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Disc brake on a motorcycle

A brake is a mechanical device which inhibits motion. Its opposite component is a clutch. The rest of this article is dedicated to various types of vehicular brakes.

Most commonly brakes use friction to convert kinetic energy into heat, though other methods of energy conversion may be employed. For example regenerative braking converts much of the energy to electrical energy, which may be stored for later use. Other methods convert kinetic energy into potential energy in such stored forms as pressurized air or pressurized oil. Eddy current brakes use magnetic fields to convert kinetic energy into electric current in the brake disc, fin, or rail, which is converted into heat. Still other braking methods even transform kinetic energy into different forms, for example by transferring the energy to a rotating flywheel.

Brakes are generally applied to rotating axles or wheels, but may also take other forms such as the surface of a moving fluid (flaps deployed into water or air). Some vehicles use a combination of braking mechanisms, such as drag racing cars with both wheel brakes and a parachute, or airplanes with both wheel brakes and drag flaps raised into the air during landing.

Since kinetic energy increases quadratically with velocity (Failed to parse (Missing texvc executable; please see math/README to configure.): K=mv^2/2 ), an object moving at 10 m/s has 100 times as much energy as one of the same mass moving at 1 m/s, and consequently the theoretical braking distance, when braking at the traction limit, is 100 times as long. In practice, fast vehicles usually have significant air drag, and energy lost to air drag rises quickly with speed.

Almost all wheeled vehicles have a brake of some sort. Even baggage carts and shopping carts may have them for use on a moving ramp. Most fixed-wing aircraft are fitted with wheel brakes on the undercarriage. Some aircraft also feature air brakes designed to reduce their speed in flight. Notable examples include gliders and some World War II-era aircraft, primarily some fighter aircraft and many dive bombers of the era. These allow the aircraft to maintain a safe speed in a steep descent. The Saab B 17 dive bomber used the deployed undercarriage as an air brake.

Friction brakes on automobiles store braking heat in the drum brake or disc brake while braking then conduct it to the air gradually. When traveling downhill some vehicles can use their engines to brake.

When the brake pedal of a modern vehicle with hydraulic brakes is pushed, ultimately a piston pushes the brake pad against the brake disc which slows the wheel down. On the brake drum it is similar as the cylinder pushes the brake shoes against the drum which also slows the wheel down.

Types[link]

Brakes may be broadly described as using friction, pumping, or electromagnetics. One brake may use several principles: for example, a pump may pass fluid through an orifice to create friction:

• Frictional brakes are most common and can be divided broadly into "shoe" or "pad" brakes, using an explicit wear surface, and hydrodynamic brakes, such as parachutes, which use friction in a working fluid and do not explicitly wear.Typically the term "friction brake" is used to mean pad/shoe brakes and excludes hydrodynamic brakes, even though hydrodynamic brakes use friction.
  Friction (pad/shoe) brakes are often rotating devices with a stationary pad and a rotating wear surface. Common configurations include shoes that contract to rub on the outside of a rotating drum, such as a band brake; a rotating drum with shoes that expand to rub the inside of a drum, commonly called a "drum brake", although other drum configurations are possible; and pads that pinch a rotating disc, commonly called a "disc brake". Other brake configurations are used, but less often. For example, PCC trolley brakes include a flat shoe which is clamped to the rail with an electromagnet; the Murphy brake pinches a rotating drum, and the Ausco Lambert disc brake uses a hollow disc (two parallel discs with a structural bridge) with shoes that sit between the disc surfaces and expand laterally.

• Pumping brakes are often used where a pump is already part of the machinery. For example, an internal-combustion piston motor can have the fuel supply stopped, and then internal pumping losses of the engine create some braking. Some engines use a valve override called a Jake brake to greatly increase pumping losses. Pumping brakes can dump energy as heat, or can be regenerative brakes that recharge a pressure reservoir called a hydraulic accumulator.

• Electromagnetic brakes are likewise often used where an electric motor is already part of the machinery. For example, many hybrid gasoline/electric vehicles use the electric motor as a generator to charge electric batteries and also as a regenerative brake. Some diesel/electric railroad locomotives use the electric motors to generate electricity which is then sent to a resistor bank and dumped as heat. Some vehicles, such as some transit buses, do not already have an electric motor but use a secondary "retarder" brake that is effectively a generator with an internal short-circuit. Related types of such a brake are eddy current brakes, and electro-mechanical brakes (which actually are magnetically driven friction brakes, but nowadays are often just called “electromagnetic brakes” as well).

Characteristics[link]

Brakes are often described according to several characteristics including:

• Peak force – The peak force is the maximum decelerating effect that can be obtained. The peak force is often greater than the traction limit of the tires, in which case the brake can cause a wheel skid.
• Continuous power dissipation – Brakes typically get hot in use, and fail when the temperature gets too high. The greatest amount of power (energy per unit time) that can be dissipated through the brake without failure is the continuous power dissipation. Continuous power dissipation often depends on e.g., the temperature and speed of ambient cooling air.
• Fade – As a brake heats, it may become less effective, called brake fade. Some designs are inherently prone to fade, while other designs are relatively immune. Further, use considerations, such as cooling, often have a big effect on fade.
• Smoothness – A brake that is grabby, pulses, has chatter, or otherwise exerts varying brake force may lead to skids. For example, railroad wheels have little traction, and friction brakes without an anti-skid mechanism often lead to skids, which increases maintenance costs and leads to a "thump thump" feeling for riders inside.

• Power – Brakes are often described as "powerful" when a small human application force leads to a braking force that is higher than typical for other brakes in the same class. This notion of "powerful" does not relate to continuous power dissipation, and may be confusing in that a brake may be "powerful" and brake strongly with a gentle brake application, yet have lower (worse) peak force than a less "powerful" brake.
• Pedal feel – Brake pedal feel encompasses subjective perception of brake power output as a function of pedal travel. Pedal travel is influenced by the fluid displacement of the brake and other factors.
• Drag – Brakes have varied amount of drag in the off-brake condition depending on design of the system to accommodate total system compliance and deformation that exists under braking with ability to retract friction material from the rubbing surface in the off-brake condition.
• Durability – Friction brakes have wear surfaces that must be renewed periodically. Wear surfaces include the brake shoes or pads, and also the brake disc or drum. There may be tradeoffs, for example a wear surface that generates high peak force may also wear quickly.
• Weight – Brakes are often "added weight" in that they serve no other function. Further, brakes are often mounted on wheels, and unsprung weight can significantly hurt traction in some circumstances. "Weight" may mean the brake itself, or may include additional support structure.
• Noise – Brakes usually create some minor noise when applied, but often create squeal or grinding noises that are quite loud.

Brake boost[link]

Most modern vehicles use a vacuum assisted brake system that greatly increases the force applied to the vehicle's brakes by its operator.^[1] This additional force is supplied by the manifold vacuum generated by air flow being obstructed by the throttle on a running engine. This force is greatly reduced when the engine is running at fully open throttle, as the difference between ambient air pressure and manifold (absolute) air pressure is reduced, and therefore available vacuum is diminished. However, brakes are rarely applied at full throttle; the driver takes the right foot off the gas pedal and moves it to the brake pedal - unless left-foot braking is used.

Because of low vacuum at high RPM, reports of unintended acceleration are often accompanied by complaints of failed or weakened brakes, as the high-revving engine, having an open throttle, is unable to provide enough vacuum to power the brake booster. This problem is exacerbated in vehicles equipped with automatic transmissions as the vehicle will automatically downshift upon application of the brakes, thereby increasing the torque delivered to the driven-wheels in contact with the road surface.

Noise[link]

Brake lever on a horse-drawn hearse

Although ideally a brake would convert all the kinetic energy into heat, in practice a significant amount may be converted into acoustic energy instead, contributing to noise pollution.

For road vehicles, the noise produced varies significantly with tire construction, road surface, and the magnitude of the deceleration.^[2] Noise can be caused by different things. These are signs that there may be issues with brakes wearing out over time.

Inefficiency[link]

A significant amount of energy is always lost while braking, even with regenerative braking which is not perfectly efficient. Therefore a good metric of efficient energy use while driving is to note how much one is braking. If the majority of deceleration is from unavoidable friction instead of braking, one is squeezing out most of the service from the vehicle. Minimizing brake use is one of the fuel economy-maximizing behaviors.

While energy is always lost during a brake event, a secondary factor that influences efficiency is "off-brake drag", or drag that occurs when the brake is not intentionally actuated. After a braking event, hydraulic pressure drops in the system, allowing the brake caliper pistons to retract. However, this retraction must accommodate all compliance in the system (under pressure) as well as thermal distortion of components like the brake disc or the brake system will drag until the contact with the disc, for example, knocks the pads and pistons back from the rubbing surface. During this time, there can be significant brake drag. This brake drag can lead to significant parasitic power loss, thus impact fuel economy and vehicle performance.

See also[link]

References[link]

External links[link]

Look up brake in Wiktionary, the free dictionary.

• How Stuff Works - Brakes

Kid Cudi
Kid Cudi performing in Denver, Colorado in 2011
Background information
Birth name	Scott Ramon Seguro Mescudi
Born	(1984-01-30) January 30, 1984 (age 28) Cleveland, Ohio, United States
Genres	Alternative hip hop, neo-psychedelia, pop rock
Occupations	Rapper, singer-songwriter, guitarist, actor
Instruments	Vocals, guitar, drums
Years active	2003–present
Labels	GOOD, Universal Republic,[1] Wicked Awesome
Associated acts	WZRD, Dot da Genius, Kanye West, Chip tha Ripper, Ratatat
Website	www.KidCudi.com

Scott Ramon Seguro Mescudi^[2] (born January 30, 1984),^[3] better known by his stage name Kid Cudi ( /ˈkɪd ˈkʌdi/ KID KUD-ee), sometimes stylized KiD CuDi, is an American alternative hip hop recording artist, singer-songwriter, guitarist and actor. He first gained major attention after the release of his debut mixtape A Kid Named Cudi. In 2009, his single "Day 'n' Nite" reached the top five of the Billboard Hot 100 and Hot R&B/Hip-Hop Songs charts. "Day 'n' Nite" was included on Cudi's debut album Man on the Moon: The End of Day, which was later certified Gold. In 2010 he released his second studio album Man on the Moon II: The Legend of Mr. Rager, preceded by the release of two singles "Erase Me" and "Mr. Rager". In October 2010, Cudi announced that he would be forming a rock band with Dot da Genius called 'Wizard', later renamed WZRD. Their self-titled debut album was released on February 28, 2012.^[4] Kid Cudi has sold over 4.6 million digital singles and has worked with Kanye West, Common, David Guetta and other artists signed to the GOOD Music label.^[5]

In 2009 Cudi, along with record producers Patrick "Plain Pat" Reynolds and Emile Haynie launched their record label, Dream On, in partnership with Kanye West's GOOD Music and Universal Motown. On February 26, 2011 Cudi took to his Twitter account to announce that the label had been dissolved due to differences. In April 2011, while performing at New York City’s Roseland Ballroom Kid Cudi announced he was launching his own label: "Wicked Awesome Records".

Biography[link]

1984-2008: Early life and career beginnings[link]

Kid Cudi was born in Cleveland, Ohio and grew up in Shaker Heights and Solon. He is the youngest of four children, with two brothers, Domingo and Dean, and a sister, Maisha.^[6] His father, a house painter, substitute teacher and World War II Air Force veteran was Mexican-Native American, while his mother, a middle-school choir teacher at Roxboro Middle School, in Cleveland Heights, Ohio, is African-American.^[7][8] When he was eleven years old, Mescudi's father died of cancer; his passing would have a significant effect on Mescudi's personality and subsequently his music.^[8] Mescudi attended Shaker Heights High School for two years, then transferred to Solon High School, and later earned his GED. Eventually, Mescudi studied film at the University of Toledo then dropped out after a year.^[6]

It was towards the end of high school that Mescudi first began rapping, inspired by alternative hip hop groups such as The Pharcyde and A Tribe Called Quest.^[8] He moved to Brooklyn in New York City to pursue a music career.^[2] In July 2008, Kid Cudi released his first mixtape, A Kid Named Cudi, in collaboration with New York street-wear brand 10.Deep as a free download.^[9] The mixtape quickly caught the attention of Kanye West, which in turn spawned his signing to GOOD Music later that year.

Kid Cudi was featured on Kanye West's 2008 album, 808s & Heartbreak, singing with West on the track "Welcome to Heartbreak", and helping with songwriting on "Heartless" and "Paranoid". "Welcome to Heartbreak" peaked at #87 on the Pop 100,^[10] and music videos for both songs have been released. Cudi was then tipped as an artist to watch for in media such as Rolling Stone, Vibe, The Source, XXL and BBC News's Sound of 2009 poll of up-and-coming acts.^[11] MTV News also reported on Cudi on a series of reports MCs To Watch In 2009.^[12]

Kid Cudi performing at Central Park Summerstage in New York City, in 2008.

His first television appearance was at the 2008 MTV Video Music Awards, alongside Travis Barker and DJ AM. On February 17, 2009, he appeared on Snoop Dogg's MTV talk show Dogg After Dark performing "Day 'n' Nite" at the end of the show. Two days later on February 19, 2009, Cudi appeared on BET's 106 & Park with Kanye West to debut the video of "Day 'n' Nite". On March 16, 2009 Kid Cudi performed on mtvU's Spring Break special, and the next day he performed three songs on NBC's Last Call with Carson Daly. He has also appeared as a musical guest on The Late Show with David Letterman and Jimmy Kimmel Live!.

Kid Cudi also made a cameo appearance next to Solange in the video for the song "T.O.N.Y." in February 2009, and later in The Black Eyed Peas' video for "I Gotta Feeling", with David Guetta. He has also been on two magazine covers, Complex (August/September 2009) and URB (August 2009). Bape awarded Cudi his own t-shirt in September 2009, in reward for his music and past employment there when living in New York City.

[edit] 2009–2010: Man on the Moon series

Kid Cudi performing on August 6, 2009.

Cudi's debut album Man on the Moon: The End of Day was released on Universal Motown Records on September 15, 2009^[13] and sold 104,419 copies in the first week and charted at #4.^[14] The album's lead single "Day 'n' Nite", Kid Cudi's greatest commercial success thus far, charted well both in the U.S. and in Europe. The second single was "Make Her Say" (originally titled "I Poke Her Face"), which features a sample from Lady Gaga's hit single "Poker Face" and performances by Kanye West and Common.^[15][16]

On February 25, 2009, Cudi self-leaked a "teaser trailer" ^[17] for the upcoming Transformers: Revenge of the Fallen film using his song "Sky Might Fall" in the background, later he posted that he made the trailer himself and was in talks to possibly make it official.^[18]

With Emile Haynie, Cudi produced an exclusive single called "Switchin Lanes" for the video game Midnight Club: Los Angeles, part of its "South Central Premium Upgrade" downloadable content (DLC) which came out March 19, 2009 for the PlayStation 3 and March 27, 2009 for the Xbox 360.^[19]

He revealed information about his future plans via his blog, saying that a possible collaboration with Chip tha Ripper could be followed with a collaboration project with electrorock duo Ratatat.^[20] During the summer of 2009, Cudi joined rapper Asher Roth for the Great Hangover concert tour.^[21] Kid Cudi was featured on the highly anticipated Jay-Z album The Blueprint 3 (2009), on the song "Already Home".^[22] In a late 2009 interview, Cudi announced that the follow-up to his debut album will be a collaboration album called Cudder and the Revolution of Evolution. He stated he has already recorded songs with Snoop Dogg, Travis Barker, Clipse, Cage and Pharrell and would also like to work with Drake, Green Day, Kings of Leon, Robin Thicke, The Killers and The Postal Service on the album. Also it was rumored that Man on the Moon: The End of Day will be followed up by a sequel titled Man on the Moon: The Ghost in the Machine and that the Man on the Moon will be a trilogy, but was not been confirmed.^[23] Kid Cudi was nominated for three 2010 Grammy Awards for his singles, "Day 'n' Nite" and "Make Her Say".^[24] Kid Cudi was featured on Snoop Dogg's re-release of Malice n Wonderland, More Malice (2010), on the song "That Tree",^[25] as well as teaming up with Johnny Polygon to remix Polygon's "The Riot Song" which appears on his mixtape, Rebel Without Applause(2010)^[26] On April 20, 2010, Kid Cudi announced that the name of his second album has been changed from Cudder and the Revolution of Evolution to Man on the Moon II: The Legend of Mr. Rager.^[27][28] On June 11, 2010, Kid Cudi was arrested in the Chelsea neighborhood of the Manhattan borough New York City and charged with felony criminal mischief and possession of a controlled substance.^[29] Despite his arrest, he was released and made it to Manchester, Tennessee in time to play at Bonnaroo.

The lead single for Cudi's second studio album titled "Erase Me" featuring Kanye West and produced by Jim Jonsin, debuted on a Cleveland radio station June 30, 2010 and was officially released to Rhythm/Crossover radio on August 17, 2010.^{[30][31][32][33]} The album debuted at number three on the US Billboard 200 chart, with first-week sales of 169,000 copies.^[34] In its second week it crossed the 200,000 sales mark.^[35] 2010 also featured Kid Cudi on a number of songs for Kanye West's weekly free music giveaway G.O.O.D. Fridays appearing on "Good Friday", "Christian Dior Denim Flow" and "The Joy", which later became a bonus track on Jay-Z and Kanye West collaborative effort Watch the Throne (2011).

2011-present: New direction and WZRD[link]

In October 2010, Cudi announced that he would be forming a rock band with Dot da Genius tentatively called 'Wizard'.^[36] However, in early 2011, he announced that he would be releasing a mixtape prior to the rock album.^[37] On February 26, 2011 Cudi took to his Twitter account to announce that Dream On, the record label he launched back in 2009 with partners Patrick “Plain Pat” Reynolds and producer Emile Haynie, has been dissolved.^[38] However in an interview with Complex Magazine he explained they were still on good terms: "I wanted to try something new, and I wanted to take control of things myself. Those are still my guys, Pat and Emile, and I'm still going to work with them in the future. When we start working on Man on the Moon III I’ll be calling them up to see if they want to be a part of it. I know Emile is definitely down. We had an issue, but we’re men and we were able to figure it out and move forward. There’s no hard feelings."^[39]

In March 2011, Cudi announced that a music video for "Marijuana" will be released in the spring,^[40] followed by a music video for "Mr. Rager" in the summer of 2011.^[40] As well as a short film inspired by his song "Maniac" with Cage, directed by Shia LaBeouf^[41] will be released in October 2011.^{[dated info][40]}

In April 2011, while performing at New York City’s Roseland Ballroom Kid Cudi announced name of the record label he is launching. The new label, which he will be releasing his third studio album on is called “Wicked Awesome Records”. He also renamed his band on the same occasion to '2 Be Continuum' renaming it from the original 'Wizard'. Kid Cudi explained his reasoning saying: "I needed something more original, something different, but it’s still wizardry at its finest."^[42] On August 12, 2011, Kid Cudi released the music video for "No One Believes Me", directed by Fright Night director Craig Gillespie. Although the song was recorded as a collaborative song with Dot da Genius, the single was released under Kid Cudi's name.^[43] On August 21, Cudi announced that he is no longer releasing the mixtape A Man Named Scott so that he can focus on his rock project and his third solo album Man on the Moon III.^[44] Kid Cudi released a video for Man on the Moon II: The Legend of Mr. Rager's title track "Mr. Rager" on September 8, 2011. The video has received all-positive reviews from critics and fans alike.^[45]

Despite saying he will not do many more features for other artists in Complex magazine's October/November 2011 cover story,^[46] he appeared on Bryan Greenberg's second studio album We Don't Have Forever (2011), Travis Barker's Give the Drummer Some (2011), The Knux's Eraser (2011), and Wale's Ambition (2011) respectively.

On October 30, Cudi released the Maniac, a short horror film co-starring Cage and directed by Shia LaBeouf, through his blog.^[47]

On November 13, 2011, a previously unreleased mixtape of material Cudi had recorded from 2002-2003 titled Rap Hard was released. On November 18, 2011 renamed his band, for the second time to 'WZRD'.^[48] He also announced that the upcoming rock project will be released on his 28th birthday, January 30, 2012.

In late 2011, Cudi was mentioned in a viral video by Ben Breedlove about his near death experiences.^[49] After Breedlove's death on December 26, 2011, Cudi commented on his thoughts about inspiring the young kid. "I am so sad about Ben Breedlove," Kid Cudi wrote on his Tumblr blog. "I watched the video he left for the world to see, and him seeing me in detail, in his vision really warmed my heart. I broke down, I am to tears because I hate how life is so unfair. This has really touched my heart in a way I cant describe, this is why I do what I do. Why I write my life, and why I love you all so much. Life is really f---- up sometimes, but I know Ben is at Peace, and I hope he gets a chance to sit and talk with my Dad. We love you Ben. Forever. Thank you for loving me. To Ben’s family, you raised a real hero, he’s definitely mine. You have my love."

In January 2012 Cudi appeared on two songs off Chip tha Ripper's mixtape Tell Ya Friends, "Ride 4 You" which also featured Far East Movement and "GloryUs" which credited the duo as they are collectively known, The Almighty GloryUs, which led to speculation that a project from the two was underway. On January 31, Cudi announced through his Twitter feed that he had completed Man on the Moon III and that his next album was the collaborative effort with Chip tha Ripper.^[50] In 2012 Cudi was featured on the soundtrack to the film The Hunger Games, crafting an original song for the film titled "The Ruler and the Killer". Cudi wrote on Twitter, "I could not have done it with out my producing partners on the project for the film, The legendary and Godly T Bone Burnett and Greg Wells!", referring to "The Ruler and the Killer"^[51]

While working on WZRD, Cudi claims he had writer's block for almost 5 months because of his new sobriety. Something that never has happened to him for such an extended period of time. According to Kid Cudi, bands that inspired the album include Electric Light Orchestra, Jimi Hendrix, Nirvana and Pink Floyd. The album includes a song titled "Where Did You Sleep Last Night?", a cover of the same titled song by Nirvana who in turn was inspired by blues guitar legend Lead Belly's rendition of the traditional folk song.^[52]

Acting career[link]

Kid Cudi starred in the new HBO comedy series How to Make It in America until its cancellation after 2 seasons. He is credited under his real name.^[53]

Personal life[link]

On March 26, 2010, his daughter, Vada Wamwene Mescudi, was born.^[54][55]

Discography[link]

Studio albums

• Man on the Moon: The End of Day (2009)
• Man on the Moon II: The Legend of Mr. Rager (2010)
• Man on the Moon III (2012)^[56]

Collaborative albums

• WZRD (2012) (with Dot da Genius as WZRD)^[37]
• Cruel Summer (2012) (with GOOD Music)^[57]
• The Almighty GloryUS (TBA) (with Chip tha Ripper)

Mixtapes

• A Kid Named Cudi (2008)

Awards and nominations[link]

Filmography[link]

References[link]

External links[link]

Wikimedia Commons has media related to: Kid Cudi

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