Pit­stops

F1 Racing - - INSIDER -

What is re­garded as a good pit­stop th­ese days?

For a stan­dard tyre change, a team should aim to be av­er­ag­ing 2.5 sec­onds. The im­por­tant thing is con­sis­tency. It is no good do­ing one stop at 2.2 sec­onds and three oth­ers at 2.9. The best stops this year have been around that lower tar­get, al­though there is al­ways a lit­tle dis­crep­ancy be­tween the times shown on the TV and the num­bers the teams work with.

Why are pit­stops so much faster th­ese days?

Un­til re­fu­elling was banned, there wasn’t much em­pha­sis on the tyre-change as­pect of a pit­stop. Since re­fu­elling took any­thing from six sec­onds up­wards, there was plenty of time to change the tyres. It was hard to speed up the re­fu­elling be­cause the ow rate of fuel was reg­u­lated, so the only time that could be shaved off came from a clean con­nect and a rapid dis­con­nect of the fuel hose when the fuel ow stopped.

What are the se­crets of a good pit­stop?

Hav­ing good equip­ment, lots of dis­ci­pline, and practising over and over again un­til the process be­comes sec­ond na­ture. That said, it is im­pos­si­ble to recre­ate the ner­vous tension of wait­ing for a car to ar­rive at the pit­stop area, know­ing that the ac­tions of a few sec­onds can put your driver out with an im­proved sit­u­a­tion, or con­versely lose that hard-won track po­si­tion.

How do teams prac­tice and how of­ten?

There are two train­ing regimes, those done at the fac­tory and those done dur­ing a race week­end. At the fac­tory, reg­u­lar prac­tice is or­gan­ised in a spe­cial area that repli­cates the pit­lane area where a stop is made. A dummy car will be used, which will have all the lat­est hub de­tails so the crew can train in a re­al­is­tic mode. The car may rely on hu­man power to pro­pel it into the pit­stop area, al­though some teams use low-power en­gines to pro­vide the drive. In ad­di­tion to this, teams have var­i­ous rigs for practising as­pects of the pit­stop and to check and cal­i­brate their equip­ment.

Do you prac­tise for un­usual events, or is it bet­ter just to deal with th­ese as they oc­cur?

There are many sce­nar­ios that dif­fer from the rou­tine sin­gle-car pit­stop and all of th­ese have to be prac­tised be­cause al­though they may oc­cur in­fre­quently, they can still make the dif­fer­ence be­tween achiev­ing a good nish­ing po­si­tion and los­ing it. The most fre­quent non-stan­dard stop is a nose change. This can be quite tricky to per­form, since the nose as­sem­bly is both heavy and un­wieldy. Of­ten th­ese tend to oc­cur on the rst lap when the pit crew have just run back from the grid and are still in the process of ready­ing the equip­ment. Even so, we would hope to be chang­ing the nose and all four wheels in well un­der ten sec­onds.

What about the equip­ment used in pit­stops – is that be­ing de­vel­oped all the time?

The engi­neer­ing be­hind pit­stops is both de­tailed and so­phis­ti­cated. All F1 teams use wheel guns de­vel­oped by Ital­ian com­pany Paoli, but they will of­ten strip and mod­ify th­ese to their own ex­act­ing re­quire­ments, at­tempt­ing to im­prove the gas ow that runs through them. In­deed, un­til it was banned, many teams used he­lium rather than com­pressed air to drive the guns in the search for im­proved per­for­mance. The de­tail de­sign of the hub and wheel nut is also fun­da­men­tal to a good pit­stop, with most cur­rent de­signs us­ing a very coarse pitch but a very ‘loose’ thread. The nut it­self, and the socket that en­gages it, are multi-drive de­vices rather than the tra­di­tional hexag­o­nal nut, so the socket can en­gage with the nut rst time.

How do the lights on the pit­stop gantry work?

Time was when the driver looked solely to the lol­lipop man. The lol­lipop man con­trolled the pit­stop, and when he was satised that all work had been prop­erly com­pleted, he would lift the ‘lol­lipop’ to al­low the driver to launch. Th­ese days we could not ac­cept the mul­ti­ple se­quen­tial hu­man re­ac­tion times in­volved in such a process, and so a sys­tem of lights is used. The driver holds the car in rst gear with the clutch pulled. The men with the wheel guns will have fol­lowed the car in and will be en­gag­ing the nut be­fore the car comes to a halt. With the wheel nuts cap­tive in the wheel, the process of loos­en­ing the nut also starts to pull the wheel off. One me­chanic re­moves this wheel as an­other one po­si­tions the new wheel. Dur­ing this time the gun man will have re­versed his gun and will fol­low the wheel on to tighten it, a process that takes just half a sec­ond. As soon as the wheel is tight he hits a but­ton on his gun. When the com­puter de­tects two ‘tight’ sig­nals, it au­to­mat­i­cally drops the jack. Once it de­tects that both jacks have been dropped, it changes the lights to green to al­low the driver to launch.

It sounds like ex­pen­sive equip­ment.

It is. Each wheel gun costs around $6,000 and there are two at each wheel sta­tion (plus ex­tras for the garage it­self and for use on the grid). The sock­ets cost $2,000 and a com­plex auto-release swiv­el­ling front jack will cost many tens of thou­sands of pounds. Even the wheel nuts cost over $600 and around 24 are made new for each race, so, as ever, the search for speed does not come cheap.

What of the hu­man el­e­ment: how do you go about trans­form­ing a me­chanic into a wheel-change guru?

A pit­stop me­chanic pri­mar­ily needs to be strong and t. The wheel guns weigh 3.5kg and pro­duce a torque of over 3,000ft/lbs, so just han­dling th­ese de­vices re­quires a cer­tain de­gree of ath­leti­cism. Couple that with the nim­ble­ness needed if the car stops slightly awry and you can see that the hu­man per­for­mance el­e­ment is all-im­por­tant. At Wil­liams we em­ploy a qualied os­teopath to train our crew in the search for per­fec­tion.

Pat Sy­monds ex­plains

THE SCIENCE BE­HIND…

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