Classification of excavators

Excavators are earth-moving machines designed to dig and move soil. All excavators are divided into two large groups: continuous action - multi-bucket and periodic (cyclic) action - single-bucket.

Continuous excavators perform both operations - digging the soil and moving it - simultaneously; intermittent excavators perform these operations sequentially, interrupting digging for the duration of the movement of the soil. Thus, the working time of the machine, during which the soil is selected, is longer for continuous excavators and their productivity is higher than the productivity of intermittent excavators. Despite this, single-bucket excavators are more common, the advantage of which lies in their versatility, i.e., the possibility of using both earthworks and loading and unloading operations and in any of the most difficult, including rocky (with preliminary blasting), soils . Bucket-wheel excavators are used mainly for digging trenches and mining non-metallic materials in quarries in homogeneous soils that do not have stone inclusions.

Both single-bucket and multi-bucket excavators are land and floating.

Land excavators have caterpillar, pneumatic wheel and walking (the latter is used only in single-bucket excavators) running equipment.

Excavator mechanisms are driven by diesel engines, carburetor, steam or electric engines. The vast majority of modern excavators are equipped with diesel and electric engines as the most economical. Less commonly used carburetor engines.

The choice of engine is determined by the conditions in which the excavator will operate. So, on excavators working on the construction of railways and highways, that is, where the machine needs to be transported relatively often from place to place, diesel engines are used. On excavators constantly working in the same place, for example, in quarries for the extraction of non-metallic materials, in coal mines, etc., it is advantageous to use electric motors, since electricity is the cheapest form of energy. In addition, maintenance is simplified and there is no need to constantly supply the machine with fuel.

Therefore, diesel engines are more often installed on excavators with buckets up to 3 m3, and electric motors are installed on excavators of greater power.

If all the mechanisms of the excavator are driven by one engine, such a drive is called single-engine. If in an excavator each mechanism (or some of the mechanisms) is driven by a separate motor (usually electric), such a drive is called multi-motor.

In the USSR, single-bucket excavators with a single-engine drive were manufactured with buckets with a capacity of up to 2.5-3 m3, abroad - up to 4-4.5 m3. Excavators are currently being prepared for production

with a diesel-electric multi-engine drive, on which buckets with a capacity of 1.6 m3 (E-1602) are installed. In addition, the production of excavators with a multi-engine hydraulic drive has begun, where buckets with a capacity of 0.25 m3 (E-2513 and E-2514) are used, and the production of hydraulic excavators with a bucket with a capacity of 0.4-0.5 m3 is being prepared.

The spread of a multi-motor drive, in particular, is explained by the fact that the excavator mechanisms are made in the form of separate units that can be easily installed during the assembly of machines and replaced during their repair (with the aggregate repair method). In addition, this design allows the use of identical or almost identical (unified) units on different machines, which will make it possible to establish large-scale specialized production of them and reduce the range of spare parts.

To transfer movement from the engine to the working mechanisms, the following types of drive are used:
- mechanical, when the movement is transmitted using shafts, gears, worm pairs, chain drives;
- hydraulic volumetric, where the role of the drive is performed by a hydraulic pump (one or more), oil pipelines and hydraulic motors (or hydraulic cylinders);
– a liquid circulates in the oil pipelines, which transfers energy from pumps to hydraulic motors (or hydraulic cylinders), which set the working mechanisms in motion; this method is based on the property of a liquid not to compress;
- hydrodynamic, where turbo couplings or turbo transformers are used to transfer energy; it is usually used in combination with mechanical for smooth operation of mechanisms and automatic control of the speed of movement depending on the magnitude of the load (with an increase in load, the speed of movement of working mechanisms decreases and vice versa);
- electric, used on excavators with a multi-engine drive in combination with a mechanical one; this drive enables the driver to adjust the speed of movement of the excavator mechanisms at will, automatically change the speed depending on the loads, and also combine working movements;
- mixed, consisting of two types of drives, for example, mechanical and electric.

The mechanical drive is the most common, so its presence on the excavator is not specified in the name of the machine, but usually only the type of engine is indicated, for example, a diesel shovel excavator with a bucket with a capacity of 0.5 m3. If a different type of drive is used, then this is indicated in the name of the excavator, for example, a diesel-electric excavator, that is, an excavator with diesel power equipment and an electric drive.

All of the above applies to both intermittent excavators (single-bucket) and continuous excavators (multi-bucket).

Thus, excavators distinguish between:
1) according to the method of movement (floating and land);
2) by type of power equipment (with diesel, carburetor, electric or steam engine);
3) by the number of engines (single-engine, multi-engine);
4) by type of drive (mechanical, hydraulic volumetric, hydrodynamic, electric, mixed);
5) according to the type of undercarriage of land excavators (caterpillar, pneumatic wheel).

In addition to the listed features of the classification, each of the groups of excavators differs in smaller features - size, power, purpose.

Single-bucket excavators are divided according to their purpose into three main groups: - construction, with buckets with a capacity of up to 3 m3, designed for excavation and loading and unloading in construction;
– quarry, with buckets with a capacity of 2 to 8 m3, intended for work in quarries in the development of ore and coal deposits, as well as rocks;
- overburden, with buckets with a capacity of more than 6 m3, intended in particular for the development of the upper layers of rocks (overburden) covering the layers of minerals (coal, ore).

Overburden excavators are characterized by elongated working equipment, which makes it possible to dump soil at a great distance from the place of development. This group of machines also includes powerful walking excavators - draglines used in mining to transfer the upper layers of rocks into the goaf, as well as in large hydraulic structures.

Single bucket excavators should be distinguished by their use with different types of working equipment.

Universal excavators are machines that have at least four types of interchangeable working equipment. Construction excavators are usually produced universal, and one type of working equipment can be replaced by another during operation.

Special excavators are called excavators that have only one type of working equipment. They, as a rule, are produced with buckets with a capacity of more than 6 m3, however, excavators with buckets of a smaller capacity (for example, underground) can also be special.

This book describes single-bucket land-based construction excavators produced by the domestic industry, full-revolving and non-revolving.

Rice. 1. Scheme of a single-bucket excavator:
1 - running equipment, 2 - turntable,

An excavator is a machine used for the mechanical extraction of non-solid or crushed rocks (Fig. 2).

Along with the separation of part of the rock from the massif, the excavator moves the mined rock a certain distance to the transport, or to the dump if the mined rock is dumped into the dump on the spot (when digging pits, when harvesting clay into cones or ridges).

The construction of the first single-bucket excavator dates back to 1836. Somewhat later, in 1860, a bucket-wheel excavator was designed.

In pre-revolutionary Russia, the first single-bucket excavator appeared much later, in 1900. A small number of such excavators were produced for the development of sand pits of the railway department. Bucket-wheel excavators at that time were not manufactured at all in our country.

In the Soviet Union, the excavator industry has received a powerful development.

According to the method of action and the location of the working projectile, excavators are divided into the following main classes: single-bucket, cable, multi-bucket.

According to the method of movement in working condition, they are divided into excavators with rail and caterpillar tracks.

In recent years, the heavy machinery industry has begun to produce heavy-duty single-bucket excavators that move in working condition using a walking mechanism.

Bucket-wheel excavators are also built as floating excavators (the so-called excavators) for deepening rivers, canals and other bodies of water. One of the varieties of such dredges are dredges used in the gold mining industry.

Rice. 2. Crawler single-bucket excavator.

Excavators are powered by AC or DC electric motors, steam engines or internal combustion engines.

TO Category: - Operation of excavators

Send your good work in the knowledge base is simple. Use the form below

Students, graduate students, young scientists who use the knowledge base in their studies and work will be very grateful to you.

Hosted at http://www.allbest.ru

Ministry of Education and Science of the Russian Federation

Federal State Autonomous Educational Institution

higher education

"NATIONAL RESEARCH

TOMSK POLYTECHNICAL UNIVERSITY"

discipline "Machinery and equipment of oil and gas facilities"

on the topic: "Classification of excavators"

Performed by student gr. Z-2B13T

Prokhanov V.V.

Head Associate Professor Shmurygin V.A.

TOMSK-2015

Introduction

1. Classification of excavators

2.2 Single-bucket excavators with front and back shovels, draglay

2.2.2 Backhoe

2.2.3 Dragline excavator

3.1 Bucket excavators

3.1.1 Scraper excavators

3.1.2 Bucket wheel excavators

3.1.3 Milling excavators

Conclusion

List of sources used

Introduction

As a versatile machine, excavators are used in almost every construction job. There are many types of excavators. They are classified according to a number of factors and every professional needs to understand this. Given the variety of different models of excavators, savvy in this topic is of particular importance.

The purpose of this work is to study the classification of excavators, their types, methods of movement, etc.

The task of this work is to study in detail the classification of excavators, which in the future will help you choose the right type of unit for certain work.

1. Classification of excavators

Excavators are distinguished by high loosening abilities. Their transporting abilities are small and are determined by the radius of action of these machines. Excavators are divided into several groups according to their purpose and power. If the machine performs all operations in a certain order, repeating them at certain intervals, it belongs to machines of discontinuous (cyclic) action.

If it performs all operations at the same time, a continuous machine. Intermittent excavators include single-bucket excavators, and continuous excavators include multi-bucket, scraper and milling excavators.

Single-bucket and multi-bucket excavators are land and floating. Land excavators have caterpillar, pneumatic wheel, rail and walking undercarriage.

All excavator mechanisms are driven by diesel engines, carburetor, steam or electric engines. The most economical are diesel and electric engines. The choice of engine is determined by the conditions in which the excavator will operate. So, on excavators working in a quarry, it is advantageous to use electric motors, since electricity? this is the cheapest form of energy, and when working on road construction, where the machine is often transported from place to place, it is advisable to use diesel engines.

If all the mechanisms of the excavator are driven by one engine, such a drive is called single-engine. If in an excavator each mechanism (or group of mechanisms) is driven by a separate engine, such a drive is called multi-engine.

In order to transfer movement from the engine to the working mechanisms, the following types of drives are used:

mechanical, when the movement is transmitted using shafts, gears, worm gears, chain drives;

volumetric hydraulic, where the role of the drive is performed by a hydraulic pump, oil pipelines and hydraulic motors (or hydraulic cylinders), a liquid circulates in the oil pipelines, transferring energy from pumps to hydraulic motors (or hydraulic cylinders), setting the working mechanisms in motion;

Hydromechanical, in which a torque converter is used to transmit energy in combination with a mechanical transmission;

electric, used on excavators with a multi-engine drive in combination with a mechanical one;

mixed, consisting of two types of drives, for example, mechanical and electric.

Thus, excavators are classified:

according to the method of movement (floating and land);

by type of power equipment (with diesel, carburetor, electric, diesel-electric, etc.);

by the number of engines (single-engine, multi-engine);

By type of drive (mechanical, hydraulic, hydromechanical, electric);

According to the type of undercarriage of land excavators (caterpillar, pneumatic wheel, rail and walking undercarriage).

2. Cyclic machines

Universal machines used for digging soils up to the VI category of strength, dismantling of weak and blasted rock. They are used for excavation from the face and loading into a transport or dump of loose and large-sized materials, destruction of old structures, clearing territories when punching routes, clearing reclamation and drainage ditches, extracting large pits and long trenches, constructing earth embankments, building tunnels and bridge crossings and at other jobs.

2.1 Classification of shovel excavators

A single-bucket universal excavator is a cyclical machine designed to excavate and move soils and other materials using one of the types of working equipment with one bucket, and to perform loading pile driving and other work with other types of replaceable working equipment.

Each of the groups of excavators differs in smaller features - size, power, purpose. Single-bucket excavators are classified according to their purpose. There are three main groups:

construction-universal with buckets with a capacity of up to 3 m3, intended for earthworks;

quarry with buckets with a capacity of 2 to 8 m3, designed to work in quarries in the development of ore and coal deposits;

Overburden with buckets with a capacity of 6 m3, designed to develop the upper layers of rocks (overburden).

Single bucket excavators are distinguished by their use with various types of working equipment.

Universal excavators are designed to work with various types of interchangeable equipment; shovel, backhoe, dragline, hook or grapple boom, pile driver, etc.

Semi-universal excavators, in addition to the main working equipment, have one or two types of additional replaceable equipment (front shovel, backhoe, dragline). Special powerful excavators have only one type of equipment, such as a straight shovel.

Single bucket excavators (Fig. 1) consist of the following main components: (1) undercarriage, (2) turntable with power equipment and (3) main kinematic links and working equipment.

Caterpillar undercarriage provides high cross-country ability and good stability during excavator operation.

In recent years, the production of excavators with a small bucket capacity on pneumatic wheels, which have high mobility and maneuverability when moving the machine from one object to another, has significantly increased. When working on soft soils, widened (or elongated) caterpillar equipment is used, the presence of which reduces the specific pressure on the ground and improves the excavator's maneuverability.

Rice. 1. Scheme of a single-bucket excavator:

1 - running gear; 2 - turntable with power equipment; 3 - main kinematic links and working equipment.

The turntable rests through rollers or a special (ball or roller) turntable on the frame of the undercarriage. The platform rotates in a horizontal plane relative to the running gear.

The angle of rotation of the undercarriage in the horizontal plane determines the ability of the excavator to be full-turn or part-turn. The rotary part of a full-revolving excavator can rotate around its axis by 360°.

For these machines, all power units, control panel, working mechanisms are mounted on a turntable, and working equipment is attached.

Working equipment includes a complex of excavator units with a working body (bucket, hook, grab, etc.). The soil is developed with a bucket, after which it is moved to the place of unloading into a dump or into a vehicle. Depending on the type of replaceable equipment, a rigid or flexible suspension of the working body is used. The nature of the work is determined by the working equipment: front shovel, backhoe, dragline, crane or grapple.

The working cycle of the excavator is carried out in the following sequence: digging the soil; moving a bucket filled with soil to the place of unloading; unloading the soil from the bucket into the dump or transporting device; bucket movement (platform rotation) to the bottom; lowering the bucket in preparation for the next digging operation.

2.2 Single bucket excavators with front and back shovels, dragline

Equipment designed to excavate soil above the level of the excavator parking lot. A straight shovel with a mechanical drive (Fig. 2) consists of the following main components: boom lifting rope, bucket, handle, boom, saddle bearing. The handle is attached to the arrow with a saddle bearing, with the help of which the handle rotates in a vertical plane relative to the arrow and reciprocates along the axis of the handle. The bucket is lifted by a lifting rope that goes around the head blocks. The pressure of the handle is carried out by a pressure mechanism, which also performs the reverse movement (return) of the handle. On universal construction excavators, rope and rack and pinion (pressure mechanisms) are used.

Rice. 2. Diagram of a front shovel excavator:

1 - caterpillar; 2 - turntable; 3 - a body with a cabin; 4 - handle; 5 - bucket; 6 - arrow; 7 - turntable.

Pressure mechanisms are divided into independent, dependent, combined. The pressure mechanism is called independent if the pressure force can be increased or decreased regardless of the magnitude of the effort in the lifting cable of the bucket, i.e. when the pressure movement of the handle with the bucket is performed regardless of the bucket lifting. If the magnitude of the pressure force depends on the magnitude of the force in the lift/multiple cable of the bucket and it is only possible to reduce the pressure, such a pressure mechanism is called dependent.

The pressure mechanism is called combined, when the magnitude of the pressure force depends on the force in the lifting cable, but when an independent part of the pressure mechanism is turned on, it can be increased as desired.

The straight shovel bucket consists of a body, a hinged bottom with a bolt and replaceable teeth. The teeth have a shank tapering towards the end, which enters the visor socket. From falling out, the teeth are held in the sockets with cotter pins.

In recent years, straight shovels are equipped with buckets with a semicircular front wall and with a visor in the form of a scoop without teeth. The bucket of this design is much lighter and has minimal resistance when digging the soil, which naturally increases the performance of the excavator.

On excavators with a front shovel, handles of two types are used: single-beam (internal type) and double-beam (external type). The single-beam handle runs inside the boom, and the double-beam handle goes outside. The handle can perform reciprocating motion in the guides of the pressure shaft saddle, and also rotate together with the saddle bearing in a vertical plane relative to the pressure shaft. The design of the handle determines the design of the pressure mechanism. In excavators that were produced in the USSR, with a single-beam handle, a cable pressure mechanism was used, and with a two-beam handle, a cremal pressure mechanism was used.

The straight shovel boom is made in the form of a welded structure made of sheet steel. The stick type determines the design of the boom. The boom is double-beam with a single-beam handle and single-beam with a two-beam handle.

In the upper part of the boom, blocks are mounted on bearings through which the bucket lifting rope and the boom-lifting rope pass. The lower end (fifth) of the arrow is attached to the turntable with fingers and can be rotated when its angle of inclination changes. The pressure shaft is located in the middle part of the boom.

2.2.2 Backhoe

This equipment is designed for excavation of soils below the level of the excavator when digging pits, trenches, excavations. A backhoe excavator (fig. 3) consists of a bucket, an arrow, a handle and a two-legged stand. The bucket is fixed rigidly to the handle pivotally attached to the upper end of the boom. When pulling the rope, the handle turns counterclockwise, the bucket crashes into the ground (position I; positions II and III correspond to the transport position and unloading the soil from the bucket).

Rice. 3. The scheme of operation of a backhoe excavator:

1 - bucket; 2 - traction rope; 3 - arrow; 4 - additional rack; 5 - lifting rope; 6 - handle.

In excavator hydraulic drives, constant-displacement pumps of gear and vane type (with a pressure of 12 MPa, 16 MPa) and piston pumps with a pressure of up to 30 MPa are used, as well as variable-displacement pumps, mainly axial-piston ones.

Pumps with a constant capacity are simple in design, but do not provide full use of engine power in all modes. Variable displacement pumps provide a more rational and stable operation of excavators.

Performance and technological schemes of operation of single-bucket excavators. The performance of single-bucket excavators is determined by many factors: the design of the machine, the level of organization of earthworks, the condition and quality of the soil and the face, the qualifications of the driver and the technical condition of the machine.

2.2.3 Dragline excavator

Dragline excavator working equipment designed to develop soil below the level of the parking lot of the machine with a bucket suspended on ropes directly to the boom. The dragline can only dig in the direction of the excavator. The digging depth, the height of the bucket unloading and the distance to which the bucket (digging radius) of the dragline can be thrown is much greater than that of an excavator equipped with working equipment with a front and back shovel (Fig. 4).

It is because of these characteristics that the dragline is used for digging large pits and trenches, in quarrying, land reclamation, as well as for filling embankments, in particular in the construction of canals, roads and railways.

But dragline working equipment has significant drawbacks. Bucket suspension with chains and ropes is quite flexible, so it does not provide high digging and unloading accuracy. Loading soil into vehicles using a dragline is difficult. Usually, unloading is carried out to a dump - from where it is reloaded using a loader or excavator with a different type of working equipment. The disadvantages include a longer working cycle and a lower digging force compared to hydraulic types of equipment.

The dragline works as follows. The bucket is lowered to the bottom of the pit or trench, and then it is pulled to the excavator with a traction rope, while the bucket is filled with cut soil. Then the loaded bucket is lifted by a lifting rope, while turning the platform to the place where the bucket is unloaded. After unloading the bucket, turn the platform with the boom to the pit and at the same time lower the bucket. The dragline boom is welded, of a lattice design, which reduces its weight and makes it possible to make it longer than the booms of the front and back shovels, using a bucket of the same capacity. Due to the lengthening of the boom, the reach of the excavator and the height of unloading are increased. The boom consists of two parts connected by bolts, the lower part is widened to the heel of the boom and pivotally fixed in the lugs of the turntable. The length of the arrow can be increased by additional inserts between the upper and lower parts of the arrow. When lengthening the boom, a bucket with a smaller capacity is used. During dragline operation, the boom angle is usually set between 30 and 45 degrees.

The dragline will only provide the necessary digging force if the bucket goes into the ground at the start of the stroke. Therefore, to work with hard soils, it is necessary to loosen them in the bucket penetration zone.

2.3 Hydraulically driven shovels

These excavators are multi-engine machines with a rigid suspension of the working equipment, which use a hydraulic volumetric drive to transfer power from the engine to the working mechanisms (Fig. 5).

Rice. 5. Hydraulic excavator:

1 - turntable; 2 - pneumatic wheel undercarriage; 3 - outrigger; 4 - turntable; 5 - power plant; 6, 8, 9 - boom hydraulic cylinders; 7 - arrow; 10 - handle; 11 - backhoe bucket; 12 - dozer blade; 13 - driver's cab.

excavator shovel dragline

The parameters of hydraulic excavators are regulated by GOST (30067-93) "Single-bucket excavators, universal full-turn". Compared to mechanical hydraulic excavators, they have a wider range of interchangeable working bodies, the number of which is constantly growing, a greater number of main and auxiliary movements of the working equipment, which significantly expands their capabilities.

3. Continuous machines

Continuous excavators are designed for excavating trenches and channels in soils I ? IV groups both in urban and field conditions. These are earth-moving machines on caterpillar or pneumatic wheels of self-propelled, semi-trailer and trailed types, which, during their forward movement during operation, destroy the soil with the help of a group of buckets, scrapers or cutters continuously moving along a closed contour, tear off a longitudinal excavation of a certain size behind them and at the same time evacuate the soil away from it (into the dump or vehicles) using a conveyor, rotor or auger.

3.1 Bucket excavators

There are two types of continuous excavators: chain and rotary. The working body of chain excavators is a single or double-row endless chain that goes around an inclined frame and carries buckets, scrapers or cutters. In bucket-wheel excavators, the working body is a rigid rotor, or a wheel with buckets or scrapers, rotating on rollers.
Depending on the working conditions and the complexity of excavation, the speed of movement of the excavator and the movement of the working body are selected so that, regardless of the depth of the trench, the calculated filling of the buckets is provided.

According to the type of working body, chain excavators are divided into single-chain, equipped with cutters and scrapers, and double-chain, between the branches of which buckets or scrapers with cutters are fixed.

3.1.1 Scraper excavators

Scraper single-chain excavators (Fig. 6 a) are designed for excavating rectangular trenches 0.14-0.4 m wide, up to 1.7 m deep in homogeneous (without stony inclusions) soils I ? III groups. The productivity of such excavators is 60 80 m3/h.

Scraper double-chain excavators (Fig. 6 b) are used for digging trenches of rectangular and trapezoidal sections up to 3.5 m deep, up to 1.1 m wide at the bottom and up to 2.8 m on top in thawed soils I ? III groups with the inclusion of stones with a diameter of up to 0.2 m and in frozen soils with a freezing depth of up to 1.2 m. The development of the soil is carried out by scraper-type cutting elements and transport dampers. For extracting trenches of a trapezoidal profile, active chain slopers are installed on the working body of the excavator. The soil separated by chains from the pillar falls to the bottom of the trench, from where it is brought to the surface by transporting dampers. Is interchangeable working equipment installed for the development of frozen soils? bucket chain with teeth-fangs. The soil lifted up by scrapers (buckets) is unloaded onto a transverse belt conveyor and taken away from the trench (up to 3 m). Productivity of double-chain excavators is up to 220 m3/h.

3.1.2 Bucket wheel excavators

This type of excavators is shown in (Fig. 6 c) they develop trenches of various sections in soils I ? IV groups with the inclusion of stones with a diameter of up to 0.3 m, as well as in frozen soils with a freezing depth of up to 1.5 m. The width of the trenches on top is up to 3.2 m, down to 2.1 m, depth up to 2.5 m.

Fig 6 Continuous excavators:

A) ? scraper single-chain: 1 ? dropped; 2? tractor; 3? chain working body; 4 ? lift mechanism? lowering the working body; 5 ? screw; 6? incisors; 7? scraper; 8 ? cleaning shoe;

b) ? scraper double-chain: 1? power point; 2? control; 3? hydraulic drive; 4 ? transmission; 5 ? mechanism for raising and lowering the working body; 6? conveyor; 7? tray; 8 ? working body;

V) ? rotary: 1? tractor; 2? frame for mounting working equipment; 3, 4? lifting and drive mechanisms; 5 ? conveyor; 6? ladle; 7? bucket rotor.

During the translational movement of the tractor and the rotational movement of the rotor, buckets with teeth are continuously developed, lifted to the surface and unloaded soil onto the transverse conveyor belt. The dimensions of the trenches are determined by the width of the buckets and the degree of penetration into the soil of the rotor. For the formation of slopes with a steepness of up to (1:.0.25) in thawed soils, excavators are equipped with passive knife slopes, in frozen soils? active milling extensions.

The productivity of rotary excavators is up to 1200 m3/h.
Ditch excavators work on the same principle as rotary excavators. Unlike rotary ones, they are able to tear off channels with gentle slopes (up to 1: 1.5) with a bottom width of up to 2.5 m, a depth of up to 3 m.
Prior to the installation of a continuous excavator on the track, it is necessary to carry out planning work. The width of the planned strip must not be less than the width of the caterpillar track of the excavator intended for digging the trench.

After planning work and laying out the axis of the trench, digging of the trench, as a rule, begins from the side of the low marks of the longitudinal profile (for the convenience of drainage) and leads towards the slope, while the dumps of the soil taken out of the trench should be placed on one side of the excavation (mainly on the upland) to protect the dug trench from the runoff of surface water and the possibility of performing subsequent installation work on the other side.

3.1.3 Milling excavators

A milling excavator is an earth-moving machine designed to develop dense and frozen rocks in layers from the surface of the massif. A milling excavator destroys rock with a milling working body, loads it onto a conveyor and transfers it through an unloading console to vehicles during its movement along the work front (Fig. 7).

The cutter is a horizontally located cylindrical structure up to 3.5 m wide with cutters. When the cutter rotates, the cutters destroy the mass at a depth of 0.1-0.35 m. The productivity of the milling excavator is 100-2500 t/h. The excavator is equipped with devices for controlling the thickness of the developed layer and the size of interlayers, which allows it to be effectively used for selective mining of rocks.

Rice. 7. Milling excavator: 1 - control cabin; 2 - cutter; 3 - conveyor unloading console.

The indexing (marking) system of machines is the principle that is embedded in the structure of the index (brand), denoting a particular excavator and reflecting its main characteristics. Previously, only the capacity of its main bucket was included in the indices used to designate domestic excavators. For example, E-652B excavator with a bucket with a capacity of 65 deciliters (0.65 m3), model 2, second modernization (B). According to the old system, the index did not give an idea either about the type of excavator undercarriage or the design of the working equipment, which is very important for the characteristics of the machine and its operational capabilities. In addition, determining the size (class) of a single-bucket excavator only by the capacity of one of the buckets used on this machine is vague and leads to a misconception about the capabilities of the machine. This is even more true for hydraulic excavators, in which the capacity of buckets used on the same machine can differ by a factor of two or more.

The size of the excavator, on which its operating parameters, productivity, etc. depend, is determined by a combination of a number of factors standardized by GOST. At the same time, the parameter that most fully (compared to the others) characterizes the size of a hydraulic excavator is the mass of the machine, which determines its stability and the possibility of effective use of buckets of these capacities at the appropriate reach, depth or height. The current indexing system for excavators is based on the size group of machines, which is determined mainly depending on the operating weight of the excavator. The capacities of the buckets used (the range of which may change as the design improves) are given for guidance only.

The operating weight is the weight of the excavator with full fuel and hydraulic fluid (without a driver). The new indexing system for single-bucket universal excavators (EO) provides for the structure of the machine index. The four main digits of the index indicate in the order of their location: the first is the size group, the second is the type of running gear, the third is the version of the working equipment and the fourth is the serial number of this model. The letters (A, B, C) indicate the next modernization of this machine, as well as its special climatic modification (HL, T, TV). For example, the EO-3322A index denotes a single-bucket universal excavator of the 3rd size group on a pneumatic wheel undercarriage with a rigid (articulated-lever) suspension of working equipment, the 2nd model, which has undergone the first modernization.

Conclusion

In this paper, the classification of excavators was described, as well as their varieties. Based on this classification, it is possible to select an excavator for a certain type of work.

Also, single-bucket excavators with front and back shovels, multi-bucket excavators were considered. The excavator indexing system is considered, which in the future will help to determine the parameters of excavators by the index.

List of used literature

1. Dobronravov S.S., Dronov V.G. Construction machines and basics of automation. - M.: Higher. school, 2001.

2. I.I. Galperin, N.G. Dombrovsky "Construction Machines", Moscow, "Higher School", 1980.

3. Nevzorov L.A., Podzelsky G.N., Romanyukha V.A. Construction tower cranes. - M.: Higher. school, 1986.

4. Shestopalov K.K. Handling, construction and road machinery and equipment: Textbook. - M.: Publishing center "Academy", 2005.

5. Machinery and equipment for oil and gas pipelines: textbook / V.G. Krets V.G. A.V. Rudachenko, V.A. Shmurygin. - Tomsk: Ed. TPU, 2013. - 375 p.

Hosted on Allbest.ru

Application of excavators

Nowadays, not a single construction site is complete without the use of certain excavators. The high level of productivity, reliability, the ability to carry out earthworks even in the most difficult conditions allow these machines to be used in various fields. Single-bucket excavators are successfully used for:

preparation of trenches and pits;
preparation of excavations, digging channels;
building dams;
overburden works;
backfilling of embankments using lateral reserves;
implementation of planning work;
crushing rocks;
loosening frozen soil;
loading and unloading of various materials;
cleaning channels during their operation;
soil backfilling;
soil compaction in sinuses, etc.

An excavator can be used in the development of land both above the level of the site where it stands at the time of the work, and below the level under consideration.

Figure 2. With a single-bucket excavator, it is easy to organize the development of soil both above and below the level of the site where it is located

The excavator is capable of:

function effectively in tight spaces
excavate soil under a layer of water,
to carry out unloading of the excavated earth in a car body,
dump it at a great distance from the development point into a dump,
carry out the final finishing of the slope and the surface of the walls of pits, trenches,
with high accuracy to plan the horizontal plane of construction sites, the bottom of the pits.

Main working equipment of excavators

A single-bucket excavator can be equipped with the main (which is launched directly for digging the soil) or additional working equipment mounted on the base machine for other operations.

straight shovel

The main working equipment that is used when excavating the soil above the site where the excavator is located is a straight shovel. With a similar design of the excavator, the bucket is mounted on a handle, which is pivotally mounted on the boom. Well, the latter is hinged on the turntable, which has already been discussed earlier.

Figure 3. Crawler excavator with a front shovel during its direct functions

During the operation of a front shovel excavator, the soil is excavated away from the machine. This attachment guarantees maximum digging force and maximum productivity (by minimizing the number of operations carried out in one digging cycle). The most logical involvement in the work of the earth-moving machines considered here seems to be when loading soil and bulk materials, as well as in the development of mineral deposits.

The classic cycle of operation of a front shovel, shown in the figure below, includes a number of operations.

1. Loading the bucket, performed by turning the handle relative to the boom. At the same time, the position of the bucket relative to the arm and the position of the boom relative to the chassis remain the same as it was.
2. Rotate the platform together with the working equipment after loading is completed. Then the bucket is sent to the unloading point. In this time period, the position of the bucket relative to the turntable remains the same.
3. Raise the boom. This operation, prior to unloading the bucket, is performed in order to increase the loading height.
4. Unload the bucket. On hydraulic models of excavators, it is done by turning the bucket relative to the handle (that is, by conventional tipping), and on mechanical models, by opening the bottom of the bucket.

Figure 4. Four stages of the working cycle of a face shovel

Backhoe

Backhoes are equipped with excavators designed to develop soil below the level of the site where the machine is located. In the situation with working equipment of this type, digging of the soil is carried out in the direction of the excavator, that is, differently than when the machine is operating with a front shovel. Hydraulic models of excavators, “armed” with a backhoe, have the ability to excavate the soil not only below, but also above the level at which the base machine is located, however, they do this with less productivity when compared with a front shovel.

Figure 5. In the case of a mini backhoe excavator

The cycle of operation of these excavators is different for models with different drives. For example, consider its main stages (shown in the figure below) for hydraulic machines with an independent drive of the arm, boom and bucket.

Figure 6. The main stages of the working cycle of a backhoe excavator

1. Deepening the boom into a recess. At the same time, the positioning of the excavator arm is performed.
2. Loading the bucket by turning it relative to the handle;
3. Boom recess.
4. Turning the handle and bucket to prevent spillage of the accumulated soil (performed simultaneously with the deepening of the boom).
5. Rotate the platform with the working equipment based on it.
6. Soil unloading.

grapple

When preparing narrow pits of great depth, as well as for loading and unloading soil and other materials, excavators come into play, in which the role of the working body is assigned to the grab. The working body of this type can be equipped with both mechanical and hydraulic excavators. In the second, the grab usually takes up space on the handle, replacing the bucket (at the same time, its jaws are hydraulically driven). In the case of mechanical excavators, the design includes ropes from which the grab is suspended.

Figure 7. Excavator with grapple in operation

Replaceable working bodies

If it is necessary to implement all kinds of specific tasks on an excavator, as a replacement for a traditional bucket, such interchangeable working equipment can be installed, such as:

hydraulic hammer (hydraulic ripper),
stump grinder,
manipulative grip,
crane equipment,
buckets for drainage works,
dumps and many others.

Figure 8. Attachments of modern excavators

Excavators with a hydraulic hammer have become very widespread these days, which perform well when loosening frozen soil, crushing oversized pieces of rock and other hard rocks into pieces, breaking up old asphalt pavements, building foundations, and compacting the soil. The drive from the pumps of the base machine's hydraulic system guarantees an optimal consumption of installed power and a reduction in operating costs.

Figure 9. Hydraulic hammer excavator

Before you start uprooting stumps with an excavator, instead of a bucket, a jaw grip is placed on it. The installation of a manipulator gripper in place of the main working equipment allows using the excavator with the maximum possible efficiency for assembly and dismantling.

Figure 10. Excavator with a manipulator in the process of dismantling the old building

Differences between full-revolving excavators and non-revolving excavators

All models of excavators are usually divided into two types: full-revolving and non-revolving. In the first case, the turntable, mounted on the chassis using a turntable (hereinafter referred to as the abbr. SLE) and serving as a base for the installation of working equipment, drives, power unit and excavator driver's cab, can be rotated relative to the SLE clockwise and against it to any desired angle.

Figure 11. An example of the construction of a full-circle excavator

Speaking about the second group of excavators (non-rotary type machines), it should be noted that here the working equipment, which is supported on the chassis with the help of a rotary column, can only rotate through a limited angle (is within no more than 90 degrees) from the initial position. In this case, the engine, cab and mechanisms are on a fixed chassis.

Figure 12. Example of a quarter turn excavator based on a wheeled tractor

Classification of excavators depending on the type of chassis

One of the most popular classifications of single-bucket excavators is the division into several groups based on the type of base chassis.

Tractor based excavators

In this case, the role of the chassis is played by a tractor, usually a pneumatic wheel. Non-rotary working equipment is placed behind (or, in rare cases, on the side) of the base tractor, on a frame provided for this purpose. As a rule, such excavators are "equipped" with buckets of the order of 0.2-0.5 cubic meters. meters. In our country, tractors with mounted excavator equipment MTZ are widely used. These machines are characterized by high speed and compact size, so they can easily move in the general traffic flow to the point of excavation.

Figure 13. Tractor-based excavator

Excavators on a car chassis

Often, trucks are used as chassis, often with increased cross-country ability. Of course, such an excavator has a high speed of movement, and therefore effectively manifests itself in situations where there is a need for a high level of mobility, whether it be military affairs, rescue operations, or, for example, clearing canals. In the vast majority of cases, the working equipment of machines of this type is a backhoe.

Pneumatic excavators

A characteristic feature of this type of earthmoving machine is the presence of its own wheeled chassis with conventional pneumatic tires. They are presented on the market as tiny models equipped with a bucket of 0.04 cubic meters. meters, and solid 20-ton machines with a bucket designed for 1.5 cubic meters. meters. As a rule, excavators on such a chassis can pick up speed up to 30 km / h and for the most part are among the “overall” (that is, they can be driven on ordinary roads without obtaining any special permission). Due to the use of a pneumatic wheel propeller, such special equipment does not cause damage to the asphalt surface, however, for the same reason, it has a low passability on soft soils. This is precisely the reason for the widespread use of these excavators, mainly in settlements during general construction work.

Crawler excavators

Such machines, in terms of a number of operational characteristics and areas of application, are in fact the exact opposite of the pneumatic wheel excavators discussed above. The minimum speed of movement (in most cases, not exceeding 12-15 km / h) and the inadmissibility of moving on asphalt (otherwise the latter will inevitably be damaged), make it possible to transport such special equipment using tractors and trailers of a special design.

Nevertheless, it is necessary to mention the existence of small-sized models of caterpillar excavators, which are often equipped with caterpillars with rubber pads that allow this equipment to move over short distances without the threat of destruction of the asphalt concrete pavement of roads. In turn, the advantage of the caterpillar mover is that such excavators, even being very heavy and large-sized (the mass of individual specimens is from 80 tons or more), have a relatively low specific pressure on the ground, and therefore can be used to work even on peat bogs. .

Other models of excavators

In addition to the widely used excavator options listed above, there are other specific types of excavator chassis that are relatively rare. For example, especially large-sized excavator models with huge buckets (from 15 cubic meters and above) are moved using a walking mechanism. The bulky machine moves in the right direction, relying in turn on the base plate and paws.

Figure 14. Walking models of excavators have more than solid dimensions

Excavators, which are designed specifically for repair and construction work on the railway, also have a special chassis, which is used as a railway platform. If it is necessary to extract sand or gravel from the bottom of rivers, lakes, clean the bottom of reservoirs and increase the depth of the latter, floating excavators are involved in the work, in which the working equipment is placed on the basis of a pontoon.

Power units mounted on excavators

Today, single-engine and multi-engine modifications of excavators are used to perform earthworks. In the first case, all the mechanisms of the earth-moving machine are driven by one power plant, and in the second, each of the mechanisms (or a group of them) receives energy from a separate engine. Most often, excavators are equipped with diesel engines that provide fully autonomous operation of the machines.

Sometimes, to drive the working equipment, electric motors are used that are powered by an external power supply or a diesel generator, which is located on the base of the excavator (usually this method of power supply is used on floating models). Such models of excavators are economical, do not pollute the air.

Classification of excavators depending on the drive of working equipment

Hydraulic excavators

Most modern excavators are equipped with a hydraulic drive. In this case, to create the necessary force on the handle, boom, bucket, hydraulic motors and hydraulic cylinders are provided. The hydraulic pump, which is responsible for maintaining the desired pressure of the working fluid in the corresponding line, receives the torque necessary for its rotation from the excavator engine.

Mechanical excavators

Today, a group mechanical drive, which provides for the transfer of force from the power plant to the working bodies using ropes driven by a winch, is used only on draglines and clamshell excavators. At the same time, the winch itself is powered by the excavator engine, receiving torque through a gear, worm, chain or friction gear. On conventional excavators, a mechanical drive is practically not used today, due to a number of factors:

design complexity associated with the use of a significant number of wear parts;
limited number of independent movements of working equipment units;
the complexity of the execution of an automated mechanical rope drive;
the impossibility of ensuring absolute fixation of the parts of the working equipment in the desired position.

Electromechanical excavators

There is another category of excavators in which, as in the case described above, ropes (chains) are used to transfer traction to the working bodies, moving due to the winch. The difference here lies in the fact that a separate electric motor is used to rotate the drum of each winch. This drive has been used on massive mining and industrial excavators.

The main modern manufacturers of excavators

Speaking of companies that are leaders in the market of single-bucket excavators, it is worth highlighting brands such as Komatsu, Volvo, JCB, Caterpiilar, Daewoo, Hitachi, Liebherr, Hyundai Robex, Orenstein & Koppel, New Holland Kobelco, Doosan Infracore. Undoubtedly, the world's largest manufacturer of excavators today is Caterpillar, headquartered in the United States. Today, the range of equipment created by the specialists of this company includes:

various modifications of hydraulic excavators (starting with mini-excavators weighing less than a ton, medium, heavy, and ending with the largest 980-ton hydraulic excavator on the planet, model 6090S, with a bucket volume of 59 cubic meters);
electric models of cable excavators with working equipment of the "straight shovel" type, equipped with buckets from 6.9 to 61.2 cubic meters. meters;
draglines equipped with buckets from 32 to 132.5 cubic meters. meters.

Under the Komatsu brand, high-performance crawler excavators of various sizes, wheeled backhoe loaders equipped with state-of-the-art hydraulic systems, powerful turbocharged power plants and large buckets are supplied to the market. The Swedish manufacturer Volvo claims that the machines of this particular brand are characterized by maximum efficiency. The last company chose traditional ways to achieve this: increasing the size of the working area, using diesel engines with increased torque and reduced toxicity of exhaust gases, and automating the selection of soil development modes.

Figure 15. The Japanese engineering company Komatsu Limited produces high-performance excavators

Single-bucket excavators have recently appeared in the range of the British company JCB. However, despite the rather short history of the production of such equipment, the company managed to find its niche in the corresponding market segment. JCB products are the clearest example of cooperation between Japanese and European suppliers. Excavators manufactured under this brand are equipped with Isuzu engines and hydraulic equipment from Sumitomo.

The designers of the Daewoo company, which succeeded in various industries, managed to achieve serious advantages over competing enterprises in a number of areas. Excavators from this manufacturer have an increased platform rotation speed, increased boom reach. The parameters of the working area are selected in such a way that the machine can perform its functions with due efficiency in cramped conditions, which is typical for settlements.

The Hitachi line of equipment includes small, medium and large crawler and wheeled excavators, as well as models designed specifically for working in rock and other heavy soils, working in hard-to-reach places, when performing demolition and dredging. New models of Hitachi excavator equipment are equipped with diesel particulate filter engines equipped with innovative exhaust gas recirculation systems. All this ensures the maximum purity of exhaust gases that meets the highest international standards.

Figure 16. Hitachi crawler excavator in operation

The well-known German manufacturer of special equipment Liebherr produces hydraulic excavators that combine the latest achievements in engineering. Among the distinguishing features of this equipment, one can single out a hydrostatic drive for caterpillar models, an automatic transmission with power shift for pneumatic wheel excavators, 4 standard operating modes for maximum efficiency in excavation in any conditions.

As for domestic manufacturers, here we can distinguish such companies engaged in the production of excavators as CJSC Tverskoy Excavator and JSC TYAZHEKS. Many models of Tver excavators are equipped with blades used to level the site and backfill trenches. When buying an excavator, the client can order such interchangeable working parts as hydraulic shears, log grab, 5-jaw grab, hydraulic hammer, milling head, etc. JSC TYAZHEX is today the leading Russian supplier of heavy earthmoving equipment. The company supplies the market with 6 modifications of excavators of the 5th and 6th size groups with a 2-way hydraulic drive and powerful power units from the Yaroslavl plant.

Figure 17. Pneumatic wheel representative of the model range of excavators of OAO Tverskoy Excavator Plant

Single bucket excavators

Excavator(from lat . excavato- hollow) - an earth-moving machine designed for digging soil with its subsequent unloading into a dump or into any vehicles.

Single bucket excavator- earth-moving machine of cyclic action for development (digging), movement and loading of soil.

The working body is a movable bucket, fixed on the boom, handle or ropes. The bucket is loaded by moving relative to the developed soil. At the same time, the body of the excavator remains motionless relative to the ground - the traction force is created by the mechanisms of the excavator. This distinguishes the excavator from the scraper and loader, where the traction force when loading the bucket is created by the movement of the machine body.

The single-bucket excavator is the most common type of earthmoving machine used in construction and mining.

Excavators replaced diggers, mechanized their labor-intensive manual labor and significantly increased the productivity of earthworks. The bucket capacity of modern construction excavators can reach 2-4 m3.

Excavators intended :

For the development of cuts and embankments;

For digging pits, channels, trenches;

During the construction of dams and clearing of territories,

Overburden and in quarries,

When handling loose building materials

When planning work and in many other cases.

Each type of work requires the use of equipment adapted to this excavator and designed for each specific case.

Application . The scope of their application in construction is practically unlimited. Where there is access for this machine, earthworks will be completed at a high rate and quality.

What kind of work are excavators intended for? They can be used in digging pits, canals, trenches, excavation and embankment, construction of dams and clearing of territories, overburden and quarries, when handling bulk building materials and planning work, and in many other cases.

Excavators can develop the soil both above the level of the site on which they stand, and below this level. They can operate in cramped conditions and develop soil under a layer of water, unload excavated soil into vehicles and dump it at a considerable distance from the place of digging into a dump, can finally finish the slope and surface of the walls of trenches and pits, and also plan a horizontal surface with sufficient accuracy. construction site or the bottom of trenches and pits.

Obviously, each type of work requires the use of excavators adapted for this and working equipment designed for each specific case.

However, bucket-type excavators have become more widespread in construction than multi-bucket ones, due to the fact that they have greater versatility.

Versatility is the ability of an excavator to perform a variety of earthworks, ranging from the construction of trenches, pits, channels and ending with embankments and dams, as well as loading and unloading. Of course, the excavator can do all this only with the help of various interchangeable working equipment.

Classification. Single-bucket excavators are classified according to the type of chassis, type of drive, type of working equipment, the possibility of turning the working equipment relative to the supporting surface.

- If possible, turn the working equipment relative to the supporting surface

A). Full revolving

Fig. Scheme of a full-circle excavator

The working equipment, drives, the driver's cab and the engine are mounted on a turntable, which in turn is mounted on the chassis by means of a turntable and can be rotated relative to it in any direction at any angle. Parts of the hydraulic system of the chassis and the turntable of full-turn excavators are connected using a manifold, which allows for an unlimited number of full turns in one direction.

b). Semi-rotary

Rice. Scheme of a part-turn excavator

on the chassis of a wheeled tractor:

1. Excavator frame mounted on a tractor;

2. Rotary column;

3. Arrow;

4. Handle;

5. Boom drive hydraulic cylinder;

6. Hydraulic cylinder drive handle;

7. Bucket drive hydraulic cylinder;

9. Option to install the bucket in the position of the backhoe;

10. Replaceable cargo hook;

11. Dozer blade;

12. Outriggers.

The working equipment is fixed on the chassis by means of a rotary column. On many machines of this type, the swivel column is mounted on transverse rails, which allows it to be moved along with the working equipment to the right and left, followed by rigid fixation for a more convenient position of the working equipment. Rotation of the working equipment is carried out at an angle of 45-90 degrees from the initial position. The engine, mechanisms, driver's cab are placed on a fixed chassis. Currently, non-rotary excavators mounted on tractors are made.

- By chassis type

A). Mounted on tractors

Rice. An excavator mounted on a Belarus tractor.

Rice. Tractor excavator of foreign production.

A tractor is used as the base chassis, most often a wheeled one. Non-rotary excavator equipment is installed behind (rarely on the side) of the tractor, on a special frame. The most common are excavators mounted on class 1.4 tractors. The characteristic volume of the bucket is 0.2-0.5 m³. They are used to perform small excavation or loading operations, most often during the repair of engineering networks. The design of the working equipment allows you to quickly rearrange the bucket for work with a front or back shovel. The bucket can be replaced by a grab, cargo fork or hook. The engine of the base tractor is used for the drive. The drive of the working equipment is hydraulic. Due to the relatively high speed, they can quickly arrive at the place of work, located at a distance of 20-30 km from the base. A tractor with mounted excavator equipment can also be used for transport and bulldozer work.

b). On a car chassis

Rice. Excavator EOV-4421 (Cuirassier) on the KrAZ-255 chassis.

Rice. UDS excavator on Tatra-141 chassis

A truck is used as the base chassis, most often with off-road capability. They have a high speed of movement. They are used in cases where high mobility is required: in military affairs (engineer troops, road troops), in rescue operations, in the construction of roads, cleaning canals. The working equipment is predominantly a backhoe. Excavators are produced with a telescopic boom and a swivel bucket, which allows you to quickly switch from a front shovel to a back shovel. For the drive, both the engine of the base vehicle and a separate engine mounted on a turntable can be used.

V). Pneumatic

Rice. Modern pneumatic wheel excavator

with hydraulic drive.

Rice. Pneumatic wheeled excavator of the 50s - 60s with a cable drive

Excavators have their own special chassis, based on wheels with pneumatic tires. They are most often performed in full rotation. To increase stability and prevent slipping when loading the bucket, they have outriggers. They have speeds up to 30 km/h. Can be towed by trucks at speeds up to 40 km/h. Passability on soft soils is limited. They are produced in a wide range of size groups - from micro-excavators with a bucket volume of 0.04 m³ to heavy wheeled excavators - with a bucket volume of up to 1,5 m³. Due to the specifics of the work performed: the development of pits, trenches, planning work - working equipment - mainly a backhoe. Can be used with a grab, jaw gripper, hydraulic hammer for loosening the soil. They are widely used in the performance of various types of construction and repair work.

The chassis wheels can be driven both from the engine of the working equipment through mechanical or hydraulic transmissions (hydraulic motors), and from a separate engine.

G). Tracked

Rice. Modern crawler excavator

Rice. The DEMAG Bagger excavator is one of the largest in its class

Excavators have their own special chassis with caterpillar propulsion. Performed in full rotation. They have high cross-country ability and low specific pressure on the ground with a large mass. They can work on weak and waterlogged soils, including peat extraction. They have a travel speed of 2-15 km / h. They are transported to the place of work by tractors on special trawls.

The working range of bucket volumes is very wide: from mini excavators with bucket volume 0,04 m³ up to quarry with bucket volume 10 m³. There are also extra heavy mining crawler excavators with bucket capacity 26 m³ manufactured by DEMAG (Germany).

Working equipment: straight shovel, backhoe, dragline. Can be used with grapple, jaw grab, hydraulic hammer for loosening the soil. They are widely used in construction and mining. A number of models of caterpillar and pneumatic wheel excavators have a unified turntable and working equipment.

D). Walkers. Walking excavator - a walking excavator, usually with dragline equipment. The use of a hydraulic walking (as opposed to caterpillar) propulsion system allows to reduce the load on the ground (the mass of machines can reach hundreds or even thousands of tons) and increase reliability.

Rice. Walking excavator:

A- general form; b- type of running gear.

The turntable with the equipment of the walking excavator is installed on the base plate. Paws are connected to the turntable, which are raised during excavator operation (do not touch the ground). When moving the excavator, the paws rest on the ground. In this case, the base plate is lifted off the ground. The excavator moves one step forward (backward movement is possible for some models). After that, the paws rise and return to their original position. On a walking course, large mining excavators with a bucket volume are produced 15 m³ - 40 m³ and arrow reach 65 m - 150 m. Working equipment - dragline. Walking excavators carry out overburden operations (clearing mineral deposits from waste rock), as well as mining and moving them to a dump (up to 40 m). Loading of minerals by walking excavators into vehicles cannot be carried out.

e). Railway.

A railway platform is used as an excavator chassis. They are used for repair work on the railway. They have a bucket volume of up to 4 m³. The turntable and equipment are often unified with crawler excavators.

and). Floating.

Rice. Floating single-bucket excavator - dredger.

Working equipment (dragline or clamshell) is installed on the pontoon. They are used for loading and unloading operations, extraction of sand, gravel from reservoirs, dredging and dredging. From floating cranes equipped with grabs, floating excavators differ in their lower height and simplified boom design.

By engine type.

A). Steam excavators - a steam engine is used as an engine. They were common at the beginning of the 20th century. Not currently released. The torque-speed characteristics of the steam engine and the working equipment of the excavator are well matched, which simplifies mechanical transmissions.

Rice. Steam shovel.

b). Excavators with internal combustion engines are the most common type. The excavator has its own engine, most often diesel. This ensures autonomy. The power range of engines installed on modern excavators is very wide (see size groups).

The torque-speed characteristics of the internal combustion engine and the working equipment of the excavator are inconsistent. This requires the use of matching gears (gearboxes, torque converters) on mechanical excavators. For hydraulic excavators, coordination is provided by hydraulic transmissions.

V). Electric excavators - to drive the working equipment, electric motors are used that receive energy from an external network or from their own diesel-electric unit. An electric drive powered by an external network is used for mining excavators. Such excavators are economical and do not pollute the atmosphere of the quarry. An electric drive powered by its own diesel-electric unit is used in floating excavators.

G). Excavators operating in an explosive environment (in mines) do not have a prime mover. Their hydraulic equipment is fed with high pressure fluid from an external oil station.

By type of mechanical gears (drives of working equipment):

A). With group mechanical rope drive (mechanical);

Mechanical excavator winches.

Traction force to the working bodies is transmitted by means of ropes (or chains) driven by winches. The drive of the winches is carried out from the excavator engine by means of mechanical gears (gear, chain, friction, worm).

The universal mechanically driven excavator is equipped with a three-drum winch. The winch boom drum is used to drive (raise and lower) the boom. The lifting drum is used to raise the bucket (or return the arm when backhoeing). The traction drum is used to pull the bucket to the excavator (when working with a dragline, backhoe). When working with a straight shovel, the traction drum is connected to the handle pressure mechanism.

Mechanical rope drive has been widely used on excavators in the past. In modern models, its use is reduced for the following reasons:

Excavators with a mechanical cable drive have a complex structure and contain a large number of wear parts (friction linings, brake bands, ropes).

The rope drive provides a limited number of independent movements of the elements of the working equipment;

It is technically difficult to make a rope drive automated;

The cable drive does not provide complete fixation of the elements of the working equipment in a given position.

On modern models, a mechanical cable drive is used only for dragline or grab.

Rice. Mechanical excavator winches

b). With individual electric winch drive (electromechanical);

Traction force to the working bodies is transmitted by means of ropes (or chains) driven by winches. The drive of each winch and auxiliary mechanisms is carried out by an individual electric motor. Such a drive is used on heavy mining (including walking) and industrial excavators.

V). With hydraulic drive;

In excavators with a hydraulic drive (hydraulic excavators), the force on the elements of the working equipment is created by hydraulic cylinders and hydraulic motors. The excavator engine drives the hydraulic pump, which creates the pressure of the working fluid in the pressure line of the hydraulic system. Through a system of hydraulic distributors, the cavities of hydraulic cylinders (hydraulic motors) are connected to the working or drain lines of the hydraulic system, which ensures the movement of working equipment. In the neutral position (with the cavities of the hydraulic cylinders locked), the position of the working equipment is fixed. For transporting the excavator with the help of a tug, it is possible to transfer the boom hydraulic cylinder and the hydraulic motor of the turning mechanism to the neutral transport (“floating”) mode.

Indexing.

The structure of the index of single-bucket universal excavators.

The numerator indicates the mass of excavators mounted on a tractor.

Specifications.

Table 1

The main characteristics of single-bucket universal excavators of the 2nd–4th size groups

Device. The excavator can be of various designs, depending on the purpose.

Working equipment- these are the machine components with which the excavator directly digs the soil (bucket, boom, handle with their drive system). In these cases, the type of undercarriage of the machines also plays a certain role: is the excavator equipped with a caterpillar drive or does it have a pneumatic wheel undercarriage that allows you to quickly move the machine from object to object. Also important is the possibility of turning the working equipment, or, in other words, the presence of a turntable, which creates ample opportunities for unloading soil and other work. Accordingly, the features of specific types of earthworks that need to be performed by an excavator, the use of excavators with certain working equipment, chassis and type of drive.

Fig.a. Excavator working equipment - backhoe:

1 - swivel frame 2 - driver's cab; 3 And 4 - the lower main and upper extension parts of the boom; 5 And 6 – hydraulic cylinders of the arm and bucket; 7 - handle ; 8 – bucket lever; 9 - bucket; 10 - traction; 11 – boom hydraulic cylinder; 12 - arrow;

Fig.b. Excavator working equipment - straight shovel:

1 - arrow; 2 - handle; 3 - traction; 4 - bucket tooth; 5 - bucket; 6 – bucket bottom loop; 7 -10 - hydraulic cylinders; I- II– position of the digging bucket.

A d e n c e

Working equipment of a single-bucket excavator.

Working equipment of single-bucket excavators - a set of working equipment of a single-bucket excavator.

The basic machine of a shovel excavator provides the operation of various working equipment. The latter can be performed interchangeably. The working equipment for digging the soil is called the main one, and the working equipment for performing other operations is called additional.

Basic working equipment.

A). straight shovel

Rice. Diagram of the working cycle of a hydraulic front shovel excavator.

Rice. A mining excavator with a straight shovel and a cable drive.

straight shovel- the main working equipment for the development (digging) of soil above the level of the excavator parking. The straight shovel bucket is fixed on the handle. The handle, in turn, is hinged to the boom. The boom is hinged on the turntable of the machine. In hydraulic excavators, the bucket on the handle is movably fixed - the bucket is unloaded by tipping it over with the help of a hydraulic cylinder. For mechanical excavators, the position of the bucket relative to the handle does not change during operation - the bucket is unloaded when its bottom is opened. Digging the soil in the direction from the excavator. A straight shovel provides the highest digging force and the highest productivity (due to the minimum number of operations in one digging cycle). It is used for mining and loading operations.

The duty cycle of a front shovel excavator consists of the following operations:

Platform rotation - after loading the bucket, the platform with the working equipment of the excavator is rotated. The bucket moves to the place of unloading. Its position relative to the turntable of the machine does not change.

Raise the boom - before unloading the bucket, raise the excavator boom to increase the loading height.

Bucket unloading - on hydraulic excavators is carried out by turning the bucket relative to the handle (tilting). On mechanical excavators, the bottom of the bucket is opened.

B). Backhoe

Rice. The scheme of operation of a hydraulic backhoe excavator

Backhoe- the main working equipment for the development (digging) of soil below the level of the excavator parking. It is used when digging pits, trenches, when planning slopes and filling embankments. Can be used for loading operations. When working with a backhoe, the soil is dug in the direction of the excavator. Hydraulic backhoes can excavate the ground and above the level of their parking lot, though with less efficiency than a straight shovel.

Depending on the type of drives used, the working cycle of the backhoe varies.

For hydraulic excavators with independent boom, bucket and stick drive:

A). Deepening the boom into the pit with simultaneous positioning of the handle;

V). Deepening of the boom with simultaneous turn of the handle and turn of the bucket to prevent soil spillage.

e). Unloading the bucket by turning it relative to the handle.

For mechanical excavators with 2-rope arm drive, dependent boom position and fixed bucket position:

A). Deepening the boom and handle into the pit (performed by releasing the lifting rope);

V). Deepening the boom and handle from the pit (performed by pulling the hoisting rope with the traction rope stretched and braked);

G). Rotation of the platform with working equipment;

e). Bucket unloading by turning the handle relative to the boom in the direction from the excavator (performed by tensioning the lifting rope while unwinding the hauling rope).

The backhoe is the most versatile piece of work equipment. Provides high accuracy of positioning of the bucket, both relative to the ground and relative to the vehicle into which the soil is loaded.

IN). Excavators with bucket rotator.

A number of excavator models, for example, UDS-114 (made in Czechoslovakia), are equipped with a bucket overturning device (rotator), which allows you to quickly switch from front shovel to back shovel mode.

G). Slope planner.

A kind of backhoe designed for planning slopes in road, land reclamation and landscape construction. The slope planner ensures that the cutting edge of the bucket moves relative to the ground in a straight line directed at a given angle to the horizon. To do this, an automated control system (hydraulic or electronic) is installed on the hydraulic excavator, which ensures the coordinated movement of the boom, stick and bucket. Telescopic boom excavators have been used as slope planners.

The plow is also used for planning work. Mounted on mechanical excavators. It is an arrow along which a trolley moves with a rope, with a bucket fixed on it. The gliding angle is determined by the angle of the boom. The direction of digging with a plow can be changed by rearranging the bucket relative to the cart.

E). Dragline.

Dragline - working equipment with a bucket flexibly suspended on ropes. It is used for excavation of soil below the level of the excavator parking lot. The soil is being dug towards the excavator. It is used in the development of pits, filling embankments, mining, dredging on reservoirs.

The dragline has the largest radius and digging depth, as well as the highest loading height compared to other types of working equipment.

To work with the dragline of a hydraulic excavator, a double-drum main winch driven by a hydraulic system is installed on it.

Re-equipment of the base machine of a mechanical excavator is not required when working with a dragline.

AND). Grab.

The grab is used to develop narrow deep pits (wells), perform loading and unloading operations. Grabs can be equipped with both hydraulic and mechanical excavators.

For hydraulic excavators, the grab is fixed on the handle instead of the bucket and has a hydraulic jaw drive. The grapple can also be mounted on a pressure rod, which ensures its penetration into the pit by 6 meters (for excavators manufactured in the CIS) or more. The pressure rod is a telescopic boom mounted on an excavator instead of a handle.

For mechanical excavators, the grab is suspended on ropes.

Rice. Double jaw grab

Rice. Grab excavator

Z). Additional working equipment:

Ripper;

Rice. KOMATSU excavator with ripper

Replaceable working equipment designed for loosening hard (frozen) soil, destruction of building structures, asphalt concrete pavement.

The ripper for mechanical excavators is a monolithic steel load, the lower part of which is made wedge-shaped or peaked. Hanging on a rope. During operation, the ripper rises due to the tension of the rope to a height of about 3-6 meters and freely falls to the ground (with the rope released). The mass of the wedge ripper, depending on the size group of the excavator, is 0.5 - 6 tons.

On hydraulic excavators, a hydraulically driven hammer-ripper is installed. The principle of its operation is similar to a jackhammer. Mounted on instead of bucket.

A diesel hammer mounted on an excavator boom can be used as a ripper.

pile driver;

Rice. Piling excavator

Crane;

Due to the fact that the base machine of the excavator and the crane have a similar design, a number of excavator models can be equipped with crane equipment. Since the speed of the vertical movement of the load at the crane must be several times less than the lifting speed of the excavator bucket, the lifting rope is stored through the chain hoist.

Manipulator;

Rice. The CATERPILAR excavator with a manipulator carries out dismantling work with the help of shears for cutting reinforced concrete

The manipulator is a grab mounted instead of a bucket, used for assembly and dismantling. Currently, a number of firms in Russia and abroad produce special manipulators based on single-bucket excavators. Such machines have a longer reach than excavators and a more complex hydraulic system that provides gripper positioning in three planes.

Stump grinder;

Excavator with hydraulic crusher;

Fig. Excavator with hydraulic crusher

Single bucket excavators can be used for uprooting stumps. On hydraulic excavators, for this purpose, a jaw gripper is installed instead of a bucket (see article grapple). For uprooting, the grip is brought to the stump, the jaws are spread, they are buried in the ground, under the root system of the stump. Next, the jaws of the capture are reduced and, by raising the arrow, they pull out the stump. The whole process is controlled by one driver.

When uprooting stumps with mechanical excavators, a special anchor is attached to the traction and lifting ropes. The excavator driver brings the anchor to the stump, and the assistant manually deepens the arm of the anchor under the root of the stump. After that, the tension of the traction rope is carried out with a weakened lifting, while the anchor is hooked on the stump. By simultaneously pulling two ropes, the stump is pulled out.

Job. Single-bucket excavators (they are sometimes called cyclical excavators) all operations for digging the soil, moving it and unloading it are performed sequentially and cyclically: first, the bucket is filled with soil, then the loaded bucket is turned, at the end of the turn, the soil is unloaded from the bucket (into a dump or vehicles) and , finally return the empty bucket to its initial position for loading. Then this cycle of operations is repeated.

Bucket excavators (also called continuous excavators) perform all the work of digging, moving and unloading the soil at the same time. While some of the buckets or knives are cutting the soil, others are moving it, and still others are unloading it. During the operation of these machines there is no pronounced repetitive cycle of work operations.

However, seam excavators have become more widespread in the construction

evidence than multi-bucket, due to the fact that they have greater versatility. Versatility is the ability of an excavator to perform a variety of earthworks, ranging from the construction of trenches, pits, channels and ending with embankments and dams, as well as loading and unloading. Of course, the excavator can do all this only with the help of various interchangeable working equipment.

The working area of the excavator, including the parking lot of vehicles, is called slaughter , movement of the excavator during excavation - sinking . Downfalls are:

Frontal (when using a backhoe - end),

And side ones.

Passages are:

longitudinal,

And transverse.

Depending on the number of penetrations along the height of the excavation, one -, two - and three-tier excavation is distinguished.

The working cycle of an excavator has five main operations:

1.set of soil;

2.moving the bucket;

3.unloading the bucket into a dump or vehicle;

4.reverse turn for ground set;

5. lowering the bucket for the subsequent set of soil.

To reduce the cycle time, excavators combine the fourth and fifth operations when loading soil into a vehicle, and the second and third operations when dumping soil into a dump.

The productivity of the excavator and other earth-moving and earth-moving machines can be increased as a result of the following measures:

Shortening the excavation cycle;

Combining work operations;

Decreasing the angle of rotation of the boom during unloading;

Loosening the soil during breaks in the supply of transport, etc.;

Increase in the volume of soil developed in one cycle;

In the case of using buckets of increased capacity, their more complete filling ("with a cap"), etc.;

Increasing the coefficient Kv in the process of reducing downtime (timely implementation of preventive maintenance, presentation of the front of work, delivery of fuels and lubricants, etc.).

Production of works by excavators.

Rice. Schemes of the faces of the excavator with a straight shovel:

A- frontal slaughter; b - side cut.

Rice. Scheme for calculating the dimensions of the face of an excavator with a straight shovel:

ABOUT- standing point of the excavator for the development of the face element; ABOUT 1 – parking of the excavator after moving by the amount l n /

table 2

Fig. Schemes for the placement of longitudinal penetrations in the excavation:

A - radiant; b - parallel; V - combined (broken);

1 – pioneer trench; 2, 3, 4, 5, 6, 7 - penetrations.

Rice. Breakdown of the cross section of the excavation into penetrations:

1 – axis of movement of the excavator; 2 – axis of movement of vehicles.

An excavator is a specialized mechanism for excavating soil. Area of use: construction industry, mining, irrigation.

Classification of earthmoving equipment

The excavator fleet is distinguished by characteristic features - dimensions, power, purpose and other technical parameters.

Chassis type

There are several main groups:

caterpillar;
walking;
wheeled;
rail;
floating;
combined chassis.

By mode of operation

Depending on the nature of the work, all earth-moving mechanisms are divided into two large classes.

Continuous Excavator

It has several buckets in its design, which allows it to simultaneously perform excavation and soil moving operations.

Good to know! The development of the rock can be carried out in a horizontal, vertical plane, in a circle.

Used on homogeneous soils. Their use is limited to the arrangement of recesses, where relocation of waste land to the surface is required. With their help, the device of ditches, trenches, channels is made. They are divided into rotary and chain. The executive body of the first group is a rotating wheel on which buckets are placed.

On chain excavators, they are fixed on a movable structure, which is a set of rippers, cutting elements, sump scrapers.

The presence of a significant number of buckets ensures the continuity of the process, optimizes the necessary efforts, reduces loads, and increases the productivity of earthworks.

The trenches are rectangular, in the form of a trapezoid, stepped and reach a depth of 4 m with a width of up to 2 m. The dump soil is stored away from the trench.

Chain-bucket trench excavators are used in areas of occurrence of soft soils of the group without the presence of large inclusions. Rotary modifications are used for overburden work in open pits.

Cyclic excavator

Equipped with one bucket. Development and excavation is carried out sequentially. Mechanisms of this design are used in mixed soils with stone inclusions of hard rocks. They represent a more unified segment of equipment compared to the multi-bucket version.

By operational purpose

Earthmoving equipment is divided into groups:

career;
overburden - for operation in places of surface mining and hard rocks;
mine combines - for underground work;
construction universal.

Working body drive model

It has several modifications:

hydraulic systems - the most numerous category, and the main advantage lies in the ability to actively use attachments in the form of hydraulic hammers, punches, specialized grippers, punchers;
diesel-electric machines - weight from several tens to hundreds of tons;
electric drive units - super excavators powered by power lines.

For power equipment

The choice of engine depends on the conditions in which the mechanisms will be operated. In quarry equipment, electric motors are more often used. This is due to the relative cheapness of electricity. When constructing highways, it is rational to use diesel plants.

If the actuators of the excavator are driven by one engine, such a drive is called a single-engine drive, and if there is a separate power plant for each group of equipment, it is called a multi-engine drive.

Features of single bucket excavators

The most common class. Their grouping has its own principles and a number of features.

Size class index

number 0-8: from extra light to extra heavy - weight from 3 to 160 tons;
by power; 10 - 800 hp;
bucket volume: 0.1 - 10 m 3.

Equipment heavier than class 8 refers to super-heavy specimens. Designed for individual orders.

By type of construction carrying the bucket

The swinging mast is a rigid element. A bucket is attached to it with cables. The turning of the working body is carried out using a system of steel ropes. Such a scheme is called a dragline. It is used on models of walking excavators, which are used in overburden and mining operations. The grapple of floating options and loaders is also suspended from masts.
The telescopic boom is similar in design to the boom of truck crane installations. Rarely used. It is used on excavators where there is no need to provide increased rigidity of the boom element during work.
The articulated boom is characterized by an increased coefficient of strength and mobility. It is applied on heavy samples of excavators.
Breaking boom - used in tandem with a hydraulic drive on most universal excavators.

By type of working body

A simple bucket (option - the presence of a folding bottom).
Straight shovel - for excavating soil above the horizon of the excavator.
Backhoe - equipment for developing the soil below the mechanism when arranging pits, trenches, excavations.
Grab - consists of two halves, which are lowered to the ground, and when lifted, they grab the ground and slam shut. It is applied on friable, loose categories of the soil.
Dragline (dragline) - cuts off the ground when pulled tangentially to the ground plane.

small mechanisms

A typical representative of this class is a compact shovel crawler excavator with a breaking boom and a hydraulic drive system. Total weight up to 1500 kg with bucket up to 0.15 cu. m. The dump is not completed, but they have a solid set of additional. equipment.

Helpful information! There are babies, with an engine up to 50 cm 3 .

Due to their cost-effectiveness, versatility and ability to work in cramped conditions, they are gaining popularity in construction. Today, there is a growing demand for earthmoving machines with a small bucket on pneumatic wheels, which have increased maneuverability for rapid relocation from one site to another.

Giant excavators

Narrow-profile tasks for specialized equipment served as an impetus for the creation of super-powerful prototypes. This applies to walking excavators. For the chassis, a base plate is used, which moves along the platform with the help of hydraulic motors. The excavation equipment placed on it has a unique performance. A vivid example is single-bucket draglines with a bucket volume of up to 100 m 3. The length of the boom varies up to 130 m. It is worth noting the rotary modifications, in which the working body is in the form of a wheel with a set of buckets with a diameter of up to 18 m. The depth of excavation reaches 45 m, and the height is 38 m. working dimensions allow for a wide coverage of the treated area. The average travel speed is up to 450 m per day.

Technical help! Similar samples were created in the 80-90s and function to this day. This testifies to the reliability of such excavators.

A feature of walking earth-moving equipment is the combination of the properties of cyclic machines and multi-bucket models.

Results

A rich set of types of excavators with a specific mode of operation, the type of power unit, the nature of the technological equipment makes it possible to choose the appropriate modification for the development of soils of categories 1-6 and various algorithms of use.

The article was prepared by the specialists of the company "Sphere". Information about

Classification of single-bucket excavators construction machines. Types of excavators: endless variety

Send your good work in the knowledge base is simple. Use the form below

Similar Documents

Application of excavators

Main working equipment of excavators

straight shovel

Backhoe

grapple

Replaceable working bodies

Differences between full-revolving excavators and non-revolving excavators

Classification of excavators depending on the type of chassis

Tractor based excavators

Excavators on a car chassis

Pneumatic excavators

Crawler excavators

Other models of excavators

Power units mounted on excavators

Classification of excavators depending on the drive of working equipment

Hydraulic excavators

Mechanical excavators

Electromechanical excavators

The main modern manufacturers of excavators

The structure of the index of single-bucket universal excavators.

The main characteristics of single-bucket universal excavators of the 2nd–4th size groups

Continuous Excavator

Cyclic excavator

Features of single bucket excavators

Giant excavators

Send your good work in the knowledge base is simple. Use the form below

Similar Documents

Application of excavators

Main working equipment of excavators

straight shovel

Backhoe

grapple

Replaceable working bodies

Differences between full-revolving excavators and non-revolving excavators

Classification of excavators depending on the type of chassis

Tractor based excavators

Excavators on a car chassis

Pneumatic excavators

Crawler excavators

Other models of excavators

Power units mounted on excavators

Classification of excavators depending on the drive of working equipment

Hydraulic excavators

Mechanical excavators

Electromechanical excavators

The main modern manufacturers of excavators

The structure of the index of single-bucket universal excavators.

The main characteristics of single-bucket universal excavators of the 2nd–4th size groups

Continuous Excavator

Cyclic excavator

Features of single bucket excavators

Giant excavators

Read also