Operator(s) Network Rail | Electric system(s) 750 V DC third rail | |
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Track gauge 1,435 mm (4 ft 8 ⁄2 in) standard gauge | ||
The British Rail Class 931 was reserved for former Southern Region electrical multiple units converted for departmental use. Originally the series was reserved for Route Learning and Stores units. In recent years, however, other types have also been given numbers in this series.
The Southern Region initially numbered its departmental EMUs in a series between S1 and S101. In 1968, a new series was adopted; 001-099. Existing units were renumbered to fit in that series, which also included other non-passenger stock, i.e. those EMUs converted for parcels traffic. Several of the numbers 001-099 have been reused for different units.
When TOPS class numbers were applied, these units mostly retained their existing numbers as the last three digits of their new TOPS class number. The table below lists all the units numbered in the Class 931 series, together with the route learning and stores units used by the SR prior to the application of TOPS numbers.