Jamaica set a new world record time of 36.84 seconds as Usain Bolt anchored them to victory in a blistering men's 4x100m final.It was the same Jamaican quartet of Nesta Carter, Michael Frater, Yohan Blake and Bolt that set the previous mark of 37.04 at the world championships in Daegu last year.The United States team of Trell Kimmons, individual bronze medallist Justin Gatlin, Tyson Gay and Ryan Bailey won silver in 37.04 to equal the old record.Canada finished third but were disqualified, leaving the athletes in tears on the track as Trinidad and Tobago were awarded the bronze.U.S. lead-off man Kimmons got a flying start and the Americans appeared to have the initial edge but by the third leg Jamaica's 100 and 200 silver medallist Blake came off the bend level with rival Tyson Gay and once Bolt got the baton there was only ever going to be one winner.To a tumultuous noise, Bolt pulled away from American Ryan Bailey and, for once, kept going all the way to the finish even dipping for the line.Bolt, who now has six Olympic gold medals from two Games, wanted to keep the baton but track officials would not let him, resulting in boos from the 80-000 strong crowd.The Jamaicans then went on a lap of honour, high-fiving and kissing members of the crowd.Bolt was asked if he could do the 'treble-treble' by winning the 100m, 200m and 4x100m again in four years' time, having achieved the feat first in Beijing and now in London.He is not convinced it is possible.Bolt said on BBC1: "I've thought about it but I think it's going to be very hard because Yohan, he's just come into the game and he's running pretty well, and I'm sure there's going to be a lot more cats coming up to run."I'm just happy. I'll take it a step at a time."Asked whether he would run more often in Britain if tax laws change - a factor in him having stayed away in the past - Bolt said: "As soon as the law changes I'll be here all the time."I love being here, I have so many Jamaican fans here and it's wonderful."