sentences:  Tom Hurry Riches, the Taff Vale Railway's Locomotive Superintendent brought out 2 similar classes, the U and the U1 for working passenger trains, both 0-6-2Ts.The only difference between the U and U1 class was in the radial wheels which were in the former and in the latter.The boilers were identical with those fitted on the N, O and O1 classes but worked at the design pressure of , the mixed traffic engines being worked at , or occasionally .