LB&SCR J Class

The LB&SCR J Class is a collective designation sometimes applied to the LBSCR's 4-6-2 Baltic tank locomotive programme developed by Douglas Earle Marsh and Lawson Billinton from 1910–1912. The J Class designator covers both the J1 and J2 variants of the 4-6-2T Baltic tank design, which were the most powerful tank locomotives the LBSCR ever operated, built for the heaviest express and semi-fast services on the Brighton main line where the six coupled wheels gave superior adhesion compared to the 4-4-2T Atlantic tanks for starting the increasingly heavy Edwardian express trains.

The 4-6-2T Baltic tank wheel arrangement — four leading wheels, six coupled driving wheels, and two trailing wheels beneath a large rear tank — was unusual in British practice at this period, combining the adhesion of six coupled wheels with generous water and coal capacity in a tank engine configuration. Marsh proposed the J Class as the LBSCR's answer to the growing weight of the London–Brighton express trains, which were beginning to exceed what the Atlantic tanks could comfortably handle on schedule.

See the individual J1 and J2 entries for the specific details of each variant. None of the J Class was preserved.