Английский язык в сфере профессиональной коммуникации. Горные машины. Учебное пособие

Caterpillar offers a choice of transmission on some models of these trucks so that the customer may select the transmission which will give the best performance on the terrain at their mine (flat ground versus steep inclines, rough ground versus smooth, long flat runs versus short twisty inclines). The computer controlled lock-up on the torque converter allows the transmission to lock the torque converter, preventing slippage, so that the wheels are driven directly by the engine as if it were a manual gearbox. This provides for greater fuel efficiency than either a torque converter or an electric drive.

Caterpillar is testing an electric drive 797B off-highway hauler. Caterpillar displayed a new 797F in the 380-400 ton range at Minexpo 2008 during September 22-24 in Las Vegas, Nevada. Caterpillar also showed the new 345 ton 795F AC electric drive off-highway hauler at the same mining show according to “The Peoria Journal Star” of September 20, 2008. Industry trade magazine “Engineering and Mining Journal” in its November 2008 did a full story about Minexpo 2008 in Las

Vegas. Caterpillar announced in 2006-2007 that they will be producing an electric drive system in some of their larger off-highway haulers. This new electric hauler will be known as the 795 and can carry between 320-350 tons. The first of the 795s are being built in Decatur, Illinois, and were first produced in late April early May, 2008. The 795F is only offered as a AC electric drive hauler. The new 5,187 c.i.d. 16 cylinder C175 engine powers the 3,400 hp hauler. The 795F's capacity is 345 tons which is just 5 tons lower the famous Terex Titan 33-19 from GM, built in 1974.

“The Engineering and Mining Journal” states the capacity of the new 795F is 345 tons. The new 797F is 4,000 hp making it the most powerful off-highway hauler in the world. The 797F also got a new engine in the 20 cylinder C175 which is 6,469 cubic inches according to Caterpillar Company. The new 797F is the first offhighway hauler with over 4,000 hp.

The nearest competitors to the Caterpillar 797F are the Liebherr T-282 dump truck which can hold 400 short tons or 360 metric tonnes, the Terex MT5500 and MT6300, the Hitachi EH5000 and the Komatsu 960E. The 960E appeared at Komatsuamerica.com in late may 2008.

The Terex MT5500 is 2700/2478 hp and can carry 360 tons. The 400 ton Terex MT6300 is 3,750 hp (2,800 kW) making it the second most powerful off-highway hauler on the market. The MT5500 is 2,700/2,478 hp and can carry 360 tons. The Hitachi EH5000 is 2700/2600 hp and can carry 351 tons. The Komatsu 960E is 3,500 hp (2,600 kW) and can carry 360 tons.

61

UNIT XV. O & K INTRODUCERS

THE RH 300 HEAVY-DUTY HYDRAULIC SHOVEL

I. Прочитайте текст „O & K Introducers the RH 300 Heavy-Duty Hydraulic Shovel”.

II. Скажите, что говорится о работе и преимуществах новой модели гидравлического экскаватора.

III. Озаглавьте письменно каждый абзац.

IV. Переведите текст на русский язык предварительно ознакомившись с новыми словами и словосочетаниями из комментария после текста.

O & K INTRODUCERS THE RH 300 HEAVY-DUTY

HYDRAULIC SHOVEL

With a service weight of 430 metric tons and an engine output of 1750 kW (2352 hp), the RH 300 is the biggest and most powerful hydraulic shovel in the world. It has been developed by O & K to meet the demand for large-capacity, highperformance open pit mining machines to remove overburden and to extract underlying minerals and ores. The machine was introduced in October 1979.

The increasing demand for raw materials nowadays makes it economic to exploit many deposits which so far have been considered too expensive to work. Hydraulic shovels offer the following well-known advantages:

*better digging kinematics due to positive control of equipment

*independent articulation of the bucket in relation to the arm

*selective digging capability

*easy maintenance

*versatility of application

The dimensions of the RH 300 have been largely determined by the dimensions of today’s trucks which have capacities of up to 300 metric tons. For loading rock and other overburden, the RH 300 uses a clamshell bucket with a capacity of 22 m3 as standard equipment. For coal, bauxite and other light materials, there is a 30 m3 bucket and for ore and other heavy materials at 17.5 m3 ore. Maximum dumping height is 12 m and maximum reach is 16.2 m.

The RH 300 is powered by two parallel drive units with either diesel or electric primary drive. For the diesel drive, two water-cooled KTA 2300 Cummins-Diesel engines are employed, with a total output of 1750 kW (2352 hp). The engines operate at a constant speed of 1950 rpm, ensuring economical operation and long service life.

The fuel tank carries fuel for 22 hours of uninterrupted operation. Each engine drives four axial piston pumps through a distribution gear. The eight main pumps provide a combined flow rate of 3840 litres per minute at a maximum operating pressure of 300 bar (4400 psi). A maximum load control system matches the power input of the hydraulic pumps to the power delivered by the diesel engines, the pumps

62

being regulated as a function of control pressure. When maximum pressure is reached, the pumps return to the zero position. The four or eight pumps operate on four hydraulic circuits. The entire hydraulic system is protected against contamination both by the system's high pressure and by return filters.

The hydraulic shovel is equipped with an automatic parking brake. An additional travel brake provides positive control when the machine is moving down slopes.

COMMENATRY

1.heavy-duty – высокомощный

2.a service weight – эксплуатационная масса машины

3.high-performance open pit mining machines – горные машины с высокими эксплуатационными параметрами, работающие на открытых разработках

4.better digging kinematics – улучшенная кинематика рабочего процесса при копании

5.in relation to the arm – по отношению к стреле (рукояти)

6.a clamshell bucket – двухчелюстной грейферный ковш

7.parallel drive units – приводные установки, соединенные параллельно

8.Cummins-Diesel engines – дизельный двигатель “Cummins”

9.axial piston pumps – аксиально-поршневые насосы

10.a distribution gear – передаточное устройство, позволяющее разветвлять мощность

11.parking brake – стояночный тормоз

12.travel brake – ходовой тормоз

V. Найдите ответы на следующие вопросы.

1.When was the RH300 heavy-duty hydraulic shovel introduced?

2.Describe the model in accordance with the plan: a) a service weight; b) an engine output; c) what is removed and excavated with its help.

3.Numerate (name) the advantages of hydraulic shovels.

4.What influenced the dimensions of the RH 300?

5.Do we consider a clamshell bucket to be standard equipment for loading rock and other overburden?

6.What is a total output of two Cummins-Diesel engines?

7.What do the engines ensure?

8.Does each engine drive four axial piston pumps?

9.How many pumps operate on 4 hydraulic circuits?

10.How is the entire hydraulic system protected against contamination?

VI. Перескажите текст по-английски, используя выученные Вами новые слова и выражения из текста и комментария.

63

VII. Прочитайте текст и постарайтесь понять его содержание при

BASIC STRUCTURE OF A HYDRAULIC SHOVEL

Hydraulic shovel excavators are employed to excavate materials and load dump trucks in surface mining operations.

Figure 1 illustrates a hydraulic shovel excavator used for bulk surface mine production operations. The hydraulic shovel consists of three major mechanisms, including the lower and upper compartments and the attachment as illustrated in figure 1(a). The lower compartment provides a stable base for the machine and includes the propel drive and crawler system. The upper compartment provides an attachment point for the power plant, pump drive, hoist and swing machinery, boom attachment, control valves, fuel and oil reservoirs, operator’s cab and supporting equipment. The attachment consists of the boom, stick and bucket and associated cylinder and valves. The primary motions of a hydraulic shovel include hoist, boom hoist and lower, stick extend and retract, bucket curl, body swing and opening and closing of bucket door. The shovel’s upper mechanism is roller and centre-pin mounted on the lower mechanism. Electric motors drive the swing transmissions that in turn drive swing pinions engaged in the swing gear. Multiple swing transmissions are typically used on hydraulic mining shovels to swing the machine from the digging face to the haulage unit and back to the formation. The digging attachment on the hydraulic shovel consists of boom, stick and bucket. Each of these structures is equipped with a pair of hydraulic cylinders for actuation. The bucket is equipped with a pair of cylinders that control opening and closing the bucket door. The work cycle of the shovel consists of three distinct phases – digging, swinging and dumping – as illustrated in figure 1(b). The digging phase involves moving the bucket to the formation, filling it and then raising it clear of the bank. After loading, the bucket is swung through an appropriate swing path and dump height until it is positioned over the haul truck. The swing motion is controlled to ensure a smooth transition between acceleration and deceleration. At this stage, the material is dumped into the waiting truck and the bucket is swung back to repeat the cycle until the truck is fully loaded.

64

ТЕКСТЫ ДЛЯ САМОСТОЯТЕЛЬНОГО ЧТЕНИЯ

TEXT I: WALKING DRAGLINE ESH-15/90А

Walking draglines are in widespread use in mining industry and in construction of hydrotechnical structures. Increased operating parameters of the walking draglines have made it possible to substantially reduce the scope of earth-moving operations1 in mining various minerals.

The ЭШ-15/90А walking dragline, is a powerful high-capacity machine fully equipped with the up-to-date complicated mechanical and electrical equipment, as well as hydraulics and pneumatics. The dragline is intended for transportless stripping operations in soils of up to IV category inclusive, involving dumping of the excavated earth either to the mined out space or to the pit bank. Earth is excavated by the dragline by means of a freely suspended bucket. The excavated earth is carried through the required swing angle and then discharged to a pile, whereupon the bucket is reface to start a new working cycle. Depending upon the particular conditions the dragline is capable of full-о circle operation by swinging through 360 degrees2. As the pit face is being excavated, the dragline moves to a new working site by its own walking mechanism. All working motions of the dragline are operated electrically. The walking mechanism is electro hydraulically operated.

Design Peculiarities

*boom with a single rigid compressing chord and trusses made of closed-type ropes3. This made it possible to considerably reduce the weight of the machine and, consequently, the electric power consumption. Nо analogous design is available abroad;

*unique construction hydraulic walking mechanism with long service life of its units and smooth travelling. The prototype of this mechanism has been used on the draglines manufactured by the Uralmash plant since 1949 and has had no analogous design in foreign practice;

*unique arrangement of the units and assemblies and rope suspension system decreased the counterweight, simplified the design of the working equipment and added to its reliability.

As compared to the earlier version of the dragline the working capacity of the present machine is increased by 15-20%. Тhe rated working cycle period is cut down from 70 to 65 seconds. As to its operating and economic characteristics the dragline ranks among the best models in the world.

Design

The dragline comprises the following principal components: bearing frame, turntable with superstructure and mechanisms, working equipment, walking mechanism, electrical equipment and auxiliary equipment.

Bearing frame is essentially a circular framework structure welded of sheet steel and reinforced with radial beams. Built-in into the framework is a centre pintle, whereas mounted on the top deck is a slewing arrangement consisting of a roller circle and a ring gear. For convenience in transport the framework la mace for separate welded sections.

65

Turntable serves as a base for all the mechanisms of the dragline. Complete with the superstructure and working equipment it makes up the swinging part of the dragline. The turnable is a welded box section frame which is composed of longitudinal and transverse I-beams, as well as a circular beam or rail to rest against the roller circle. The platform is sectionalized for transportation, all sections being assembled "in situ".

Superstructure is a dimensional system consisting of a number of trusses and serving as a bearing structure to suspend the boom and the walking mechanism. Besides, it mounts the pulleys for a hoisting and pulling ropes.

Hoist and pull winches differ from each other only in the direction of the grooves on the winch drums. Each winch is driven from two electric motors and comprises two drums. One of the jaw couplings is so designed as to permit disengagement of one of the drums to equalize the length of ropes.

Swing mechanism comprises four vertical reducers mounted on the turntable, and the ring gear mounted on the bearing frame. The reducers incorporate spur gears enclosed in an oiltight housing4.

Working equipment of the dragline incorporates the boom, bucket with ropes, and guide pulleys.

The boom consists of a vertical truss, two sloping trusses and a common tubular compressed chord. The bucket consists of a cast and welded body with the lip made of high-manganese alloy steel. The lip is provided with teeth. For hoisting and pulling the bucket multi-strand 56 mm diameter steel ropes are used. Closed-type ropes are employed for the boom guys. The pulling ropes from the bucket go round the lower guide pulleys and up to the superstructure front strut head pulleys5, wherefrom they pass downwards to the winch drums located on the turntable.

Walking mechanism comprises two pairs of hydraulic jacks which raise up and propel the dragline. Suspended from the common bottom hinges are supporting shoes.

Special pumping units are provided for forcing hydraulic fluid into the hydraulic system, whereas to control the flows of the fluid the electro hydraulic equipment is provided.

Supporting shoes are box-section welded structures incorporating longitudinal stiffening beams to take up the weight load of the dragline while walking.

Electrical equipment. The dragline receives three-phase 6000 V A.C. through a flexible power cable to energize the following units:

-convertor unit to actuate the main working mechanisms of the dragline;

-6000/380 and 6000/230 V step-down transformers of the auxiliary electric drives and lighting fixtures;

-electric motors of the walking mechanism hydraulic pumps.

The drive of the main mechanism includes D.C. electric motors employing the Ward-Leonard system controlled through magnetic power amplifiers in conjunction with intermediate magnetic amplifiers.

The main drive control system includes static apparatus, i.e. power and intermediate magnetic amplifiers which are more dependable and slimier in attending as compared to rotary amplifiers. The electric drives of the auxiliary mechanisms

66

incorporate all necessary interlocking and signalization and can be controlled both locally and remotely.

Two 260-kW motors are provided to drive the walking mechanism hydraulic pumps. The walking control system includes limit switches. The dragline lighting system is rated for 220 V. A gasoline generating set 230 V, 4 kW is provided to supply the lightning system in case of emergency.

Auxiliary equipment is intended for performing various operations in erecting, servicing and repairing the dragline. It comprises a derrick winch, a 20-ton capacity bridge crane, an 8-ton jib crane, three electric telphers, a 5-ton capacity winch located on the machine house roof, as well as a system of pulleys and devices for manipulating with working ropes, opening the house doors, etc.

SPECIFICATIONS

Note. Bulk (gravel) counterweight is not supplied by the Manufacturer.

67

COMMENTARY

1.the scope of earth-moving operations – объем перевалочных работ

2.the dragline is capable of full circle operation by swinging through 360 degrees – драглайн может работать "вкруговую" с поворотом на 360°

3.boom with a single rigid compressing chord and trusses made of closedtype ropes – применена стрела с одним жестким поясом сжатия и фермами из канатов закрытого типа

4.the reducers incorporate spur gears enclosed in an oiltight housing –

зубчатые передачи редукторов прямозубные и заключены в маслонепроницаемый корпус

5.go round the lower guide pulleys and up to the superstructure front strut heart pulleys – огибают нижние направляющие блоки и затем идут вверх к блокам, установленным на голове передней стойки надстройки

СЛОВА К ТЕКСТУ WALKING DRAHLINE ESH-15/90А

68

TEXT II: WALKING EXCAVATOR ESH-14/65

The ESH-14/65 walking excavator is a high-output full-swing large size electric machine of high power.

It is fitted with a bucket, 14 cu. m capacity and a long boom, allowing to move earth to a considerable distance without the use of auxiliary transportation means.

The ESH-14/65 excavator is used for open coal mines, also for excavation on hydrotechnical projects with dumping onto the border and for embankment construction.

An important feature of this excavator is its walking mechanism ensuring smooth travelling, which is not available in machines of other type.

When operating the ESH-14/65 excavator is seated on its supporting frame having a large surface, thus ensuring high stability, unattainable in other designs.

The ESH-14/65 consists of a supporting frame, swinging platform with mechanisms, operating equipment, walking mechanist and electric equipment.

Supporting Frame

The supporting frame is a round welded plate, 14 m diameter of alloy steel; it serves as the main structure, on which the excavator is seated when operating. A rail track on which rollers move is attached to the supporting frame. A similar rail track located on rollers is attached to the underside of the rotating part of the excavator. This arrangement permits easy rotating of the upper part of the excavator.

Swinging Platform with Mechanisms

The swinging platform serves as a base for the mechanisms mounted thereon, and together with the superstructure, walking mechanism and operating equipment constitutes the swinging part of the excavator.

69

The swinging platform proper comprises a grating of 1-section steels welded together and a flooring.

To facilitate transportation on railway, the swinging platform is made in three parts, which when being erected are riveted together. All the necessary equipment with electric motors, ensuring all operating and auxiliary movements of the excavator are located on the swinging platform.

The front part of the excavator carries the changer set. The roar part of the machine carries the heavier units: traction winch, hoisting and pumping sets for the walking mechanism.

The rotating mechanisms are located near the changer set.

All the electrical starting and control gears are arranged on a special platform in the front part of the body over the changer set. The body is fitted with doors.

Operating Equipment

The operating equipment comprises: the bucket, boom, and rope tackle. The body of the bucket is made of welded alloy sheet steel. The front part of the body of the bucket is reinforced by a closed girdle cast in special high resistance steel, to impart high rigidity to the body. The lip of the cutting part is provided with teeth. The bucket has a bow on the top and eyes at the sides for connection of the hoisting and suspension equipment. The bucket has a capacity of 14 m3.

The boom of the excavator is of light tubular construction, combining high rigidity with minimum weight.

The rope tackle system is of original design and considerable dimensions.

Walking Mechanism

The walking mechanism consists of four hydraulic cylinders (two hoisting and two auxiliary) and two supporting shoes, hingedly supported on the one and the other sides of the excavator.

When at rest, the shoes are parallel to the ground and about 2 ft. above it. While walking, the hydraulic cylinders cause the shoes to move backwards and downwards.

The cylinders are operated from a special motor-pump set provided with a suitable apparatus (hydraulic and electric).

Electric Equipment

The excavator is fed on overhead three-phase 6000 V system. The principal electric equipment comprises:

1.A motor-generator set consisting of six machines mounted on one foundation frame; all the machines of this set are of the open self-cooled type;

2.Two D. C. separately excited motors of special design driving the hoisting and traction winches; the motors are of the horizontal enclosed type, forced ventilated;

3.D. C. separately excited motors of the swinging mechanism; the motors are of the vertical enclosed type, forced ventilated;

4.A. C. squirrel-cage induction motors driving the pumping sets of the walking mechanism. Reliability of operation and ease of control are ensured by suitable electric apparatus. The total output of all electric machines is approximately 7500 kw; the output of the main motor is 1750 kw.

70