There are also many other attachments that are available to be attached to the excavator for boring, ripping, crushing, cutting, lifting, etc. Buckets have numerous shapes and sizes for various applications. A general purpose (GP) bucket is generally smaller, stronger, and has hardened side cutters and teeth used to break through hard ground and rocks. 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. On the end of the stick is usually a bucket. Most common is mono stick but there are also, for example, telescopic sticks. The stick length is optional depending whether reach (longer stick) or break-out power (shorter stick) is required. The stick provides the digging movement needed to pull the bucket through the ground. These are also called triple-articulated booms (TAB) or 3 piece booms.Īttached to the end of the boom is the stick (or dipper arm). Variable angle booms have additional joint in the middle of the boom to change the curvature of the boom.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.Some others have a knuckle boom which can also move left and right in line with the machine.Most common are mono booms these have no movement apart from straight up and down.It can be one of several different configurations: The boom attaches to the house and provides the up-and-down movement. Arm consist typically of boom, stick and bucket with three joints between them and the house. The arm provides the up-and-down and closer-and-further (or digging movement) movements. 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 house attaches to the undercarriage by way of a center pin. The house includes the operator cab, counterweight, engine, fuel and hydraulic oil tanks. Undercarriage can also have blade similar to that of a bulldozer. The undercarriage includes tracks, track frame, and final drives, which have a hydraulic motor and gearing providing the drive to the individual tracks. The three main sections of an excavator are the undercarriage, the house and the arm (also boom is used). The arrangement of the pumps in the excavator unit changes with different manufacturers using different formats. Generally, the 3 pumps used in excavators consist of 2 variable displacement piston pumps and a gear pump. 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. Hydraulic excavators usually couple engine power to (commonly) three hydraulic pumps rather than to mechanical drivetrains. For example, Caterpillar's smallest mini-excavator weighs 2,060 pounds (930 kg) 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 2,160,510 pounds (979,990 kg), has 4500 hp, and a bucket as large as 52.0 m³. The smaller ones are called mini or compact excavators. Modern hydraulic excavators come in a wide variety of sizes. ( February 2021) ( Learn how and when to remove this template message) Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources. This section needs additional citations for verification.