excavator

See wikt:excavator for other meanings.

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A typical modern excavator:
a CAT 325C, fitted with quick coupler and tilting bucket

An excavator is a heavy equipment consisting of an articulated arm (backhoe), bucket and cab mounted on a pivot (a rotating platform, like a Lazy Susan) atop an undercarriage with tracks or wheels. Their design is a natural progression from the steam shovel.

Usage

Excavator demolishing a house. Note the hydraulic thumb

Link-Belt excavator trenching.

Excavators are used in many ways:

• Digging of trenches, holes, foundations
• Material handling
• Brush cutting with hydraulic attachments
• Forestry work
• Demolition
• General grading/landscaping
• Heavy lift, e.g. lifting and placing of pipes
• Mining, especially, but not only open-pit mining
• River dredging
• Driving piles, in conjunction with a Pile Driver

Configurations

Excavators come in a wide variety of sizes. The smaller ones are called a mini-excavator or compact excavator. One manufacturer's^[who?] largest model weighs 84,980 kg (187,360 lb) and has a maximum bucket size of 4.5 m³ (5.9 yd³). The same manufacturer's smallest mini-excavator weighs 1470 kg (3240 lb), has a maximum bucket size of 0.036 m³ (0.048 yd³) and the width of its tracks can be adjusted to 89 cm (35 inches). Another company^[who?] makes a mini excavator that will fit through a doorway with tracks that can be adjusted to only 70 cm (28 inches) wide.

To identify the basic pieces, the cab attaches by way of a pin to the deck which holds the final drives which have a gear that drives the tracks. The Boom attaches to the cab by way of a large pin. Attached to the Boom is the Stick. Attached to the stick is the bucket and optionally, the thumb. Usually 2 large hydraulic cylinders lift the boom. Some booms have a swivel capability so the boom can swing independent of the cab. The stick provides the reach along with the boom. Usually a model of excavator has optional lengths of stick that enhance either reach (longer stick) or break-out power (shorter stick). Bucket sizes and configurations are used for varying purposes. A wide "clean-up" bucket is used in situations where too much dig force would make the surfaces uneven. It "cleans-up" a site smoothing and filling the ground. A "dig bucket" is much smaller and usually has teeth to break into the ground. Buckets have numerous shapes and sizes for various applications. "V-shaped" buckets can penetrate frozen ground.

Excavator attachments

In recent years, 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 auger, the excavator is frequently used in many applications other than excavation. Many excavators feature quick-attach mounting systems for simplified attachment mounting, increasing the machine's utilization on the jobsite. Excavators are usually employed together with loaders and bulldozers. Most wheeled versions, and smaller, compact excavators have a small backfill (or dozer-) blade. This is a horizontal bulldozer-like blade attached to the undercarriage and is used for pushing removed material back into a hole. Prior to the 1990s, all excavators had a hang over, or "conventional" counterweight that hung off the rear of the machine to provide more digging force and lifting capacity. This became a nuisance in tight turn areas - the machine could not swing the second half of its cycle due to restricted turn radius. In the early 1990s The Komatsu Engineering Company launched a new concept excavator line that did away with the "conventional" counterweight design, and so started building the world's first tight tail swing excavators (PC128.PC138,PC228,PC308). These machines are now widely used though out the world.

An excavator with sheepsfoot compactor attachment	Excavator with a hydraulic thumb attachment	Link-Belt excavator with a thumb used in demolition.	Excavator with a pulverizer attachment
This excavator is fit up for logging.	An excavator with a hammer attachment in a rock quarry	Link-Belt 240 X2 excavator equipped with a hydraulic cab riser and magnet attachment loading scrap metal

Terminology

Excavators are also called diggers and 360-degree excavators, sometimes abbreviated simply to a 360. Tracked excavators are sometimes called trackhoes by analogy to the backhoe. Even though the 'back' in backhoe refers to the action of the bucket (which pulls "back" toward the machine) and not the location of the shovel, excavators are also occasionally referred to as fronthoes or even just "hoes". In North America, digging excavators are sometimes referred to as "hi-hoes" and often simply as "shovels".

In the UK, wheeled excavators are sometimes known as 'Rubber ducks'.^[1]

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In Japan, the alias Yumbo (ユンボ, Yunbo^?) is a more popular name for excavators. In 1954 after the patent right was obtained from Italy, the French company SICAM produced an excavator model Yumbo S25 . SICAM licensed this technology to many companies, such as Drott in United States, Priestman in UK, and Mitsubishi in Japan and other countries in the early 1960s.^[2] The first excavator from Mitsubishi using this technology was named Yumbo Y35 which was aimed for the international market in 1961. Since then, Yumbo has become the popular name and de facto standard in Japan because of its use in Classified ads even though this is not the formal name there.

The excavating technology of Mars rovers

This section requires expansion.

NASA’s Phoenix Mars Lander’s solar panel and the lander’s Robotic Arm with a sample in the scoop (June 10, 2008)

The Phoenix spacecraft has a robotic excavating arm, controlled by an on-board computer system or the terrestrial command center, and equipped with a bucket, a drill, a camera and other sensors. Because of the extreme climatic conditions of Mars there were several malfunctioning problems with Phoenix's "excavator".

Gallery

John Deere excavator 330C.	Mini digger by Kubota	Caterpillar excavator.	Older American 35A in borrow pit
Brand new excavator in Brittany (France).	Link-Belt 210X2 excavator	excavator on rail tracks

Notable manufacturers

• Bobcat Company
• Case CE
• Caterpillar Inc.
• CNH Global
• Doosan Infracore (formerly Daewoo Heavy Industries & Machinery)
• Hitachi Construction Machinery
• Hydrema
• Hyundai Heavy Industries
• John Deere
• J. C. Bamford (JCB)
• Komatsu Limited
• ThyssenKrupp
• Kubota
• Liebherr
• Manitowoc Cranes
• Mitsubishi Heavy Industries
• New Holland
• Orenstein & Koppel (O&K)
• Poclain
• ST Kinetics
• Terex Corporation
• Volvo Construction Equipment

See also

Types of excavator

• Compact excavator
• Dragline excavator
• Long reach excavator
• Steam shovel
• Power shovel
• Suction excavator

Other

• Bulldozer
• Civil Engineering
• Heavy equipment
• National Association of Heavy Equipment Training Schools – US educational organisation
• Mining Simulation

Notes and references

External links

Wikimedia Commons has media related to: Excavators

• User-Controlled VRML Simulation of an Excavator
• NIOSH Publication: Preventing Injuries When Working With Hydraulic Excavators and Backhoe Loaders