Excavators are heavy construction equipment primarily consisting of a boom, dipper (or stick),

bucket A bucket is typically a watertight, vertical Cylinder (geometry), cylinder or Truncation (geometry), truncated Cone (geometry), cone or square, with an open top and a flat bottom that is attached to a semicircular carrying handle (grip), handle ...

, and cab on a rotating platform known as the "house". The modern excavator's house sits atop an undercarriage with tracks or

wheel A wheel is a rotating component (typically circular in shape) that is intended to turn on an axle Bearing (mechanical), bearing. The wheel is one of the key components of the wheel and axle which is one of the Simple machine, six simple machin ...

s, being an evolution of the

steam shovel A steam shovel is a large steam engine, steam-powered excavating machine designed for lifting and moving material such as Rock (geology), rock and soil. It is the earliest type of power shovel or excavator. Steam shovels played a major role in ...

(which itself evolved into the

power shovel A power shovel, also known as a motor shovel, stripping shovel, front shovel, mining shovel or rope shovel, is a bucket-equipped machine usually powered by steam, diesel fuel, gasoline or electricity and used for digging and loading earth or frag ...

when steam was replaced by diesel and electric power). All excavation-related movement and functions of a hydraulic excavator are accomplished through the use of hydraulic fluid, with

hydraulic cylinder A hydraulic cylinder (also called a linear hydraulic motor) is a mechanical actuator that is used to give a unidirectional force through a unidirectional stroke. It has many applications, notably in construction equipment ( engineering vehicles ...

s and hydraulic motors, which replaced winches, chains, and steel ropes. Another principle change was the direction of the digging action, with modern excavators pulling their buckets toward them like a dragline rather than pushing them away to fill them the way the first powered shovels did.

Terminology

Excavators are also called diggers, scoopers, mechanical shovels, or 360-degree excavators (sometimes abbreviated simply to "360"). Tracked excavators are sometimes called "trackhoes" by analogy to the backhoe. In the UK, wheeled excavators are sometimes known as "rubber ducks".

Usage

Excavators are used in many ways: * Digging of

trench A trench is a type of digging, excavation or depression in the ground that is generally deeper than it is wide (as opposed to a swale (landform), swale or a bar ditch), and narrow compared with its length (as opposed to a simple hole or trapping ...

es, holes, foundations * Material handling * Brush cutting with hydraulic saw, mower, and stump removal attachments * Forestry work *

Forestry mulching Forestry mulching is a land clearing method that uses a single machine to cut, grind, and clear vegetation. A forestry mulching machine, also referred to as a forestry mulcher, forest masticator, or brushcutter, uses a rotary drum equipped wit ...

Demolition Demolition (also known as razing and wrecking) is the science and engineering in safely and efficiently tearing down buildings and other artificial structures. Demolition contrasts with deconstruction (building), deconstruction, which inv ...

with hydraulic claw, cutter and

breaker Breaker may refer to: Objects * A breaking wave on water, or a "breaker", a shallow over which waves break * Circuit breaker, an electrical overload switch * Breaker (hydraulic), a percussion hammer attached to an excavator People * Breaker ...

attachments *

Mining Mining is the Resource extraction, extraction of valuable geological materials and minerals from the surface of the Earth. Mining is required to obtain most materials that cannot be grown through agriculture, agricultural processes, or feasib ...

, especially, but not only

open-pit mining Open-pit mining, also known as open-cast or open-cut mining and in larger contexts mega-mining, is a surface mining technique that extracts rock (geology), rock or minerals from the earth. Open-pit mines are used when deposits of commercially ...

River A river is a natural stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...

dredging Dredging is the excavation of material from a water environment. Possible reasons for dredging include improving existing water features; reshaping land and water features to alter drainage, navigability, and commercial use; constructing d ...

* Hydro excavation to access fragile underground infrastructure using high pressure water * Driving piles, in conjunction with a pile driver * Drilling shafts for footings and

rock blasting Drilling and blasting is the controlled use of explosives and other methods, such as gas pressure blasting pyrotechnics, to break rock for excavation. It is practiced most often in mining, quarrying and civil engineering such as dam, tunnel ...

, by use of an auger or hydraulic drill attachment *

Snow removal Snow removal or snow clearing is the job of removing snow after a snowfall to make travel easier and safer. This is done both by individual households and by governments institutions, and commercial businesses. De-icing and anti-icing De-icin ...

with

snowplow A snowplow (also snow plow, snowplough or snow plough) is a device intended for mounting on a vehicle, used for removing snow and ice from outdoor surfaces, typically those serving transportation purposes. Although this term is often used to ref ...

and snow blower attachments * Aircraft recycling File:Old excavator.jpg, A cable-operated excavator under the Northwest (now Terex) name at the Pageant of Steam grounds File:Liebherr 314 excavator.JPG, Liebherr 314 wheeled excavator File:LinkBelt290X2Excavator.jpg, Link-Belt excavator trenching File:Caterpillar5230.jpg, CAT 5230 in coal mining operation FEMA - 28723 - Photograph by Mark Wolfe taken on 03-03-2007 in Alabama.jpg, Caterpillar 315C L Excavator cleaning up tornado debris File:L&T Komatsu Excavator.jpg, An L&T Komatsu excavator seen in

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

File:New Holland E215 03.jpg, A New Holland E215 in Hamburg, Germany File:Caterpillar 350L excavator with pincher claw Louisville Kentucky USA March 2001 file a1c018.jpg,

Caterpillar Caterpillars ( ) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths). As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder ...

350L excavator in

Louisville, Kentucky Louisville is the List of cities in Kentucky, most populous city in the Commonwealth of Kentucky, sixth-most populous city in the Southeastern United States, Southeast, and the list of United States cities by population, 27th-most-populous city ...

, USA, 2001. Note the hydraulic

thumb The thumb is the first digit of the hand, next to the index finger. When a person is standing in the medical anatomical position (where the palm is facing to the front), the thumb is the outermost digit. The Medical Latin English noun for thumb ...

. File:Grävmaskin - Ystad-2021.jpg, A smaller excavator is digging for the laying of a

broadband In telecommunications, broadband or high speed is the wide-bandwidth (signal processing), bandwidth data transmission that exploits signals at a wide spread of frequencies or several different simultaneous frequencies, and is used in fast Inter ...

cable in central Ystad in 2021 File:Daewoo digger.jpg, Waterways Ireland

Daewoo Daewoo ( ; ; ; ; literally "great universe" and a portmanteau of "''dae''" meaning great, and the given name of founder and chairman Kim Woo-choong) also known as the Daewoo Group, was a major South Korean chaebol (type of conglomerate) and aut ...

Solar 150LC-V crawler excavator, used for

canal Canals or artificial waterways are waterways or engineered channels built for drainage management (e.g. flood control and irrigation) or for conveyancing water transport vehicles (e.g. water taxi). They carry free, calm surface ...

maintenance File:Crawler excavator.JPG, Crawler excavator File:Crawler chassis.JPG, Crawler chassis File:Excavator, SH200, Sumitomo.JPG, Excavator, SH200 Sumitomo, in storage/parking lot for 8-10 units in Chiba

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

in 2008

Configurations

Modern hydraulic excavators come in a wide variety of sizes. The smaller ones are called mini or compact excavators. For example, Caterpillar's smallest mini-excavator weighs and has 13 hp; their largest model is the largest excavator available (developed and produced by the Orenstein & Koppel, Germany, until the takeover 2011 by Caterpillar, named »RH400«), the CAT 6090, which weighs in excess of , has 4500 hp, and a bucket as large as 52.0 m³. Hydraulic excavators usually couple engine power to (commonly) three hydraulic pumps rather than to mechanical drivetrains. The two main pumps supply oil at high pressure (up to 5000

psi Psi, PSI or Ψ may refer to: Alphabetic letters * Psi (Greek) (Ψ or ψ), the twenty-third letter of the Greek alphabet * Psi (Cyrillic), letter of the early Cyrillic alphabet, adopted from Greek Arts and entertainment * "Psi" as an abbreviat ...

, 345 bar) for the

arms Arms or ARMS may refer to: *Arm or arms, the upper limbs of the body Arm, Arms, or ARMS may also refer to: People * Ida A. T. Arms (1856–1931), American missionary-educator, temperance leader Coat of arms or weapons *Armaments or weapons **Fi ...

, swing motor, track motors and accessories while the third is a lower pressure (≈700

, 48 bar) pump for pilot control of the spool valves; this third circuit allows for reduced physical effort when operating the controls. Generally, the 3 pumps used in excavators consist of 2 variable displacement piston pumps and a gear pump. The arrangement of the pumps in the excavator unit changes with different manufacturers using different formats. The three main sections of an excavator are the undercarriage, the house and the arm. The boom, the front part that is attached to the cab itself and holds the arm, is also used. The undercarriage includes tracks, track frame, and final drives, which have a hydraulic motor and gearing providing the drive to the individual tracks. The undercarriage, especially frequently for a mini-excavator, can also have

blade A blade is the Sharpness (cutting), sharp, cutting portion of a tool, weapon, or machine, specifically designed to puncture, chop, slice, or scrape surfaces or materials. Blades are typically made from materials that are harder than those they a ...

similar to that of a bulldozer. The house includes the operator cab,

counterweight A counterweight is a weight (object), weight that, by applying an opposite force, provides balance and stability of a machine, mechanical system. The purpose of a counterweight is to make lifting the load faster and more efficient, which saves e ...

, engine, fuel and hydraulic oil tanks. The house attaches to the undercarriage by way of a center pin. High-pressure oil is supplied to the tracks' hydraulic motors through a hydraulic swivel at the axis of the pin, allowing the machine to slew 360° unhindered and thus provides the left-and-right movement. The arm provides the up-and-down and closer-and-further (or digging movement) movements. Arms typically consist of a boom, stick and bucket with three joints between them and the house. Excavator mechanism

The boom attaches to the house and provides the up-and-down movement. It can be one of several different configurations: * Most common are mono booms; these have no movement apart from straight up and down. * Some others have a knuckle boom which can also move left and right in line with the machine. * Another option is a hinge at the base of the boom allowing it to hydraulically pivot up to 180° independent to the house; however, this is generally available only to compact excavators. * Variable angle booms have additional joint in the middle of the boom to change the curvature of the boom. These are also called triple-articulated booms (TAB) or 3 piece booms. Attached to the end of the boom is the stick (or dipper arm). The stick provides the digging movement needed to pull the bucket through the ground. The stick length is optional depending whether reach (longer stick) or break-out power (shorter stick) is required. Most common is mono stick but there are also, for example, telescopic sticks. The largest form ever of an excavator, the dragline excavator, eliminated the dipper in favor of a line and

winch A winch is a mechanical device that is used to pull in (wind up) or let out (wind out) or otherwise adjust the tension (physics), tension of a rope or wire rope (also called "cable" or "wire cable"). In its simplest form, it consists of a Bobb ...

. On the end of the stick is usually a

. A wide, large capacity (mud) bucket with a straight cutting edge is used for cleanup and levelling or where the material to be dug is soft, and teeth are not required. A general purpose (GP) bucket is generally smaller, stronger, and has hardened side cutters and teeth used to break through hard ground and rocks. Buckets have numerous shapes and sizes for various applications. There are also many other attachments that are available to be attached to the excavator for boring, ripping, crushing, cutting, lifting, etc. Attachments can be attached with pins similar to other parts of the arm or with some variety of quick coupler. Excavators in Scandinavia often feature a tiltrotator which allows attachments rotate 360 degrees and tilt +/- 45 degrees, in order to increase the flexibility and precision of the excavator. Before the 1990s, all excavators had a long or conventional counterweight that hung off the rear of the machine to provide more digging force and lifting capacity. This became a nuisance when working in confined areas. In 1993 Yanmar launched the world's first Zero Tail Swing excavator, which allows the counterweight to stay inside the width of the tracks as it slews, thus being safer and more user friendly when used in a confined space. This type of machine is now widely used throughout the world. Minibagger Beschreibung

There are two main types of control configuration used in excavators to control the boom and bucket, each distributing the four primary digging functions across two x-y joysticks. This allows a skilled operator to control all four functions simultaneously. The most popular configuration in the US is the SAE controls configuration while in other parts of the world, the ISO control configuration is more common. Some manufacturers such as Takeuchi have switches that allow the operator to select which control configuration to use.

Excavator attachments

Hydraulic excavators now perform tasks well beyond

excavation. With the advent of hydraulic-powered attachments such as a

, a cutter, a grapple or an auger,a crusher and screening buckets the excavator is frequently used in many applications other than excavation. Many excavators feature a quick coupler for simplified attachment mounting, increasing the machine's utilization on the jobsite. Excavators are usually employed together with loaders and

bulldozer A bulldozer or dozer (also called a crawler) is a large tractor equipped with a metal #Blade, blade at the front for pushing material (soil, sand, snow, rubble, or rock) during construction work. It travels most commonly on continuous tracks, ...

s. Most wheeled,

compact Compact as used in politics may refer broadly to a pact or treaty; in more specific cases it may refer to: * Interstate compact, a type of agreement used by U.S. states * Blood compact, an ancient ritual of the Philippines * Compact government, a t ...

and some medium-sized (11 to 18-tonne) excavators have a backfill (or dozer) blade. This is a horizontal bulldozer-like blade attached to the undercarriage and is used for leveling and pushing removed material back into a hole.

Notable manufacturers

Current manufacturers

As of July 2021, current excavator manufacturers include:

References

External links

* {{Authority control Excavators Excavating equipment Heavy equipment Mining equipment Tracked vehicles