Four-Coupled Tank Locomotive Classes Built by the Great Western RailwayFour Coupled Tank Locomotive Classes Built by the Great Western Railway 30. 00 This book is a comprehensive history of all twenty six classes of four coupled tank engines commissioned by the Great Western Railway or built at their Wolverhampton and Swindon Works, from the Broad Gauge 2 4 0 and 4 4 0 tanks of the 1840s and 1850s to the well known Collett 0 4 2 branch line engines of classes 48XX (later renumbered 14XX) and 58XX of the 1930s. As well as