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Excavators are heavy construction equipment that are used for many tasks and functions including digging and material handling, mining, river dredging, construction, forestry, demolition, and any other jobs that require the digging and moving of soil and other types of materials.
Excavators are the workhouse of industry and one of the most common pieces of heavy equipment on construction sites around the globe. These machines are incredibly versatile and can be operated in many different types of environments ranging from the typical construction site, to environments that require the scaling of extremely steep slopes and hillsides.
Excavators are designed with either wheels or tracks that allow the machine to move across a job site. They are also constructed with a boom and stick assembly that can be affixed with many different types of attachments that can perform many tasks. Excavator attachments include buckets, shears for demolition, augers for drilling holes, hammer, rippers, and dredge pumps. Different types of couplers are also used for quickly switching attachments when the excavator is used for different tasks.
Most excavators use a hydraulic system to power the movement of the boom/stick/bucket assembly to perform the specific jobs required such as digging, trenching, debris removal, demolition, dredging, and many other tasks. The hydraulic system is powered by the diesel motor, but when a larger quantity of power is required, a separate Hydraulic Power Unit (HPU) can be used. An HPU can be a stand-alone unit or be affixed to the backside of the excavator.
Excavators are available in four sizes: mini (less than 7 tons), mid-size (7 to 10 tons), standard size (10 to 45 tons), and large size (greater than 45 tons).
Excavators are critical in many industries and vary in type and build depending on what specific uses they are expected to perform.
Standard excavators are one of the most popular excavators used because they are designed for the bulk of excavation jobs. They are available in sizes ranging from mini-excavators to large heavy-duty excavators. These excavators include a boom/stick combination, and a bucket attached to the end of the stick. These excavators run on two tracks that allow the weight of the excavator to be distributed more evenly and not be concentrated in one specific area. This makes this type of excavator more suited for working on soft terrain. They also have a cab assembly that can rotate 360 degrees. Digging and lifting of materials is accomplished by the boom/stick/bucket hydraulic assembly retracting and extending. Buckets are available in various sizes to accommodate many different types of tasks from digging, demolition, dredging and many others. These excavators are ideally suited for mining construction, forestry, farming, and any other industries that require the use of this type of machinery.
There are a number of variations to the standard excavator, the long reach excavator is one of them. These can be either wheeled or tracked and allow the excavator to have an increased ability to reach further distances and do jobs that other types of excavators cannot perform. Some of the jobs they are ideally suited for are dredging in water, industrial demolition, large digging projects, and any task where a standard boom/stick assembly is not efficient or practical. Standard reach excavators have a reach up to 40 feet, and long reach can extend the reach up to 100 feet; long reach has the reaching capability of 2X times greater than standard reach.
Another variation of the standard excavator is the wheeled excavator. Although these excavators can achieve the same tasks as the standard track excavator, it is better suited for situations where the excavator must operate on hard surfaces such as concrete and asphalt. Wheeled excavators are easier to maneuver and can move about a worksite at faster speeds. This can be a big time saver and increase the potential of completing jobs in a shorter period of time. Some wheeled excavators can be driven on city streets which allows the excavator to be driven to a job site.
Backhoe excavators can perform multiple tasks without having to switch out boom attachments as often because this type of excavator is designed with a boom/stick/bucket assembly on one end, and a bucket on the other. Able to accomplish the same tasks as a standard excavator, the backhoe excavator is more versatile than standard excavators because of the bucket located at the front of the machine. They are capable of moving larger volumes of materials than standard excavators, and can be fitted with many more attachments. They are ideally suited for landscaping, mining, construction, loading and unloading materials and debris and many other types of uses.
Hydraulic shovels are heavy-duty and designed for very extreme lifting and digging jobs. They are typically found in mining jobs and have much larger lifting arms and buckets than do standard and other types of excavators. They can haul large rocks, soil, and other materials that are too heavy for other types of machines. Hydraulic shovels are similar to standard excavators in that they have a boom/stick/bucket assembly located at the front of the excavator, but they can also be affixed at the back of the excavator. They also have a cab assembly that can rotate 360 degrees which is consistent with most other types of excavators.
Demolition excavators are used for the demolition of industrial structures, buildings, and any other structure that requires dismantling. They are built with special guards that cover the cab and windows of the cab to protect the operator from falling debris resulting from the demolition work that is being performed. Demolition excavators are also fitted with heady duty undercarriages to withstand the harsh environment that these excavators operate. Shearing attachments are commonly used on this type of excavator for shearing metal girders, and other materials that must be cut into pieces as part of the demolition process.
Vacuum trucks are used in situations that require precision removal of material without damaging surrounding cables and piping that can be located under or overground. They are constructed with high-pressure vacuum and water jets that are used to loosen and precisely draw material into the vacuum piping and into the holding tank located on the vacuum truck. These machines offer greater safety in comparison to other types of excavators.
These excavators are designed with the boom/stick/bucket assembly facing away from the operator; this orientation is opposite of a standard excavator. Very common at construction sites, they are used for cleaning debris from job sites, digging pools, and useful in work areas where space is limited but the materials to be moved are located at further distances. They are also more maneuverable than other types of excavators and are capable of overcoming challenging turning conditions.
Spider excavators are one of the most unique and impressive-looking types of excavators and are designed with spider-like legs that can operate independently. This unique excavator is designed for specialized situations that require the excavator to maneuver on extremely steep hillsides and the most challenging terrains. The legs can be fixed or telescoping so that the wheels at each end of the legs can be located on secure footing whether it be angular sides of gullies, cliff ledges, or anywhere else solid footing is required to allow for safe and effective excavation.
These are very special machines and considered the mountain goats of the machine world. Consistent with other types of excavators, the cab sits on a rotating platform that can rotate 360 degrees, and the boom/stick/bucket assembly is located at the front of the excavator. Not seen at many construction sites, they are ideal for forestry due to the steep cliff faces and challenging terrain.
The knuckle boom excavator is another variation of the standard excavator but is designed with an extra joint on the boom/stick assembly. This extra knuckle allows the stick and bucket to rotate from side to side, which increases maneuverability for working in tight spaces and excavating around obstacles. Although the knuckle excavator is one of the least commonly used excavators, it can be greatly beneficial in the right situations.
Amphibious excavators are another one of the specialized excavator types and are used for sediments and debris that can be located at the bottom of bodies of water such as lakes, harbors, rivers, ponds, and other types of waterways. Over a period of time sedimentation begins to fill harbors, and rivers that can interfere with the passage of cargo vessels that are being used to transport materials and goods. Amphibious excavators are used to performing a function called dredging that, essentially, is the removal and transport of this sediment to a location away from the existing waterway. They are also used for control of vegetation and installing underwater cables and piping. These excavators are uniquely designed with an amphibious undercarriage, sealed pontoons, and a buoyancy tank which allows the excavator to float on the surface of the waterway. Also included in the design of this excavator are main hydraulic pumps with traveling motors to help propel the amphibious excavator through the water.
With most types of construction projects, removal of the topsoil is a critical part of the process of preparing a stable and solid foundation for the building and construction process to take place. Prior to the process of removing the topsoil, the area that is to be excavated is marked with the use of a process called ground tracing. Ground tracing identifies the specific area that the excavation will occur. Along with ground tracing, a specific depth of soil removal will be indicated. Once this part of the process is complete an excavator will be used to begin removing the topsoil and relocating it to another desired location.
When excavating some areas the soil can be rocky and contain large boulders or large fragments. When this is the case, the larger boulders and rock fragments must be removed by either mechanical means or introducing explosives to break the large boulders into smaller rock fragments. Rock excavation is the removal and extraction of isolated boulders and rock fragments that are in excess of 1-cubic yard. Due to the involvement of explosives and heavy duty excavation equipment rock excavation is very dangerous, and can be one of the most risky types of excavation.
Prior to beginning construction on any buildings, bridges, and any other structures footings are formed to make sure the building has a strong and stable foundation. This is done to ensure that the structure does not sink or collapse. Sinking or collapsing can occur due to such things as settlement of the structure over a period of time, as well as freezing and thawing that can occur in the colder months of the year. Before a footing can be constructed, footing execution is executed which consists of digging a continuous trench that is usually between 4-ft. and 10-ft. in depth. Footer depths can be as deep as 15-ft. or deeper, especially in cold climate areas where the footer depth extends below the frost line.
This type of excavation involves the removal of the layer of soil just beneath the topsoil which is called spoil (soil, dirt, rubble). Once spoil is removed it is typically used for constructing embankments and foundations. This layer of soil is also excavated to allow for the constructing buildings, bridges, and drainage ditches.
This type of excavation is where the toil soil, and sometimes the next depth of soil below the topsoil is cut and stripped, and used as fill for making embankments and elevated sections. The material that is extracted in this type of excavation is also used as filler for constructing foundations of buildings.
Trench excavation is similar to footing excavation except that trench excavation can be done for a wider range of reasons than creating a footing for a structure. As an example trenches can be dug for pipelines and sewers. Trenches that are less than 19-ft. Deep are considered shallow, and trenches that are 19-ft. or greater are considered deep. When excavating trenches, the process is conducted in phases to safeguard against the collapse of the trench.
Dredging is a crucial form of excavation that involves the removal of sediment and debris that collects over a period of time from the bottom of lakes, channels, harbors, rivers, ponds, and any other bodies of water where sediments collect at the bottom. Sedimentation consists of sand and silt and when it collects and build-up occurs it restricts the path of boats, ships, and other water vehicles that transverse the waterways. Sediment and debris is removed on a periodic basis to restore the restricted waterways, allowing boats and ships an unobstructed voyage to the destination.
