 6. Современные краны могут обрабатывать грузы на довольно высокой скорости. 7. Электрический привод является самым распространенным типом привода. 8. При электрическом приводе, как правило, все механизмы имеют самостоятельные моторы. 9. В настоящее время строительство кранов идет по пути дальнейшей стандартизации отдельных узлов, уменьшения веса, повышения степени безопасности работы. 10. В новых портовых кранах гидравлический привод применен не только для подъема стрелы, но и для подъема груза и поворота крана. 11. Подъемный механизм является основным в грузоподъемных машинах. 12. Для механизации погрузочно-разгрузоч- ных работ со штучными грузами используются, главным образом, краны различных типов грузоподъемностью до 50 т.
Lesson seven
HEAVY LIFT CRANE
In the foregoing pages, the description has been confined to the cargo quay crane of normal capacity. There are, however, occasional lifts to be dealt with, exceeding the normal limits. For these it is customary to provide a few heavy-powered cranes at each port and one or more floating cranes, which can lie alongside a vessel or a quay, as the case may be. The cost of a floating crane is, of course, greater, both as regards construction and working, but it has corresponding advantages. Floating cranes range in power from 10 or 15 tons to 50 or 100 tons. There are cranes of 200 to 500 tons capacity. A 50- or 60-ton crane, however, is generally capable of handling almost everything. Fixed quay cranes are of equivalent capacity.
FLOATING CRANES FOR BULK HANDLING
The grabbing floating cranes are mainly employed to handle bulk goods, such as ore, coal, phosphate, fertilizers, etc.
The use of floating cranes reduces demurrage as well as the harbour dues to be paid. In addition, very considerable costs can sometimes be saved on the warping or towing of sea-going vessels.
Fig. 8. The balancer-type design ensures a horizontal movement of the load
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Floating cranes can be employed at the ship's berth in the harbour, for example when the loading or unloading of ships is to be accelerated. The floating cranes are also suited for assisting quay cranes in cargo handling, particularly for lifting cargo weighing up to 12.5 tons, which is too heavy for the usual 3-ton harbour cranes.
These cranes are notable for their extremely accurate automatic weighing equipment.
For the rope-pull-operated weighing equipment, a compression member consisting of a lattice girder has been provided.
The axles of the guide pulleys at the front are supported by this compression member and by the upper compression girder located in the platform. The bottom end of the compression member is supported in the weighing direction at some point.
Positions, which result from the operation of the balancer, are also compensated for by a special device, as is the influence of the pontoon's heel.
An automatic weighing machine installed in the operator's cab enables the weight of the load to be recorded with an accuracy of approximately 10 lb. The automatic weighing machine is equipped with a tare weight beam for balancing out the deadweight of either the grab or the hook sling, so that only the weight of the bulk material or cargo being lifted is measured, recorded and summed up.
The resultant is obtained from the total load consisting of the weights of the grab bucket contents, the bucket and the ropes themselves as well as of the rope pull.
150-TON FLOATING CRANE
This type of crane has many uses. It oftea carries out work which cannot be done by any other handling equipment. It is usually mounted on a steel platform, which draws nearly seven feet of water. A weight of 150 tons can be taken to a height of 178 ft. with the main hoist, and 50 tons to a height of 216 ft. with an auxiliary hoist. Other details are as follows: height of base 84 ft., length of steel jib 140 ft., the main hoist can lift at a distance of 60 ft. from the pontoon and the auxiliary hoist has a maximum outreach of 100 ft. from the pontoon.
When required, this crane can be towed by two or three tugs; the large parts and heavy lifts can be carried on the pontoon if necessary as the deck has been specially strengthened.
DOCKSIDE CRANES
One of the new types of cranes introduced in recent years is the mobile and flexible level-luffing slewing crane which is completely ousting the old type of crane with fixed jib. These modern level- luffing slewing cranes with luffable jib can alter their radius quickly under load.
They can cover from a central point a wide circular area and therefore do not need to be travelled to and fro at each working cycle.
The transhipping performance of these cranes is still further enhanced by measures which permit of the slewing gear running quicker at short radii and of the hoisting speed with light loads and empty hook being increased to three or four times that of the speed with heavy loads.
WORDS AND PHRASES
heavy lift crane тяжелый кран
occasional [э'ке!зпэ1] случайный
fertilizer ['fa:tilaizaj удобрение
warping 'w3:pig] верпование
towing ['touig] буксирование
to accelerate [ak'selereit] ускорять
notable ['noutabl] известный, славящийся
accurate ['sekjunt] точный, правильный, тщательный
the rope-pull-operated weighing equipment взвешивающее устройство с канатными блоками compression member элемент, работающий на сжатие
lattice girder ['laetis 'ga:da] решетчатая ферма
axle [asksl] ось
guide pulley ['gaid 'puli] направляющий шкив
in the weighing direction в направлении взвешивающего элемента
to result (from) являться результатом (ч.-л.)
balancer ['baslansa] стабилизатор, уравнитель
to compensate уравновешивать
automatic weighing machine автоматические весы
cab кабина
to record [ri'kDrd] регистрировать
lb. (лат. librum) = pound фунт
tare weight beam противовес, уравновешивающий тару
grab грейфер
hook sling подвеска с захватом
to sum up суммировать, подводить итог
resultant - итог
grab bucket храповой ковш
auxiliary - вспомогательный
hoist -таль, лебедка
pontoon - понтон
level-luffing slewing crane - поворотный кран с горизонтальным
перемещением груза при изменении вылета стрелы
toalter['о:Нэ] (из) менять
tooust [aust] вытеснять
performance - действие, производительность
to enhance [in'hct:ns] повышать, увеличивать, усиливать
EXERCISES
I. Answer the following questions:
1. What capacity of the cargo quay crane is considered normal?
2. In what case are heavy-powered cranes provided?
3. What are floating cranes used for?
4. Why is the cost of a floating crane greater?
5. What are the advantages of a floating crane?
6. What is the average capacity of the floating crane?
7. What are the grabbing floating cranes used for?
8. Does the use of floating cranes reduce demurrage?
9. What does the compression member support?
10. Where is an automatic weighing machine installed?
11. What is an automatic weighing machine equipped with?
12. How is the resultant obtained?
13. What does the total load consist of?
II. What are the functions of the -ed form in the following sentences? Translate the sentences into Russian:
1. In this manner we achieved an important economy of time compared with the old method. 2. Soviet dockers are skilled machine operators. 3. The main advantages gained by the new installation can be summarized as follows. 4. This type of floating crane was designed by a Soviet engineer. 5. Wagons were unloaded by two electrically operated side-discharge tipplers and weighers located between the tracks. 6. This complex equipment incorporated numerous improvements.
III. Translate the following sentences into English:
1. Поворотные краны с постоянным и переменным вылетом стрелы были созданы в XIV в. 2. Поворотные краны бывают стационарными и передвижными. 3. Краны с горизонтальным перемещением груза изменяют вылет с подвешенным грузом. 4. Средняя скорость изменения вылета для кранов до 10 т— около 0,5 м/сек. 5. Скорость подъема груза в кранах небольшой грузоподъемности равна 1 —1,5 м/сек. 6. В кранах большой грузоподъемности скорость меньше. 7. Максимальная рабочая нагрузка этого крана равна 10 г на вылете стрелы 12 м. 8. Известно, что наибольший вылет стрелы этого крана 40 м, наименьший—10 м, 9. Плавучие краны большой грузоподъемности применяются для перегрузки тяжеловесов. 10. Плавучие краны монтируются на плавучем понтоне и передвигаются внутри порта с помощью буксиров или собственным ходом. 11. Плавучие краны бывают как самоходными, так и несамоходными. 12. В плавучих кранах применяется как паровой, так и моторный привод. 13. Моторный привод имеет более высокий к.п.д., чем паровой. 14. Кран поднимает груз на высоту 1 м над комингсом люка. 15. В конце 1958 года в Ленинградском порту была организована выставка, на которой демонстрировались новые грузоподъемные устройства. 16. Наш завод отправляет краны в страны народной демократии. 17. Совершенствуя процесс погрузки угля на суда, портовики добились высоких результатов. 18. Современные причалы следует оснащать новыми типами береговых кранов. 19. В нашем порту есть плавучий кран грузоподъемностью 100т.
Lesson eight
MOBILE CRANES
Safeguarding stability is the most important factor for mobile cranes.
The overloading of a mobile crane may result in: —
(a) Fracture of a component due to overstress.
(b) A condition of instability followed by overturning.
In practice, failure due to (a) is extremely rare, certainly far less frequent than failure due to (b), the reason being that the designer practically does not know weight distribution when dealing- with load stresses on the crane structure and mechanical components. Therefore he is able to adopt normal factors of safety of not less than 4'/2 or 5 for structure and 6 or 7 for gearing and ropes.
The factor of stability is synonymous with the factor of safety. A mobile crane must travel over average road surfaces, perhaps on a gradient with load suspended from the hook. It may be, and more often is, without outriggers, draw beams or other aids to stability. There are limitations the designer must observe regarding wheel loads, axle loads and tyre pressure. Wind velocity and gradients must be allowed for and care taken that an „excess of tail weight does not render the crane unstable backward when the jib and fittings are removed.
Cranes operating grabs or flat-bottomed skips encounter indeterminate overloads due to suction or to the grab jaws closing on some submerged object such as a pile.
Similarly, when operating with an electromagnet an overload may be imposed due to the magnetization of the billets in contact with the magnet.
Again, where cargo is being handled from a wharf or elevated gantry there is no chance of recovery from an overload by allowing the suspended load to rest on the ground. In many other classes of work, such as the handling of miscellaneous scrap metal, the weights lifted are often more guesswork. With reasonable care it will generally be found possible to pick up any load at the appropriate radius which, of course, is better not only for the machine but for the goods handled.
A HEAVY MOBILE CRANE
This crane embodies a number of new and original features. High speeds are required for duties such as grabbing and magnet operation.
The controls of this crane are simple in operation and are so placed as to avoid fatigue of the driver. There are only three foot pedals (for engine clutch, travelling brake and engine speed) and steering is by a large diameter steering wheel, set at the optimum angle for easy manipulation. The levers are light in operation and are placed conveniently to hand so that any chance of confusion is avoided. The weatherproof saloon cab has large safety-glass windows all round which give an exceptionally wide range of vision. A cab heater for use in cold weather can be fitted if required.
The crane is a full-circle slewing type and uses the direct mechanical transmission system with diesel prime mover. The four motions of hoisting, slewing, travelling and luffing are independently operated and reversible.
A new feature, the advantages of which will be readily appreciated by engineers, is the application of unit construction to the various crane motions. Each motion, i.e. hoisting, slewing, luffing and travelling, has its own gearbox with enclosed bearings and gears with oilbath lubrication. The hoisting and luffing brakes, which are semi-automatic in operation, are arranged for manual adjustment without tools, in order to facilitate regular attention.
The maximum load of six tons can be hoisted at speeds up to 1220 cm. per minute, but lighter loads up to two tons can be handled at 3,648 cm. per minute, enabling high outputs to be attained when the crane is used for grabbing. For accurate placing of loads an inching movement is provided, either for lifting or lowering, bv a small movement of the joy-stick type lever.
The crane slews on a large diameter ring of live-rollers, which give extremely smooth action. The slewing speed is variable up to 2'/2 r.p.m. in either direction and slewing can be carried out simultaneously with hoisting if this is desired for fast operation.
The luffing gear, which is completely independent of the other motions, will raise the jib, with load if necessary, from maximum to minimum radius in 20 seconds.
A full load of six tons can be carried on level ground at speeds of up to 3 miles an hour. Without loads, on level ground the crane can travel at six miles an hour and can turn in a circle of 699 cm. radius. Travelling speed is operated by accelerator pedal, and large plate clutch in conjunction with a three-speed gearbox gives extremely smooth flexible control. Brakes of 2-leading shoe-type are fitted on all four travelling wheels, which make for maximum safety under all road conditions. The brakes are operated by foot pedal.
Pneumatic tyres are employed on wheels of special design which are slightly smaller in overall diameter than the tyres. Such wheels have many proven advantages. They limit deflection of the tyres when slewing and thus obviate instability which might arise if, for example, the tyres were under-inflated. They provide a large additional bearing area which prevents the cranes from sinking in soft ground. They protect the side walls of the tyres from damage when the crane is working in, say, steel stock-yards, scrap yards, or alongside the kerb.
Finally, in the event of a sudden blow out the resistor wheels take the weight immediately, so avoiding what might be a serious accident.
The standard power unit is a diesel engine of 37 b.h.p., fitted with maximum speed governor in addition to the variable speed control operated by the accelerator pedal in the driver's cab.
WORDS AND PHRASES
stability [sts'bihti]устойчивость
fracture ['frsektja]разрыв
overstress перенапряжение
overturning опрокидывание
the reason being that по той причине, что
to adopt допускать
factors of safety факторы безопасности gradient уклон
outrigger укосина
draw beam стрела для поднятия тяжестей
regarding относительно
tyre [taia] шина
velocity скорость
tail weight противовес
skip опрокидная бадья
to encounter встречать
indeterminate неопределенный
overload перегрузка
suction всасывание
jaw [d33:] захват или зажимное приспособление
submerged [s3b'ma:d3d] погруженный в воду pileсвая
to impose налагать; зд. возникать
billetболванка, заготовка
gantry портальный кран
miscellaneous [,mis9'leinj3s]смешанный, разнообразный
scrap metal металлический лом, скрап
to embody воплощать в себе
are so placed as так расположены, чтобы
fatigue {fa'ti:g] утомление
foot pedal ножная педаль
engine clutch муфта сцепления двигателя
brakeтормоз
to steer управлять
set at the optimum angleрасположенного под оптимальным углом
weather proofзащищенный от непогоды safety-glassнебьющееся стекло
range of vision кругозор
heater подогреватель
full-circle slewing type полноповоротный тип
reversible реверсивный
gear box коробка передач (скоростей)
enclosed закрытый
oil bath масляная ванна
lubrication смазка
semi-automatic полуавтоматический
to facilitate облегчать
enabling high outputs to be attained достигая высокой производительности
inch дюйм
joy-stick рычаг управления
live-rollers рольганг
travelling speed транспортное передвижение
accelerator pedal акселераторная педаль
plate clutch пластинчатая муфта
three-speed gearbox трехскоростная коробка передач
brake of 2-leading shoe-type тормоз двухколодочного типа
to make for способствовать, обеспечивать
pneumatic tyres are employedзд.пневматические шины, насаживаются
overalldiameter [dai'semita] общий диаметр
deflection отклонение от прямого направления
obviate ['obvieit] устранять
under-inflated спущенный
scrap yard склад железного лома, скрапа
kerb обочина
blow-out разрыв (шины)
EXERCISES
I. Answer the following questions:
1. Why is safeguarding stability the most important factor for mobile cranes?
2. What may the overloading of a mobile crane result in?
3. What does "the factor of stability" mean?
4. What may the reason of overloading be when operating with an electromagnet?
5. What new and original features does a heavy mobile crane ■embody?
6. For what duties are high speeds required?
7. How are the controls of this crane placed?
8. What is the maximum load at speeds up to 1220 cm. per minute?
9. What is a heavy mobile crane provided with for accurate placing of loads?
10. Has each motion its own gearbox?
11. How are the hoisting and luffing brakes arranged?
12. How does a heavy mobile crane slew?
13. What motions can be carried out simultaneously?
14. What gear raises the jib?
15. At what speed can a full load be carried?
16. How is travelling speed operated?
II. Translate the following sentences into English using the verb "should:"
1. При проектировании новых типов кранов следует обращать большое внимание на снижение их веса и стоимости. 2. Нам следует обратить внимание на совершенствование системы управления и автоматической сигнализации. 3. Все перегрузочные операции следует выполнять с помощью механизмов. 4. Проблему механизации трюмных работ следует разрешить полностью. 5. Мы хотим построить новый кран, который будет более производительным. 6. Вам следовало бы знать об этом раньше.
III. What are the three principal forms of the following verbs?
catch, choose, pay, rise, set, leave, hang, deal, throw, lie, give, sink, say, make.
IV. Translate the following sentences into English:
1. Основным перегрузочным оборудованием в портах являются портальные и плавучие краны. 2. Большинство портальных кранов в морских портах имеет грузоподъемность до 15 т. 3. Часто встречаются портальные краны грузоподъемностью до 40 т. 4. Вылет стрел портальных кранов достигает 30—40 м. 5. На строительстве атомной электростанции использовались краны большой грузоподъемности. 6. Наш завод будет выпускать шесть моделей стреловых кранов на пневмоколесном ходу грузоподъемностью 10—35 т с вылетом стрелы более 12 м. 7. Изменение вылета стрелы используется для захвата и укладки груза на различных расстояниях от оси крана. В портах применяются железнодорожные, гусеничные и автомобильные краны. 9. Передвижные краны устанавливаются на железнодорожной платформе, автомобиле, электрической тележке, на понтоне, на портале, на гусеничной платформе. 10. Поворотная часть портального крана может быть установлена, кроме портала, и на другое основание. 11. Конструкторы направляют все силы на то, чтобы кран работал с наибольшей производительностью. 12. Силовая установка этого крана состоит из дизеля и трех генераторов постоянного тока. 13. Вращение поворотной части крана должно быть плавным. 14. Мы получим инструкцию к новому крану на автомобильном шасси. 15. В этом году был введен в эксплуатацию еще один пятнадцатитонный портальный кран. 16. Новый гусеничный 20-тонный кран имеет большой вылет стрелы. 17. В будущем году мы получим 6 автомобильных кранов грузоподъемностью до 10 т. 18. Широкие люки позволяют вести погрузку и выгрузку леса непосредственно портальными кранами.
Lesson nine
DECK LEVEL LUFFING CRANES
In the course of time two standard types of deck level luffing cranes have been developed, the one type with elevated platform and the other with low-lying platform. Preference was given at the beginning to the first-named type of crane with elevated platform, on which the driving gear parts were mounted. The chief advantage of this type is that the deck space is not interfered with in any way by the revolving parts of the crane, because the only part that reaches down the deck is the comparatively slim column. The driver can keep the movements of the load well in view from his seat with the result that there is no need to have a man standing at the hatchway to direct the movements.
One disadvantage of this type is the high-lying centre of gravity, because this can react unfavourably on the stability of small vessels. Another drawback is that it is naturally more difficult to dismount driving-gear parts or electrical equipment from the elevated platform. For this reason sometimes it is better to depart from this construction and have the crane provided with a low- lying platform; yet this type of crane has the disadvantages of much deck space being lost when it is mounted right on the deck, because the entire area within the slewing range of the low-lying platform can no longer be used for other purposes. This difficulty is overcome frequently in the case of large vessels by placing the crane column higher, so that the platform can be arranged at a certain height above the deck without having to employ the type with elevated platform.
The chief advantage of a level-luffing crane, i. e. a crane with the jib capable of being luffed under load, is that with its load hook it covers not only a circular line but also a circular area, so that loads can be picked up or set down at any point within the circle.
When the vessel is at sea the jib can be lowered and roped firmly to appropriate stanchions on the deck, so that they suffer no damage even in stormy weather. The cranes can be set up again ready for working in a very short time just with the help of their own mechanical equipment.
The deck crane is suited also for ships on inland waterways, the only exception being that in most cases it must be possible for the crane column, besides the jib, to be laid on the deck.
CRANES USED WITH ELECTRO-MAGNETS
Lifting magnets are used in conjunction with a diversity of lifting and handling machinery. These include overhead electric travelling cranes, steam and diesel-driven locomotive and mobile jib cranes, telphers, furnace charges and, more recently, fork lift trucks.
These cover the handling of scrap, swarf, pig iron, cold or hot ingots, steel plates, rails, rolled sections, coils of strip or bales of compressed scrap, also breaking up iron scrap with a skullcracker ball and subsequently loading it.
The contactor panel and resistor may be mounted elsewhere on the crane, or on the bridge platform of an overhead travelling crane. If the crane is a standard type, i. e. not designed specifically for magnet duty, it may be advisable to de-rate its lifting capacity.
Where a d. c. supply is not available on a. c. cranes, a separate rectifier must be provided for the magnet circuit.
If the current potential exceeds 250 v., a series reducing is required.
CIRCULAR MAGNETS
Sturdy construction coupled with compactness and adaptability has given solid ground for the adoption of this type of lifting magnet in a majority of applications. Its shape renders accurate positioning over the load by the crane operator unnecessary and the strong magnetic field generated over the area presented to the load ensures good penetration and effective lifting power on most classes of materials, such as scrap, swarf, pig iron, ingots, steel plates, stampings, bars, billets, and rails.
RECTANGULAR AND BIPOLAR MAGNETS
Rectangular or bipolar magnets may be used singly or in pairs attached to a spreader beam for lifting and stocking billets, ingots,rails, bars and rolled sections. Whether a spreader beem is required or not is determined by length or flexibility of the load.
LIFTING MAGNETS CONTROL AND CONTACTOR GEAR
Control of the lifting and discharging operations of the magnet is extremely simple and is effected by a master switch and magnetic contactor panel. Operation of the master switch may be by hand or foot as desired.
WORDS AND PHRASES
in the course of time со временем
elevated J'eliveitidJ platform приподнятая платформа
low-lying platform низкая платформа
to interfere with мешать
revolving part вращающаяся часть
slim column тонкая колонна
centre of gravity центр тяжести
to react воздействовать
appropriate подходящий
stanchion опора, подпорка
so that they suffer no damage так что они не испытывают повреждений
diversity [dai'vs:siti] разнообразие
overhead electric travelling crane потолочный электрокран
telpher тельфер
furnace charge кран для загрузки шихты swarfмелкие железные опилки pigiron ['aian]чугун в болванках ingotчушка, болванка
rolledsectionsпрокатные балки, прокатные бруски coilБИТОК
compressed scrap сжатыйскрап
to break up разламывать, разбивать
crackerкрекер (дробилка)
contactor panel контактнаяпанель
resistor сопротивление
bridge platform мостовая платформа
to de-rate вычислять еще раз
d. с. (= direct current) постоянный ток
а. с. (=alternating current) переменный ток
rectifier выпрямитель (тока)
circular magnet круглый магнит
to couple зд. сочетать
adaptability пригодность, применимость
to render делать
to generate производить
penetration проникновениеst
amping штампованнаядеталь
spreaderbeam шредер
contactor gear электромеханический выключатель
masterswitch главный выключатель
magnetic contactor panel электромагнитная контактная панель
| EXERCISES |
I. Answer the following questions:
1. What standard types of deck level luffing cranes do you know?
2. Why was preference given at the beginning to the cranes with elevated platform?
3. What are the advantages of the cranes with elevated platform?
4. What are the disadvantages of the crane with elevated platform?
5. When is it desirable to have the crane provided with a low- lying platform?
6. What are the disadvantages of the crane with low-lying platform?
7. What is the chief advantages of a level luffing crane? 1
8. What is the deck crane suited for?
9. How are lifting magnets used?
10. What does the handling machinery include?
11. Where may the contactor panel and resistor be mounted on the cranes with electro-magnets?
12. Is control of the lifting and discharging operations of the magnet simple?
13. How is the control of the lifting and discharging operations of the magnet effected?
14. What operations do modern cranes with electromagnet perform?
15. In what case must a separate rectifier be provided for the magnet circuit?
II. Analyse the following sentences:
1. At this berth luffing cranes capable of discharging by means of electromagnets have been erected.
2. Laboratory investigations are being carried out on controller handles and foot controllers.
III. Form verbs and nouns from the following adjectives and translate them into Russian:
deep, fast, long, weak, circular, simple, hard, strong.
IV. Translate the following sentences into English:
1. Так как производительность судовой грузовой стрелы ограничена, в больших портах используются портальные краны.
2. Порты с малым грузооборотом почти не оснащаются кранами.
3. Известно, что палубные краны бывают двух типов. 4. Для подъема и перемещения материалов из черных металлов применяют подъемные электромагниты. 5. Основной частью подъемного электромагнита является стальной литой корпус. 6. Подъемные электромагниты подразделяются на круглые и прямоугольные. 7. Круглые электромагниты применяются для работы по подъему и перемещению болванок, чушек, стальных и чугунных отливок. 8. Прямоугольные магниты предназначены для работы по подъему и перемещению листовой стали, труб, блоков. 9. В этом порту суда загружаются чугуном портальными кранами с электромагнитами грузоподъемностью 10 т. 10. Наш порт оборудован тремя кранами грузоподъемностью по 15 т, подающими руду из судов на ленточный конвейер. 11. Портальные краны, используемые при разгрузке трюмов судов, выполняются с подъемом стрелы во время рабочего цикла. 12. У магнитных кранов, предназначенных для перегрузки отходов из черного металла, захватным органом является грузовой электромагнит. 13. В портах для погрузки сыпучих грузов применяются краны с грейферами емкостью 3 куб. м. 14. На причалах будет применяться много новых захватных приспособлений. 15. Электромагниты прямоугольного типа применяются на судостроительной верфи. 16. Точное регулирование силы притяжения посредством специального механизма изменяет нагрузку магнита. 17. При помощи такого электромагнита можно подбирать из пачки один или несколько листов, а затем сбрасывать там, где это требуется.
Lesson ten
TRUCKING
Among the means of handling goods over a quay or through quay shed, either to a place of deposit, or to a point of loading on to road vehicles, or railway wagons, for inland delivery there is scarcely anything so flexible and effective as a system of trucking.
In very restricted space and where the distance to be run is short, hand trucking is employed for shed work at ports. Within its limits, it is extremely efficient and exceedingly adaptable tolocal conditions. Hand trucks are usually dealing with general goods.
The modern quayside truck, which has been developed from the platform truck, is a specialized appliance with several varieties of type, each of which possesses some particular advantage. Thus, for heavy objects, a low platform is desirable, and the truck floor in such cases is depressed between the wheels within a few inches of the ground. Another class of truck is not directly loaded, but has an adjustable platform, which can be inserted beneath a skid, tray, or stillage, previously loaded, and can then elevate it from the ground for transportation. Some trucks have three wheels to enable them to turn at a very short radius; they are more suitable for an uneven running surface; other -trucks have four wheels, which give them a steadier and broader base for supporting heavy loads.
The normal, and perhaps the most serviceable, capacity of a quayside motor truck is 2-3 tons. A two-ton truck is about 10 feet long, and can turn within a radius of 12 feet. It has a loading area of about 30 square feet.
The motors are 12 h. p., actuated by storage batteries, which are charged generally once in 24 hours. The usual practice is to recharge during the night, the operation requiring a number of hours. But if a machine is required to be run continuously, it can be equipped with replaceable batteries. The operation of changing requires about five minutes.
The speed of a motor truck depends on the nature of the floor. Generally about 10 to 15 miles per hour is attained, and short grades can be mounted without difficulty, as also longer grades of less inclination.
The control of the machine by the operator is very effective. The driving mechanism is so arranged that the operator can cut off the current immediately and the brake automatically applied. The controlling lever also promptly returns to the neutral position, when left free of control.
The Elevated Truck
In place of the self-loaded truck, an elevating truck may be used in conjunction with a number of skids, platforms, or stillages. The truck can depress its carrier frame so as to pass underneath a skid, which stands on bearers about 12 inches above the ground. These skids can be loaded while the truck is transporting, so saving an appreciable amount of useful time.
WORDS AND PHRASES
Trucking перевозка грузов на грузовых автомобилях, тележках- погрузчиках
Truck тележка, товарная платформа, грузовой автомобиль
To truck перевозить на грузовых автомобилях, тележках, погрузчиках
deposit [di'pozitf] склад
for inland delivery для доставки на территорию, удаленную от моря
to depress [di'pres] опускать, понижать
adjustable передвижной, переставной
to insert вставить
skid рейка; брус, по которому спускается груз; лоток
stillage стеллаж, низкая подставка
previously loaded предварительно нагруженный
uneven [An'i.vn] неровный
steady ['stedi] устойчивый
serviceable ['sarvisgbl] нужный (в эксплуатации)
to actuate ['aektjueit] приводить в движение
storage battery аккумулятор
to charge заряжать
to recharge перезаряжать
delay [di'lei[ задержка
if a machine is required to be run continuously если необходимо,
чтобымашинаработаланепрерывно
replaceable заменяемые
motor truck аккумуляторнаятележка
grade подъем,уклон
to mount подниматься
inclination подъем
to cut off отключать
the brake automatically applied тормозможетработатьавтоматически
self-loaded самонагружающийся
carrier frame основнаярама, каретка
underneath [,And3'ni:0] под
| EXERCISES |
1. Answer the following questions:
1. In what cases is hand trucking employed?
2. What sorts of goods are hand trucks usually dealing with?
3. What are some of the advantages of trucking?
4. Why is trucking a great convenience in ports?
5. What operations do modern trucks usually perform besides carrying cargoes?
6. What is a quayside truck?
7. What is the average capacity of an electric truck?
8. Why have the batteries to be charged at night?
9. In what case are the trucks equipped with replaceable batteries?
10. What is the elevated truck used for?
11. What does the speed of a motor depend on?
12. What is the average speed of a motor truck on good roads?
II. Analyze the following sentences:
1. The forks having raised the load, the assembly is retracted within the truck and the load is deposited on deck.
2. When delivering a load, the procedure is reverse.
III. What are the three principal forms of the following verbs?
build, cut, cost, deal, mean, draw, drive, grow, feed, find, bear, bring, get, grow, hand, leave, lead, give.
IV. Translate the following sentences into English:
1. В настоящее время ручные тележки используются редко.
2. Самоходная тележка является прототипом автопогрузчика.
3. Для транспортировки штучных грузов по территории порта и. внутри складов широко применяются аккумуляторные тележки и автотележки. 4. Выбор источника энергии зависит от условий эксплуатации. 5. Сложность конструкции и большая стоимость являются недостатком автотележек. 6. Необходимость часто перезаряжать аккумулятор является недостатком аккумуляторной тележки. 7. Простейший тип аккумуляторной тележки имеет покрытую настилом раму, которая опирается на четыре колеса. 8. Аккумуляторы расположены под настилом рамы. 9. Средняя грузоподъемность автопогрузчика 2—3 т. 10. Скорость автопогрузчика зависит от состояния дороги. 11. Грузоподъемность автопогрузчиков, изготовляемых этим заводом, от 0,5 до 10 т. 12. Привод механизма передвижения электропогрузчика электрический. 13. Тележка с подъемной платформой от ручного гидравлического привода может быть использована на внутри- складских работах. 14. Завод выпускает ручные тележки новой модели, которые поднимают грузы весом до 508 кг при вылете стрелы 381 мм. 15. Привод этих ручных тележек электрогидравлический, он осуществляется от 12-ваттной аккумуляторной батареи. 16. Автопогрузчик используется для погрузки и разгрузки железнодорожных вагонов и автомобилей и для штабелирования грузов на складах. 17. Для перемещения груза и для подъема его на высоту 1,5—2 м автопогрузчик снабжен вильчатыми захватами.
Lesson eleven
ELECTRIC FORK TRUCK
Fabricated from steel plate, the main frame is securely braced and seam-welded to form a rigid construction. Pivotally mounted on a main frame extention is the lifting mast consisting of steel uprights in which the fork carriage is mounted. Housed in the centre of the uprights is a large diameter hydraulic jack, provided with a cross-head carrying twin sprockets over which run the lifting chains.
A motor-driven hydraulic pump supplies fluid to the main lifting cylinder.
Operation of the hoist mechanism is effected by means of a suitable hydraulic control valve with accessible operating lever. The valve is fitted with control switches to energize the pump motor contactor when the hoisting operation is carried out. The 100-amp. S. P. magnetic contactor is fitted with an overload release.
TILTING-TYPE TRUCKS
Where required, the mast can be arranged for a backward tilt of 10 deg. from vertical and forward tilt of 3 deg., under the action of double-acting twin hydraulic jacks fed from the hydraulic pump and operated by separate control valve in a similar manner to the hoisting motion.
When the truck is required for operation in situations with low headroom, telescopic uprights are fitted.
GUIDED TRUCK
The driverless remotely controlled truck is of outstanding interest. The method of control is a simple one, but is absolutely foolproof and safe. One or a number of powered trolleys can be remotely controlled from a central point. Standard trucks are used so that, when required, they can be driver-operated in the usual way.
Over a desired route a wire is laid, either taped to the surface, for a temporary route, or laid just beneath the flooring if the installation is to be permanent. An a. c. current of specific frequency is passed through the wire. Two sensing coils fixed to the front of the truck pick up signal currents from the magnetic field, thus setting up and keeping the truck on the desired path. There is no physical contact between the wire and the guiding device.
The system permits the operation of several trucks over a common route.Immediately the control current is switched on, the brakes are automatically released and the trolley sets off on its unaidedjourney along the wire. Safety devices which instantly stop the trolley if the route is obstructed, or in the event of a failure in the control system, minimize the possibility of accidents.
As long as the trolley remains on its true course, the current magnetically induced into the two pick-up coils is equal and the steering control is not operated. Immediately it tends to wander, however, the current induced becomes unbalanced and amplified signals operate a servo-motor coupled to the steering mechanism. The motor immediately restores the trolley to its intended course.
|
Fig. 9. The guided truck
The complete control system has a very low power consumption and facilities for operating entirely from batteries can be provided, thereby making possible the use of this equipment on temporary sites, such as building and civil engineering projects where main supplies may not be available.
For almost all practical requirements the distance over which the trolley may be controlled is unlimited.
The connection of automatic control in no way affects the manual operation of the trolley. Changeover from automatic to manual control is accomplished simply by moving a single lever mounted on the trolley.
Looking to the future it may well be possible to introduce full automation over complex networks enabling loads to be automatically coupled, taken to the desired destination and off-loaded without any supervision whatsoever.
WORDS AND PHRASES
electric fork truck вилочныйавтопогрузчик с электрическим приводом
to fabricate изготавливать
steel plate стальная пластина
frame рама
to brace скреплять
seam стык, шов
to weld сваривать
rigid ['ridgid] жесткий
pivotally mounted on a main frame extention is the lifting mast
подъемная рама подвижно соединена с главной рамой
upright стойка, вертикальная рама
to mount монтировать
fork carriage вилочная каретка
housed in the centre of the uprights is a large diameter hydraulic jack, provided with a cross-head carrying twin sprockets в центральной части вертикальной рамы установлен гидравлический цилиндр большого диаметра, на головке плунжера которого установлены две звездочки torun (ran, run)перемещаться
jack [dgaek]зд. цилиндр
lifting chain подъемная цепь
fluid [fluid] жидкость
motor-driven hydraulic pump гидравлический насос, приводимый
в движение электромотором
main lifting cylinder ['silinda] главный подъемный цилиндр
pump motor contactor контактор электродвигателя насоса
amp. (= ampere) ампер
S. P. (=single pole) однополюсный
Overload release реле, предохраняющее от перегрузки tiltнаклон
deg. (=degree) градус
under the action of double-acting twin hydraulic jacksот двух соединенных между собой гидравлических цилиндров
control valve-клапан управления
headroomзд. высота помещения
telescopic [/teli'skopik] телескопический, выдвижной
guided truck управляемая тележка
remotely controlled truck тележка с дистанционным управлением
fool proof защищенный от неумелого обращения
safe безопасный
trolley ['troll] тележка
central point центральный пункт
route [ru.t] маршрут, направление
a wire is laid прокладывается кабель
to tape зд.прикреплять
specific frequency высокая частота
sensing coil чувствительная катушка
to set up направлять
производительными. 6. Автопогрузчик отличается от тележки консольным расположением устройств, поддерживающих груз, по отношению к ходовым колесам. 7. Погрузчик с самозахватывающим приспособлением предназначен для работы с мешковым грузом на складе. 8. Гидравлические приводы широко применяются в автопогрузчиках. 9. Самоходная тележка предназначена для механизации перегрузочных работ со штучными грузами весом до 1,5 т внутри крытых железнодорожных вагонов, на складах, в трюмах и твиндеках. 10. Новый трюмный погрузчик грузоподъемностью 1,5 г предназначен для ступенчатой укладки штучных грузов. 11. Эта погрузочная машина подает уголь, руду и другие навалочные грузы из подпалубного пространства на просвет люка. 12. Емкость ковшей погрузочной машины должна соответствовать емкости загружаемых вагонеток. 13. Погрузчик с боковой разгрузкой ковша более производителен. 14. Грузоподъемность нового автопогрузчика должна быть до 907 кг, при вылете стрелы 69,8 м. 15. Высота вилочного захвата над полом в опущенном положении равна 100 мм, высота подъема груза — 4,3.п. 16. Скорость передвижения груженой тележки с дистанционным управлением — около 8 км1час.
Lesson twelve
SIDE LOADERS AND SIDE CARRIERS
The handling of materials in long lengths has always been a problem. The advent of side loading trucks and the side carrying truck has changed these materials handling problems beyond all recognition. These trucks are made with small wheels where they are used internally or are equipped with pneumatic tyres for travelling in storage yards, quay sides or over the public highway.
The loader has a control cabin forward and on one corner of the deck. Immediately behind the driver's cab is a fork truck mast with forks which virtually divides the load-carrying deck into two halves. The entire assembly can be moved in and out, from one side of the deck to the other so that the forks can extend beyond the side of the truck and pick up a suitable load placed parallel to the length of the truck. The forks having raised the load, the mast assembly is retracted within the truck and the load is deposited on the deck. When delivering a load the reverse procedure takes place. It is therefore possible for one man, the truck driver, to pick up a load of several tons, take it to its destination and deposit it, entirely single- handed.
This truck will operate in gangways little wider than the truck itself. Allowance must, of course, be made for adequate space wherever in the layout it may be necessary for the truck to turn when loaded with material which frequently is longer than the truck itself. According to circumstances trucks are obtainable with diesel engines or electric motors driven by batteries carried on the truck.
Lifting heights and fork lengths can be made to suit the individual handling problem as with the conventional fork lift truck. Unit loads of timber need only be separated in the stack by timber spacers so that the forks can enter between the loads. Some unit loads such as cases or drums can be stored and stacked on special long pallets which would be picked up centrally.
TRUCK ATTACHMENTS
The fork lift truck is basically designed to transport and stack materials contained in or on pallets. It does this by means of two forks which can be raised or lowered on a carriage moving vertically between two sides. It was soon realized, however, that if the forks could be substituted by other attachments its versatility could be substantially increased. Further, it has been found that by the use of other attachments certain categories of goods could be handled and stacked without pallets. Much capital investment and pallet maintenance costs can be saved in this way.
At the moment quite a few of these attachments have been developed and tried out. Further developments will undoubtedly take place when a demand arises. Some of these devices are a permanent fixture to the truck in which case the machine can hardly be called a fork lift truck any longer. The number so produced is increasing continually. The object of the designer is, however, to make them as attachments, if at all possible, so that they can readily be interchanged with the standard forks. The basic machine has now become an exceedingly versatile and highly efficient piece of industrial plant.
It must, however, be borne in mind that most attachments alter the load centre. Therefore, the effect of the attachment is usually to down-rate the carrying capacity of the truck. This point should be checked before a decision is made.
The usual attachments are as follows: (1) fork extensions, (2) ram, (3) jib, (4) side-shift, (5) scoop and shovel, (6) grab, (7) clamps, etc.
WORDS AND PHRASES
sideloaderгрузовой автомобиль с боковым захватом
sidecarrierгрузовой автомобиль, у которого груз в процессе захвата и перемещения находится сбоку
highway шоссе
deck помост для укладки (бревен и т. п.)
assembly [a'sembli] агрегат
to pick upподхватывать, захватывать
to retract [ri'trgekt] втягивать(ся)
gangway проход
adequate достаточный
conventional обычный
spacer распорный стержень
truck attachment сменное оборудование погрузчика
to substitute заменять
versatility разносторонность
maintenance costs эксплуатационные расходы
fixture приспособление
object цель
if at all possible если это вообще возможно
load centre центр тяжести
to down-rate снижать
fork extension выдвижной вилочный захват
ram безблочная стрела
jib крановая стрела
side-shift боковая смена
scoop ковш
shovel лопата
clamps зажимы
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