During its forward movement, the blade cuts the ground and the loosened earth collected in the body of scraper. When the scraper is fully loaded, it is raised above ground d taken to the site of dumping. The earth from the scarper is than taken out by opening the bottom of it and the earth is laid in layer of required thickness.

1. SUBJECT :- ADVANCED CONSTRUCTION AND EQUIPMENTS
SCRAPER

2. Scraper
• This equipment consists of a large bucket called the scraper and it is
attached to a tractor. Varies from 3𝑚3to 9𝑚3. The scraper has a cutting edge
or blade at the bottom and it is the possible to dig earth to depth of about
250mm.
• During its forward movement, the blade cuts the ground and the loosened
earth collected in the body of scraper. When the scraper is fully loaded, it is
raised above ground d taken to the site of dumping. The earth from the
scarper is than taken out by opening the bottom of it and the earth is laid in
layer of required thickness. The scraper thus combines three operation.
Namely, those of digging conveying and dumping

4. Scraper operation
• The basic operation parts of scraper
 Bowl: the bowl is the loading and, carrying component of a scarper. It has
a cutting edge that extends horizontally across its front bottom edge . The
bowl is lowered for loading and raised during travel.
 Apron: the apron is the front wall of the bowl. It is independent of the
bowl. It is raised during the loading and dumping operations to enable the
material to flow into or out of the bowl. The apron is lowered during
hauling to prevent material spillage.
 Ejector: the ejector is rear vertical wall of the bowl. The ejector is in the
rear position during loading and hauling. During spreading the ejector is
activated and move forward, providing positive discharge of the material is
the bowl.

5. • Classification of scrappers
• There are several types of scrappers, primarily classified according to the
number of powered axle or by the method of loading. These are will
tractor machine that to hydraulically operated wheeled trailer bowl. In the
past, crawler – tractor towed two axle scrappers bowls were
manufactured.
1) Pusher loaded
a . Single
b . Tandem
2) Self loading
a . Push pull
b . Elevating
c . Auger

6. 1. Push loaded scraper
the push loaded wheel type tractor scraper has the potential for high
travels speeds on favorable haul roads. Many model can achieve speed a
great as 54 kmph when fully loaded. This extents the economic haul distance
of the units however, this units are at a disadvantages when it comes to
individually providing the high tractive effort required for economical loading
for the single powered excel only a portion ,on the order of 50 to 55
percentage of the total loaded weight, bears on the drive axle.

7. • Single – powered axle pusher-loaded tractor scarper are suited for jobs
where haul-road rolling resistance is law end grades are minimum. They
become uneconomical when
• Haul grades are grater then 5 percentage
• Returns grades are greater then 12 percentage
• Tandem – powered axle wheel-tractor scrapers have separate engines
for the wheel-tractor unit and for the scraper unit.
• This twin-engine arrangement produces extra power for overcoming high
rolling resistance and steep grades.

8. 2. Self loading scrapers
it is although heavier and more costly to purchase than corbel conventional
scarper, can be economical in certain application, particularly in isolated work and
for stripping material.
• Push pull-scrapers
This are basically and -powered axle scrapers having a cushioned-push block and
bail mounted on he front and a hook on the rear about the usually block. these
features enable two scrapers to assist one another during loading by pushing
pulling one another. The trailing scrapper pushes the lead scrapper as it loads.
Then the lead scrapper puss the trailing scrapper to assist in it loading. This feature
enables two scrappers to work without assistance from a push tractor. They can
also function individually with a pusher.
Elevating scrappers
This is a completely self contained loading and hauling scrapper. A chain elevator
mountain vertical on the front of the bowl, serves as the loading mechanism. The
disadvantages of this machine is that the weight of the elevator loading assembly
is dead weight during the whole cycle. Such a scrappers are economical in short
haul situations where the ratio of haul time to load time remains low.

9. • Elevating scrapers are used for utility work dressing up behind hide
production spread, shifting material during fine grading operations. They are
very good in very small quantity situations.
• Augers scrapper
• This is another completely self contained loading and hauling scrapper.
Augers scrapper can self load in difficult condition, such as laminated rock,
granular materials, or frozen material. In a soft limestone mining operation,
44-cy-capacity tender-power augers scrappers making 3-5 in deep cuts
achieved an average load time of about one and half minute.
• Advantage of scrapper:
• Most suitable for the ground which is free from mud and rock.
• Digging and loading operations are performed simultaneously.
• Load is discharge in finally controlled layer.
• Efficiency is high for smaller depth of cut.
• Quite suitable in case of big area is to be excavated.

10.  Disadvantages of scraper:
• Require considerable area for its operation. Hence it is not recommended for use
where excavation is on a small localized area.
• Depth of cut is small.
• It cannot be used directly if the soil is hard.
• Rippers may be used for hard soil for subsequent use of a scrapper.
• Can only cut the ground at its bottom. Therefore, for side cutting, other equipment
have been use.
 Output of a scrapper :
• Loading
• Travelling to fill
• Dumping
• Turning
• Returning to the pit
• Getting back in position to load

11.  Factors affecting output of scrapper
• Type of material to be handled
• Size o tractor
• Use of helper
• Tractor during loading
• Condition of haul road
• Haul distance
• Slope of haul road
• Altitude