Train wheels are affixed to a straight axle, such that both wheels rotate in unison. This is called a wheelset.

An axle is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to its surroundings, with the wheels rotating around the axle. In the former case, bearings or bushings are provided at the mounting points where the axle is supported. In the latter case, a bearing or bushing sits inside the hole in the wheel to allow the wheel or gear to rotate around the axle. Sometimes, especially on bicycles, the latter type is referred to as a spindle.

On cars and trucks, several senses of the word "axle" co-occur in casual usage, referring to the shaft itself, its housing, or simply any transverse pair of wheels. The shaft itself rotates with the wheel, being either bolted or splined in fixed relation to it, and is called an "axle" or "axle shaft". However, it is equally true that the housing around it (typically a casting) is also called an "axle" (or "axle housing"). An even broader (somewhat figurative) sense of the word refers to every transverse pair of wheels, whether they are connected to each other or not. Thus even transverse pairs of wheels in an independent suspension are usually called "an axle".

Vehicle axles[link]

Axles are an integral component of a wheeled vehicle. In a live-axle suspension system, the axles serve to transmit driving torque to the wheel, as well as to maintain the position of the wheels relative to each other and to the vehicle body. The axles in this system must also bear the weight of the vehicle plus any cargo. A non-driving axle, such as the front beam axle in Heavy duty trucks and some 2 wheel drive light trucks and vans, will have no shaft. It serves only as a suspension and steering component. Conversely, many front wheel drive cars have a solid rear beam axle.

In other types of suspension systems, the axles serve only to transmit driving torque to the wheels; The position and angle of the wheel hubs is a function of the suspension system. This is typical of the independent suspension found on most newer cars and SUV's, and on the front of many light trucks. These systems still have a differential, but it will not have attached axle housing tubes. It may be attached to the vehicle frame or body, or integral in a transaxle. The axle shafts (usually C.V. type) then transmit driving torque to the wheels. Like a full floating axle system, the shafts in an independent suspension system do not support and vehicle weight.

"Axle" in reference to a vehicle also has a more ambiguous definition, meaning parallel wheels on opposing sides of the vehicle, regardless of their mechanical connection type to each other and the vehicle frame or body.

Structural features[link]

0 Series Shinkansen Wheel

A straight axle is a single rigid shaft connecting a wheel on the left side of the vehicle to a wheel on the right side. The axis of rotation fixed by the axle is common to both wheels. Such a design can keep the wheel positions steady under heavy stress, and can therefore support heavy loads. Straight axles are used on trains, for the rear axles of commercial trucks, and on heavy duty off-road vehicles. The axle can be protected and further reinforced by enclosing the length of the axle in a housing.

In split-axle designs, the wheel on each side is attached to a separate shaft. Modern passenger cars have split drive axles. In some designs, this allows independent suspension of the left and right wheels, and therefore a smoother ride. Even when the suspension is not independent, split axles permit the use of a differential, allowing the left and right drive wheels to be driven at different speeds as the automobile turns, improving traction and extending tire life.

A tandem axle is a group of two or more axles situated close together. Trucks designs will use such a configuration to provide a greater weight capacity than a single axle. Semi trailers usually have a tandem axle at the rear.

Drive axles[link]

Splines on a front drive axle.

An axle that is driven by the engine is called a drive axle.

Modern front wheel drive cars typically combine the transmission and front axle into a single unit called a transaxle. The drive axle is a split axle with a differential and universal joints between the two half axles. Each half axle connects to the wheel by use of a constant velocity (CV) joint which allows the wheel assembly to move freely vertically as well as to pivot when making turns.

In rear wheel drive cars and trucks, the engine turns a driveshaft which transmits rotational force to a drive axle at the rear of the vehicle. The drive axle may be a live axle, but modern automobiles generally use a split axle with a differential.

Some simple vehicle designs, such as lesiure go-karts, may have a single driven wheel where the drive axle is a split axle with only one of the two shafts driven by the engine, or else have both wheels connected to one shaft without a differential (kart racing).

Dead axles/lazy axles[link]

This dump truck has an airlift pusher axle, shown in the raised position.

A dead axle, also called lazy axle, is not part of the drivetrain but is instead free-rotating. The rear axle of a front-wheel drive car may be considered a dead axle. Many trucks and trailers use dead axles for strictly load-bearing purposes. A dead axle located immediately in front of a drive axle is called a pusher axle. A tag axle is a dead axle situated behind a drive axle. On some vehicles (such as motorcoaches), the tag axle may be steerable.

Some dump trucks and trailers are configured with lift axles (also known as airlift axles or drop axles), which may be mechanically raised or lowered. The axle is lowered to increase the weight capacity, or to distribute the weight of the cargo over more wheels, for example to cross a weight restricted bridge. When not needed, the axle is lifted off the ground to save wear on the tires and axle and to increase traction in the remaining wheels. Lifting an axle also alleviates lateral scrubbing of the additional axle in very tight turns, allowing the vehicle to turn more readily. In some situations removal of pressure from the additional axle is necessary for the vehicle to complete a turn at all.^[1]

Several manufacturers offer computer-controlled airlift, so that the dead axles are automatically lowered when the main axle reaches its weight limit. The dead axles can still be lifted by the press of a button if needed.

Full-floating vs semi-floating[link]

Full-floating[link]

The full-floating design is typically used in most 3/4 and 1-ton light trucks, medium duty trucks and heavy-duty trucks, as well as most agricultural applications, such as large tractors and combines. There are a few exceptions, such as many Land-Rover vehicles. A full-floating axle can be identified by a protruding hub to which the axle shaft flange is bolted. These axles can carry more weight than a semi-floating or non-floating axle assembly because the hubs have two bearings riding on a fixed spindle. The axle shafts themselves do not carry any weight; they serve only to transmit torque from the differential to the wheels. Full-floating axle shafts are retained by the aforementioned flange bolted to the hub, while the hub and bearings are retained on the spindle by a large nut.

Semi-floating[link]

The semi-floating design carry the weight of the vehicle on the axle shaft itself; there is a single bearing at the end of the axle housing that carries the load from the axle and that the axle rotates through. With a semi-floating axle, the axles themselves serve as the inner bearing race and are retained by c-clips that are in the differential carrier. This design is found under most 1/2 ton and lighter trucks and SUV's.

See also[link]

Wikisource has the text of the 1911 Encyclopædia Britannica article Axle.

• All pages beginning with "Axle"
• All pages with titles containing "Axle"
• Klien-Lindner axle
• Portal axle
• Wheel and axle

Table of simple mechanisms, from Chambers' Cyclopedia, 1728.^[1] Simple machines provide a "vocabulary" for understanding more complex machines.

A simple machine is a mechanical device that changes the direction or magnitude of a force.^[2] In general, they can be defined as the simplest mechanisms that provide mechanical advantage (also called leverage).^[3]

Usually the term refers to the six classical simple machines which were defined by Renaissance scientists:^[4]

• Lever
• Wheel and axle
• Pulley
• Inclined plane
• Wedge
• Screw

A simple machine is an elementary device that has a specific movement (often called a mechanism), which can be combined with other devices and movements to form a machine. Thus simple machines are considered to be the "building blocks" of more complicated machines. This analytical view of machines as decomposable into simple machines first arose in the Renaissance as a neoclassical amplification of ancient Greek texts on technology,^[5] and is still a central part of engineering in today's age of applied science. For example, wheels, levers, and pulleys are all used in the mechanism of a bicycle.^[6][7] Between the simple machines and complex assemblies, several intermediate classes can be defined, which may be termed "compound machines"^[8][3][9] or "machine elements".^[10] The mechanical advantage of a compound machine is simply the product of the mechanical advantages of the simple machines of which it is composed.

Various authors have compiled lists of simple machines and machine elements, sometimes lumping them together under a single term such as "simple machines",^[1] "basic machines",^[6] "compound machines",^[8] or "machine elements"; the use of the term "simple machines" in this broader sense is a departure from the neoclassical sense of the six essential simple machines, which is why many authors prefer to avoid its use, preferring the other terms (such as "machine element"). In all cases, the theme of an analytical and synthetic connection from simple to compound to complex is at work. A page from a 1728 text by Ephraim Chambers^[1] (in the figure to the right) shows more machine elements. By the late 1800s, Franz Reuleaux^[11] identified hundreds of machine elements (calling them "simple machines"). Models of these devices can be found at Cornell University's KMODDL website.^[12]

History[link]

The idea of a "simple machine" originated with the Greek philosopher Archimedes around the 3rd century BC, who studied the "Archimedean" simple machines: lever, pulley, and screw.^[3][13] He discovered the principle of mechanical advantage in the lever.^[14] Later Greek philosophers defined the classic five simple machines (excluding the inclined plane) and were able to roughly calculate their mechanical advantage.^[5] Heron of Alexandria (ca. 10–75 AD) in his work Mechanics lists five mechanisms that can "set a load in motion"; lever, windlass, pulley, wedge, and screw,^[13] and describes their fabrication and uses.^[15] However the Greeks' understanding was limited to the statics of simple machines; the balance of forces, and did not include dynamics; the tradeoff between force and distance, or the concept of work.

During the Renaissance the dynamics of the Mechanical Powers, as the simple machines were called, began to be studied from the standpoint of how much useful work they could perform, leading eventually to the new concept of mechanical work. In 1586 Flemish engineer Simon Stevin derived the mechanical advantage of the inclined plane, and it was included with the other simple machines. The complete dynamic theory of simple machines was worked out by Italian scientist Galileo Galilei in 1600 in Le Meccaniche ("On Mechanics").^[16][17] He was the first to understand that simple machines do not create energy, only transform it.^[16]

The classic rules of sliding friction in machines were discovered by Leonardo Da Vinci (1452–1519), but remained unpublished in his notebooks. They were rediscovered by Guillaume Amontons (1699) and were further developed by Charles-Augustin de Coulomb (1785).^[18]

Mechanical advantage[link]

A simple machine has an applied force that works against a load force. If there are no friction losses, the work done on the load is equal to the work done by the applied force. This allows an increase in the output force at the cost of a proportional decrease in the distance moved by the load. The ratio of the output force to the input force is the mechanical advantage of the machine.

If the simple machine does not dissipate or absorb energy, then its mechanical advantage can be calculated from the machine's geometry. For example, the mechanical advantage of a lever is equal to the ratio of its lever arms. A simple machine with no friction or elasticity is often called an ideal machine.^[19][20]

The mechanical advantage of an ideal simple machine is easily obtained from the requirement the rate of energy in, or power in, equals the rate of energy out, or power out, that is

Failed to parse (Missing texvc executable; please see math/README to configure.): P_{in} = P_{out}.\!

Because power is the product of a force and the velocity of its point of application, the applied force times the velocity the input point moves, v_in, must be equal to the load force times the velocity the load moves, v_out, given by

Failed to parse (Missing texvc executable; please see math/README to configure.): F_{in}v_{in} = F_{out}v_{out}.\,

So the ratio of output to input force, the mechanical advantage, of a frictionless machine is equal to the "velocity ratio"; the ratio of input velocity to output velocity:

Failed to parse (Missing texvc executable; please see math/README to configure.): MA = \frac{F_{out}}{F_{in}} = \frac{v_{in}}{v_{out}} \,

      (Ideal Mechanical Advantage)

In the screw, which uses rotational motion, the input force should be replaced by the torque, and the velocity by the angular velocity the shaft is turned.

Compound machine[link]

A compound machine is a machine formed from a set of simple machines connected in series with the output force of one providing the input force to the next. For example a bench vise consists of a lever (the vise's handle) in series with a screw, and a simple gear train consists of a number of gears (wheels and axles) connected in series.

The mechanical advantage of a compound machine is the ratio of the output force exerted by the last machine in the series divided by the input force applied to the first machine, that is

Failed to parse (Missing texvc executable; please see math/README to configure.): \mathrm{MA}_{compound} = \frac {F_{\mathrm{out} n}} {F_{\mathrm{in} 1}}. \,

Because the output force of each machine is the input of the next, Failed to parse (Missing texvc executable; please see math/README to configure.): F_{out 1}=F_{in 2} \,

and Failed to parse (Missing texvc executable; please see math/README to configure.):  F_{out k} =F_{in k+1} \,

, this mechanical advantage is also given by,

Failed to parse (Missing texvc executable; please see math/README to configure.): \mathrm{MA}_{compound} = \frac {F_{out 1}} {F_{in 1}} \frac {F_{out 2}} {F_{in 2}} \ldots\frac {F_{out n}} {F_{in n}}. \,

Thus, the mechanical advantage of the compound machine is equal to the product of the mechanical advantages of the series of simple machines that form it,

Failed to parse (Missing texvc executable; please see math/README to configure.): \mathrm{MA}_{compound} = \mathrm{MA}_1 \mathrm{MA}_2 \ldots\mathrm{MA}_n \,

Energy losses and efficiency[link]

Machines lose energy through friction, deformation and wear, which is dissipated as heat. This means the power out of the machine is less than power in. The ratio of power out to power in is the efficiency η of the machine, and is a measure of the energy losses,

Failed to parse (Missing texvc executable; please see math/README to configure.): \eta = \frac{P_{out}}{P_{in}}. \,

The velocity ratio of a machine is fixed by its dimensions, so it is the mechanical advantage that is reduced by the losses, that is

Failed to parse (Missing texvc executable; please see math/README to configure.): MA = \frac{F_{out}}{F_{in}} = \eta \frac{v_{in}}{v_{out}}.

So in non-ideal machines, the mechanical advantage is always less than the velocity ratio by the product with the efficiency η. So a machine that includes losses such as friction, deformation and wear, will not be able to move as large a load as a corresponding ideal machine using the same input force.

The efficiency of a compound machine is the product of the efficiencies of the series of simple machines that form it,

Failed to parse (Missing texvc executable; please see math/README to configure.): \eta_{compound} = \eta_1 \eta_2 \ldots \eta_n.\,

Kinematic chains[link]

Illustration of a four-bar linkage from Kinematics of Machinery, 1876

Simple machines are elementary examples of kinematic chains that are used to model mechanical systems ranging from the steam engine to robot manipulators. The bearings that form the fulcrum of a lever and that allow the wheel and axle and pulleys to rotate are examples of a kinematic pair called a hinged joint. Similarly, the flat surface of an inclined plane and wedge are examples of the kinematic pair called a sliding joint. The screw is usually identified as its own kinematic pair called a helical joint.

Two levers, or cranks, are combined into a planar four-bar linkage by attaching a link that connects the output of one crank to the input of another. Additional links can be attached to form a six-bar linkage or in series to form a robot.^[19]

Classification of machines[link]

The identification of simple machines arises from a desire for a systematic method to invent new machines. Therefore, an important concern is how simple machines are combined to make more complex machines. One approach is to attach simple machines in series to obtain compound machines.

However, a more successful strategy was identified by Franz Reuleaux, who collected and studied over 800 elementary machines. He realized that a lever, pulley and wheel and axle are in essence the same device, a body rotating about a hinge, and that an inclined plane, wedge and screw are similarly a block sliding on a flat surface.^[21]

This realization shows that it is the joints, or the connections that provide movement, that are the primary elements of a machine. Starting with four types of joints, the rotary joint, sliding joint, cam joint and gear joint, and related connections such as cables and belts, it is possible to understand a machine as an assembly of solid parts that connect these joints.^[19]

See also[link]

• Machine (mechanical)
• Mechanism (engineering)
• Linkage (mechanical)
• Four-bar linkage
• Six-bar linkage
• Gear train
• Mechanical advantage
• Power (physics)

References[link]

Tony Hawk

Hawk in November 2006
Personal information
Full name	Anthony Frank Tony Hawk
Nickname(s)	The Birdman
Born	(1968-05-12) May 12, 1968 (age 44) Carlsbad, California, United States
Height	6 ft 3 in (1.91 m)
Weight	170 lb (77 kg)
Sport
Country	United States
Sport	Skateboarding
Medal record Summer X Games medal record Competitor for  United States Gold 1995 Rhode Island Vert Gold 1997 San Diego Vert Gold 1997 San Diego Vert Doubles Gold 1998 San Diego Vert Doubles Gold 1999 San Francisco Vert Doubles Gold 1999 San Francisco Vert Best Trick Gold 2000 San Francisco Vert Doubles Gold 2001 Philadelphia Vert Doubles Gold 2002 Philadelphia Vert Doubles Silver 1995 Rhode Island Park Silver 1996 Rhode Island Vert Silver 2001 Philadelphia Vert Best Trick Bronze 1998 San Diego Vert Bronze 1999 San Francisco Vert

Anthony Frank "Tony" Hawk (born May 12, 1968), nicknamed "The Birdman" is an American professional skateboarder and actor. Hawk gained significant fame for completing the first 900 as well as his licensed video game titles distributed by Activision. He is widely considered one of the most successful and influential pioneers of modern vertical skateboarding.^[1]

Raised in San Diego, California, Hawk was described as being "hyperactive" as a child. His parents supported his skateboarding because it served as an outlet for his excessive energy, and as Hawk's skills developed, he became a professional skateboarder at age fourteen. In 1999, he became the first skater to land a 900. In 2002, he created the Boom Boom HuckJam, an extreme sports exhibition and tour which launched in Las Vegas.

Throughout his career, Hawk has made numerous appearances in films and other media, as well as his own series of video games. He has also been involved in various philanthropic activities including his own Tony Hawk Foundation which helps build skateparks in underprivileged areas, and also including collaborations with other athletes in the charity Athletes for Hope.

Early life[link]

Hawk was born in Carlsbad, California, to, Frank Peter Rupert Hawk. ^[2][3] When Hawk was young, he was described as being "hyperactive,"^[3] and his mother says that he was "so hard on himself and expected himself to do so many things."^[1] One time, Tony struck out in baseball and was so distraught that he hid in a ravine and had to be "physically coaxed out" by his father. His frustration with himself was so harsh that his parents had him psychologically evaluated at school. The results were that Tony was "gifted," and school advisors recommended placing him in advanced classes.^[1]

Hawk attended Jean Farb Middle School from 1980 to 1981, and recently went back there for the show "Homecoming" where he set up a ramp and did a demonstration.

He turned pro by the age of 14^[1] and was the National Skateboard Association world champion for 12 consecutive years.

The 900[link]

On July 27, 1999, Hawk was the first skater to land a 900. He successfully landed the trick, which involves completing two-and-a-half revolutions with the skateboard, on the eleventh attempt. After completing the trick, he commented, "This is the best day of my life."^[4] Nearly 12 years later Hawk was still able to land his famous 900 and posted a video of the trick via his Twitter account stating "I'm 42 and I did a 900 today."^[5]

Endorsements[link]

Boom Boom HuckJam[link]

In 1998, Tony Hawk started freestyle motocross, skateboarding, and BMX with a show in Las Vegas and then on to 31 cities around the USA and eventually to Six Flags amusement parks.^[6]

Video Game Series[link]

A video game series based on his skateboarding debuted in 1999. Since then, the series has spawned 16 titles, including main series titles, spin-offs, and repackages. The latest game of the series is the Tony Hawk: Ride, which involves riding on a skateboard-shaped controller.

Hawk's role in the series was usurped by customizable player characters in later installments,^[7] but he has remained a prominent character. In the 2003 game Tony Hawk's Underground, he is a minor non-player character whom the player meets in Tampa, Florida and skates against. Impressed with the player's skills, Hawk grants them entry into a skate competition.^[8] He later appears in Moscow to teach them the "360 Varial Heelflip Lien" move.^[9] Hawk and other skaters are briefly playable near the end of the game when they skate in a promotional video for the player's skate team,^[10] and in all gameplay modes except the story mode.^[11] He appeared as a kid in the Backyard Sports series Backyard Skateboarding.

Amusement Park Ride[link]

A series of amusement park rides known as Tony Hawk's Big Spin were built in three Six Flags parks in 2007 and 2008. The ride was originally billed as the "total Tony Hawk experience" and was designed to have the look and feel of a giant red-and-black skatepark. It offered a full "extreme sports" experience, with monitors in the queue lines displaying highlights of the history of action sports and a large spinning Tony Hawk figure crowning the ride. The ride was later demolished to make way for a new ride known as Superman: Ultimate Flight (Six Flags Discovery Kingdom) announced to be open in Spring 2012. Additionally, a water park ride called Tony Hawk's Halfpipe was opened at Six Flags America in Bowie, MD.

Film and television appearances[link]

In 1986, Tony Hawk was a featured skateboarder and skater-double for Josh Brolin in the movie Thrashin'. In 1989, he appeared as a skateboarder in Gleaming the Cube. In 2002, he appeared in Neal H. Moritzs's and Christopher Gilcrest's film xXx playing the role of one of Xander Cages stuntman friends, and later in the movie, a skateboarder at a party. In 2004 he played himself in the Australian skateboarding movie Deck Dogz. In 2006, Tony Hawk appeared in a cameo on the film Drake & Josh Go Hollywood as himself; when Drake & Josh steal his car to escape from two crooks with the Geo (iPods) that carry illegal information for counterfeiting money. Tony Hawk also asks for the cops to give Drake & Josh a police escort to Sunset Studios, for a performance on TRL. Hawk has had a cameo in the movie, The New Guy. Hawk appeared in Jackass: The Movie with Mat Hoffman and Bam Margera, skateboarding in a fat suit and Jackass 2, while skateboarding through an obstacle course. Tony appears in the film following the 2006 Gumball Rally, 3000 Miles, again with Bam Margera. He also plays the police officer who arrests Ryan Dunn in the movie Haggard: The Movie. Hawk also made a brief cameo appearance in Lords Of Dogtown as an astronaut, where he is shown comically falling off the skateboard as he is a "rookie". He played himself in an episode of Rocket Power.

Hawk was featured as an extra in the "Weird Al" Yankovic video "Smells like Nirvana". He can be seen sitting in the bleachers during the crowd sweep near Dick Van Patten. He also made a cameo appearance in the Simple Plan music video for "I'm Just a Kid", he can be seen, in a crowd, watching kids at a high school skating..

On television, he has also appeared in Action (TV series), What I Like About You, The Suite Life of Zack & Cody, The Tom Green Show, The Naked Brothers Band and Zeke and Luther, So Random, and All That. Hawk was a guest on the kid's show on Nickelodeon, Yo Gabba Gabba.^[12] In 2000, he played himself in Max Steel. He also guest voiced on The Simpsons episode "Barting Over", where he played himself, along with fellow San Diegans Blink-182. In the episode, Hawk lends Homer a new board from his brand where complete rookies are able to perform at the top levels. He ends up having a comical play off with him after Homer begins to show him up. On the PBS Kids show Cyberchase, he guest starred as Slider's long-lost father, Coop. In the CSI: Miami episode "Game Over" he played a game programmer who was murdered. In 2008, he played on Million Dollar Password. Hawk also played on Fox's Are You Smarter Than a 5th Grader. Tony Hawk helped design the world famous Canvey Island skate park in 1982 and has hosted Cartoon Network's "Hall of Game" sports award show on February 25, 2011. Hawk was also on the Live-Action/Animated Talk Show Take Two With Phineas and Ferb. Hawk appeared on the internet cooking show Epic Meal Time on October 28, 2011 to celebrate the show's one year anniversary, where he can be seen in the final scene eating a deep-fried pizza cake. He also guest starred on the ABC comedy, Last Man Standing. He also played a skater in Police Academy 4: Citizens On Patrol.

Skate videos[link]

This section requires expansion.

• 1984: The Bones Brigade Video Show (Powell-Peralta)
• 1985: Future Primitive (Powell-Peralta)
• 1987: The Search for Animal Chin (Powell-Peralta)
• 1988: Public Domain (Powell-Peralta)
• 1989: Ban This (Powell-Peralta)
• 1992: Feasters (Birdhouse)
• 1992: Untitled (Birdhouse)
• 1993: Ravers (Birdhouse)
• 1998: The End (Birdhouse)
• 2001: One Step Beyond (Adio)
• 2007: The Beginning (Birdhouse)

Personal life[link]

Hawk with Lhotse Merriam in 2007.

Hawk married Cindy Dunbar in April 1990.^[13] They had a son, Riley Hawk (born December 6, 1992) whom they named for one of Hawk's ancestors.^[14] Riley also skates for Lakai Limited Footwear and Baker Skateboards.^[15] The couple divorced in 1993.^[3] Hawk married Erin Lee in 1996. They had two sons, Spencer (born March 26, 1999) and Keegan (born July 18, 2001). Lee and Hawk divorced in 2004.^[3] Hawk married Lhotse Merriam on January 12, 2006, on the island of Tavarua, Fiji.^[16] The couple's first child, a daughter named Kadence Clover Hawk, was born on June 30, 2008. The couple announced their divorce on February 7, 2011.^[17]

Tony launched the Tony Hawk Foundation, which has given away more than $3.4 million to help build well over 400 skateparks around the U.S.A. The Foundation supports projects in low income areas and helps underprivileged kids. In 2007, Hawk, Andre Agassi, Muhammad Ali, Lance Armstrong, Warrick Dunn, Jeff Gordon, Mia Hamm, Andrea Jaeger, Jackie Joyner-Kersee, Mario Lemieux, Alonzo Mourning and Cal Ripken, Jr. founded the charity Athletes for Hope^[18] which helps professional athletes get involved in charitable causes and aims to inspire all people to volunteer and support their communities.

References[link]

External links[link]

Wikimedia Commons has media related to: Tony Hawk

• Official website
• tonyhawkfoundation.org
• Tony's Birdhouse Skateboards website
• Tony Hawk at the Internet Movie Database

This biographical article needs additional citations for verification. Please help by adding reliable sources. Contentious material about living persons that is unsourced or poorly sourced must be removed immediately, especially if potentially libelous or harmful. (March 2009)

Colin McKay

Personal information
Full name	Colin McKay
Nickname(s)	Col
Nationality	Canada
Born	(1975-08-29) August 29, 1975 (age 36)
Sport
Sport	Skateboarding
Event(s)	Vert
Turned pro	1992

Colin McKay (born August 29, 1975, in Saskatchewan) is a professional skateboarder^[1] from North Vancouver, British Columbia, Canada.

Videography[link]

• Public Domain, 1988 by Powell Peralta
• Ban This!, 1989 by Powell Peralta
• Propaganda, 1990 by Powell Peralta
• Eight, 1991 by Powell Peralta
• Celebrity Tropical Fish, 1991 by Powell Peralta
• Questionable, 1992 by Plan B
• Virtual Reality, 1993 by Plan B
• Second Hand Smoke, 1995 by Plan B
• The Revolution, 1998 by Plan B
• The Chocolate Tour, 1999 by Girl/Chocolate
• RDS/FSU/2002 Red Dragons Video
• The DC Video, 2003 by DC Shoes
• Remember The Name, 2005
• Life After Death 2006 Plan B promo film
• SuperFuture 2008 Plan B promo film

References[link]