K9 Class

The GER K9 Class was a series of 0-4-2 tank locomotives built for the Great Eastern Railway from 1877 under the superintendency of Massey Bromley, designed for branch passenger and light mixed-traffic working on the GER's East Anglian secondary and branch network. The 0-4-2T wheel arrangement — four coupled driving wheels with a trailing single axle — gave good adhesion for the light passenger trains of rural East Anglian branches while the trailing axle supported the firebox weight and the tank configuration provided water without a separate tender for the short-distance branch workings.

The K9 Class was a utility branch tank engine in the Victorian tradition, suited to the modest traffic of the GER's rural branches in Norfolk, Suffolk, and Cambridgeshire where a small, economical locomotive was more appropriate than the larger suburban tanks deployed on the heavier Liverpool Street services. The class worked the light passenger services on the secondary GER routes that connected market towns and agricultural communities with the main-line network.

The K9 Class gave service through the late Victorian and Edwardian periods before being superseded by later GER tank designs. None was preserved.