Excavators are heavy construction equipment consisting of a

boom Boom may refer to: Objects * Boom (containment), a temporary floating barrier used to contain an oil spill * Boom (navigational barrier), an obstacle used to control or block marine navigation * Boom (sailing), a sailboat part * Boom (windsurfin ...

, dipper (or stick), bucket and cab on a rotating platform known as the "house". The house sits atop an undercarriage with tracks or wheels. They are a natural progression from the steam shovels and often mistakenly called power shovels. All movement and functions of a hydraulic excavator are accomplished through the use of

hydraulic fluid A hydraulic fluid or hydraulic liquid is the medium by which power is transferred in hydraulic machinery. Common hydraulic fluids are based on mineral oil or water. Examples of equipment that might use hydraulic fluids are excavators and backhoe ...

, with hydraulic cylinders and hydraulic motors. Due to the linear actuation of hydraulic cylinders, their mode of operation is fundamentally different from cable-operated excavators which use

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 of a rope or wire rope (also called "cable" or "wire cable"). In its simplest form, it consists of a spool (or drum) attach ...

es and

steel rope Steel wire rope (right hand lang lay) Wire rope is several strands of metal wire twisted into a helix forming a composite '' rope'', in a pattern known as ''laid rope''. Larger diameter wire rope consists of multiple strands of such laid rope in ...

s to accomplish the movements.

Terminology

Excavators are also called diggers, JCBs (a proprietary name, in an example of a

generic trademark A generic trademark, also known as a genericized trademark or proprietary eponym, is a trademark or brand name that, because of its popularity or significance, has become the generic term for, or synonymous with, a general class of products ...

), 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 and

Ireland Ireland ( ; ga, Éire ; Ulster-Scots: ) is an island in the North Atlantic Ocean, in north-western Europe. It is separated from Great Britain to its east by the North Channel, the Irish Sea, and St George's Channel. Ireland is the s ...

, wheeled excavators are sometimes known as "rubber ducks".

Usage

House destroyed by an excavator 2 - Invermere, British Columbia

Excavators are used in many ways: *Digging of trenches, holes, foundations *Material handling *Brush cutting with hydraulic saw and mower attachments *Forestry work * Forestry mulching * Demolition with hydraulic claw, cutter and breaker attachments *

Mining Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or placer deposit. The exploitation of these deposits for raw material is based on the econom ...

, 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 of extracting rock or minerals from the earth from an open-air pit, sometimes known as a borrow. This form of mini ...

River A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body 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 Hemorrhoids (or haemorrhoids), also known as piles, are vascular structures in the anal canal. In their normal state, they are cushions that help with stool control. They become a disease when swollen or inflamed; the unqualified term ''he ...

, in conjunction with a pile driver *Drilling shafts for footings and rock blasting, by use of an

auger Auger may refer to: Engineering * Wood auger, a drill for making holes in wood (or in the ground) ** Auger bit, a drill bit * Auger conveyor, a device for moving material by means of a rotating helical flighting * Auger (platform), the world's f ...

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 by both individual households and by governments and institutions. De-icing and anti-icing De-icing is defined as removal ...

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 r ...

and snow blower attachments *

Aircraft recycling Aircraft recycling is the process of scrapping and disassembling retired aircraft, and re-purposing their parts as spare parts or scrap. Airplanes are made of around 800 to 1000 parts that can be recycled, with the majority of them made from met ...

File:Old excavator.jpg, A cable-operated excavator under the Northwest (now Terex) name at the

Pageant of Steam Pageant of Steam is an annual steam fair held on Gehan Road in Canandaigua, New York ( Town of Hopewell). It started in 1960 and is hosted by the New York Steam Engine Association. The pageant is held the second full weekend of August, starting o ...

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. File:L&T Komatsu Excavator.jpg, A L&T Komatsu excavator seen in

India India, officially the Republic of India (Hindi: ), 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 and dependencies by population, second-most populous ...

. 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 350L excavator in

Louisville, Kentucky Louisville ( , , ) is the largest city in the Commonwealth of Kentucky and the 28th most-populous city in the United States. Louisville is the historical seat and, since 2003, the nominal seat of Jefferson County, on the Indiana border ...

, USA, 2001. Note the hydraulic thumb. File:Grävmaskin - Ystad-2021.jpg, A smaller excavator is digging for the laying of a

broadband In telecommunications, broadband is wide bandwidth data transmission which transports multiple signals at a wide range of frequencies and Internet traffic types, that enables messages to be sent simultaneously, used in fast internet connections. ...

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

maintenance. File:Crawler excavator.JPG, Crawler excavator File:Crawler chassis.JPG, Crawler chassis

Configurations

Modern hydraulic excavators come in a wide variety of sizes. The smaller ones are called mini or

compact excavator A compact or mini excavator is a tracked or wheeled vehicle with an approximate operating weight from 0.7 to 8.5 tonnes. It generally includes a standard backfill blade and features independent boom swing. Hydraulic excavators are somewhat diffe ...

s. 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, 345 bar) for the arms, swing motor, track motors and accessories while the third is a lower pressure (~700 psi, 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 (also boom is used). The undercarriage includes tracks, track frame, and final drives, which have a hydraulic motor and gearing providing the drive to the individual tracks. Undercarriage can also have blade similar to that of a bulldozer. The house includes the operator cab,

counterweight A counterweight is a weight that, by applying an opposite force, provides balance and stability of a mechanical system. The purpose of a counterweight is to make lifting the load faster and more efficient, which saves energy and causes less we ...

, 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. 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

s. *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. On the end of the stick is usually a bucket. 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 Quick couplers (also called quick hitches) are used with construction machines to allow the rapid change of buckets and attachments on the machine. They remove the need to use hammers to manually drive out and insert the mounting pins for attach ...

. 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. Minibagger Beschreibung

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. There are two main types of "Control" configuration generally use in excavators to control the boom and bucket, both of which spread the four main digging controls between 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 excavator capabilities have expanded far beyond excavation tasks with buckets. With the advent of hydraulic-powered attachments such as a breaker, a grapple or an

, the excavator is frequently used in many applications other than excavation. Many excavators feature a

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, motorized machine equipped with a metal blade to the front for pushing material: soil, sand, snow, rubble, or rock during construction work. It travels most commonly on continuous track ...

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 * Blood compact, an ancient ritual of the Philippines * Compact government, a type of colonial rule utilized in Britis ...

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 levelling 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 Excavating equipment Heavy equipment Mining equipment Tracked vehicles