How To Select The Right Excavator For The Job
It
is important to select the right machine for the job to be performed.
Incorrect selection will result in underutilization of machine or
is inappropriate for the job. These resulted in wasting time and
resources. Furthermore the progress of the job or project will be
affected.
An excavator ( back hoe ) loading a hauling unit
What
are the factors to consider then during the selection process? The
two basic factors which should be taken into consideration are:
-
- The cost per
unit of excavation and
- The job condition
the machine will work in
Lets
discuss more in details these two factors. The meaning of cost per
unit of excavation means how much does it cost to excavate per unit
volume of the material found in the job site. The factors to take
into account when working out the cost per unit of excavation are
:-
- The size of
the job, as a larger job may justify the higher cost of a large
machine.
- The cost of
transportation ( larger ones more cost)
- In quarry
works, there is the combined cost of drilling or blasting to
be considered. If a large excavator is used, these costs may
be less than if a small one as a large machine will handle bigger
rocks better than a small one. Hence a large machine may permit
savings in drilling and blasting costs.
Normally it works out that the unit cost per volume of excavation
is less for large excavators than small ones.
As for the job considerations, this determine the type of bucket
or the size of machines to be used. There are different types of
buckets in terms of size and make. Hence if the material to be excavated
is hard and tough, the bucket of a large machine which can exert
higher digging pressure will handle the material more easily. If
blasted rock is to be excavated, the large-size bucket will handle
bigger individual pieces better and easily. Then if the project
time is short and a high production is required, either multiple
small machines or a single large one can be used.
Another factor which is often missed is the type of hauling units
available. If small hauling units are used then the size of the
excavator should be small, where as if large or heavy hauling units
are used then a large excavator should be used. Finally it is also
important to take into account the maximum dumping height of the
excavator when loading hauling units.
As
for back hoes, beside the above, there are additional factors to
consider and these are:-
- Maximum digging
depth required
- Minimum digging
depth available
- Working radius
for digging and dumping
- dumping height
required
- digging width
required ( trench operation)
- clearance
for carrier, superstructure and boom
- hosting capability.
If
the work is a trenching operation, then the primary concern is to
match the hoe's ability to excavate linear length per unit of time
with the pipe / cable laying production. Usually, the volume of
material moved is not the question.
Thus
the above are factors to be taken into when selecting the right
excavators for the work and it is also advisable to always consult
manufacturers specification in the planning and selection.