The idea of "scrape" the material is to remove it by "scraping" in thin layers rather than digging in deeper water, as you would with a spade or shovel, since before the beginning of this century. The "pigs" or scrapers served, among other things, for the construction of railway lines in the second half of the 18th century. Iron sheets were pulled by horses or mules.
In 1920’s “animal power” was replaced by crawler tractors and scrapers: scrapers to "roll" or "rotary scrapers" or "revolving scrapers”. The scrapers of the last generation were studied in the late 50s and gradually put on the market over the past decade.
Different types of scrapers
This equipment can be pushed by a bulldozer equipped with a special blade called "push". This type of scraper called "trailed scraper" is the most common. It can also be self-powered. It charges and discharges on its own through a chain lift. Self-powered scraper stay in line to load materials: one behind the other one. The time required for the attachment only takes a few seconds.
Components of scrapers
The “head scraper” is the first to load. It is pushed by the “back scraper” which is empty. Once the front scraper is loaded, the operator raises the bucket and closes the deck. The back scraper starts to load, assisted by the head scraper. Then it pulls the back scraper through its hook.
Once the bucket is filled up, the two parts charged to help each other get out the excavation as quick as possible. Once the ground is stable, the two parts stand out from each other, while driving, and head independently towards the discharge. They spread it and return to empty. Then it starts again.
The scraper is big equipment. It can excavate, transport and apply the elements of the ground at high speed (up to 70 km per hour). It can also be dangerous because of its high working speed combined with a very large weight (up to 120 tons) which gives a high inertia. As mentioned above, the scraper is used for moving materials constituting the ground. For economic reasons it is recommended to use it over medium distances, between 100 m and 200 m. This machine has a single diesel engine mounted on a tractor. The scraper can be pushed by a bulldozer when the engine is not powerful enough to operate stripping.
SCRAPER WITH 2 ENGINES, KNOWN AS PULL-PUSH
This machine is equipped of a second engine mounted at the rear. Then it pushes another scraper that will help in return (mutual assistance).
Scrapers’ tools moves and can improve the machine and avoid the use of a pusher tractor.
Screw is mounted at the center of the bucket to raise the material bit by bit as it passes over the cutting blade, like an auger.
This unit is an independent body mounted behind a tractor site.