 They retained the same boiler as the V2 class although the pressure was increased to 225psi, giving an increased tractive effort of .The firebox was also the same as the V2 although these were the first LNER locomotives to be fitted with a rocking grate and ashpan.Rather than have all three cylinders driving a single axle Thompson adopted divided drive with the middle cylinder driving the first pair of driving wheels and the outside cylinders the middle pair.