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Excavator: What It Consists of and How It Works

Modern construction and specialized machinery are extremely diverse. Yet, an excavator keeps the palm when it comes to the performance of most ground and construction works.

Excavator’s construction underwent improvements for decades, and the construction we use today is being steadily modernized, and the machine itself is receiving additional functions and new specializations.

What Excavators Can Be? The Basic Classification

A classic digger is a mechanism which is intended to work with soil and complete tasks like soil excavation, relief planning, digging pits and trenches, mining, construction of dumps and embankments, and loading and unloading of various types of soil.

The classification of digging machinery is provided according to their specialization:

  • construction and road construction models;
  • quarry excavators designed for the development of hard rock and the extraction of minerals or construction materials;
  • all-purpose models;
  • excavators for working underground;
  • loading excavators.

Besides, there are numerous other less common types.

Each of them is distinguished by their performance, type, and the number of motors, the type of drive of the working body, design, and dimensions of the bucket.

Since the machinery is expensive and complex, many enterprises and private entrepreneurs prefer used excavators which already accumulated operating hours instead of buying new ones. There is a comfy option how to select spare parts for excavators, various attachments, and even excavators themselves. You can do it in the Machineryline catalog.

Also, the type of chassis, dimensions, and operating gross weight also are significant for choosing the machinery besides the characteristics mentioned before. Operating gross weight often shows the performance capacity of a machine and its scope of use. 

Thus, the size group of an excavator is often regulated. For example, the first group consists of machines weighing up to 6.3 tons, the second offers machines up to 10 tons. Excavators of the most productive sixth-size group have an operating gross weight of 50 to 70 tons.

One more distinctive feature of excavators is the number of buckets. Today, there are single-bucket and multi-bucket excavators. The last type is continuous machines for making ditches, trenches, and mining. A circular bucket operation scheme is implemented in such excavators and most often their design allows for transporting soil or rock directly to the loading point if there is such a need.

Single-bucket excavators are divided into machines with direct and reverse buckets. In the first case, the soil is taken above the excavator installation level, in the second, the work is performed below the machinery parking point.

The Working Principle and Basic Construction of Excavator

A single-bucket excavator is the most popular type of ground-digging machinery for construction sites and mining sites when constructing roads and embankments. Such machines use a cycling working principle. The machine of a certain bucket’s configuration extracts and removes a specified amount of soil or other bulk material.

You should know exactly a machine’s performance to select an excavator which fits the industry’s requirements. This feature depends not only on the bucket’s volume but on the working cycle time which features extraction, loading, and returning the bucket to its original position. Also the type of soil (sand, loam, clay, or crushed stone) plays a role. 

If we provide a scheme for any excavator’s construction, it consists of various nodes, aggregates, and their complexes:

  1. The chassis of an excavator can be wheeled, pneumatic, tracked, railed, on a floating platform, and some other options. The wheeled chassis is equipped with folding stops for additional stability during operation.
  2. Rotating platform. It can be fully rotated 360°, or rotated at a certain angle.
  3. Power part. Depending on the design solution, it includes an internal combustion engine (mainly diesel), hydraulic pumps and motors, and a generator and electric motors.
  4. Boom with the working body. Typically, it has a hydraulic drive, less often it can have a mechanical drive, with a flexible cable drive of the boom and bucket.
  5. Operator’s cabin with controls.

The Excavator’s Bucket Construction

Excavator buckets are made of carbide steel, they have different volumes and design features. The design of the bucket depends on the scope of its application. For example, the most common configurations are the following:

  • A standard all-purpose bucket. It has from 3 to 6 carbide steel teeth with a volume from 0.49 to 2.5 cubic meters. The width varies from 600 to 1,800 mm;
  • A cleaning bucket has no teeth. Instead, it has a blade installed for cleaning and cutting soil with a maximum width of 1,500 mm. The leveling bucket has a similar design, but its width can reach 1,800 mm;
  • A profile bucket. Most often, it has a triangular cross-section;
  • A loading bucket is used for transportation and shipment of bulk materials. Its volume varies from 1 to 2.5 cubic meters;
  • A rock bucket is intended for hard rock mining and its width is from 600 to 850 mm;
  • A trench bucket with width up to 800 mm; 
  • A ripper bucket. It has three teeth and a standard width of 1,000-1,200 mm.

The Construction of a Hydraulic System of an Excavator

The hydraulic system of a modern excavator is a complex and multi-component system. Its tasks include not only the drive of the working body but, in some models, the transmission of torque from the engine to the drive wheels or rollers of the caterpillar propulsion system.
The main components and assemblies of hydraulics are as follows:

  • a hydraulic pump with control of pressure and transmitted power;
  • hydraulic lines, hoses, and fittings;
  • liquid filtration system;
  • axial hydraulic motors for chassis drive;
  • working hydraulic cylinders;
  • splitters, valve hydraulic units, pressure control sensors, and other elements depending on the specific design.

Construction of the Undercarriage of a Crawler Excavator and Machinery on a Wheeled Chassis

The undercarriage of a wheeled excavator is a frame construction with drive axles and axial (or electric) motors placed on it to drive the wheels. Besides, there is also a support ring located on the frame, which is included in the rotating mechanism of the excavator.

A crawler chassis is considered to be more stable, and therefore, unlike a wheeled one, it does not use outriggers. On the supporting frame of the crawler excavator, the following parts are installed:


• hydraulic drive of driving rollers;
• support and guide rollers;
• excavator track tensioner device;
• tracks.

During its drive, the final drive device blocks one of the tracks, thereby allowing you to change the direction of movement.

The crawler chassis is inferior to the wheeled chassis in terms of transportation speed, but it provides better maneuverability and stability during operation. The advantages of a wheeled chassis are maneuverability and speed of transportation. The advantages of a crawler vehicle are cross-country ability and stability on unstable soils.If you want to make the right choice among specialized machinery and quickly select the required attachments or spare parts for it, you are welcome to use the Machineryline website e-catalog.

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