Hydraulic Systems in Excavators: How They Work and Their Importance

One of the primary reasons excavators are so popular in construction operations of all types and scales is their extreme versatility. These machines are not just limited to excavation work; they can be used for everything from demolition and material handling to landscaping, grading, and levelling.

While excavators are built with many different parts, the hydraulic system is essentially the heart of the excavator. It is vital as it provides the power and control necessary for the machine’s various functions, enabling it to perform heavy-duty tasks like digging, lifting, and moving materials with precision and efficiency.

It is an excavator’s hydraulic system that allows for the smooth and precise movements of its other components. This is crucial for tasks that require force and accuracy, such as digging trenches, breaking rock and other sturdy materials, or lifting heavy loads.

The hydraulic system also enhances the versatility of an excavator, since adjustments to the hydraulic pressure and flow allow the operator to manage the speed and force of the excavator’s attachments.

Thus, a hydraulic system’s ability to convert mechanical energy into hydraulic force, coupled with its versatility and efficiency, makes it an indispensable component of excavators.

Main Components of an Excavator Hydraulic System and How They Work

Of course, the hydraulic system is just one component of many that work together within an excavator to ensure its functions are optimally performed. However, even within the hydraulic system, there are many parts that each play an integral role in the operation of the overall system.

In order for the hydraulic system to deliver the power and precision that an excavator requires, these various parts must work together, performing their functions individually and collectively. The following are some of the main components of an excavator hydraulic system, as well as descriptions of how they work:

1. The hydraulic fluid

Hydraulic fluid is a type of non-compressible fluid used to transmit power through the hydraulic system of an excavator. In addition, this fluid helps maintain lubrication within the hydraulic system’s hoses and components, thus preventing corrosion and wearing.

Without hydraulic fluid, an excavator would be unable to move at all, so this fluid is an absolutely essential component of the system.

2. The oil reservoir

The oil reservoir is the part of the hydraulic system where the hydraulic fluid is stored, and which is used to power the excavator. This fluid is pumped from the oil reservoir to the hydraulic system’s other components and is returned to the reservoir after being used.

In addition, the oil reservoir helps to cool down the excavator’s hydraulic oil once it has been used and reduces the amount of heavy contaminants recirculating into the system through the hydraulic fluid.

3. The hydraulic pump

In order to circulate the hydraulic fluid around the hydraulic system, it must be pumped from the oil reservoir to the other parts. This is the responsibility of the hydraulic pump, which is powered by the excavator’s engine.

There are two main types of hydraulic pumps that can potentially be used in excavators’ hydraulic systems: gear pumps and piston pumps. These two types of pumps vary in many ways.

Piston pumps tend to be the preferred option since they are more efficient and can handle higher pressures and speeds, which allows them to move more liquid. However, gear pumps are generally less expensive than piston pumps.

4. The safety release valve

Sometimes, excess pressure can build up inside an excavator’s hydraulic system. The safety release valve is designed to release this pressure when that occurs.

There are various causes behind such pressure build-ups, such as a collection of debris in the system or a faulty component. The safety release valve ensures that the system’s pressure does not exceed safe levels and releases excess pressure before it can cause any damage.

Safety release valves contain springs inside them that eventually fail over time. When this occurs, a valve replacement is necessary.

5. The main control valve

The operator of an excavator needs to control the flow of the hydraulic fluid. The main control valve allows them to do so.

The main control valve helps the operator to distribute the hydraulic fluid between the various parts of the excavator’s hydraulic circuit, such as the linear and rotary actuators. Thus, the operator can control the movement of the excavator thanks to this valve.

6. The linear and rotary actuators

In an excavator’s hydraulic system, both linear and rotary actuators play crucial roles in enabling the machine to perform its diverse functions. Each of these actuators serves a distinct purpose.

Linear actuators are essential for providing the straight-line motion required for many of the excavator’s core operations. These actuators are typically hydraulic cylinders that extend and retract to move the excavator’s boom, arm, and bucket. When hydraulic fluid is pumped into the cylinder, it creates pressure that forces a piston to move within the cylinder, resulting in linear motion.

On the other hand, rotary actuators provide rotational motion and are thus used to control the rotation of the excavator’s upper structure, or cab, relative to its undercarriage. This rotational capacity is crucial, as it allows the machine to manoeuvre and position itself accurately at excavation sites.

Rotary actuators function similarly to linear actuators, except when the hydraulic fluid creates pressure, it generates rotational force. This is then transferred to the actuator’s output shaft, which connects to the part that needs to be rotated.

7. The hydraulic accumulator

With a hybrid excavator, there are some additional parts and the function of the hydraulics system is slightly different. One major difference is the inclusion of a hydraulic accumulator, which is mounted just behind the boom.

As the boom moves downward, the high-pressure oil goes into the accumulator instead of the tank, giving it a high-pressure charge that is routed back into the cylinders on the upswing through assist motors.

How Nors Can Help You Find Excavators With High-Quality Hydraulic Systems

Now that you have a finer understanding of how an excavator’s hydraulic system functions, you may have an even stronger appreciation for this machine’s power, efficiency, and versatility.

If you are looking for excavators for sale in BC, Nors can help. We have a large assortment of both new and used excavators for sale from some of the most reliable brands in the industry.

Whether you purchase a new or used excavator from us, you can rest assured that your machine will perform at the absolute highest standards. Most of our used equipment undergoes a 140-plus point inspection by our highly skilled technicians and has been reconditioned to ensure its optimal functionality.

If you are uncertain about the most optimal excavator for your needs, or the best attachments to go with it, someone from our team of heavy equipment experts would be happy to guide you in the right direction.

For more information about our excavators for sale in BC, Alberta, Manitoba, or the Yukon or to learn more about the various types of excavators that we carry in stock, call Nors at 1-833-730-0613 or contact us here.