 The absence of a rear bunker and the small size of the cab provided the driver with a clear view of the buffer bar when reversing onto a train.The H shared their simple domeless boiler design with the H1 (J78) and H2 (J79) classes.The locos were originally fitted with dumb buffers, but these were changed for small round buffers during the 1930s, some also gaining vacuum brakes during this period; only hand and steam brakes were fitted when built.