Excavator

Excavators are heavy construction equipment primarily consisting of a boom, dipper (or stick), bucket, and cab on a rotating platform known as the "house".

[3] Another principle change was the direction of the digging action, with modern excavators pulling their buckets toward them like a dragline rather than pushing them away to fill them the way the first powered shovels did.

[7] For example, Caterpillar's smallest mini-excavator weighs 2,060 pounds (930 kg) and has 13 hp;[8] 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 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.

The house includes the operator cab, counterweight, engine, fuel and hydraulic oil tanks.

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.

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.

In 1993 Yanmar launched the world's first Zero Tail Swing excavator,[10] 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.

Many excavators feature a quick coupler for simplified attachment mounting, increasing the machine's utilization on the jobsite.

This is a horizontal bulldozer-like blade attached to the undercarriage and is used for leveling and pushing removed material back into a hole.