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The Hydraulic Functions of Excavators – BAS World

How does an excavator work?

An excavator uses a hydraulic system that works similarly to a bicycle pump or water pistol. In an excavator, oil is used instead of water because oil withstands high temperatures better and maintains its viscosity. In an excavator, oil is pumped through the hydraulic lines by a motor-driven hydraulic pump. The oil eventually reaches the hydraulic cylinders that control the movement of the excavator's arm and bucket. The silver rod in the cylinder moves back and forth, allowing the excavator’s arm to move up and down.

What is a hydraulic system?

A hydraulic system converts mechanical energy into hydraulic pressure, enabling the transmission of power and movement. This energy is used to move various parts of the excavator. The main components of a hydraulic system in an excavator are:

Hydraulic pump: Converts mechanical energy into hydraulic energy, ensuring a continuous flow of pressurized oil.

Hydraulic valves: Regulate the flow of hydraulic oil to different cylinders and motors.

Hydraulic cylinders: Convert hydraulic pressure into mechanical movement, enabling different parts to move.

Hydraulic motors: Convert hydraulic pressure into rotational movement, for instance, to drive a track.

Hydraulic systems are the heart of an excavator. They provide the necessary power for digging and moving materials, while also offering the precision required for accurate movements.

Single-acting vs. Double-acting Hydraulic Systems

Excavators work with a double-acting hydraulic system. Oil is pumped on both sides of the piston, allowing it to move in two directions—up and down.

A single-acting hydraulic system also exists. An example of this is a dump truck. In this system, oil is pumped on only one side of the cylinder, causing the truck bed to lift. When the valve is opened, the bed lowers by its own weight.

Key Hydraulic Functions

These systems enable movement, but what are the key hydraulic functions in an excavator? Below are a few examples:

Movement of the boom, arm, and bucket

The boom, arm, and bucket are the most important moving parts of an excavator. They are powered entirely by hydraulic cylinders, allowing for both powerful and precise movements, depending on the task at hand.

Rotating the upper structure

If you're working on a construction site with limited space, it’s essential that an excavator can rotate its upper structure. This movement is driven by a hydraulic motor that powers a slewing ring, making it easy to position the machine in various orientations.

Driving the tracks

Some excavators use tracks. Hydraulic motors power these tracks, with the operator having precise control over speed and direction. This enables smooth movement in tight spaces and challenging terrain, such as muddy ground.

Specialized Hydraulic Functions

In addition to general functions, there are specific hydraulic features that enhance an excavator’s versatility:

Hammer line: The hammer line operates a hydraulic hammer, one of the most basic hydraulic functions. The hammer line allows the excavator to apply powerful force, often used in demolition work to break concrete or rock.

Quick coupler function: The quick coupler feature allows for quick attachment changes without manual intervention. This system enables the operator to swiftly swap between buckets, grapples, or hammers, making the machine highly adaptable on-site.

Rotation line: The rotation line is necessary to operate a rotating sorting grapple and always accompanies the hammer line. It allows the attachment to rotate during use, which is particularly useful for sorting tasks or demolition jobs.

A hydraulic excavator's hydraulic functions make it indispensable for construction and agricultural tasks. These systems provide both the power and precision necessary for various jobs, from digging and moving earth to demolition and material handling. If you’re looking to purchase an excavator, consider the versatility provided by these hydraulic systems.