stop-work

Pit stop

In motorsports, a pit stop is where a racing vehicle stops in the pits during a race for refuelling, new tires, repairs, mechanical adjustments, a driver change, or any combination of the above.

The pits usually comprise of a pit lane which runs parallel to the start/finish straight and is connected at each end to the main track, and a row of garages (usually one per team) outside which the work is done. Pit stop work is carried out by anywhere from five to twenty mechanics (also called a pit crew), depending on the series, while the driver waits in the vehicle (except where a driver change is involved). In American racing series, a pit lane consists of a number of pit stalls and a concrete pit wall which separates the pit lane from the infield, with the garages on a separate road in the infield; European racing series typically have the individual garage stalls open directly onto the pit lane through the team's assigned pit stall.

By making pit stops cars can carry less fuel, and therefore be lighter and faster, and use softer tires that wear faster but provide more grip. Teams usually plan for each of their cars to pit following a planned schedule, the number of stops determined by the fuel capacity of the car, tire lifespan, and tradeoff of time lost in the pits versus how much time may be gained on the race track through the benefits of pit stops. Choosing the optimum pit strategy of how many stops to make and when to make them is crucial in having a successful race. It is also important for teams to take competitors' strategies into account when planning pit stops, to avoid being "held up" behind other cars and unable to overtake them. An unscheduled or extended stop, such as for a repair, can be very costly for a driver's chance of success, because while the car is stopped for service, cars remaining on the track can rapidly gain distance on the stopped car.

Pit strategy

In any racing series that permits scheduled pit stops, pit strategy becomes one of the most important features of the race; this is because a race car travelling at 100 miles per hour (160 kilometers per hour) will travel approximately 150 feet (45 meters) per second. During a ten-second pit stop, all of a car's competitors will gain approximately one-quarter mile (one-half kilometer) over the stopped car.

However, the car that made the additional pit stop will run faster on the race track than cars that did not make the stop, both because it can carry a smaller amount, and thus lower weight, of fuel, and will also have less wear on its tires, providing more traction and allowing higher speeds in the corners. In racing series where teams have their choice of different compound tires, the lower tire wear may be enough to allow the team to choose to use a tire with a softer rubber compound that provides increased grip at the expense of faster wear; going longer between stops may even cause enough wear on the softer tire to cause the tires to fail.

Because of this, race teams plan a pit strategy prior to the start of every race. This is a schedule for each car's planned pit stops during the race, and takes into account factors such as rate of fuel consumption, weight of fuel, cornering speed with each available tire compound, rate of tire wear, the effect of tire wear on cornering speed, the length of pit road and the track's pit road speed limit, and even expected changes in weather and lighting conditions. The pit strategy does not just include a schedule of when pit stops will happen; it also includes what service and adjustments are scheduled for each pit stop, particularly in endurance racing, where scheduled changes of wear-limited parts such as brake pads may be planned for specific points during the race. The pit strategy is calculated carefully so that the amount of time to be "given away" to other competitors in pit stops is balanced out by the time gained while on the track, resulting, theoretically, in the shortest possible time to cover the scheduled distance.

However, a team's pit strategy is not a fixed, immutable thing; it is subject to change during the race to take into account the unpredictable events that happen in every race. In road racing, for example, if the weather changes from dry to rain, teams will be forced to recalculate their pit strategy based on the unscheduled stop to change from dry-weather "slick" tires to treaded wet-weather tires. Full-course caution periods often see mass pit stops by many teams, hoping to take advantage of the slowed pace to reduce the ground lost to other teams while making pit stops; this forces teams that do so to immediately recalculate their pit strategy to optimize it for the remaining race distance after the stop.

Even when a team chooses not to take advantage of the opportunity to stop during a full-course caution, it can still result in significant changes to pit strategy; under caution, the cars run at a reduced speed that results in greatly reduced tire wear and fuel burn for a distance traveled. Depending on the circumstances, this may be enough for a team to gain more by choosing not to pit, hoping that the reduced fuel burn and tire wear will allow them to make one pit stop fewer than the other teams, allowing them to gain distance and time on their opponents. At tracks noted for frequent full-course cautions, teams may even plan their entire race strategy around this, using a suspension and aerodynamic setup suited to short sprints instead of extended runs to gain positions in the short bursts of green-flag racing, and planning their pit strategy on the assumption that cautions will extend their fuel mileage and tire wear enough to make fewer stops than would otherwise be needed to complete the race distance.

Services performed

During a scheduled pit stop, the team's pit crew services the car as swiftly as possible, completing a number of different services. The most visible services performed are refuelling the car and changing tires.

Other services performed in routine pit stops include removing debris from radiator air intakes; cleaining the windshield; and making adjustments to tire pressure, suspension settings, and aerodynamic devices to optimize the car's performance for the current conditions. In endurance racing, scheduled driver changes and brake pad replacements are also considered "routine" service when done as part of a scheduled pit stop.

An unscheduled pit stop may see other service performed; because unscheduled stops are usually due to damage or mechanical problems, they frequently see emergency repairs performed on the car. These tend to have extremely long duration, due to the need to diagnose the car's problems prior to the time-consuming repairs.

Pit stops in Formula One

In Formula One, cars make pit stops with the primary purpose of refueling and changing tires, although during the 2005 season tyre changing during the race was prohibited. Teams sometimes also make adjustments to the front and rear wings and perform minor repairs, most commonly replacing the nose and front wing assembly. Pit strategies generally call for between one and three scheduled stops, depending on the course.

When the car is approximately one lap away from making its stop, the team's pit crew will set up fresh tyres and all needed pit equipment. Because of the overhead fuel and pneumatic rig, the team may have all pit mechanics in position prior to the car's arrival, with the exception of the rear jack man.

A pit stop involves about twenty mechanics, with the aim of completing the stop as quickly as possible. It lasts for six to twelve seconds depending on how much fuel is put into the car. However, if there is a problem, such as a fuel pump failing or the engine stalling, or repairs having to be made, it can take much longer. Cars are fuelled at a rate of more than 12 litres per second. This is accomplished by a fairly complex closed system that pumps air out of the car's fuel tank as the fuel is being pumped in.

As refuelling is a potentially hazardous situation, the mechanics are all wearing fire-resistant multi-layer suits & flame-resistant gloves, long underwear, balaclava, socks and shoes, which have to meet the guidelines set by FIA Standard 8856-2000.

Interestingly, unlike almost all other forms of racing that feature routine pit stops, Formula One rules limit teams to a single pit crew for the mandatory two cars entered. Therefore, teams must stagger their pit schedules so that only one of their two cars is in the pits at any given time. Most other racing series that feature routine pit stops permit each car its own pit stall and crew.

List of Formula One Pit Crew

The "Lollipop Man" holds the team's pit sign, helping the driver identify his pit stall on a possibly crowded pit road. During the stop, he holds the sign in position to remind the driver to keep his brakes on while tyres are being changed, and then to remember to put the car in first gear once the jacks are lowered. He also gives the driver the sign to depart his pit stall by raising the sign from in front of the driver.
The four tyre changers, one at each corner of the car, have the sole responsibility of using a pneumatic wrench to remove the car's single locking lug nut from each tyre, then reinstall it on the new tyre.
Eight tyre carriers are used, two at each corner of the car, one assigned the task of removing the old tyre from the car, and one to install the new tyre on it. The front new tyre carriers also have the responsibility of adjusting the car's front wing during the stop.
The fuel man has the responsibility of attaching and removing the refueling hose to the car's fuel receptacle, and must hold it in place during the entire fueling operation.
The front and rear jack men use simple lever-type jacks to lift the car and permit the changing of tyres. The job of front jack man is considered the most hazardous, as it requires standing directly in front of the car as it enters its pit stall. By contrast, due to the location of his duties directly behind the car, the rear jack man is the only team member not in his working position before the car enters its pit stall.
The fire extinguisher man does not actually work on the car; instead, he stands ready with a hand-held fire extinguisher to try and stop any accidental fires that may occur during a stop, at least long enough for the pit crew and driver to evacuate. This job became standard following Jos Verstappen's 1994 pit fire (see below).
The starter man does not normally work on the car. His job is to stand ready with a starter tool to restart the car should the driver stall his engine during the stop.

Pit stops in NASCAR

Pit crew members were once the mechanics on the racecar, but most teams feature individuals dedicated to pit stops only, and often former collegiate or professional athletes are used for pit stops. Former NFL player Tim Goad is regarded as the first former professional athlete involved in a pit crew, as a jackman. Nonetheless, pit crew members work with the team in fabricating or designing the race cars during the week while training for their "pit job" on the weekends.

The crew chief is the head person on a pit crew and assigns a Pit Crew Coach to help coordinate the pit stops and train the pit crew members how to stay in good physical shape. NASCAR regulations dictate that only seven individuals can go "over the wall" to service a racecar during a pit stop. The tool limits on the crew are two impact wrenches, one jack, and two cans of gasoline. Other tools may be used if needed, but major work must be performed in the garage area.

Teams will be penalized if the car is serviced outside of the designated pit stall, if the car drives over an air hose, or if any of the old tires are not on the pit wall side (usually left) of the vehicle's centerline before the car leaves. A pit stop for four tires and fuel in the Sprint Cup Series can last 12-16 seconds depending upon any suspension adjustments done and the quality of the crew.

NASCAR Sprint Cup Series team pit strategies vary widely, depending on the track. The road courses on the schedule may see as few as two scheduled stops; oval race tracks generally see between four and six scheduled stops. Theoretically, the races at short tracks such as Bristol Motor Speedway and Martinsville Speedway are short enough to be completed with only two scheduled pit stops, given the typical amount of time spent running under caution at those tracks, but teams plan on more stops due to rapid tire wear and significant loss of cornering speed on worn tires.

List of NASCAR Pit Crew

The jackman raises each side of the car so that the tires can be replaced. The jackman will, also, usually pull the old right rear tire from the car after the rear tire changer loosens the lug nuts. This is to help get the new right rear tire on faster. The jackman is the one who signals for the driver to leave the pits by lowering the car. Many jackmen take on the responsibility of watching the tire changers and making sure they hit all five lug nuts on the tire changes.
The front tire changer changes only the front tires. He removes lug nuts, removes the old tire, and tightens the new tire's lug nuts.
The rear tire changer changes only the rear tires. He removes lug nuts, removes the old tire, and tightens the new tire's lug nuts.
The gas man fills the car with gasoline with a special gas can. The gas man may, also, help pull old tires from race car after lug nuts are loosened if the car does not need fuel or if the car needs little fuel and the gas man finishes his job before any one else.
The catch can man catches any fuel overflow in a small gas can and usually holds one gas can while the gas man fills car with the second gas can in the latter portions of a pit stop. The catch can man may also add or take out wedge and/or adjust the rear track bar during a pit stop. The refueling gear is designed not to permit fuelling of the car without the catch can being attached to the car's overflow vent.
The front tire carrier brings the new front tires over the pit wall and guides them onto the studs. He also rolls the old front tires to the pit wall after the front tire changer pulls them from the car. The front tire carrier is usually responsible for clearing debris from the grill of a racecar and/or pulling the front fenders away from the tire if necessary. He may also be responsible for adding or removing tape to/from the grille during a pit stop adjust front-end downforce and engine temperatures.
The rear tire carrier is responsible for bringing new rear tires over the pit wall. Typically, on the side of the car furthest from the pit wall, he will be responsible for guiding the new tire onto the studs, making any necessary adjustments to the rear track bar and/or wedge (unless done by the catch can man), and rolling the old tire back to the pit wall. On the side of the car closest to the pit wall, he is usually responsible for only sliding the new tire onto the studs.

During the second half of the race, an eighth man is permitted over the wall. This person may only clean the windshield, and in some situations, is permitted to attach extra dark shields to reduce glare as the sun begins to set (in the event that this happens during a race), and supply the driver with fresh drinking water. The eighth man may not make any changes to the car beyond these issues. Races at Atlanta Motor Speedway, Homestead Miami Speedway, North Carolina Speedway (now an ARCA circuit where driver development is frequently conducted, and testing), and Phoenix International Raceway, were known as events where the setting sun would lead to glare issues on the cars.

2008 NASCAR Rule Changes

Both tire carriers must be in contact with the outside tire until that tire has reached the inside half of the pit box before it leaves its assigned box or is handed over the pit wall under a new NASCAR rule for 2008.
Cars may not be pushed past

The paddle man at the end of pit road.
Three pit stalls past their own.

Pit stops in the Indy Racing League

In the Indy Racing League IndyCar Series, a pit stop is a more complex operation than in NASCAR, but far less so than in Formula One. Rules permit six mechanics over the pit wall during a stop. The pit rules and procedures have origins in USAC National Championship racing.

During a routine pit stop in either series, the tires are laid out and three of the four tire changers are pre-positioned before the car enters its pit stall; the fourth tire changer, whose responsibility is the rear tire on the far side of pit road from the pit wall, doesn't take his position until after the car arrives, due to a rule against having the car run over the feed hose for the impact wrench used to change the tires.

Once the car arrives, the first step, taken while the fourth tire changer takes his position, is for a mechanic to insert the "vent hose" into its socket on the engine cowling. This hose vents the air out of the fuel tank, captures any overflow fuel, and also activates the car's built-in pneumatic jacks. Once the vent hose is in place, another mechanic attaches the refuelling hose to its socket, allowing the ethanol fuel to flow into the fuel tank. Simultaneously, the four tire changers remove the tires and install the new ones. Once the tire changes are complete, the front tire changers may use manual adjusters to adjust the angle of the car's front wing.

Once the tire changes are complete, the vent hose is removed, allowing the car to return to its wheels. However, the driver usually must wait until the fueling is finished and the fuel hose is removed from the car. The right front tire changer (who is usually also the crew chief) signals the driver when the stop is complete. Before the car departs its pit stall, a crew member must use a squirt of water to wash any excess fuel from the fuel hose and vent hose sockets; this is usually done with a pressurized hose by a crew member behind the pit wall.

Under normal conditions, a routine stop for an IndyCar team lasts between ten and fourteen seconds. IndyCar teams are permitted to set their own pit strategies.

Pit stops in endurance racing

In the various forms of sports car endurance racing, pit stops are a more leisurely affair, but no less important than in other forms of racing. While stops take longer, much more routine maintenance is scheduled during such pit stops, needed to keep the car running for as long as twenty-four hours; this includes major aerodynamic changes to deal with the changing temperature in such a long race, and replacement of certain wear-limited parts, such as brake pads. Due to the fact that the race is scheduled to last a certain length of time rather than a specific distance, pit strategies are generally not designed to be synchronized with the race distance, but rather to happen on a schedule based on the car's requirements for routine service.

Under the rules of the 24 Hours of Le Mans, also used by the American Le Mans Series, only five mechanics are permitted to work on the car. One man is permitted to fuel the car; all fuelling must be completed before any other service occurs. The other four mechanics on pit lane at any given time are typically two tire changers and two tire carriers, each of whom handles his task on only one side of the car. Automatic pneumatic jacks are used, integrated into the car itself.

In endurance racing, driver changes are mandatory; the shortest endurance races are scheduled for four hours, one hour longer than the longest nonstop time permitted behind the wheel. During a pit stop with a driver change, the new driver and a driver change assistant are permitted into the pit lane. The assistant, who may not do any mechanical work on the car, is tasked with helping the current driver out of the car, removing or swapping driver seat inserts, helping the new driver into the car, and helping the new driver tightly fasten his safety harness and connect his various helmet connections to the car's systems, including the two-way team radio and the drink bottle used to stave off dehydration.

A routine pit stop with no scheduled maintenance and no driver change generally lasts from thirty to forty seconds. With a driver change included, that time increases by about ten seconds. Should there be significant scheduled maintenance, such as changing brake pads, the stop can easily last well more than a minute.

Unlike most other forms of racing, the rules of endurance racing require that the car's engine be shut off during the stop. Another difference from most forms of racing is found in the practice of "double-stinting" or even "triple-stinting" tires; tires hard enough to withstand the rigors of racing in the heat of the daytime may be so hard that they do not wear significantly during the nighttime hours. In a race where this is an issue, significant time can be gained by choosing to leave worn tires on the car during the first stop after they were put on the car; if the temperature drops low enough, teams may even be able to go two pit stops without changing tires.

Notable pit stops

1963 Daytona 500: Wood Brothers Racing develops choreographed pit stops to reduce the amount of time spent on pit road. Driver, Tiny Lund, spends so little time on pit road that he would go on to win the race with out changing his tires once. For this, Wood Brothers Racing is often credited with inventing the modern pit stop.
1965 Indianapolis 500: Wood Brothers Racing fielded a Ford powered Lotus driven by Scottish Formula One driver Jim Clark. This brought their new concept of fast pit stops into open-wheel racing. Clark won the race with an average speed of 150.686 (a new Indianapolis 500 record). This was Ford's first win at Indy.
1976 Indianapolis 500: A world record was set for time taken in a pit-stop when Bobby Unser pitted in for four seconds
1993 Australian Grand Prix: McLaren's Ayrton Senna came into the pit unexpectedly for new tires; the team serviced the car in under four seconds.
1994 German Grand Prix: Benetton driver, Jos Verstappen, came into the pits; while refuelling, some fuel was accidentally sprayed onto the hot bodywork of the car, a few seconds later the fuel ignited and Verstappen's car was engulfed in a ball of flames. Verstappen escaped the incident with burns around his eyes, as he had his visor up during the pit stop.
1996 24 Hours of Daytona: "Mad Max" Papis was charging around the track on the final stint of the race, trying to catch the leader. On his final pit stop, Papis entered the pit area at full speed (~200 mph). Despite still finishing second, the startling sight held earn him the name "Mad Max."
1998 British Grand Prix: Ferrari driver, Michael Schumacher, Two laps from the finish, Schumacher was issued with a stop-and-go penalty, meaning he had to drive through the pit lane obeying the speed limit, stop at his pit box and remain stationary for ten seconds before leaving the pits and continuing with the race. On the final lap of the race, Schumacher came in to serve the penalty and in doing so crossed the finish line (which extends across the pit lane) before reaching his pit box and before Mika Häkkinen crossed the finish line on the race track.
2000 Spanish Grand Prix: Ferrari's Michael Schumacher was given the signal to go by the lollipop when the refuelling hose was still attached to his car, knocking Nigel Stepney down and damaging the latter's ankle ligaments.
2001 24 Hours of Le Mans: Joest Racing changes the transaxle on their Audi R8 (a process that usually takes hours) in less than 5 minutes. They would go on to win the overall race.
2002 The Winston: Roush Racing's Jeff Burton made a pit stop on the final lap of the first segment. A pit stop for tires was mandatory during the segment, but the rule did not stipulate when it had to be taken. By selecting a pit stall only 100 yards shy of the start/finish line, Burton did not have to spend the time all the other drivers took traveling the entire length of pit road. Burton was only able to finish second in the segment due to problems with his clutch exiting his pit stall. This practice was banned by the next season.
2003 Austrian Grand Prix: While Ferrari's Michael Schumacher was in the pits, some fuel was accidentally sprayed onto the hot bodywork of the car and ignited. The fire was minor and easily extinguished, so his stop ended up being around 20 seconds, whereas 8 seconds is usually the norm. Schumacher, however, did win the race.
2007 French Grand Prix: Spyker's Christijan Albers ignored the lollipop which signaled to him not to leave, driving off with part of the fuel rig still attached. Albers expressed relief that nobody was hurt, but he received a €5,000 penalty for dangerous driving. Spyker technical director Mike Gascoyne commented that he was mystified by the mistake, and Niki Lauda described the incident as the most stupid thing he had ever seen in F1.
2008 Singapore Grand Prix: Ferrari's Felipe Massa drove off with the fuel hose still attached to the car knocking down a member of the pit crew while he attempted to head back to the track as he was mistakenly shown the green signal. The problem was later attributed to the Ferrari's light system failure.