19-11-2012, 02:58 PM
BACKHOE
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backhoe, also called a rear actor or back actor, is a piece of excavating equipment ordigger consisting of a digging bucket on the end of a two-part articulated arm. They are typically mounted on the back of a tractor or front loader. The section of the arm closest to the vehicle is known as the boom, and the section which carries the bucket is known as the dipper or dipper-stick (the terms "boom" and "dipper" having been used previously on steam shovels). The boom is attached to the vehicle through a pivot known as the king-post, which allows the arm to slew left and right, usually through a total of around 200 degrees. Modern backhoes are powered byhydraulics.
Characteristics
Most backhoes are at their strongest curling the bucket, with the dipper arm next most powerful, and boom movements the least powerful.
Similar attachments for skid loaders are still called backhoes even though they are mounted on the front. This is because the name refers to the action of the shovel, not its location on the vehicle: a backhoe digs by drawing earth backwards, rather than lifting it with a forward motion like a bulldozer or a man shoveling.
A backhoe loader is a tractor-like vehicle with an arm and bucket mounted on the back and afront loader mounted on the front. This type of vehicle is often known colloquially as a JCB in Europe (after its inventor) and simply a Backhoe or a Tractor Loader Backhoe (TLB) in North America. In North American terms, a Backhoe includes both a front bucket and a rear hoe, on a chassis originally derived from farm tractors. A dedicated hoe on its own chassis is more properly referred to as an excavator.
Backhoes can be designed and manufactured from the start as such, or can be the result of a farm tractor equipped with a Front End Loader (FEL) and rear hoe. Though similar looking, the designed backhoes are much stronger, with the farm variation more suitable for light work. The farm variation also requires that the operator switch seats from sitting in front of the backhoe controls to the tractor seat in order to reposition the equipment while digging, and this often slows down the digging process.
Thumb
The backhoe's scoop may have a metal bar called a "thumb" hinged to the scoop: see images in Excavator#Excavator attachments. It grips against the scoop like a man's thumb to pick up objects. When not needed some sorts can lie back against the backhoe arm.
Origins
Although Case produced the first “integrated” Tractor Loader Backhoe in 1957 (whereby all the components were manufactured and warrantied by the same manufacturer), the invention of the first backhoe swing frame was developed in July 1947 by Vaino J. Holopainen (pronounced “Waino”) and Roy E. Handy, Jr., (thus the company name “Wain-Roy”) and assigned to Wain-Roy Corporation of Hubbardston, Massachusetts, United States. In July 1948, patent # 2,698,697 was filed by Vaino J. Holopainen. The swing frame breakthrough allowed the hydraulic digging arm to swing to the side to dump the bucket. This patent also included the invention of the out-rigger bar, and high flow control. In April 1948 Wain-Roy Corporation sold the very first all hydraulic backhoe, mounted to a Ford Model 8N tractor, to the Connecticut Light and Power Company. Wain-Roy made 24 units in 1948. Wain-Roy also made them for Sherman Products of Royal Oak, Michigan and Ford. Approximately 7000 Wain-Roy Backhoes were manufactured and sold between the fall of 1948 and early 1954, mainly through Ford dealers.
The patent for the first reversible seat was developed at Wain-Roy by Carroll Arnold and Vaino Holopainen and then filed by Vaino under patent # 2,784,768, and in June 1954, Vaino filed patent # 2,781,927 for individually controlled outriggers. John S. Pilch of Ware Machine Works, Ware, MA, developed the first 4-bar linkage to achieve greater bucket digging and dumping rotation. Pilch filed for patent #2,678,741 in September 1950. The 4-bar linkages were also used on the Wain-Roy backhoes after 1954. The first hydraulic wheel loader was invented by Frank G. Hough in the mid 1940’s under patents 2,782,946 and 2,726,778. The first Tractor Loader Backhoe was a Wain-Roy backhoe mounted to a Frank G. Hough model “HE” in 1952 in Holden, MA for the Holden Water Department. The F.G. Hough Company was a subsidiary of the International Harvester Company. By early 1954, two Hough “Payloader” model wheel loaders, the HE and the HF were available with Wain-Roy Backhoes. In 1954 Wain-Roy Corporation got a deal with IH for the Hough TLB full scale production on several other models of Hough loaders.