Dozers and scrapers

A bulldozer is a crawler equipped with a substantial metal plate (known as a blade) used to push large quantities of soil, sand, rubble, and other materials during construction work and typically equipped at the rear with a ripper to loosen densely compacted materials.

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Bulldozers can be found on a wide range of sites, including road construction site. Most often bulldozers are large and powerful tracked heavy equipment. The tracks give them excellent ground holding capability and mobility through very rough terrain. Wide tracks help distribute the bulldozer’s weight over a large area, thus preventing it from sinking in sandy or muddy ground. The bulldozer’s primary tools are the blade and the ripper.

Bulldozers have been further modified over time to evolve into new machines which can work in ways that the original bulldozer cannot.

In an angledozer the blade can be pushed forward at one end to make it easier to push material away to the side.

Another modification is a tree dozer which is an attachment for a tractor or bulldozer consisting of metal bars and a cutting blade, used to clear bushes and small trees.

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Scrapers are large motorized machines used for digging, hauling and leveling out materials in a variety of construction jobs. Running on massive rubber tires, motorized scrapers quickly move large quantities of earth around a construction site.

Motor scraper

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A standard motor scraper is comprised of a bowl, an apron to drop down over a load of material in order to retain it, and an ejector to push out the load hydraulically. Due to its hydraulic system, these components can all function independently.

Elevating

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Instead of an apron, these scrapers include a hydraulically- or electrically-driven elevator made of two chains equipped with a series of crossbars. The elevator’s purpose is to aid in loading material into the scraper’s elevating bowl.

Pull type

Pull scrapers are able to move in soft, wet soils, as well as sand. Unlike the motor scraper, pull scrapers are not motorized and must therefore be pulled by another vehicle.

Tractors

Nowadays tractors are widely used in agriculture and industry. In different branches of industry tractors are used as road transport tractors hauling heavy loads. Tractors may be agricultural, special and road transport tractors.

Road transport tractors are equipped with a load carrying platform. Special tractors are usually equipped with auxiliary devices. Tractors may belong either to wheeled-type tractors or to track-laying type tractors.

The construction of a tractor includes the following main units:

1. Power unit which includes the engine with all auxiliary devices – a radiator, a fan, a starter device, a fuel tank, a pump, etc.

2. Transmission which consists of a clutch, a speed control unit, universal joints, gearing mechanisms, shafts, steering mechanisms, a final drive, axles.

3. Driver which includes driving, supporting and controlling mechanisms.

4. A steering unit.

5. The tractor frame.

6. Working and auxiliary equipment.

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Tractor engines have internal combustion engines as the source of power. Tractor engines requirements differ considerably from the requirements of the automotive engines. Automotive engines are generally unsuitable for tractors.

A cable tractor is widely used in clearing the site. It is a machine used for pulling cables which either can be an electrical cable or wire ropes.

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