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Motor Scraper

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2005 Caterpillar 621G Motor Scraper
Motor scrapers
, also known as self-propelled scrapers, are large motorized machines used for digging, hauling and leveling out materials in a variety of construction jobs. Running on massive rubber tires, these machines quickly move large quantities of earth around a construction site, unlike the less popular pull-type scraper. There are four main types of motor scrapers: Standard motor scrapers (self-propelled), elevating scrapers, auger scrapers, and push-pull type scraper.


[edit] History

The motor scraper’s true predecessor was a configuration without wheels, pulled by horses or mules. These early pull-type scrapers resembled a scoop with handles, and were controlled by an operator walking behind it. By the late 19th century, these scrapers began to include wheels.

[edit] The Pioneer of Motor Scrapers

Robert Gilmore LeTourneau, the proprietor of an earthmoving business, was the developer of the first motor scraper.[1] Having previously developed such pull-type scrapers as the Model A and Model B Carryall, he was prepared to move in another direction. His introduction of the Model A Tournapull in the late 1930s was the first scraper to be mounted on large rubber tires. The two-wheeled tractor was designed with a 90-degree swing in either direction, a first in the industry. This machine could travel up to 20 miles (32 km) per hour.

LeTourneau’s earthmoving company was sold to the Westinghouse Air Brake Co. in 1953, forming the LeTourneau-Westinghouse Co. With this acquisition came the upgrade of LeTourneau’s models, which would be known as Wabco products by the early 1960s.

Developments such as the Model B and C Speedpull arose in the late 1950s. These motor scrapers had three axles and four wheels, 600 horsepower, and could travel at speeds of up to 40 miles (64 km) per hour. By 1960, Wabco had added a second bowl onto the Speedpull—the tandem Model B was outfitted with two 29-cubic yard (22-m3) scrapers. More powerful, faster models were subsequently developed.

By 1961, Wabco entered the market of elevating scrapers by selling models manufactured by Hancock Manufacturing Co. The company promoted elevating scrapers through the following decade. By 1977, the Model 353FT was introduced. With a capacity of 36 cubic yards (28 m3), and a combined horsepower of 1,025 from two engines, this was the most powerful elevating scraper ever made.[2] This type of scraper, however, would eventually lose popularity, as it was not an efficient or cost-effective means of moving materials; contractors preferred to use a fleet of standard scrapers. Wabco sold its last scraper in 1980.

[edit] Euclid: The Other Pioneer

While LeTourneau was developing new models for his product line, another company, Euclid, was making its own progress. By the late 1930s, this company had developed a prototype known as the 1SH—the frontrunner of the product line they would develop over the next 30 years. The models produced by Euclid came with either two-wheel (overhung) or four-wheel tractors.

The company had many developments over the years including its first twin scraper in 1949, with engines at the front and rear. These machines were outfitted with a hydraulic operation system.  One of the world’s most famous scrapers, the TS-24, further catapulted the company's advancement in 1957.[3] This scraper was twin-powered and had a capacity of 24 cubic yards (18 m3). In 1968, GM, the parent company of Euclid since 1953, made the decision to rename their earthmoving products Terex. The TS-24 is still in production today; however, it is now known as the Terex TS-24C. The company continued to advance in the market with such introductions as TTS-14, a self-loading scraper, in 1963 and the twin-powered S-12E, an elevating scraper, in 1964.

1973 Caterpillar 631C Motor Scraper

[edit] Caterpillar Enters the Picture

In 1941, Caterpillar unveiled their first motor scraper, known as the DW-10. Rather than using the two-wheeled concept of LeTourneau, Caterpillar employed a four-wheel tractor with a 100 horsepower engine. This tractor pulled a scraper with a 10-cubic yard (7.6-m3) capacity. A decade later, Caterpillar introduced the DW-21. This model included the company’s first two-wheeled tractor attached to a cable-operated scraper with a capacity of 18 cubic yards (13.8 m3). It was capable of ninety-degree steering, making it a true forerunner of Caterpillar’s present line of motor scrapers. Smaller models in this series were introduced throughout the 1950s until the introduction of the 600-series in 1960.

Caterpillar began manufacturing elevating scrapers in 1964, the J619 being its first. The company’s largest, most powerful scraper, the 639D, was a twin-powered, 34-cubic yard (26-m3) model; it was sold from 1979 to 1984, the same year the company started offering auger scrapers. These self-loading scrapers were an alternative to elevating models, and could be single or twin-powered.

[edit] Competing Companies

Though there were some obvious leaders during the dawn of the motor scraper industry, there were others that should be noted.

The Michigan Co. began selling scrapers through the Construction Machinery Division of Clark Equipment Co. in 1957. The company entered the market with the introduction of the Model 110 with a 10-cubic yard (7.6-m3) capacity, Model 210 with 18 cubic yards (13.8 m3), and the 310 with 27 cubic yards (21 m3). These models were upgraded through the 1960s and 1970s. The company also entered the elevating scraper market in 1965, with a machine designed and built by Hancock Manufacturing Co. Clark took over Hancock, one of the original developers of the elevating scraper, in 1966. Clark-Michigan produced several elevating scrapers including their largest-ever, the 310-H, with a 32-cubic yard (24.5 m3) capacity and 495 horsepower.

In 1953, Bucyrus-Erie made a deal with International Harvester, giving IH control of the Bucyrus-Erie scraper and bulldozer equipment; IH began marketing it under the International brand name. The same year, International also acquired the manufacturing and design rights of motor scrapers developed by the Heil Co. of Milwaukee. In 1972, International reorganized its line and introduced the 400-series, a line consisting of single- or twin-powered, conventional or elevating scrapers. With the development of these 14-cubic yard (11-m3) scrapers, International stopped manufacturing larger scrapers. The 400-series remained in production until 1984, two years after Dresser Industries Inc. purchased International Harvester’s Construction Machinery Division. The only remaining 400-series model is the 412B, sold as a Dresser scraper by Komatsu America International Co.

John Deere entered the scraper market in 1957, concentrating solely on elevating models. The first version was a John Deere 820 tractor pulling a four-wheeled Hancock eight-cubic yard (6.1-m3) elevating scraper. Through the next three decades, the company produced scrapers in various sizes. Today, the company continues to offer elevating scrapers: the 762B and 862B are available with 11- to 16-yard (8.4- to 12-m3) capacities, respectively.

[edit] Monstrous Machines

Increasing the size of a machine has been a trend for many heavy equipment manufacturers, and motor scrapers are no exception.

With the development of the Electric Digger series in the 1950s, LeTourneau’s company manufactured the world’s largest motor scrapers.[4] The Goliath, or Model A4, was the biggest motor scraper built to date. This model contained an electric motor in every wheel. Following the Goliath was the development of the LT-360. This scraper, the biggest ever built, included three bowls for a capacity of 216 cubic yards (165 m3). It moved, with the power of eight 635 horsepower engines, on eight wheels that each measured more than 10 feet (3 m) in diameter. LeTourneau’s scrapers never sold in large numbers; they were mostly considered experimental.

With the 1960s came the introduction of Caterpillar’s 600-series of motor scrapers. Among this product line was the 666, a scraper with a four-wheel tractor, two engines, and a combined horsepower of 980. This scraper, renamed the 666B in 1969, was produced until 1978 and was the largest one Caterpillar would ever build.

Following this advancement came Euclid’s 1963 development of the TSS-40, with a capacity of 40 cubic yards (31 m3). It also included a four-wheeled tractor with 810 horsepower provided by two GM engines. Shortly after, the TSS-40 was dwarfed by a newer model, the TTSS-40. This model was developed at the request of Western Contracting Corp., an earthmoving company who required scrapers larger than anything available at the time. With three GM engines and two bowls for a capacity greater than 80 cubic yards (61 m3), this was the largest scraper ever built by Euclid.

In 1962, a scraper line was introduced to compete with Caterpillar’s 600 line. Allis-Chalmers introduced the biggest scrapers ever to leave its factory. Included were the TS-460, a single-engine model with a 24-cubic yard (18-m3) capacity, and the 562, a twin-engine machine with a 30-cubic yard (23-m3) capacity. The TS-460, later to be known as the C Model, continued to be produced until Fiat of Italy purchased Allis-Chalmers in majority in 1974.

The following year, Clark-Michigan produced its largest-ever motor scraper, the Model 410. This single-engine machine, intended to compete with Caterpillar’s 651, had a capacity of 44 cubic yards and 635 horsepower. Only 20 scrapers were produced, and the line was discontinued in 1970.

[edit] Features/How it Works/Types

The motor scraper, propelled by at least one engine and mounted on large rubber tires, consists of a bowl, which is used to haul and unload materials (topsoil that has been cut into using the scraper’s blade). Other features vary depending on the type. The material stripped from the earth by a non-self-loading scraper is loaded with the assistance of another unit, such as a crawler tractor. As previously mentioned, there are four main types of motor scrapers: standard motor (self-propelled), elevating, auger, and push-pull.

[edit] Standard Motor (Self-propelled) Scraper

1972 Wabco 101G Elevating Motor Scraper
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 hydraulically push out the load. Due to its hydraulic system, these components can all function independently. Standard motor scrapers can vary in the number of engines, bowls, and wheels they include.

[edit] Elevating Scraper

Instead of an apron, these machines 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. Dumping material is achieved by sliding the floor of the bowl backwards; the elevator can be reversed in order to assist in dumping the load evenly.

[edit] Auger

The auger is a self-loading type of scraper. Two vertical augers are mounted inside the bowl. They are hydraulically rotated, assisting in raising material into the bowl. In an auger as well as an elevating scraper, a full load is always certain—the same amount of power is needed for the first yard of material as for the last.

[edit] Push-Pull

This is a system enabling the scraper to be pushed or pulled. It is achieved by coupling two standard scrapers during the loading of material. By employing this system, the machines can self-load, as the four engines’ power is used simultaneously to load each bowl in turn.

[edit] Common Manufacturers

[edit] Additional Photos

2004 Caterpillar 657E Motor Scraper
1977 Terex TS14B Motor Scraper
1989 Caterpillar 623E Elevating Motor Scraper
1997 John Deere 862B Series II Elevating Motor Scraper

[edit] References

  1. Haddock, Keith. Giant Earthmovers: An Illustrated History. MBI Publishing Company: 1998.
  2. Haddock, Keith. Giant Earthmovers: An Illustrated History. MBI Publishing Company: 1998.
  3. Alves, Michael and Haddock, Keith and Halberstadt, Hans and Sargent, Sam. Heavy Equipment. Crestline: 2003.
  4. Alves, Michael and Haddock, Keith and Halberstadt, Hans and Sargent, Sam. Heavy Equipment. Crestline: 2003.