Excavator Introduction
Excavators or shovels
are machines designed for digging or earthmoving works and they
come in all shapes and sizes. They are very common nowadays and
mainly found in construction projects, mines, quarries or just about
any place where excavation is required.
The ancestor of
the modern excavator as we know it today was probably the Steam
Shovel, patented by William Smith Otis in 1839. Steam shovels used
a system of pulleys to move their arms and bucket. However it's
working principle is exactly the same with the modern excavator.
Prior to the advent
of the steam shovel all earthmoving had to be done manually. The
steam shovel revolutionized the construction and civil engineering
industries, bringing projects which before deemed impractical into
reality.
A
Modern Hydraulic Excavator
Modern excavators
are diesel powered and make use of hydraulics power to perform digging.
Thus these machines are also called hydraulic excavators. The basic
parts that make up an excavator consist of the bucket, the stick,
boom and the cab. The cab is where the operator sits and is also
where the engine and hydraulic systems are located. The whole thing
is either mounted on top of a tracked or wheel base and can swing
360 degrees.
Excavators are
classified according to their bucket action. A downward arch bucket
motion is known as a hoe or back hoe. A back hoe perform excavation
by pulling the bucket towards the machine and curling the bucket
inward. On the other hand when the bucket motion is an upward motion,
the machine is known as a front shovel. The front shovel perform
excavation by crowding the material away from the machine.
Demolition
using an excavator
Excavators are
very versatile and beside digging they can be adapted by replacing
the bucket with other tools for a variety of task. These are but
not limited to the following
* Demolition (
as shown in the left picture )
* General grading/landscaping
* Lifting
* River dredging
Excavators are
sized according to their weights and bucket sizes. The smaller ones
are called a mini-excavator or compact excavator. The largest model
from one of the manufacturers can weight up to 805,000kg (1,770,000
lb) and with a bucket volume of 40.0m3 (52.3yd3).
On the other end,
from the same manufacturer, a mini excavator, the smallest one weights
1740kg (3836 lb) and with a bucket size of 0.02m3 (0.026yd3). Most
of the time medium excavator are the popular choices. Medium size
excavators can weight ranging from 6300kg to 37800kg ( 13900 lb
to 83335 lb) with bucket volume of 0.13m3 to 1.5 m3 ( 0.17yd3 to
1.96yd3 )
Note :- m3 is cubic meters and yd3 is cubic
yards.