A mini excavator is a compact piece of construction equipment used for digging or light demolition work, depending on the attachment it is fitted with. An excavator with an operating weight ranging from 1.5 to 8 tons (1.36 to 7.25 metric tons) and engine power up to 60 hp is referred to as a mini excavator. A mini excavator is built identically to its larger hydraulic excavator counterpart, consisting of the same main parts: cab, engine, undercarriage, boom arm, and attachment.
The cab, where the operator sits, houses the controls and can usually rotate 360° with the help of a swing gear that rests on the undercarriage. The undercarriage consists of either tracks or wheels, which move the unit over various types of surfaces. Wheels are used mainly for mini excavators that operate on very stable ground, such as roads, cemented areas, and inside buildings. Tracks are used for increased stability on rough terrain.
There are two types of tracks: rubber and steel. Steel tracks are usually used for machines that will be working mainly in mud and on loose soil, while rubber is used for units that will also be operating on asphalt, pavement, and landscaped areas. The rubber helps to protect these surfaces from damage. In either type, the tracks generally operate independently of each other, with a control for the right and one for the left. Their range of motion is only forwards and backward, so to turn the machine left, for example, the operator moves only the right track forward, keeping the other motionless.
A diesel engine often provides power to move the unit as well as run the hydraulic systems that operate the boom and its attachment. The standard attachment for a mini excavator is a bucket for digging into dirt, but there are many other attachments available, such as hammers, ditching buckets, and augers. Some units come equipped with swing booms, a system which allows movement of the whole digging arm left or right of center. This feature allows the excavator to dig a trench parallel to its tracks, such as next to walls or structures.
Mini excavators are designed to carry out work in small areas and to tackle light jobs, such as digging narrow ditches for pipe laying. They are ideal for indoor use as well, especially for light demolition on jobs where an electric breaker would not be powerful enough. These small earth movers are often a cost-effective solution for jobs that are too large to be carried out manually, but too small to justify the use of larger excavation equipment.