The Taff Vale Railway U and U1 classes were 0-6-2T steam tank locomotive operated by Taff Vale Railway, Wales, from 1895.
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 boilers were identical with those fitted on the N, O and O1 classes but worked at the design pressure of 160 pounds-force per square inch (1.10 MPa), the mixed traffic engines being worked at 150 psi (1.03 MPa), or occasionally 140 psi (0.97 MPa).
The main differences from the mixed traffic engines were larger diameter driving wheels, a longer wheelbase and replacing the usual four bar motion with single bar.
This article relating to steam locomotives operated in the United Kingdom is a stub.