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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. Not all are allowed in all formulae.
The pits usually comprise 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 regulations, while the driver waits in the vehicle (except where a driver change is involved).
Depending on the circuit, the garage may be located on pit lane or in a separate area. Most North American circuits feature a pit lane with number of pit stalls (typically 30-50) and a pit wall which separates the pit lane from the infield, with the garages (if used) on a separate road in the infield. In races where there are different series racing together, each series has its own separate garage or are parked in their own area. Circuits in other areas (used in F1) typically have the individual garage stalls open directly onto the pit lane through the team's assigned pit stall. In American English, it is common to drop the definite article and just refer to "pit road", whereas in British English one would always refer to "the pit lane". A further difference is that in British English, the term "pit box" is universally used, whereas in American English one would say "pit stall". It is important to note that in NASCAR, a pit box is a tool (see below), though there is a definitive term used for them.
For all but the shortest races, refueling is the primary purpose of a pit stop. Race engines generate high power but also burn fuel at an extreme rate, and most series have a limit on the size of the car's fuel tank, so many races will require multiple stops for fuel based on the distance of the race alone. However, many other adjustments can be performed during a pit stop, and some can even be performed without taking any more time than refueling. By making pit stops, cars can carry less fuel, and therefore be lighter and faster. During refueling, the tires can be changed as well, which permits the use of softer tires that wear faster but provide more grip. Teams usually plan for each of their cars to pit following a planned schedule, with 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. 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.
In most series (except NASCAR), pit assignments may be assigned by points standings, race results, or previous qualifying results before the start of the race meet. In NASCAR and in INDYCAR's Indianapolis 500, typically pit assignments are made after qualifying, with the fastest qualifiers choosing their pit stall first. This practice rewards qualifying with affecting the race.
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 kilometres per hour) will travel approximately 150 feet (45 metres) per second. During a ten-second pit stop, a car's competitors will gain approximately one-quarter mile (400 metres) 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. Safety car 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 travelled. 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.
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; cleaning 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.
In Formula One, mid-race refuelling has been banned since 2010, and cars make pit stops with the primary purpose of changing tyres. 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 two and four scheduled stops, depending on the circuit. The drives between pit stops are commonly known as 'stints'.
When the car is approximately one lap away from making its stop, the team's pit crew will set up fresh tires and all needed pit equipment. Because of the overhead 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.
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.
Refuelling was permitted from the 1994 season until the end of the 2009 season. During this period, a pit stop involved about twenty mechanics, with the aim of completing the stop as quickly as possible. Stops generally lasted 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 were fuelled at a rate of more than 12 litres per second. This was accomplished by a fairly complex closed system that pumped air out of the car's fuel tank as the fuel was being pumped in.
As refuelling is a potentially hazardous situation, the mechanics wore 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.
Crew chiefs lead the pit crew during pit stops in addition to coaching the driver during the race. 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, some 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. Teams have built full training centers similar to that of professional athletes for their pit crews.
There are a number of penalties that can be incurred on a pit stop. The driver must keep the car below the pit road speed from the pit entrance to the pit exit; the speed limit is typically 35-55 mph depending on the size of the track. Teams can 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. The most common penalty for a pit infraction is a "drive-through": the driver must enter the pits again, under the green flag, and maintain the pit speed limit for the entire length of pit road. If a car stalls, the pit crew may provide a push start, but the car cannot be pushed beyond three pit stalls ahead of its own, or beyond the pit exit light and steward at the end of pit road.
Pit stops are timed from the moment the car stops in its pit stall, until service is finished and the car leaves the stall. A pit stop for four tires and fuel can last 12–16 seconds, and a stop for two tires and fuel may take 5–7 seconds. Late in a race, a team may only need a small amount of fuel to make it to finish; this is called a "splash and go" and may take as little as 2–3 seconds. These times depend upon any suspension adjustments performed and the quality of the crew.
NASCAR Sprint Cup Series team pit strategies vary widely, depending on the track. Fuel is generally a more limiting factor than tyre wear, and the phrase "fuel window" or "pit window" is used to indicate the maximum number of laps possible with a full load of fuel, assuming continuous green flag conditions and a small reserve. The window is used to calculate (or recalculate after a stop) the minimum number of pit stops required to complete the race. 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. Races at short tracks such as Bristol Motor Speedway and Martinsville Speedway are short enough to be completed with only two scheduled stops for fuel, but teams plan on more stops due to rapid tire wear and significant loss of cornering speed on worn tires. If one team pits for tyres and is considerably faster (between 1-3 seconds per lap), then teams will usually follow quickly to avoid losing time.
Pit strategy can play a significant role in the outcome of a NASCAR race, perhaps more so than other racing series. Under caution, most teams use similar strategies to avoid being caught alone, typically following the leaders decision to stay out or pit, but sometimes teams will deliberately pit "off-sequence" if they feel they can gain an advantage later. Race tactics can affect strategy as well. Late in a race, drivers can reduce throttle input to save fuel at the cost of slower lap times, but by doing so they can stretch their pit window to the end of the race and skip the final pit stop. A late caution can force teams to make a tough call: stay out on worn tires, or pit and give up track position. The green-white-checker rule can cause headaches, as it can potentially extend the race an unknown number of both green-flag and yellow-flag laps. Furthermore, strategy can be determined by qualifying position. A team that qualifies in the top six positions will have the best choice of pit stalls, most often choosing the first, last, or a stall with an opening either in front of or behind that one. A team that qualifies deeper in the field will have a greater opportunity to be stacked behind cars during a pit stop, slowing them down.
In the 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. The spare fuel for IndyCar competition is stored in large pitside fuel tanks. Each team's tank is filled to a specified volume of fuel, depending upon the race distance. Teams are also given a certain allotment of spare tires sets, likewise owing to the race distance. All of the spare tires are pre-mounted on wheels before the race.
During a routine pit stop, the tires are laid out beforehand, 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, does not 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, and a prohibition of using an overhead boom to support air hoses.
As soon as the car comes to a halt, the first step, taken while the fourth tire changer assumes his position, is for a mechanic to activate the car's built-in pneumatic jacks. A pressurized air hose is inserted into a receiving nozzle at the rear of the car, under the rear wing. Previously, this device was inserted on the side of the car, but for safety reasons, the location was moved in the 2000s. At the same instant, another crew member begins the refueling process. A fueling hose is inserted into a socket (called the "buckeye"), allowing a gravity-fed hose to refill the car's fuel tank. The fuel hose has a built-in vent/overflow hose as part of the mechanism, an invention of the mid-2000s. Previously, a second "vent hose" was utilized, but it was phased out to improve safety.
Simultaneously, the four tire changers remove the wheels and install the new ones. IndyCar wheels are affixed to the hubs with a single lug nut, making it easier and faster to change them. After the tire changes are complete, the front tire changers may use manual adjusters to adjust the angle of the car's front wing, remove debris from air intakes, or make other minor repairs. While the service is being completed by the over-the-wall crew, another crew member behind the wall may use a stick to offer the driver a refreshment.
After the tire changes are complete, the air hose is removed, dropping the car to the ground. However, the driver usually must wait additional seconds until the refueling is complete. 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 squirt water to wash any excess spilled fuel from the fuel buckeye; this is usually done with a pressurized water hose by a crew member behind the pit wall.
Under normal conditions, a routine stop for an IndyCar team lasts between six and ten seconds. IndyCar teams are permitted to set their own pit strategies.
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 Automobile Club de l'Ouest (ACO) 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. At all times the car's engine must be shut off during the stop, and may start only when the stop has concluded.
IMSA allows only four mechanics to service a car during a pit stop. One crew member will refuel the car while the other three are responsible for changing tires and operating the pneumatic jacks. A fifth crewmember must serve as the teams designated firefighter and must stand ready in the pit stall with a fire extinguisher while the car is being refuelled. A sixth crewmember may assist in a driver change. Neither the firefighter or driver's assistant may perform any additional service to the car itself. Unlike the ACO, IMSA does not force crews to wait for fuelling to complete before changing tires, and does not require the car's engine be shut off during the stop.
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 practice of "double-stinting" or even "triple-stinting" tires is commonplace in longer races; tires hard enough to withstand the rigours 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.
The frequency of pit stops depends on a large number of factors, such as fuel consumption, fuel tank size, and tire wear. In endurance events such as Super GT, the pitstops and driver changes during the race are done within mandatory windows, which is similar to the two stops that are obligatory under the rules of Deutsche Tourenwagen Masters. Since the 2007 Formula One season, two different tyre compounds must be used during a race, effectively setting the minimum number of pitstops to one.
|Event||Class||Number of stops per car||Race distance (km)||Distance between stops|
|2011 Italian Grand Prix||F1||1.7||307||114|
|2011 Hungarian Grand Prix||F1||3.5||307||68|
|2012 DTM season||DTM||2||189||63|
|2012 24 Hours of Le Mans||LMP1||33||5151||152|
|2012 Clipsal 500 (race 1)||V8 Supercars||3||251||63|
|2012 GP2 Series season (race 1)||GP2||1||170||85|
|2012 Fuji GT 500km||Super GT||2||501||167|
|1000 km Suzuka||Super GT||5||1004||167|
|2008 1000 km of Monza||LMP1||7||1002||125|
|2009 1000 km of Nürburgring||LMP1||6||1001||143|
|2012 Bathurst 12 Hour||GT3||11||1677||139|
|2009 Dubai 24 Hour||GT3||15||3088||193|
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