Classification of backhoe loaders and their application. Structure of the index of single-bucket universal excavators Single-bucket excavators classification general structure

10.06.2021 Insulin

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Excavator types: endless variety

Excavation work is one of the most time consuming and most necessary of all times. Machines equipped with a special working body for digging - a bucket and designed for excavation and movement of soil and / or minerals, have been known since ancient times; they were designed by Archimedes. The Romans called them excavators, from excavao - to hammer, make a cavity, a deepening.

During the time of the Great Leonardo, the excavator was not a brilliant insight - their use in fortification and for clearing and deepening canals in Venice was common. The excavators of that time were powered by human power or draft animals. The idea of an excavator was brought to the East by Marco Polo, for which he earned the special favor of the fifth great Mongol kagan and at the same time the first emperor of the Chinese dynasty Yuan Kublai.

The first excavator with a mechanical - steam - engine was manufactured by the American engineer James Otis in 1843. Otis was a direct descendant of one of the "fathers of the nation", also James Otis, who put forward the principle: "There are no taxes without representation", under which he began War of Independence of the United States.

The Otis excavator had a capacity of 15 hp, giving a productivity of 40-50 cubic meters. m per hour (which is very, very good for such a power and according to modern concepts) and replaced 50 experienced strong excavators. One of the first excavators survived, in a rather damaged condition, and is exhibited in the museum.

The first steam excavators immediately found application on the then construction sites of the century: the Suez Canal and the Nikolaev railway in Russia. However, government contractors were not happy with them: serf workers and prisoners-convicts were cheaper. All 4 machines were sold to the Urals by Demidov in 1848, where they immediately showed high efficiency in stripping operations. It was the appearance of Otis excavators in the Urals that gave impetus to the development of heavy engineering there.

Excavators today

Now the excavator is the most widespread, the best-selling and the most cost-effective type of special equipment. There are excavators that four adult men can carry with their hands, and excavators make up the three most ambitious land vehicles. By the way, the widespread opinion that the largest excavators are walking ones is incorrect. All three mechanical titans: Bagger 288, Bucyrus-Erie 1850-B "Big Brutus" and Marion 6360 "Captain" are self-propelled tracked vehicles, the latter two being single-bucket vehicles. "Captain" is already retired, but still alive - exhibited in the technical museum of Arkansas, and "Bagger" and "Brutus" are still working. The lightest of them pulls 12 thousand tons.

Excavators perform a wide variety of jobs in a wide variety of conditions. All types of excavators are hardly known even to an experienced mechanical engineer. Have you heard of special excavators for removing the top fertile soil layer? About underground excavators? About underwater bottom excavators? All of these exist and work.

Nevertheless, the absolutely dominant species of mighty, obedient and useful "Exkazavrs" are universal construction excavators, single-bucket, with a hydraulic drive, a breaking boom, on caterpillar or pneumatic wheels. They are primarily associated with the word "excavator".

Universal excavators are most often equipped with a bulldozer blade and then they are a bulldozer excavator. Often, instead of a blade, a reloading bucket can be hung on a fork moving in a vertical plane. Then you get a backhoe loader. There are also special backhoe loaders, which have no other business how to rake in the front and toss them behind their backs.

Excavator classification

To describe all types of excavators and "put them on the shelves" would have puzzled Linnaeus himself. Excavators are divided into types according to different criteria, and it should be noted that each specific machine is present in several of them.

By appointment

Universal ones have already been described.
Backhoe loaders - with a dumping bucket-box (described above), with a shovel-one-piece and with a folding bottom, with a grab, with a conveyor and a metering hopper. Backhoe loaders differ from others in that they pour out a portion of soil measured by weight or volume, which does not exceed the carrying capacity of the collection facilities.
Quarry - overburden and mining.
Special - railway, swamp, rescue, excavator-destroyers, underground, underwater, etc., etc.

By mobility

Self-propelled - they can independently move from object to object.
Semi-self-propelled - they can move themselves within the working area.
Restricted self-propelled - can move along specially laid paths, for example. on railroad tracks.
Fully revolving.
Part-turn.

By type of chassis

Note 1: airlift is a device for lifting soft and loose soil from great depths. Air is blown into the pipe near its lower end, the bubbles pull water along with them, and the resulting suction draws in the soil. The deeper the airlift, the more effective it is. For the development of deposits of iron-manganese nodules in the Pacific Ocean, airlifts have been developed with a working depth of up to 6 km. The pipe is supported by the belts of the floats so as not to break.

By drive of the working body

Mechanical are almost a thing of the past.
Hydraulic are the most common.
Diesel-electric - heavy and very heavy autonomous.
Electric - superheavy powered by power lines.

By duty cycle

Continuous action - rotary multi-bucket, with a disk or cylindrical (frontal) cutter, with a toothed chain (trench).
Cyclic action (single bucket).

Classification of single bucket cyclic excavators

Single bucket excavators are the most widespread, the most numerous, the most versatile and the most diverse at the same time. They are, so to speak, a kingdom within a kingdom. Therefore, their classification is the subject of a special discussion.

By size group number

0 - extra light: up to 3 tons, 10-40 hp, bucket up to 0.1 cubic meters.
1 - light-1: 5-6 tons, 30-50 hp, 0.15-0.4 cubic meters.
2 - light-2: 8-9 tons, 40-60 hp, 0.25-06 cubic meters.
3 - medium-1: 10-12 tons, 50-80 hp, 0.3-1.0 cubic meters.
4 - medium-2: 19-30 tons, 80-130 hp, 0.65-1.6 cubic meters.
5 - heavy-1: 30-40 tons, 100-200 hp, 1.2-2.5 cubic meters.
6 - heavy-2: 55-60 tons, 200-350 hp 1.6-4.0 cubic meters
7 - especially heavy-1: 80-100 tons, 300-500 hp, 2.5-6.3 cubic meters.
8 - especially heavy-2: 100-160 tons, 400-800 hp, 5-10 cubic meters.

Excavators heavier than group 8 are considered super heavy and are designed according to individual specifications.

By type of load-bearing bucket structure

The swinging mast is a rigid openwork construction. Most often, a trailing bucket is suspended from the mast on cables. The bucket is also tilted with ropes. This design is called a dragline. It is used in open-pit mining excavators, overburden and mining excavators. But the grab of a floating excavator or backhoe loader can also be suspended from a mast.
The telescopic boom is designed similarly to the boom of a truck crane. It is rarely used in excavators, where an increased rigidity of the boom is needed with a monotonous nature of work.
Articulated boom. This is what Otis used. Bulky, heavy, but strong and mobile. It is used in heavy and extra heavy machines.
Breaking arrow. In combination with a hydraulic drive, they are used in most universal excavators.

By type of working body

Ladle.
Drop-bottom bucket.
The bucket is a straight shovel.
Bucket - Backhoe.
Grapple.
Transfer bucket (box).

Note 2: The bucket digs into the ground, the shovel bucket rakes it in. The grab, consisting of two hinged halves, is lowered open to the ground, when it is lifted, it grabs the ground and slams. The grab is used on loose and liquid soils. The box rakes in the already loosened soil from the side.

Mini excavators

A typical mini-excavator is a single-bucket crawler excavator with a breaking boom and a hydraulic drive of the working body, weighing up to 1.5-1.7 tons, with a 10-20 hp engine. and a bucket up to 0.15 cubic meters. m. Even if they are equipped with a bulldozer blade, it is “just for the sake of it”: the tractive effort is not enough for bulldozer work. But they are equipped with an extensive set of additional equipment (see below).

Among the mini and very little ones, with an engine up to 50 cc. To manage such, you do not need permits, rights, tractor driver's licenses. I bought it and use it.

Despite the difficulties of transportation (traffic rules do not allow any tracked vehicles on public roads with a hard surface), mini-excavators, due to their economy, versatility and ability to work in the most cramped conditions, are becoming increasingly popular in small-scale construction.

What else can an excavator do

On many excavators with a working hydraulic drive, instead of a bucket, you can attach a hammer, a hydraulic hammer, shears, auger, forks, clamp / gripper, rippers, chisel, etc. So the breaking boom shovel is an amazingly versatile machine.

Excavators - purpose and classification

Excavators (the name comes from the Latin words "ex" and caveo ", meaning" digger ") are distinguished by their high loosening ability. Their transporting capacity is small and is determined by the range of these machines. Excavators are divided into several groups according to purpose and power. If a machine performs all operations in a certain order, repeating them at some intervals of time, it refers to machines of intermittent (cyclic) action, if it performs all operations at the same time, it is a continuous action machine. Discontinuous excavators include single-bucket excavators, and continuous excavators - multi-bucket, scraper and milling excavators.

Single-bucket and multi-bucket excavators are land-based and floating. Land excavators are equipped with caterpillar, pneumatic, rail and walking undercarriage.

All excavator mechanisms are driven by diesel, carburetor, steam or electric motors. The most economical are diesel and electric motors. 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 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 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 motor, such a drive is called multi-motor.

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; - hydraulic volumetric, where the role of the drive is performed by a hydraulic pump, oil pipelines and hydraulic motors (or hydraulic cylinders); fluid circulates in the oil pipelines, transferring energy from pumps to hydraulic motors (or hydraulic cylinders), which set 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-motor drive in combination with a mechanical one; - mixed, consisting of two types of drives, for example, mechanical and electrical.

Thus, excavators are classified: - by the way of movement (floating and land); - by the type of power equipment (diesel, carburetor, electric, diesel-electric, etc.); - by the number of engines (single-engine, multi-engine); - by type of drive (mechanical, hydraulic, hydromechanical, electrical); - by the type of undercarriage of land excavators (tracked, pneumatic, rail and with walking undercarriage).

Each of the groups of excavators is distinguished by smaller features - size, power, purpose.

Single bucket excavators are classified by purpose.

There are three main groups: - construction-universal - with buckets with a capacity of up to 3 m3, intended for earthworks; - open pit - with buckets with a capacity of 2 to 8 m3, intended for work in open pits on the development of ore and coal deposits; - overburden - with buckets with a capacity of more than 6 m3, intended for the development of 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 replaceable equipment; shovel, shovel, dragline, crane boom with hook suspension or grab, pile driver, etc.

Semi-universal excavators, in addition to the main working equipment, have one or two types of additional replaceable equipment (front shovel, back shovel, dragline).

Special powerful excavators have only one type of equipment, for example, a straight shovel.

Single bucket excavators. A single-bucket universal excavator is a cyclical machine designed for excavating and moving soil and other materials using one of the types of working equipment with one bucket, and for performing loading pile driving and other works with other types of replaceable working equipment.

Single-bucket excavators (Fig. 72) consist of the following main units: undercarriage, turntable with power equipment and main kinematic links and working equipment.

Crawler undercarriage provides high maneuverability and good stability during excavator operation.

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

Rice. 72. Scheme of a single bucket excavator

Rice. 74. Scheme of work of a straight shovel

The slewing platform is supported through rollers or a special (ball or roller) slewing support on the chassis frame. The platform pivots in a horizontal plane relative to the chassis.

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 swivel part of a full-revolving excavator can rotate around its axis through 360 °.

These machines have all the power units, control panel, working mechanisms mounted on a turntable, and working equipment is attached.

The working equipment includes a complex of units of an excavator with a working body (bucket, hook, grab, etc.). The soil is mined 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: a front shovel, back shovel, dragline, crane or grab.

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

Indexing system for single-bucket universal excavators. The machine indexing system is a principle that is incorporated into the structure of the index (brand), designating a particular excavator and reflecting its main characteristics. In 1968, a new indexing system for single-bucket universal excavators was introduced in our country. The excavator index has four main numbers, respectively denoting: the size group of the machine, the type of chassis, the design of the working equipment and the serial number of the model of this type. Thus, the excavator index contains information about its main characteristics. So, EO-3313 BTV is a universal single-bucket excavator, of the 3rd size group, on a pneumatic wheel running device, with a rope suspension of working equipment, the 3rd model, which has undergone the second modernization, is designed for work in the humid tropics.

A straight shovel is an equipment designed for excavation of the soil above the level of the excavator parking lot. A straight shovel with a mechanical drive (fig. 74) consists of the following main units: a rope for lifting the boom, bucket, stick, boom, saddle bearing. The handle is attached to the arrow by a saddle bearing, with which the handle rotates in a vertical plane relative to the boom and reciprocates along the axis of the handle. When digging the soil, the bucket needs to go through the -IV positions shown in Fig. 74. The bucket is lifted by a hoisting rope that bends 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.

The thrust mechanisms are divided into independent, dependent, combined - The thrust mechanism is called independent if the thrust force can be increased or decreased regardless of the force in the bucket lifting cable, i.e. when the thrust movement of the handle with the bucket is performed independently of the bucket lifting. If the magnitude of the head force depends on the magnitude of the force in the lifting / mnom rope of the bucket and it is only possible to reduce the head, 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 the independent part of the pressure mechanism is turned on, it can be increased at will.

The shovel bucket consists of a body, a hinged bottom with a deadbolt and replaceable teeth. The teeth have a shank tapering towards the end that fits into the socket of the visor. The teeth are kept in the seats with cotter pins from falling out.

In recent years, straight shovels have been equipped with buckets with a semicircular front wall and with a visor in the form of a scoop without teeth. A bucket of this design is much lighter and has minimal resistance when digging the ground, which, of course, increases the productivity of the excavator.

On excavators with a front shovel, two types of handles are used: single-girder (internal type) and double-girder (external type). The single-boom stick runs inside the boom and the double-bar stick runs outside. The handle can make a reciprocating motion in the guides of the saddle of the pressure shaft, and also rotate together with the saddle bearing in the vertical plane relative to the pressure shaft. The design of the handle determines the design of the pressure mechanism. In excavators produced in the USSR, with a single-girder handle, a rope pressure mechanism is used, and with a double-girder handle, a ratchet pressure mechanism is used.

The shovel boom is a welded sheet steel structure. The stick type determines the boom design. The boom can be double-girder with a single-girder handle and single-girder with a double-girder 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 boom is attached to the turntable with fingers and can be rotated when its angle of inclination is changed. A pressure shaft is located in the middle of the boom.

Backhoe is an equipment designed for excavation of soil below the level of the excavator parking when digging pits, trenches, and excavations.

Backhoe (fig. 75) consists of a bucket, boom, stick and two-legged rack. 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 cuts into the ground (position /; positions // and /// correspond to the transport position and unloading the soil from the bucket).

Rice. 75. Scheme of work of the backhoe:

The process of excavating the soil with a bucket. The total excavation resistance R0 is overcome by the active force W0, directed tangentially to the bucket path, which can be decomposed into the cutting and soil shear force WVi directed tangentially to the bucket cutting edge, and the pushing force WB directed normally to the bucket cutting edge.

The main parameters of hydraulic single-bucket excavators are: bucket capacity q, excavator weight C, engine power N, excavator working dimensions, as well as pump pressure and performance.

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

Constant displacement pumps are simple yci, but do not fully utilize the engine power in all modes. Variable displacement pumps provide more efficient and sustainable excavator operation.

Performance and flow diagrams 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 excavation work, the condition and quality of the soil and face, the qualifications of the driver and the technical condition of the machine.

In fig. 77, b shows a diagram of the dragline operation during the construction of an embankment of a roadbed from a reserve. Excavation of the soil is carried out on two grabs; on one of them, the next layer of soil is poured and leveled by a bulldozer, and on the other, freshly poured soil is compacted by compaction machines.

Bucket excavators. Multi-bucket excavators are earth-moving machines that have a multi-bucket chain or a rotor wheel with buckets rigidly fixed around the perimeter as a working body. They are used: in road construction works; when digging pits, canals and trenches for laying pipes or for foundations, the installation, control panel, gearbox, working body are installed on the chassis.

Note. Excavators EO-1621 (E-153A), EO-1627 (E-1514) are additionally equipped with bulldozer equipment: blade width 2000 mm, height 680 mm, cutting depth 500 mm. Excavators EO-ZZPB (E-302) are equipped with dragline equipment with the following parameters: boom length 7500 mm, boom angle 40 °, cutting depth 4450 mm, cutting radius 6500 and 10 100 mm, unloading height 3900 and 6300 mm, respectively, rad s unloading respectively 6390 and 8300 mm.

Single bucket excavator- a kind of excavator, a cyclic earthmoving machine for development (digging), movement and loading of soil. The working body is a movable bucket of different cubic volume, fixed on the boom, stick or ropes. The bucket is loaded by moving relative to the excavated soil. At the same time, the body of the excavator remains stationary 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 pulling 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 machinery used in construction and mining. By the type of work, two main types of excavator are noted in the direction of the bucket tooth - a backhoe or a straight shovel. Front shovel excavators are used only in quarries when loading rock mass into dump cars or for loading mining dump trucks with ore or other rock. A distinctive feature of such an excavator is the opening bucket bottom.

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

If possible, the rotation of the working equipment relative to the supporting surface

· Fully revolving

Diagram of a full-revolving 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 slewing support (slewing ring), and can rotate relative to it in any direction at any angle. Parts of the hydraulic system of the chassis and turntable of full-revolving excavators are connected using a manifold, which allows an unlimited number of full turns in one direction.

· Part-turn

Diagram of a part-turn excavator on the chassis of a wheeled tractor 1. Excavator frame, fixed on the tractor; 2. Swivel column; 3. Arrow; 4. Handle; 5. Hydraulic cylinder for boom drive; 6. Hydraulic cylinder of the handle drive; 7. Hydraulic cylinder for bucket drive; 8. Bucket in backhoe position; 9. Variant of the bucket installation in the straight shovel position; 10. Replaceable cargo hook; 11. Bulldozer blade; 12. Outriggers

The work equipment is secured to the chassis using a rotary column. On many machines of this type, the rotary column is mounted on transverse guides, 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 located on a non-rotating chassis. Currently, excavators mounted on tractors are performed as part-turn

By chassis type

· Tractor-mounted

A tractor, most often wheeled, is used as the base chassis. Part-turn excavator equipment is installed at the rear (less often on the side) of the tractor, on a special frame. The most common are excavators mounted on tractors of class 1.4. The typical bucket volume is 0.2-0.5 m3. They are used to perform small earthmoving or loading operations, most often when repairing engineering networks. The design of the working equipment allows you to quickly rearrange the bucket for work with a forward or backward shovel. The bucket can be replaced with a grapple, 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 travel speed, they can quickly arrive at the place of work located at a distance of 20-30 km from the base. A tractor with a mounted excavator equipment can also be used for transport and dozer work.

· On a car chassis

A truck is used as the base chassis, most often with an all-terrain vehicle. They have a high speed of movement. They are used in cases where high mobility is required: in military affairs (engineering troops, road troops), when performing rescue operations, when building roads, cleaning canals. Work equipment - mainly a backhoe. Excavators with a telescopic boom and a swivel bucket are produced, allowing you to quickly switch from a front shovel to a reverse shovel. For the drive, both the engine of the base vehicle and a separate engine mounted on the turntable can be used.

· Pneumatic

The excavators have their own special chassis supported by pneumatic tires. They are performed most often full-turn. To increase stability and prevent slipping when loading the bucket, they have outriggers. They have a speed of up to 30 km / h. Can be towed by trucks at speeds up to 40 km / h. Passage 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 grab, jaw grab, hydraulic hammer for loosening soil. They have become widespread when performing various types of construction and repair work.

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

· Tracked

DEMAG Bagger excavator. Execution: straight shovel. - One of the largest hydraulic excavators in its class

The excavators have their own special tracked chassis. They are carried out full-turn. They have a high cross-country ability and low specific pressure on the ground with a large mass. They can work on soft and waterlogged soils, including peat extraction. They have a speed of 2-15 km / h. They are transported to the place of work by tractors on special trailers.

The working range of bucket volumes is very wide: from mini excavators with a bucket volume of 0.04 m3 to open pit excavators with a bucket volume of 10 m3. There are also very heavy mining crawler excavators with a bucket volume of 26 m3 manufactured by DEMAG (Germany).

Attachments: front shovel, backhoe, dragline. Can be used with grab, jaw grab, hydraulic breaker. They became widespread in construction and in the extraction of minerals. A number of models of tracked and pneumatic-wheeled excavators have a unified slewing platform and working equipment.

· Marching

The turntable with walking excavator equipment is installed on a base plate. The legs are connected to the turntable, which are raised during excavator operation (do not touch the ground). When moving the excavator, the legs rest on the ground. In this case, the base plate is lifted from the ground. The excavator moves one step forward (some models can move backward). After that, the paws are raised and returned to their original position. Large mining excavators with a bucket volume of 15 m³ - 40 m³ and an outreach of up to 65 m - 150 m are produced on a walking run. Working equipment is a dragline. Walking excavators perform stripping operations (clearing mineral deposits from waste rock), as well as mining and moving them to a dump (up to 40m high). Loading of minerals by walking excavators into vehicles cannot be carried out.

· Railroad

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 slewing platform and equipment are often unified with crawler excavators.

· Floating

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

By engine type

· Steam excavators

A steam engine is used as an engine. They were widespread at the beginning of the 20th century. Currently not available. The moment-speed characteristics of the steam engine and the working equipment of the excavator are well matched (the steam engine can develop torque even with a braked shaft), which simplifies mechanical transmissions.

· Excavators with combustion engines

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

The moment-speed characteristics of the internal combustion engine and the working equipment of the excavator are not coordinated. In particular, the internal combustion engine cannot develop torque when the crankshaft is braked. This requires the use of matching gears (clutches, gearboxes, torque converters) on mechanical excavators. On hydraulic excavators, matching is provided by hydraulic transmissions.

· Electric excavators

To drive the working equipment, electric motors are used, which receive energy from an external network or from their own diesel-electric unit. Electric drive powered from 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. Like a steam engine, an electric motor develops torque when the anchor is braked, so an electric excavator does not need complex mechanical transmissions.

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

By the type of mechanical transmissions (drives of working equipment)

· With group mechanical rope drive (mechanical)

The traction force is transmitted to the working bodies by means of ropes (or chains) driven by winches. The winches are driven by the excavator engine by means of mechanical transmissions (gear, chain, friction, worm).

The universal excavator with a mechanical drive is equipped with a three-drum winch. The winch boom drum is used to drive (raise and lower) the boom. The lift drum is used to lift the bucket (or return the stick when shoveling). The traction drum is used to pull the bucket towards the excavator (when working with a dragline, backhoe). When working with a straight shovel, the traction drum is connected to the handle thrust mechanism.

The 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 rope drive have a complex design and contain a large number of high-wear items (clutch linings, brake bands, ropes).
· The rope drive provides a limited number of independent movements of the working equipment elements;
· The rope drive is technically difficult to make automated;
· The rope drive does not provide complete fixation of the elements of the working equipment in the given position.

On modern models, the mechanical rope drive is used only for the dragline or grab.

· With individual electric winch drive (electromechanical)

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

· Hydraulically driven

Excavators with hydraulic drive ( hydraulic excavators) the force on the elements of the working equipment is created by hydraulic cylinders and hydraulic motors. The excavator motor drives a hydraulic pump in rotation, which creates pressure of the working fluid in the pressure line of the hydraulic system. Through a system of hydraulic valves, the cavities of the hydraulic cylinders (hydraulic motors) are connected to the working or drain lines of the hydraulic system, which ensures the movement of the working equipment. In the neutral position (with the closed cavities of the hydraulic cylinders), the position of the working equipment is fixed. For transportation of an excavator using a tug, it is possible to transfer the hydraulic cylinder of the boom and the hydraulic motor of the swing mechanism to the neutral transport ("floating") mode.

Currently, hydraulic excavators are predominantly used.

Excavator classification

Excavators are earthmoving machines designed for digging and moving 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 and moving the soil - simultaneously; Batch excavators perform these operations sequentially, interrupting digging while the soil is moving. Thus, the working time of the machine, during which the soil is selected, is longer for continuous excavators and their productivity is higher than that of intermittent excavators. Despite this, single-bucket excavators are more widespread, the advantage of which lies in their versatility, that is, the possibility of using both on earth and on loading and unloading operations and in any of the most difficult, including rocky (with preliminary blasting), soils ... Multi-bucket excavators are used mainly for digging trenches and for the extraction of nonmetallic materials in quarries in homogeneous soils that do not have stone inclusions.

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

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

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

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 car 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 nonmetallic 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 for a constant supply of fuel to the machine.

Therefore, diesel engines are more often installed on excavators with buckets with a capacity of up to 3 m3, and electric motors are more often installed on excavators of higher 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-motor 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 began, 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 of 0.4-0.5 m3 is being prepared.

The spread of the multi-motor drive is, in particular, due to the fact that the mechanisms of the excavator are made in the form of separate units, which can be easily installed during the assembly of machines and replaced during their repair (with the aggregate method of repair). In addition, such a design makes it possible to use the same 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 by means of shafts, gears, worm gears, chain drives;
- hydraulic volumetric, where the role of the drive is performed by a hydraulic pump (one or more), oil lines and hydraulic motors (or 'hydraulic cylinders);
- a fluid circulates in the oil pipelines, transferring 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 turbine couplings or turbotransformers are used to transfer energy; it is usually used in combination with a mechanical one for smooth operation of mechanisms and automatic control of the speed of movement depending on the magnitude of the load (with an increase in the load, the speed of movement of the working mechanisms decreases and vice versa);
- electric, used on excavators with a multi-motor drive in combination with a mechanical one; this drive makes it possible for 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 the working movements;
- mixed, consisting of two types of drives, for example, mechanical and electrical.

A mechanical drive is the most common, therefore its presence on an excavator is not specified in the name of the machine, but usually only the type of engine is indicated, for example, a diesel single-bucket 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 periodic excavators (single-bucket) and continuous excavators (multi-bucket).

Thus, excavators are distinguished:
1) by the way of movement (floating and land);
2) by the 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) by the type of undercarriage equipment of land excavators (tracked, pneumatic).

In addition to the listed characteristics of the classification, each of the groups of excavators is distinguished by smaller characteristics - 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, intended for excavation and loading and unloading operations in construction;
- quarry, with buckets with a capacity of 2 to 8 m3, intended for work in quarries for the development of ore and coal deposits, as well as rocks;
- overburden, with buckets with a capacity of over 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 distinguished by elongated working equipment, which makes it possible to dump the soil a long distance from the place of production. This group of machines also includes powerful walking excavators - draglines used in mining to transfer the upper layers of rocks into the mined-out space, 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 as universal ones, and one type of working equipment can be replaced by another during operation.

Excavators are called special if they have only a type of working equipment. As a rule, they are produced with buckets with a capacity of more than 6 m3, but excavators with buckets of smaller capacity (for example, underground) can also be special.

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

Rice. 1. Diagram of a single-bucket excavator:
1 - undercarriage equipment, 2 - turntable,

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

Along with the separation of a 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 a dump on the spot (when digging pits, when preparing clay into cones or ridges).

The construction of the first single-bucket excavator dates back to 1836. A little later, in 1860, a multi-bucket excavator was constructed.

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. Multi-bucket excavators were not manufactured in our country at all at that time.

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

According to the mode 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 engineering industry has begun to produce heavy-duty single-bucket excavators moving in working order using a walking mechanism.

Multi-bucket excavators are also built by floaters (so-called dredgers) for work on deepening rivers, canals and other bodies of water. One of the varieties of such dredges are dredges used in the gold mining industry.