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  • Writer's pictureRALPH COPE

A Beginner's Guide to Excavators

Vikfin is a specialist in excavators and used excavator spares. This is a simple primer on the basic things you need to understand about these machines. Excavators are heavy construction equipment consisting of a boom, dipper (or stick), bucket, and cab on a rotating platform known as the "house". The house sits atop an undercarriage with tracks or wheels.


Understanding the Component Parts

There are 12 major component parts to an excavator

1) CAB (ROPS)

For many years, excavators unlike most other items of earthmoving and construction equipment have been exempted from the requirement to have a ROPS (rollover protection structure). However, that has all changed with the publication of ISO 12117-2: 2008 which sets out laboratory tests and performance requirements for protective structures on excavators weighing between 6 tonnes and 50 tonnes. Mini excavators up to 6 tonnes have had an ISO ROPS standard for a number of years.


2) ARM

The excavator's arm is one of the most important attachments of an excavator. The arm has to work reliably under uncertain working conditions with high load. Hence it is necessary to design equipment that has maximum reliability and minimum weight, keeping the design safe under all loading conditions.


3) BOOM

The boom is the angled arm that is attached to the excavator itself and the arm is pinned to the boom. The arm is sometimes called the dipper or stick. A knuckle boom can move right or left in line with the machine, unlike standard booms that can only move up or down.


4) BUCKET, BOOM & ARM CYLINDERS

Hydraulic cylinders are used for creating mechanical force in a linear motion. A hydraulic cylinder is a tube capped at either end with a rod sticking out of one side. The piston rod is attached to the part of the machine requiring motion. Pumps squeeze fluids in a hydraulic system through small diameter hoses and pipes — pressure in, pressure out — and mechanical force is created.


5) HYDRAULIC PUMPS

When a hydraulic pump operates, it performs two functions. First, its mechanical action creates a vacuum at the pump inlet which allows atmospheric pressure to force liquid from the reservoir into the inlet line to the pump. Second, its mechanical action delivers this liquid to the pump outlet and forces it into the hydraulic system.


6) CONTROL VALVES Main control valves are core elements necessary for the operation of excavators. Piston pumps that form the oil pressure using engine power and main control valves convey the oil pressure to each part. After this, the main control valves which are hydraulic devices help excavators move forward or backward and operate.


7) SLEW MOTOR

Slew motors (also referred to as swing motors or swing drive motors) provide rotation. For example, a slew motor is what enables the house of an excavator to rotate. While still hydraulic motors, they serve a very different purpose from drive motors and thus are designed differently.


8) SWING GEARBOX

A swing gearbox ensures that excavators can rotate around their axis with relatively little force. A swing gearbox consists of various gears that increase the power of the engine.

9) ENGINE

The main function of the excavator engine is to drive the hydraulic pumps that provide oil at high pressure to the slew motor, rams, track motors, and several accessories. Mostly, the boom can move only up and down, or in addition, also shift towards the left and right of the machine.


10) FINAL DRIVE

A final drive transfers the power from the drive motor to the wheels or tracks. It consists of various internal gears that increase the drive motor's power.


11) BUCKET

Excavator buckets are digging attachments with teeth that can be fixed to the arm of an excavator. The buckets are controlled by the excavator operator using controls in the cabin. There are different types of excavator buckets that are used depending on where the digging has to be done. Excavator buckets can also be used to move dirt or load dump trucks for transportation to dumping sites. Excavators are used in conventional trenching methods for laying pipelines and also used for digging trial pits for geotechnical investigation.


12) TRACKS

The tracks of the excavators today come in three types. You can get rubber tracks, iron or steel tracks, and steel tracks with street pads installed. Rubber tracks are most common in the small or mini class of excavators. These tracks vary in width and length and come in different tread designs also.


Frequently Asked Excavator Questions

What are the Different Excavator Sizes?

There are three primary excavator size classes, according to the weight of the machine. Mini excavators are any excavators that weigh less than seven metric tons. Standard-sized excavators weigh between seven and 45 metric tons. Large excavators weigh more than 45 metric tons.

What do the Numbers Mean on Excavators?

3 stands for excavator (product type), 20 stands for 20ton (tonnage), D represents D series, D is a newer machine compare with B, C. If L is after series letter, for example, CAT320DL.

What do the Letters “L” and LC” Mean on Excavators?

Many excavator models contain the letter "L", which refers to the "longer type crawler". The purpose is to increase the contact area between the track and the ground, which is generally used for the construction of soft working conditions on the ground L. "LC" is a more common symbol in all brands that have excavators. The "LC" here means that the model uses a widened longer track. The purpose is also to increase the contact area with the ground, generally used in the construction of soft ground conditions.

What is the Difference between an Excavator and a Backhoe?

The main difference between the two machines is size — excavators are larger and heavier, while backhoes are slightly smaller. The excavator is typically a better fit for demolition projects, mining, driving piles, drilling shafts for rock blasting, and overall large-scale industrial projects.

What are the Best Excavators?

The largest excavator manufacturers by market sales are Volvo, Caterpillar, Komatsu, Doosan, JCB, Liebherr, and Hyundai.

Is an Excavator a Digger?

Excavators are also called diggers, JCBs (a proprietary name, in an example of a generic trademark), mechanical shovels, or 360-degree excavators (sometimes abbreviated simply to "360").

Are Excavator Buckets Universal?

In short; no. However, there are times where machine fitments are often crossed over, so buckets that fit on one machine will also work on other machines. For example, a standard JCB 801 bucket, will fit on a standard Kubota KX36 machine, or a Bobcat X335 will also fit a Volvo ECR58 machine.

What is the Useful Life of an Excavator?

60,000 to 100,000 hours. Large mining-class machines should be able to attain service lives ranging anywhere from 60,000 to 100,000 hours, depending on local maintenance and repair capabilities and costs.

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