This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (July 2008)

A working bulldozer from the First Tractor Company, on Xinbu Island, Hainan, China.

A bulldozer is a crawler (continuous tracked tractor) equipped with a substantial metal plate (known as a blade) used to push large quantities of soil, sand, rubble, or other such material during construction or conversion work and typically equipped at the rear with a claw-like device (known as a ripper) to loosen densely-compacted materials.

Bulldozers can be found on a wide range of sites, mines and quarries, military bases, heavy industry factories, engineering projects and farms.

The term "bulldozer" is often used erroneously to mean any heavy equipment (sometimes a loader and sometimes an excavator), but precisely, the term refers only to a tractor (usually tracked) fitted with a dozer blade. That is the meaning used here.

Description[link]

A Caterpillar D10N bulldozer equipped with a single shank ripper.

Most often, bulldozers are large and powerful tracked heavy equipment. The tracks give them excellent ground hold and mobility through very rough terrain. Wide tracks help distribute the bulldozer's weight over a large area (decreasing pressure), thus preventing it from sinking in sandy or muddy ground. Extra wide tracks are known as 'swamp tracks'. Bulldozers have excellent ground hold and a torque divider designed to convert the engine's power into improved dragging ability. The Caterpillar D9, for example, can easily tow tanks that weigh more than 70 tons. Because of these attributes, bulldozers are used to clear areas of obstacles, shrubbery, burnt vehicles, and remains of structures.

The bulldozer's primary tools are the blade and the ripper.

Blade[link]

Bulldozer blade

The bulldozer blade is a heavy metal plate on the front of the tractor, used to push objects, and shoving sand, soil and debris. Dozer blades usually come in three varieties:

1. A straight blade ("S blade") which is short and has no lateral curve and no side wings and can be used for fine grading.
2. A universal blade ("U blade") which is tall and very curved, and has large side wings to carry more material.
3. An "S-U" combination blade which is shorter, has less curvature, and smaller side wings. This blade is typically used for pushing piles of large rocks, such as at a quarry.

Blades can be fitted straight across the frame, or at an angle, sometimes using additional 'tilt cylinders' to vary the angle while moving. The bottom edge of the blade can be sharpened, e.g. to cut tree stumps.

Sometimes a bulldozer is used to push another piece of earth moving equipment known as a "scraper". The towed Fresno Scraper, invented in 1883 by James Porteous, was the first design to enable this to be done economically, removing the soil from the cut and depositing it elsewhere on shallow ground (fill). Many dozer blades have a reinforced center section with this purpose in mind, and are called "bull blades".

In military use, dozer blades are fixed on combat engineering vehicles and can optionally be fitted on other vehicles, such as artillery tractors such as the Type 73 or M8 Tractor. Dozer blades can also be mounted on main battle tanks, where it can be used to clear antitank obstacles, mines, and dig improvised shelters. Combat applications for dozer blades include clearing battlefield obstacles and preparing fire positions.^[1]

Ripper[link]

Multi-shank ripper

The ripper is the long claw-like device on the back of the bulldozer. Rippers can come as a single (single shank/giant ripper) or in groups of two or more (multi shank rippers). Usually, a single shank is preferred for heavy ripping. The ripper shank is fitted with a replaceable tungsten steel alloy tip.

Ripping rock breaks the ground surface rock or pavement into small rubble easy to handle and transport, which can then be removed so grading can take place. With agricultural ripping, a farmer breaks up rocky or very hard earth (such as podzol hardpan) which is otherwise unploughable, in order to farm it. For example, much of the best land in the California wine country consists of old lava flows. The grower shatters the lava with heavy bulldozers so surface crops or trees can be planted.

A less common rear attachment is a stumpbuster, which is a single spike that protrudes horizontally and can be raised to get it (mostly) out of the way. A stumpbuster is used to split a tree stump. A bulldozer with a stumpbuster is used for landclearing operations, and probably has a brush-rake blade.

Modifications[link]

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

One example is that loader tractors were created by removing the blade and substituting a large volume bucket and hydraulic arms which can raise and lower the bucket, thus making it useful for scooping up earth and loading it into trucks, these are often known as a Drott.

Aveling-Barford Calfdozer compact bulldozer

Other modifications to the original bulldozer include making it smaller to let it operate in small work areas where movement is limited, such as in mining. A very small bulldozer is sometimes called a calfdozer.

Some lightweight form of bulldozer are commonly used in snow removal and as a tool for preparing winter sports areas for ski and snowboard sports.

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

Nevertheless, the original earthmoving bulldozers are still irreplaceable as their tasks are concentrated in deforestation, earthmoving, ground levelling, and road carving. Heavy bulldozers are mainly employed to level the terrain to prepare it for construction. The construction, however, is mainly done by small bulldozers and loader tractors.

Armored bulldozers[link]

An armored Caterpillar D9R Bulldozer used by Israel Defense forces

Some bulldozers, especially bulldozers in military usage, have been fitted with armor to protect the driver from enemy fire, enabling the bulldozer to operate in battle zones. The best-known use of an armored bulldozer is probably the use by the Israeli Defence Forces (IDF) of the IDF Caterpillar D9, for earth moving, clearing terrain obstacles, opening routes, detonating explosive charges and demolishing structures whilst under fire. The extensive use of armored bulldozers during the Second Intifada drew controversy and criticism from human rights organizations while military experts saw it as a key factor in reducing IDF casualties.

Some bulldozers have been fitted with armor by non-government civilian operators to prevent bystanders or police from interfering with the work performed by the bulldozer, as in the case of strikes or demolition of condemned buildings. This has also been done by civilians with a dispute with the authorities, such as Marvin Heemeyer, who outfitted his Komatsu D355A bulldozer with homemade composite armor to then demolish government buildings.

History[link]

A Liebherr bulldozer with a multi-shank ripper.

Caterpillar D9 "cable-rig" bulldozer in the museum at Sinsheim, Germany.

The first bulldozers were adapted from Holt farm tractors that were used to plow fields. The versatility of tractors in soft ground for logging and road building contributed to the development of the armoured tank in World War I.

In 1923, a young farmer named James Cummings and a draftsman named J. Earl McLeod made the first designs for the bulldozer. A replica is on display at the city park in Morrowville, Kansas where the two built the first bulldozer.^[2] On December 18, 1923, Cummings and McLeod filed U.S. patent #1,522,378 that was later issued on January 6, 1925 for an "Attachment for Tractors."^[3]

By the 1920s, tracked vehicles became common, particularly the Caterpillar 60. Rubber tired vehicles came into use in the 1940s. To dig canals, raise earth dams, and do other earth moving jobs, these tractors were equipped with a large thick metal plate in front. (The blade got its curved shape later). In some early models the driver sat on top in the open without a cabin. There are three main types of bulldozer blades: a U-blade for pushing and carrying dirt relatively long distances, a straight blade for "knocking down" and spreading piles of dirt, and a brush rake for removing brush and roots. These attachments (home-built or built by small equipment manufacturers of attachments for wheeled and crawler tractors and trucks) appeared by 1929.

Widespread acceptance of the bull-grader does not seem to appear before the mid-1930s. The addition of power down-force provided by hydraulic cylinders instead of just the weight of the blade made them the preferred excavation machine for large and small contractors alike by the 1940s, by which time the term "bulldozer" referred to the entire machine and not just the attachment.

Over the years, bulldozers got bigger and more powerful in response to the demand for equipment suited for ever larger earthworks. Firms like Caterpillar, Komatsu, Case, JCB, Euclid,^[4] Allis Chalmers, Liebherr, LiuGong, Terex, Fiat-Allis, John Deere and International Harvester manufactured large tracked-type earthmoving machines. R.G. LeTourneau and Caterpillar manufactured large rubber tired bulldozers.^[5]

Bulldozers grew more sophisticated as time passed. Improvements include drivetrains analogous to (in automobiles) an automatic transmission instead of a manual transmission such as the early Euclid C-6 and TC-12 or Model C Tournadozer, blade movement controlled by hydraulic cylinders or electric motors instead of early models' cable winch/brake, and automatic grade control. Hydraulic cylinders enabled the application of down force, more precise manipulation of the blade and automated controls.

A more recent innovation is the outfitting of bulldozers with GPS technology, such as manufactured by Topcon Positioning Systems, Inc., Trimble Inc, or Leica Geosystems for precise grade control and (potentially) "stakeless" construction. As a response to the many, -and often varying claims about these systems, The Kellogg Report ^[6] published in 2010 a detailed comparison of all the manufacturers' systems, evaluating more than 200 features for dozers alone.

The best known maker of bulldozers is probably Caterpillar in the USA, which earned its reputation by making tough, durable, reliable machines. Komatsu, JCB and John Deere are present-day competitors. Although these machines began as modified farm tractors, they became the mainstay for big civil construction projects, and found their way into use by military construction units worldwide. The best known model, the Caterpillar D9, was also used to clear mines and demolish enemy structures.

History of the word[link]

• 19th century: term used in engineering for a horizontal forging press.
• Around 1880: In the USA, a "bull-dose" was a large and efficient dose of any sort of medicine or punishment. 'Bull-dosing' meant a severe whipping or coercion, or other intimidation such as at gunpoint.^[7]
• 1886: "bulldozer" meant a large-caliber pistol and the person who wielded it.^[7]
• Late 19th century: "bulldozing" meant using big force to push over or through any obstacle.^[7]
• 1930s: applied to the vehicle.

These appeared as early as 1929, but were known as "bull grader" blades, and the term "bulldozer blade" did not appear to come into widespread use until the mid 1930s' "Bulldozer" now refers to the whole machine not just the attachment. In contemporary usage, "bulldozer" is often shortened to "dozer".

See also[link]

• Athanas for the 'bulldozer shrimp' (from the way it pushes sand about)

References[link]

1. ^ Trewhitt, Philip (1999). Armoured Fighting Vehicles. Dempsey-Parr. ISBN 1-84084-328-4. 
2. ^ Kansas Curiosities: Quirky Characters, Roadside Oddities & Other Offbeat Stuff. http://books.google.com/books?id=OZVrxulVBtoC&pg=PA189&dq=James+Cummings+J.+Earl+McLeod+bulldozer&hl=en&sa=X&ei=Gtt4T_S_L_Cu2AXLoYW2Bg&ved=0CDAQ6AEwAA#v=onepage&q=James%20Cummings%20J.%20Earl%20McLeod%20bulldozer&f=false. Retrieved 2012-04-01. 
3. ^ Patent 1522378, Attachment For Tractors, John E McLeod and James D Cummings, Filed December 18, 1923.
4. ^ Haddock, Keith. "Euclid-General Motors' Crawler Tractor". PEI Tractor Club. http://pendergast.ca/antiqueengine/euclid.htm. Retrieved 11 September 2011. 
5. ^ "Tournadozer Built for Speedy Earthmoving". Construction Equipment. http://www.constructionequipment.com/tournadozer-built-speedy-earthmoving. Retrieved 11 September 2011. 
6. ^ The Kellogg Report LLC (2010). Article: The Kellogg Report. Retrieved December 15, 2010 from kelloggreport.com
7. ^ ^{a b c} "History of the Bulldozer". http://inventors.about.com/od/bstartinventions/a/bulldozer.htm. Retrieved 2008-12-17. 

External links[link]

Media related to Bulldozers at Wikimedia Commons

• The mechanism of a bulldozer (Short illustrated explanations, with flash animations, suitable for kids)
• Van Natta Bulldozers Further information about working bulldozers
• Old engine Bulldozer pages photos

Felicia Day
Born	Kathryn Felicia Day (1979-06-28) June 28, 1979 (age 32)[1] Huntsville, Alabama, United States
Residence	Los Angeles, California
Nationality	American
Occupation	Actress/Writer/Singer
Years active	2001-present
Website
http://www.feliciaday.com/

Kathryn Felicia Day^[2] (born on June 28, 1979^[1]) is an American actress and singer, known for her work as "Vi" on the TV series Buffy the Vampire Slayer and for parts in movies such as Bring It On Again and June, as well as the Internet musical, Dr. Horrible's Sing-Along Blog. Day is also the star, script writer and producer of the original web series The Guild, a show loosely based on her life as a gamer. She also starred in the Dragon Age web series Dragon Age: Redemption, which she wrote. She is a member of the Board of Directors of the International Academy of Web Television.^[3]

Personal life and education[link]

Day began her acting career at the age of 7 when she starred as Scout in a local production of To Kill a Mockingbird. She studied operatic singing and ballet professionally, performing at concerts and competitions nationwide. Home-schooled throughout much of her childhood, she began college at the age of 16.^[4]

She was a National Merit Scholar (1995)^[5] and graduated as valedictorian of her class. ^[4][6] An accomplished violinist,^[4] Day was accepted to the Juilliard School of Music but chose to attend the University of Texas at Austin on a full scholarship in violin performance. She double majored in mathematics and music performance.^[7][6]

Day is an avid player of a wide variety of video game genres. Much of her work on The Guild web series was based on her personal experience with video games.^[8]

Career[link]

Early career[link]

After graduation, Day moved to Los Angeles to pursue a career in acting. She landed several roles in various short and independent films, as well as commercials and guest spots on television shows, including Undeclared and Maybe It's Me. These parts propelled her to larger roles: a part in the film Bring It On Again, the starring role in June, and a recurring guest spot as potential Slayer Vi on television's Buffy the Vampire Slayer, a recurring role that is still occasionally utilized in that show's eighth season comic book series.

[edit] The Guild

Felicia Day

Day is the creator, writer, and star of The Guild, a web series which started airing its fifth season in July 2011. The first season was primarily hosted on YouTube where it garnered millions of views.^[9] Its second season premiered on Microsoft's three major video channels Xbox Live, MSN Video and The Zune Marketplace after Microsoft made a deal with The Guild, allowing Day, her cast, and her crew to be paid for their work. Day also created a song and music video called "(Do You Wanna Date My) Avatar", featuring the cast dressed up as their in-game personae. The final moments of the music video itself also detailed that the release date for the 3rd season of Day's The Guild would be August 25, 2009. A second song and video "Game On" was released prior to the premiere of the 4th season of The Guild.

The Guild has won multiple awards, including the Greenlight Award for Best Original Digital Series Production at the South by Southwest festivals,^[10] the YouTube Video Award for Best Series,^[11] the Yahoo! Video Award for Best Series,^[12] and 2009 Streamy Awards for Best Comedy Web Series, Best Female Actor in a Comedy Web Series, and Best Ensemble Cast in a Web Series.^[13]

Other work[link]

In July 2008, Day starred as Penny in the three-part web-based musical Dr. Horrible's Sing-Along Blog (created by Joss Whedon, who also created Firefly and Buffy the Vampire Slayer in which Day has a minor role as the potential slayer Vi during the seventh season).^[14] Day was featured as a patient in the episode "Not Cancer" of the medical drama House,^[15] and had a guest starring role in the sci-fi drama Dollhouse's unaired episode "Epitaph One",^[16] as well as its series finale "Epitaph Two."^[17] In 2008, Day was featured in a series of commercials for Sears.^[18][19] She also appeared in the first of the revitalized Cheetos commercials.^[20] In the series Lie to Me, on the episode called "Tractor Man", airing December 14, 2009, Day sang a song called "White Lie" alongside Brendan Hines.^{[citation needed]} Day starred in the Syfy film adaption of the saga Little Red Riding Hood, called Red;^[21] it was produced by Angela Mancuso.^[22] Day also played the continuing role of Dr. Holly Marten in the Syfy channel's original series, Eureka, appearing for 10 episodes until episode 2 of series 5.

Day also starred in Guild co-star Sandeep Parikh's web-series The Legend of Neil, in which she portrayed a Fairy. She sings in the second season musical episode, in which she obliquely references her history of internet musicals.

Day lent her voice to the character Veronica Santangelo in the video game Fallout: New Vegas.

In February 2011, Day announced that she would be starring in a new web miniseries. Called Dragon Age: Redemption, it is based on the Dragon Age video games made by BioWare^[23] and aired on October 10, 2011.^[24] She also voices the elf Tallis, the protagonist of the Dragon Age downloadable content "Mark of the Assassin".

In March 2012, Day announced that she would be launching a premium YouTube channel, "Geek & Sundry," on April 2. ^[25]

In April 2012 it was announced that Day will host the 2012 IndieCade Awards Ceremony on October 4th, 2012. ^[26]

On April 29, 2012 she also appeared on the YouTube show MyMusic as a Norwegian Black Metal singer named Gorgol^[27].

Awards[link]

In September 2008, TV Week included her in their list of Top 10 Web Video Creators.^[28]

During the inaugural Streamy Awards held in Los Angeles on March 28, 2009, Day received the award for the "Best Female Actor in a Comedy" for her work as protagonist Cyd Sherman in The Guild, and won the same award again in 2010.^[29] She was also recognized for her work on Dr. Horrible's Sing-Along Blog in 2009.

Filmography[link]

TV series/internet productions[link]

Video games[link]

References[link]

Further Reading

• Schramm, Mike. (Aug. 24, 2009) BlizzCon 2009: WoW.com interviews Felicia Day. (part 2)

External links[link]

Wikimedia Commons has media related to: Felicia Day

• Felicia Day Online - official website and blog
• Felicia Day at the Internet Movie Database