Wheel tractor-scraper

The scraper (also motor scrapers, Motorschrapper or scraper ) is a device for layered ablation, for transporting and heaping of soil. The scraper was invented in the 1930s by Robert Gilmour LeTourneau in the USA.

Design and operation

Motor Scrapers consist of front and rear car. On the front of the car is the driver's seat and at least one drive motor (in single-engine aircraft ) acting on the front wheels. The rear section consists mainly of the hydraulically adjustable scrapers and the rear axle. For twin-engine designs is on the back of another car drive motor acting on the rear axle ( dual-motor scraper, all-wheel drive ). Both parts of the vehicle are connected to a hydraulically powered articulation ( articulated steering ). To record the Earth masses of the dragline is lowered by hydraulics. The forward movement of the machine is achieved by means of the cutting edge of the scraper bowl earth and pushed into the bucket. After filling the bucket is raised and also by means of a hydraulically operated front wall ( Kübeltor ) closed. Then the machine moves to the unloading, the Kübeltor is opened and by advancing the rear tub wall, the soil material is ejected during the slow continue again in a distributed area.

Scrapers can record material in volume 8-34 m³ depending on the design. The engine capacities are between 140 and 470 kW. The maximum speed is up to 50 km / h

Early Scrapers ( 30s to 50s ) were equipped with hydraulic place with complex cables. In early forms of the front of the car was still made up a sort of oversized tractor- before its smaller front axle was omitted and the now well-known form was articulated.

One variant is the so-called elevator Scrapers ( conveyor scrapers ), in which the absorption of the earth into the bucket through a special funding mechanism ( band-like guided "bars" made ​​of steel) is supported.

In single-engine scrapers, the tensile force is generally sufficient only for driving, but not for digging ( because only two wheels driven ), at least in firmer soils. Therefore, these machines are supported during the mining process, usually by bulldozers, the imaginary to the rear by means of a scraper for sprung pressure plate over her blade push ( push assist, push bead). Another variation is the coupling of two scrapers during the prospecting - first one side and then the other machine - so that it has the power both vehicles is available ( so-called push-pull scraper ). The machines are equipped with appropriate sprung to coupling mechanisms that can be hydraulically connected and disconnected from the driving position, according to the power -consuming digging the vehicles separate and drive separately to the unloading point.

Another type are attachments scrapers pulled by bulldozers or heavy wheeled tractors without own motor.

In particular, since the advent of hydraulic excavators but the use of scrapers at ground movements is declining, even in the U.S., the ancestral homeland of the scrapers. There, this type of machine has always played a much larger role than in Europe. In rocky, very hard ground, but even in the wet and mud scrapers are only very limited use. As the only German company Henschel works in Kassel Scrapers have built on the American model, but found no significant proliferation.

The typical U.S. manufacturer of scrapers were or are companies like Caterpillar, IHC, Euclid / Terex, John Deere, Le Tourneau and Allis- Chalmers, also from Komatsu Japan builds Scrapers.