These remarkable tank locomotives were designed for the broad-gauge Bristol & Exeter Railway by Locomotive Superintendent James Pearson and eight (running numbers 39 to 46) were built by Rothwell & Co of Bolton in 1853 and 1854. They were intended specially for working the B & ER’s section of the London to Exeter express route, including the “Flying Dutchman”, at that time the fastest train in the world. They had the largest driving wheels ever successfully used on a locomotive and no one has come up with an authentic recording of any higher speed previous to one of 130kmh (81mph) made behind a Pearson single while descending the Wellington incline south of Taunton.
The engines were guided by a four-wheel bogie at each end, and they were propelled along by the huge flangeless set of driving wheels located more or less centrally between the two bogies. As with all locomotives that ran on Isador Brunel’s broad-gauge lines, the cylinders and motion were located inside the frames. Water was carried in the tank at the rear as well as in a well-tank between the frames. Pearson’s singles were untypical , thought, in that they carried no names, only numbers.
After 14 years of service four of the engines (39-42) were rebuilt, with the 9-foot driving wheels replaced by wheels measuring 8 feet 10 inches. On the 29th of July 1876, 39 derailed with loss of life near Long Ashton near Bristol, and had to be scrapped. As a consequence, the remaining three locomotives were completely rebuilt on more conventional lines as 4-2-2 singles, which were regarded by many as the most handsome locomotive ever to run on the broad-gauge track, with the last engine being withdrawn from service in 1890.
“The Great Book of Trains” by Brian Hollingsworth and Arthur Cook – Salamander Books, NY, 1987. pp 44-45 was used as the basis of this blog post.