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Hydraulic Excavator

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Caterpillar 235 Hydraulic Excavator
The hydraulic excavator is most commonly used for digging rocks and soil, but with its many attachments it can also be used for cutting steel, breaking concrete, drilling holes in the earth, laying gravel onto the road prior to paving, crushing rocks, steel, and concrete, and even mowing landscapes.[1] Hydraulic excavators have an operating weight of 20,000 pounds (9,072 kg) or higher.[2]

The invention of the hydraulic excavator, with its easier operation and cheaper production has replaced the cable excavator.


[edit] History

[edit] Early Hydraulic Shovels

The earliest recorded hydraulic shovel appeared in 1882 and was produced by Sir W.G. Armstrong & Co., a British company that previously built hull docks. Unrelated Armstrongs also built two water hydraulic shovels. Another company to make an attempt was the Kilgore Machine Co. of Minneapolis in Minnesota, who patented the shovel in 1897.

In 1948, a wheeled prototype of the excavator was developed by Carlo and Mario Bruneri. They gave up the patent and manufacture rights to a French company named SICAM in 1954, the same year SICAM built the Yumbo. The Yumbo, an S25 excavator, had a truck mounted on it. Wheelers and crawlers made their way into the picture as buyers became interested in the product.

HY-MAC All Hydraulic Excavator. Hymac was the pioneer of all hydraulic 360 excavators, a bbc documentry 1960 show the hymac 580 range, that progressed to the 580c and 610 wheeled excavator 590 880 1080 models. Hymac originally was part of hydraulic machinery company america, Peter Hamilton formed hydraulic machinery company uk, which later became HYMAC LIMITED, manufactured at Ryynmey Wales.

Many thousand machines were sold around the world, and are still in use today, can be seen at plant shows and exibited at vintage fairs in the uk and europe.


[edit] The Poclain Hydraulic Excavator

One of the first hydraulic excavators, the TU, was produced in 1951 by Poclain in France. A departure from excavators which transmitted their digging power by the use of cables and winches, it employed a hydraulic pump and cylinders. The TU was unable to rotate a full 360 degrees of rotation. Poclain subsequently introduced the TY45, the first machine to fully revolve, in 1960. By the early 1970s, the hydraulic excavator, with its easier operation and higher rate of production, had largely replaced its predecessor—the cable excavator.[3]

[edit] The Gradall Tractor

The Gradall tractor was invented by Ray and Koop Ferwerda of Cleveland, Ohio. Ferwerda is known for creating a telescoping-boom excavator that was unique for being mounted on a truck. The Ferwerda brothers, who moved from the Netherlands to the U.S., became partners in a highway contracting firm. Due to many men leaving the workforce for the war effort, the Ferwerda brothers were in need of a machine that could perform slope grading work. Their first design, a tractor-mounted excavator, had two beams that sat on a rotating platform and a telescopic cylinder that moved the beams forward and back, producing the excavation motion. Although not produced for commercial purposes until a later date, the hydraulic excavator, available in 15, 24, 36 and 60-inch bucket sizes, was launched in 1941. The success of this led to the production of three more between 1942 and 1944.[4]

[edit] Other Developments

H-2: produced by the Milwaukee Hyraulics Corp. in 1948, it was the first hydrocrane. The H-3 and H-5 were more advanced versions launched later.

O&K RH-300: a bucket excavator with the ability to dig 30 cubic yards (23 m3) was produced in 1980.

[edit] Hydraulic Excavators Today

Models such as Hitachi’s 570-ton EX5500 and Caterpillar’s 360-ton Model 5230B  are among some of the most notable machines in the industry. However, they are no match to Liebherr R996, which weighs 720 tons and has a 44-cubic yards (34 m3) capacity; the Komatsu PC8000, a 755-ton model with 46-cubic yard (35 m3) capacity; or the Terex/O&K RH-400, a machine capable of excavating 57 cubic yards (44 m3).[5]

[edit] Features/How it Works

[edit] The Arm

The hydraulic excavator operates on different levels. The first is the arm of the vehicle. The arm is comprised of two hydraulic cylinders, a bucket and a boom, which is on the upper part of the arm. The arm moves in two parts just like a human arm would: at the wrist and the elbow.

Inside of the hydraulic cylinder is a rod, which is the inner part of the cylinder, and a piston, which is at the end of the cylinder and enables the arm to move with the help of oil. If there were no oil in the cylinder, the piston would drop to the bottom, but because of the nature of oil, its volume always stays the same.

Oil is pumped through the end of the piston and in turn pushes the rod through the cylinder, thus creating movement of one or both parts of the arm. By controlling the amount of oil is pumped through the valve, the accuracy of the arm can be easily manipulated. This movement is activated by the use of control valves that are positioned inside the cab where the driver seat is.[6]

Caterpillar 235B Hydraulic Excavator

[edit] The Engine

Power in an automobile is normally received straight from the engine but it works differently in a hydraulic excavator. Because the machine uses a lot of force, it is able to move by changing the energy it receives from the engine into hydraulic power.

[edit] The Swing

One of the functions of this machine is its ability to turn. The swing of the excavator enables it to turn. The swing circle comprises of several components: an outer race, an inner race, ball bearings and a pinion. As the outer race turns, the pinion runs alongside the unmoving inner race. The ball bearings work to ensure that this is done smoothly.

[edit] The Cab

The third part of the hydraulic excavator is the upper structure where the driver’s seat is located and the controls are positioned. With the help of two levers on both side and two in the front, the driver can move both at the same time to control direction and height.

[edit] The Feet

There are two types of excavator bases. One type has wheels just as a regular car would, also known as the wheel type. Because of the nature of the base, it is primarily used on hard surfaces, such as concrete and gravel.

The second type is known as a crawler because of its ability to drive on less stable surfaces, such as mud and sand. Unlike the wheel type, the crawler covers more of the ground and thus will not sink into the ground. It does just as the name suggests, crawls, with a conveyor belt-like mechanism. This machine can only be used on site and would have to be transported by another vehicle to get from one point to another.[7]

[edit] Types

Some of the different types of excavators are a loader backhoe, bucket wheel excavator, midi excavator and compact excavator (also referred to as a mini excavator).

The loader backhoe is a tractor with a front shovel bucket and a small backhoe located in the rear of the machine.

Excavators are also commonly referred to as diggers or 360s, for their ability to swivel in a 360-degree motion.[8]

Other types of excavators include:

[edit] Common Manufacturers

[edit] Different Names For The Same Thing

This is a list of alternate names for hydraulic excavators.

  • Excavator
  • Digger
  • 360

[edit] Additional Photos

See Hydraulic Excavator (Photo Gallery)

[edit] Used & Unused Excavators for Sale

Search for unused and used excavators being sold at Ritchie Bros. unreserved public auctions.

[edit] References

  1. Excavator. Kenkenkikki. 2008-09-24.
  2. RitchieSpecs. 02-02-09.
  3. Haddock, Keith. The Earthmover Encylopedia. Motorbooks: St. Paul, 2002. 225-263.
  4. History. Gradall. 2008-10-07.
  5. Haddock, Keith. The Earthmover Encylopedia. Motorbooks: St. Paul, 2002. 225-263.
  6. Hydraulic Excavator. Kenkenkikki. 2008-09-24.
  7. Hydraulic Excavator. Kenkenkikki. 2008-09-24.
  8. Articles About Excavation Equipment. Excavation Equipment. 2008-09-24.