Hydraulic Excavator: Components, Types and Operation

Most heavy-duty equipment uses hydraulics for its working because of its ability to carry heavy loads and the power of the control mechanism. One such heavy equipment is the hydraulic excavator which is popularly used in the construction and mining industry. The major components of the excavator are a bucket, arm, rotating cab, and movable tracks; and its operations are controlled by hydraulics. The primary function of an excavator in the construction industry is digging ditches, trenches, foundations, and holes and for quarrying and mining river beds in the mining industry. Also, with excavators, it is possible to safely lift and move soil or other heavy materials from one place to another. In this article, we can discuss all the important topics related to the excavator and its operation.

Important Hydraulic Excavator types

Crawler Excavators: Crawler excavators are used for mining purposes, trench digging, and landscape grading and they appear a little bit different from excavators that run on wheels. This excavator looks similar to tracked tanks that are used in the army and they run on two endless tracks. The chain wheel system of this compact excavator provides greater balance, flexibility, and stability, but it reduces speed.

Dragline Excavators: The dragline excavator used for underwater options, road excavation, and piledriving has a key feature of a unique hoist rope and dragline system. Unlike the normal excavators, this excavator uses a hoist rope system where the bucket is attached via a hoist coupler. For raising and lowering the bucket hoist rope is used and to pull the bucket toward the driver it uses the dragline. Mostly, these excavators are assembled on-site because of their larger size and weight.

Suction Excavators: The suction excavator also known as a vacuum excavator is used for underground applications, delicate digging projects, and debris cleanup from holes or land. This wheeled vehicle with high-pressure vacuum and water jets has sharp teeth at the edge that create a vacuum and take away soil or other debris. The construction of a suction excavator is similar to that of a vacuum truck except for the width of the suction hose.

Skid Steer Excavators: The four-wheel skid steer excavator is a compact, rigid-frame, engine-powered machine that can be used in residential projects, and for removing spread-out or piled-up debris. The bucket is oriented away from the driver and this type of excavator is suitable for space-limited sites requiring maneuvering tricky turns.

Long Reach Excavators: The long-reach excavator has a 40-100-foot extendable arm that simplifies industrial demolition and heavy-duty digging projects. The design features enable it to be used in hard-to-reach locations. By affixing certain attachments to the arm, this excavator can also perform many other operations like cutting and crushing.

Hydraulic Excavator Important Components

Undercarriage: Undercarriage is an essential part of heavy equipment that contains other components necessary for the movement of the excavator. The undercarriage components that assist in excavator movement are the sprocket, final drive unit, track shoe, track link, track frame, track roller, and front idler. Among these, the final drive unit has key functions like transmitting power from the engine and increasing the torque.

Cab: The cab is the location from where the operator controls the movement of the excavator and it needs to offer excellent visibility to the operator. Controls, gauges, and monitor panels are located inside the cab. The operator cab can rotate 360° makes it possible to dig, move, and dump things easily.

Hoe: The Hoe is constructed with three important parts boom, dipper arm, and bucket.  Boom is a hydraulically actuated arm and its hydraulic boom cylinder will enable the operator to move the dipper arm with respect to the instruction passed from the cab. The dipper arm transfers the power from the boom to the bucket and it has a dipper arm cylinder that is necessary for raising, lowering, and aligning the bucket. The bucket is an important part of Hoe that allows digging. 

Counterweight: Solid iron or other materials are used as counterweight in excavators to counterbalance the weight of excavated earth. There are high chances for the heavy equipment to tip over during its operation if a proper counterweight is not included. The excavators are designed in such a way that, the counterweight can be removed in some situations to ease transportation.

Controls: Operators can control excavator operations from the cab using travel pedals, levers, and joysticks. Simple operations on these controls will help to move the dipper arm & boom and load & unload the bucket. The travel pedals and levers in the excavator will control the speed, direction, and rotation. Whereas, the two joysticks located on the left and right side of the operator will control the movements.

Attachments: Augers, compactors, hammers, rippers, grapples, etc… are some types of attachments used in excavators. The attachment augers can make the excavator function as a hole digger. Similarly, compactors are used for hard-pounding base fill, hammers for breaking rocks, rippers for pavement work, and grapples for lifting logs, bales, or lumber.

Hydraulic Excavator Operation

The design of the hydraulic excavator is similar to that of a human arm where it can safely perform different operations in the construction and mining industry. It is the three hydraulic cylinders that are controlled using the joysticks located inside the operator's cabin, making it possible to move the excavator hoe as per the operator's instruction. The diesel power engine is an important component that produces the energy required for the excavator to raise, lower, or move the hoe for digging or other operations. 

         The hose which consists of a boom, dipper arm, and bucket is attached to the lower part of the excavator chassis. The arm of the excavator has two main sections that are connected with a hinge. A hydraulic cylinder is placed at the bottom of the first section and another cylinder above the second section. When the operator works on the joystick to raise the arm, the fluid will be pumped from the reservoir into the first cylinder located below the first section of the arm. This will extend the piston rod and will raise the arm. Similarly, the second piston also extends or retracts to raise or lower the second part. The third cylinder is used to control the forward and backward movement of the bucket.