Front End Loaders
Hello everyone, I welcome you all to the lecture 13 of this course construction methods and
equipment management. So, in this series of lectures on earth moving equipment, today we
are going to discuss about the front end loaders. So, in the last lecture, we have discussed
about the scraper.
(Refer Slide Time: 00:44)
Like the types of scraper, application, operation scraper and how to estimate the productivity
of scraper we have discussed. So, let us see what is the outline of today's presentation? In
today's presentation we are going to discuss about the types of front end loaders, what are all
the different possible attachments for the front end loaders and what are the applications?
And how to do the packet rating for the front end loader and the significance of bucket fill
factor and how to check the payload from stability perspective and how to define the
production cycle of the loader and what are the components of production cycle and
illustrations of how to estimate the productivity of the front end loader. So, these are the
components which are going to discuss today.
(Refer Slide Time: 01:28)
So, as the name indicates, the front end loader means it is basically a tractor with a bucket at
the front end a tractor provided with the front end bucket is called the front end loader. So,
you might have seen this front end loader very commonly in many project sites. So, the basic
difference between this machine and the; earlier machines which have discussed like
bulldozer and scrapers jet.
This machine has a mechanism which facilitates it to lift the material and load it into the
truck. So, you have a boom kind of thing which allows you to lift the material, you can lift
the bucket and load it into the truck. So, this is not possible with the bulldozer and scraper
where you cannot lift the material and load it into the truck. So, that is one advantage of this
machine over the earlier machines what we discussed.
So, this is basically a kind of excavator, which is good and excavating at or above the ground
level. So, in addition to that, it can also transport the material to certain distance that is one
advantage of this loader. So, it can excavate as well as transport the material. So, that is the
advantage of the loader. But when you compare this machine with the other excavators like
fixed position excavators which we are going to discuss in the upcoming lecture.
Like front shovel the shovel so, we can compare this machine with this front shovel, you can
see that this fixed position the front shovel is a fixed portion excavator, which is very good in
excavation, but it cannot transport the material to a particular distance, it has very poor
mobility. So, it has very poor mobility when compared to loaded front end loader. So, your
front end loader can give you an economic haul distance of say it is going to wheel loader it
can even go up to 200 meter.
So, if it is going to be crawler loader it will be less than 100 meter, but if you look into this
front shovels the haul distance will be maybe less than 20 meters. So, this is not designed for
transporting the material, this front shovel. Front shovel are fixed position excavators which
can just stay at one place. And you can just swing the boom from the loading to a dumping
So, but the advantage of the loader is it can excavate the material as well as it can move it to
certain haul distances, say depending upon the mounting you can go up to 200 meter for
wheel loader or less than 100 meter for crawler loader. So, that advantage you can have with
the front end loaders, when compared to other excavators like front shovels. So, we have just
completed the front shovel and the front end loader.
But basically discus from the cost perspective, you can see that the loaders are cheaper when
compared to front shovels, there is another advantage.
(Refer Slide Time: 04:17)
So, very commonly, you can see this front end loader in the batching plants your ready mix
concrete factories or asphalt batching plants, you can see this machine very commonly. So,
like in the batching plants, you can see that the aggregates will be brought with a truck from
the aggregate production plant and the truck will dump the aggregate at the batching plant.
So, from the dumping stockpile, this material the aggregates will be carried by the loader and
loaded will feed the material into the storage bins. So into the aggregate storage bins, there
will be some storage bins for aggregates at the RMC batching plant that charging up
aggregate storage bins will be done with the help of loader.
So, the loader will carry the material and then load it into the storage bins. So, that is another
application and another thing is it is also used in aggregate crushing plants. In crushing
plants, you can see that the loader can dig the quarried rock the blasted rock or a short rock.
So, this loader can dig it, load it and then it can transport it to a certain distance and then take
it to the aggregate crusher.
And fill it into the hopper of the aggregate crusher, so that they can help. See in certain cases
where the haul distance the transporting distance is not favourable for this shovels your front
shovel when it is not favourable for the shovel, in that case, you can go for a loader which is
both good in excavation as well as you can transport it to the required distance. So, in that
case a loader will become advantages when compared to the shovel. So, these are the
applications of the loader.
(Refer Slide Time: 06:08)
So, let me just summarize. So, basically the loader is good in excavating at or above the
wheel or track level and also it is used to transport the material to certain economic haul
distance. We have discussed the haul distance, it varies depending upon the mounting of the
machine and it is designed for excavating soft medium hard material, with softer medium
hard material, you can get a good productivity.
But for a very hard material you can do it but the productivity will be slightly lesser and very
commonly you can see in the quarries, should load the plastic material into the truck that is
one application. And as I mentioned just now, it can load the hoppers and bins in the asphalt
and the concrete plans to load the aggregate bins in the asphalt and the concrete plants and
also to feed the aggregate crusher use a loader. So, these are the different applications of the
(Refer Slide Time: 07:05)
Now let us see what are all the types of loaders you can classify the loader based upon the
capacity of the bucket or based upon the mounting or based upon the frame. So, based upon
the capacity of bucket, you have a huge range of the capacity say starting from less than 1
meter cube say 0.2 meter cube to as big as say 15 meter cube bucket is also available. So,
depending upon your requirement you can go for the corresponding bucket the size
And based upon the mounting as we discussed earlier machines also it can be either a crawler
mounted or track motor or it can be wheel mounted and based on the frame, it can be rigid
frame or articulate type frame, we are going to discuss all these things one by one in the
(Refer Slide Time: 07:50)
So, first let us compare the wheel loader versus the track loader. Obviously, as you know,
wheel loader will give you high mobility. So, wherever you need higher speed and greater
haul distance, you can go for the wheel loader, with wheel loader I can go for economical
haul distance of up to 200 meter. So, excellent job mobility and greater speed, but the main
advantage of track loader is it has all terrain capability.
That means it is suitable for very poor underfoot conditions, it can climb steeper grades for a
very rocky terrain or clay terrain very poor underfoot conditions also it can give you better
productivity with the track loader. So, another important thing you should know that so,
obviously the track loader will give you a better traction. So, because of the tractive effort
generator and the breakout force generated will be more in the case of track loader.
So, that is way for very tough job conditions, particularly for the quarries for handling the
rock, it is preferable to go for the track loader, which can generate more amount of tractive
effort and you can see that these loaders are particularly since it is carrying the material and
travelling for a particular haul distance we are very much concerned about the stability of
loader, we should take care that the machine should not tip, it should not tip forward.
So, for that case we have to see that machine stability should be taken care. So, basically even
in the track loaders, you can see that the tracks will be generally longer and wider. So, that
you can increase the stability; particularly for the loaders that tracks will be longer and wider.
So, from the safety perspective and also most of the crawler loaders you can see that the
engine will be at the rear end.
Because weight of the; engine will also act like a counterweight to the load in the bucket. So
for the purpose they might have engine at the rear end. So, if you compare the cost obviously
your track loaders are going to be costlier. The ownership cost is going to be costlier for your
track loader. But you estimate the cost, work out the economics through the life of the
equipment you can see that the replacement cost of the tyres the wear and tear of the tyres
will be more for the wheel loaders.
So, that will make the wheel loaders expensive when you consider the tyre cost in the
operating life of the machine.
(Refer Slide Time: 10:14)
So, we have to work out the economics and select accordingly. Then based upon the type of
frame, you can either go for a rigid frame or you can go for a articulated frame. So, what is
this articulated frame, basically there is a pivot joint between the front axle and the rear axle,
there will be a pivot joint the machine is hinged between the front and the rear axle. So, this
joint will facilitate better turning or manure it.
So, like you will have a better turning ability for this machine. So, even in a very confined
area, it is possible to work with this machine. Say for example, you are working on the side
of the road some trenching work is being done on one side of the road. In that case turning
will be very easier to work in narrow spaces with the help of articulated wheel loader when
compared to rigid frame loader.
Because this machine will have a better turning ability due to the joint, the pivot joint
between the front and the rear part. So, you can have an articulation of say 40 degree in the
horizontal plane either to the left or to the right. So, we can see this in the picture. So they are
basically hinged between the front and the rear axle to provide greater maneuverability, it
allows an angle of up to 40 degree in the horizontal plane either to the left or to the right.
So, this machine can easily work in small turning circle. Of course, it is going to be costlier
than the rigid frame, but the cost can be justified whenever you want the machine to work in
a very confined area or spaces with space restriction. Now, let us see what are all the possible
(Refer Slide Time: 11:53)
There are different types of attachments possible depending upon the attachment where
application of the loader will vary. So, the first one is a general purpose bucket, which we
commonly used for handling the earth. So, as we discussed earlier for the bulldozer, even for
this bucket or the bucket proper, you will have the cutting edge. So, generally the cutting
edge gets over fast due to the varying time.
So, this cutting edge will be just bolted on it will be just bolted on to the bucket proper. So,
you need not replace the bucket frequently. So, only the cutting edge we need to replace it
frequently depending upon your usage. So, the cutting edge is just bolted on. So, in general
purpose bucket there will be just one plain cutting edge you may not even have this teeth,
these are called as a teeth, they are the V shaped cutting edge with a bucket teeth.
So, basically, in the general purpose bucket, you can see the cutting edge of the plain. You do
not have the V shaped cutting edge of the teeth for handling the rock. But if you are going to
handle the rock, you have to go for a special bucket like this rock bucket with this kind of
teeth with V shaped the cutting edge. The teeth have the shaped cutting edge with which it
can easily loosen the rock and it can easily fill the bucket with the rock.
So, this type of cutting edge will help you to loosen the rock. So, this is usually used for the
rock bucket. And there is something called a side dump bucket. So, generally, instead of
dumping in the front end, if I wanted to dump in the side end, either to the left side or to the
right side, then I can go for this side dump bucket attachment. So, this will be more
convenient if you are going to work in the confined areas.
Like say for example; as I told you, when I am doing some trenching work on the side of a
road. In the case, if you want to dump into side end with the side dump attachment, it will be
very easier to dump instead of turning the entire machine, then multipurpose bucket. This is
something called 4 in 1 bucket, that the same bucket can be used for different applications.
You can either use it as a bulldozer blade, or you can use it as a scraper, or you can use it as a
loader or you can use it as a clamshell.
We will see what is it an upcoming slide and another attachment called forklift for lifting the
objects, for lifting the precast elements. I can use this forklift. Then plow blades attachment,
particularly in the snowy areas for clearing the snow. Then light material bucket. Basically
when you are going to handle a material with the lower density, you can go for bigger bucket,
but if you are handling denser material then you have to go for a smaller size bucket. This is
mainly from the safety perspective of the stability of the machine perspective.
(Refer Slide Time: 14:45)
This is a picture of the rock bucket which shows the V shape cutting edge, you can see the V
shaped cutting edge with this, even this bucket teeth is bolted on you can easily replace the
bucket teeth when it gets own out. So, this is particularly use for handling the rocks. When
you are working with the loader in the quarries to handle the blasted rock or a short rock, then
you have to go for this rock bucket, which can easily loosen the rock and load bucket.
(Refer Slide Time: 15:16)
This is the side dump attachment. This is a schematic picture of the side dump attachment,
which you can use it in confined areas that you want to do the dumping on one side, I do not
want to do the dumping in the front end, but I wanted to do the dumping either to the left side
or to the right side, then I can go for this kind of side dump attachment.
(Refer Slide Time: 15:39)
Forklift: So, you can remove the bucket and attach the forklift to the tractor. So, that you can
use the loader for carrying the elements say for example, you want to carry some objects
precast elements, you can use the forklift attachment.
(Refer Slide Time: 15:55)
Then the one is multipurpose 4 in 1 bucket. As I told you, all these 4 functions are possible
with the same attachment, you can either use that bucket as a dosing blade or you can use it
as a normal loader or you can use it as a scraper or you can use it as a clamshell. So,
clamshell is something which is used for digging vertically. So, for deeper digging, we can go
for this clamshell. So, the same bucket, I can use for any of these functions that is what is
called a multipurpose bucket.
(Refer Slide Time: 16:30)
Now, let us see about the bucket ratings, see the manufacturer provide you the information on
what is the heaped capacity of the bucket. So, this bucket rating is done by the manufacturer
in a standard manner with a particular material, say they heat the material at a standard angle
of repose say is 2 to 1 and then rate the bucket based on that. So, that bucket rating, we are
going to use it for the estimation of the productivity of the loader.
So, but in your actual project site, the material which you are going to handle that may be of
different from the material which was used for the rating of the bucket by the manufacturer.
So, you know that different material will have different filling ability. Say for example, we
are going to handle sand. Sand has a particular filling ability, if we compare sand and if you
compare the coarse aggregate, if you compare bigger size coarse aggregate, sand has better
filling ability when compared to the coarse aggregate.
Similarly, when I compare the aggregate versus the blasted rock or the short rock obviously,
aggregates will have the better filling ability. So, the filling ability of the material into the
bucket will vary from material to material. So, that is why according to the material which
you are going to handle at your project site you have to apply the correction factor to the
rated bucket volume by the manufacturer.
So, the manufacturer would have rated the bucket. So, that is the heaped bucket volume. This
data, I can get it from the manufacturer for different bucket capacities, for different bucket
sizes, I can get it from the manufacturer, this value, I have to adjust according to my material
type, which I am going to handle at my project site. So, I have to multiply this rated bucket
volume given to the manufacturer with a bucket fill factor, which depends upon the material
So, this value also I can get it from the literature for different materials, depending upon the
size of the material, the filling ability will vary. So, the bucket fill factor will also vary. So, it
not only depends upon the material type, it also depends upon the mounting of your machine.
So, your machine will be either wheel mounted or it can be either track mounted. So,
generally as you know, the track mounted machine will give you better tractive effort, it will
be able to generate more amount of breakout force.
So, say it can easily loosen the material and it can easily fill the material into the bucket. So,
the filling ability will be more when we go for the track mounted machine when compared to
the wheel mounted machine. So, that is the type of the mounting will also affect the bucket
fill factor. So, this bucket fill factor helps to make the best estimate of the actual bucket
So, the fill factor corrections for the loader bucket adjust the heat capacity given by the
manufacturer, based on the material type and the type of mounting of your machine. So, the
material type which you are going to handle the material, which you are going to handle at
your project and the type of mounting of your machine, according to that your fill factor will
vary. With that fill factor you adjust the actual bucket volume rated by the manufacturer.
As the traction depends upon the mounting the bucket fill factor also varies for the wheel and
track mounted loaders. So, the track mounted loaders will give you better traction. So, it can
easily loosen the material and it can easily fill the material into the bucket. So, the bucket fill
factor will be better, will be different for the track mounted loader and wheel mounted loader.
(Refer Slide Time: 20:33)
Now another important thing which we need to check particularly for the front end loaders is
way to check for a payload weight from the stability point of view. So, you know that your
front end loader is going to carry the material in the bucket in the front end and it has to travel
for some economical haul distance. So, unlike the other excavators, which I discussed earlier,
say your front shovels see if you compare this machine with your front shovel, which is also
an excavator machine.
So, that is not going to travel from loading to dumping position, they are fixed position
machines, but this loader will be travelling loader can moving material from the loading to
the dumping point, that is why in this machine, we are more concerned about the stability,
there are more chances for the tipping of the loader machine if you overload the bucket.
So, that is why we have to check for the payload weight. So, these machines are basically are
travelling with fully loaded bucket. And the bucket will be in the raised position in the front
of the tractor and it will be travelling. So, that is why there are more chances for instability.
So, we have to carefully balance, we have to match the size of the bucket and the size of the
tractor, for a very small tractor, we should not put a bigger bucket.
So, that will affect the stability of your machine, safety against tipping forward is taken care
by checking these static tipping load. So, how this static tipping load is determined we are
going to discuss in the next slide. So, we have to check whether the payload weight, the
actual load in the bucket is within the static tipping load prescribed by the manufacturer.
(Refer Slide Time: 22:22)
What is this tipping load? See just like you imagine you see some like if you are going to put
more material into this bucket as you keep on adding material into the bucket. So, at one
point of time, you can see that if the bucket is overloaded, the rear wheel will be lifted off the
ground. So, that is what is called as a tipping of the bucket. So, your rear wheel will be lifted
off the ground as you put more and more material into the bucket.
So, this static tipping load is determined by the manufacturer under standard conditions. So,
how do they do this test? So, basically, what they do is they carry out the test by putting
material into this bucket, they look for that particular point of time at which the rear wheel
will be lifted off the ground, that particular load is called the tipping load.
So, how much load we need to add into the bucket which will cause the lifting of the rear
view of the ground that is called as a tipping load. So, this test will be done to the
manufacturer and they do this test to static condition to avoid the variability and the machine
will be fully turned condition or articulated condition that is going to be highly risky.
(Refer Slide Time: 23:39)
So, the machine will be in fully turn condition when they do the test. I hope you understand
the difference between straight and fully turn. So, when it is fully turn it is going to be more
risky. So, they carry out the test in the fully turn condition. So, basically full turn static
tipping load is the loaded weight which will lift the rear wheel off the ground with the
machine in static condition and fully articulated state.
So, this is how they determine the full turn static tipping load, this value you can get it from
the equipment handbook, the manufacturer will provide you for different bucket capacities,
what is the full term static tipping load of the machine that value I can get it.
(Refer Slide Time: 24:28)
And we have to check whether the operating load of your machine that is the load in the
bucket should be well within the full turn static tipping load prescribed by the manufacturer
for that particular machine. So, the load in the bucket should be well within that. So, we
should go for a very high factor of safety. The factor of safety depends upon the mounting of
So, the guidelines are available in the literature, say if it is going to be wheel loader the
operating node the bucket is limited to 50% of the rated full turn static typing load defined by
the manufacturer. Similarly, if it is going to be track loader, the operating load is limited to
35% of the static tipping load. So, you have to ensure that the loads which are going to put in
the bucket of the loader should be well within the full turn static tipping load.
So, the factor of safety will depend upon the loading of your machine. So, as I told you the
specifications I can get it from the manufacturer.
(Refer Slide Time: 25:32)
Now, let us define what is the production cycle of the loader? So, what are all the
components of the production cycle as we discussed earlier the same way we can split the
production cycle time into 2 components, one is fixed time, other one is variable time. The
fixed time does not depend upon the haul distance, say the time needed for the loading
dumping, turning, you are maneuvering the changing gears and also for sporting your truck.
So, the loader has to spot the truck, then only you can dump the material, if it is not able to
spot the truck, the truck is not really available even that will increase you cycle time. So, the
fixed time is reasonably constant the time required to load the bucket, shift the gears, to turn
and to dump the load. The maneuvering time and the time for spotting the hauler also come
under the fixed time.
So, obviously the variable time will depend upon your haul distance and the speed of the
machine. The speed of the machine, you can get it from the performance or as we discussed
earlier or you can get it directly from the manufacturer, manufacturer may provide you the
possible speed for different capacities of the loader or different capacities of the bucket, what
is the maximum possible speed the first gear, second gear, third gear, all these information
are provided by the manufacturer.
So, based upon that also, you can estimate your variable time. The variable time includes the
travel time, required to travel from loading to the dumping position and the time required to
return to the loading position. So, obviously it depends upon the travel speed and the distance
(Refer Slide Time: 27:17)
So, this picture shows the plan for the ideal loader setup. So, basically though the loader is
able to transport the material for certain haul distance, it is always preferable to place the
truck as close to the loader as possible particularly for the track mountain loader for which
the economical distance is less than 100 meter, it is always preferable to have the truck as
close as possible, so that we can improve the productivity of your loader.
So, that is what we call it is ideal loader setup. So, you can see the production cycle here, this
is your truck and this is the bank to which the loader is excavating. So, this shows the path of
the loader. So, the loader is first moving to the back excavating the material, then it will take
apply the reverse gear and move in the reverse direction. Now, it will move forward to the
truck and dump the material into the truck, again take the reverse gear move in the reverse
direction and get ready for the next cycle.
This is how the production cycle gets repeated. This is called the ideal plan. This is because
the travel time is minimum here particularly the crawler loaders are also not designed for a
very high haul distance. So, it is preferable to minimize the travel time of the loader, but
everything depends upon your actual project condition or the site requirement. And another
important thing to note that is when the travel time is minimum say if the truck is placed very
close to the loader say less than 5 meters or approximately 15 feet.
So, in that case, the travel time is going to be travel distance is negligible, I can see the travel
distance is negligible and the travel time is minimum. So, in that case directly I can take the
fixed cycle time for the loader from the manufacturer because for distance is less than 5
meters, there is not much variation in the fixed cycle time. So, that is why you can take it
directly from the manufacturer the fix cycle time based upon the bucket capacity of your
That itself will give you the total cycle time of the loader then the travel distance is
negligible. That means when the truck is placed very close to the loader say within 5 meters.
(Refer Slide Time: 29:52)
But if the travel distance is not negligible, so in that case, you have to estimate your variable
time. So, how to estimate the variable time, there are some guidelines given in the literature,
you can follow the guidelines. Say obviously, you know that when the machine is travelling
with the loader during the onward journey, then the speed is going to be lesser, when
compared to the return journey, where the packet is going to be empty.
And also the speed possible depends upon the haul distance, if the haul distance is going to be
lesser, in that case, the travel speed is going to be lesser, for distance is less than say 30
meters, your average travel speed with a loaded bucket for the wheel loader should be 80% of
the maximum speed in the low gear. So, this is a guideline available in literature which we
can use it in the estimation of the speed when you estimate the productivity.
So, for the onward journey with the load for the wheel loader you should take the travel speed
as 80% of the maximum speed in the low gear as given by the manufacturer. So, as I told you
for different bucket capacities what is the maximum speed possible the first gear, second
gear, third gear and the top gear is given by the manufacturer. So, you can use it and find this
and similarly, for the return journey when the bucket is empty, the return speed should be
about 60% of the maximum in the second gear. So, you can see that the return speed is high
in the second gear.
(Refer Slide Time: 31:28)
So, if the distance is more than 30 meter in that case the return speed will still more, the
return speed will be for the empty bucket, it will be 80% of maximum speed in the second
gear, remember when the distances are less than 30 meter, the return speed was only 60% of
maximum in the second gear, but for distances greater than 30 meter, the return speed will be
80% of maximum in the second gear, it is greater for the greater
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