A compact or mini

excavator Excavators are heavy equipment (construction), heavy construction equipment primarily consisting of a backhoe, boom, dipper (or stick), Bucket (machine part), bucket, and cab on a rotating platform known as the "house". The modern excavator's ...

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 different from other construction equipment in that all movement and functions of the machine are accomplished through the transfer 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 backho ...

. The compact excavator's work group and blade are activated by

acting upon hydraulic cylinders. The excavator's slew (rotation) and travel functions are also activated by hydraulic fluid powering hydraulic motors.

History

The compact excavator has its origins with equipment manufacturer Akio Takeuchi who founded the Takeuchi Manufacturing company in 1963. Created as an improvement to overcome issues that other manufacturers typically ignored. It was first introduced in 1971 when Akio was asked to create a smaller excavator that could work specifically on house foundations. This excavator was more compact, versatile and able to perform greater than its larger counterparts.

Structure

Most compact hydraulic excavators have three distinct assemblies: house, undercarriage and workgroup.

House

The house structure contains the operator's compartment, engine compartment,

hydraulic pump A hydraulic pump is a mechanical source of power that converts mechanical power into hydraulic energy ( hydrostatic energy i.e. flow, pressure). Hydraulic pumps are used in hydraulic drive systems and can be hydrostatic or hydrodynamic. They gen ...

and distribution components. The house structure is attached to the top of the undercarriage via a swing bearing. The house, along with the workgroup, is able to rotate or slew upon the undercarriage without limit due to a hydraulic distribution valve which supplies oil to the undercarriage components.

Slew

Slewing refers to rotating the excavator's house assembly. Unlike a conventional

backhoe A backhoe is a type of excavating equipment, or excavator, consisting of a digging bucket on the end of a two-part articulated arm. It is typically mounted on the back of a tractor or loader (equipment), front loader, the latter forming a "backh ...

, the operator can slew the entire house and workgroup upon the undercarriage for spoil placement.

Undercarriage

The undercarriage consists of rubber or steel tracks, drive sprockets, rollers, idlers and associated components/structures. The undercarriage supports the house structure and the workgroup.

Workgroup

The workgroup of a compact hydraulic excavator consists of the boom, dipper or arm, and attachment (e.g. auger, bucket or breaker). It is connected to the front of the excavator's house structure via a swing frame that allows the workgroup to be hydraulically pivoted left or right to achieve offset digging for trenching parallel with the tracks. Certain manufacturers including Terex and Caterpillar (CAT) offer an extendable boom option, much like the extendable boom of a backhoe loader.

Independent boom swing

The primary purpose of boom swing is for offset digging around obstacles or along foundations, walls or forms. A secondary use is cycling in areas too narrow for cab rotation. Independent boom swing is one of the major advantages of a compact excavator over other excavation equipment.

Backfill blade

The backfill blade is used for grading, leveling, backfilling, trenching, and general dozer work. The blade can be used to increase dump height and digging depth depending on its position in relation to the excavator's workgroup, this makes it very versatile. It is also used to stabilize the machine while digging.

Attachments

NPK GH-07 breaker fitted to a mini-excavator 1

In recent years, hydraulic excavator capabilities have expanded far beyond excavation tasks. With the advent of hydraulic powered attachments such as a tiltrotator,

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 ...

, a grapple or an auger, the excavator is frequently used in many applications other than excavation and with the tiltrotator attachment, actually serves as an effective tool carrier. Many excavators feature quick coupler (quick-attach) mounting systems for simplified attachment mounting, dramatically increasing the machine's utilization on the jobsite.

Zero-tail swing

There are two distinct classes of compact excavators, conventional tail swing - units that have a rear

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 ...

that will extend beyond the tracks when the house rotates, and zero-tail swing - units with a house whose diameter stays within the width of the tracks through full rotation. Zero-tail swing units allow operators to focus on digging and not looking at where they are swinging and are intended for operation in limited spaces, like next to a wall.

Notable manufacturers

* Bobcat Company * Caterpillar Inc. * CASE CE * CNH Global * Dingo Australia * Doosan Infracore (formerly

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 ...

Heavy Industries & Machinery) - including Solar brand * Gehl * Hitachi Construction Machinery * JCB *

John Deere Deere & Company, Trade name, doing business as John Deere (), is an American corporation that manufactures agricultural machinery, heavy equipment, forestry machinery, diesel engines, drivetrains (axles, Transmission (mechanical device), transmi ...

* Kobelco (Kobe Steel Group) * Komatsu Limited * Kubota * IHI Construction Machinery * Takeuchi Manufacturing *

Volvo Construction Equipment Volvo Construction Equipment - Volvo CE - (originally Munktells, Bolinder-Munktell, Volvo BM) is a major international company which develops, manufactures, and markets equipment for construction and related industries. It is a subsidiary and bu ...

* Wacker Neuson *

Yanmar is a Japanese diesel engine, heavy machinery and agricultural machinery manufacturer founded in Osaka, Japan, in 1912. Yanmar manufactures and sells engines used in a wide range of applications, including seagoing vessels, pleasure boats, cons ...

References

External links

Compact Excavator Specifications and Comparisons
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