Editing Excavator (section)

==Configurations==
{{more citations needed section|date=February 2021}}
Modern hydraulic excavators come in a wide variety of sizes. The smaller ones are called mini or [[compact excavator]]s.<ref>{{cite web|title=Tips to Help You Operate Your Mini Excavator|url=http://natparts.com/tips-to-help-you-operate-your-mini-excavator/|access-date=29 December 2013|url-status=live|archive-url=https://web.archive.org/web/20131231002035/http://natparts.com/tips-to-help-you-operate-your-mini-excavator/|archive-date=31 December 2013}}</ref> For example, [[Caterpillar Inc.|Caterpillar's]] smallest mini-excavator weighs {{convert|2,060|lb|kg}} and has 13 [[Horsepower|hp]];<ref>{{cite web|title=300.9D Mini Excavator {{!}} Cat {{!}} Caterpillar|url=https://www.cat.com/en_US/products/new/equipment/excavators/mini-excavators/18099279.html|access-date=2023-10-03|archive-date=2023-10-09|archive-url=https://web.archive.org/web/20231009113119/https://www.cat.com/en_US/products/new/equipment/excavators/mini-excavators/18099279.html|url-status=live}}</ref> 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 {{convert|2,160,510|lb|kg}}, has 4500&nbsp;hp, and a bucket as large as 52.0 m<sup>3</sup>.

Hydraulic excavators usually couple engine power to (commonly) three [[hydraulic pump]]s rather than to mechanical [[drivetrain]]s. The two main pumps supply oil at high pressure (up to 5000 [[Pounds per square inch|psi]], 345 bar) for the [[Hydraulic cylinder|arms]], swing motor, track motors and accessories while the third is a lower pressure (≈700 [[Pounds per square inch|psi]], 48 bar) pump for pilot control of the [[Hydraulic machinery#Control valves|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 [[Chassis|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 [[Bulldozer#Blade|blade]] similar to that of a bulldozer. The house includes the operator cab, [[counterweight]], 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.<ref name=mx270a>{{cite web|url=https://www.youtube.com/watch?v=oUVE2PIV5_k|title=How it works: The track motor spool in an Excavator|last=Lance Lefebure|date=2 December 2010|access-date=5 May 2018|website=YouTube|url-status=live|archive-url=https://web.archive.org/web/20160217014851/https://www.youtube.com/watch?v=oUVE2PIV5_k|archive-date=17 February 2016}}</ref> 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.

[[File:Excavator mechanism.gif|thumb|The principle of a hydraulic excavator]]
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.{{Clarify|do you mean straighten and curl like a knuckle|date=July 2019}}
* 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 excavator]]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. The largest form ever of an excavator, the [[dragline excavator]], eliminated the dipper in favor of a line and [[winch]].

On the end of the stick is usually a [[Bucket (machine part)|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]]. 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,<ref>{{cite web |url=http://www.yanmar.com/construction/products/excavators/ |title=Yanmar America Corporation - Excavators |access-date=2009-11-22 |url-status=dead |archive-url=https://web.archive.org/web/20100330033515/http://www.yanmar.com/construction/products/excavators/ |archive-date=2010-03-30 }}</ref> 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.
[[File:Minibagger Beschreibung.jpg|thumb|Hydraulic excavator controls illustration, color of the control matches the moving part]]
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.