The Class 37/7 is a sub-class of the Class 37, intended primarily for heavy freight.
Again, as part of the major refurbishment scheme of the Class 37 locomotives in the 1980s, another freight dedicated fleet of 44 Class 37s was created; the Class 37/7 subclass which was identical to the 37/5 subclass except for the addition of a ballast weight to give extra 'pulling power' when hauling heavy freight trains such as the metals trains in South Wales. Again, like the 37/5s, there were two batches completed; from phase 1 and phase 2 Class 37/0 locos. The batch numbered 37701 upwards were from phase 1 build locos and have the flush front ends and the batch numbered from 37899 downwards were rebuilds from phase 2 locos, having the central headcode box (plated over). A further complication was created; locos numbered 37796-37803 had a different type of electrical equipment fitted as part of a trial and differ from the other locos in the subclass internally.
In British Rail use, the sub-class were particularly common in South Wales on heavy coal and metals work. They were particularly adept at working coal trains up and down the short but steeply graded branch lines around Swansea and Cardiff to collieries such as Tower, Coed Bach and Cwm Bargoed. They operated Merry-Go-Round coal trains of 32 ton HAA air-braked hoppers, usually numbering between 20 and 30 wagons, between collieries, washeries, open cast mines and disposal points to power stations such as Aberthaw and occasionally further afield.
Their use on Metals Sector trains, usually from Llanwern, Port Talbot or English metal works such as Scunthorpe, saw them hauling incredibly heavy trains between docks, works and purchasers in Britain. Indeed, the use of 3 Class 37/0 locomotives on Llanwern-Port Talbot Docks steel trains (the heaviest on the British rail network at 3,300 long tons (3,400 t) was soon abandoned when Class 37/7s became available, requiring only two locomotives. Cardiff had a large allocation of 37/7s, some waiting on standby, ready for a call from the mills requiring more wagons to handle any extra traffic. Eventually this work was taken over by Class 56's and Class 60's. This Metals traffic would also become the domain of the sub-class 37/9, which to all intents and purposes was a 37/7 but with a different prime mover.
When EWS introduced its 250 Class 66's from 1998, many of the sub-class were put into store. Some have since been involved in construction work in France and Spain building new high-speed lines. 15 were sent to Spain; an additional two were sent to Italy.
EWS has been selling off the sub-class. Four were purchased by West Coast Railways, based in Carnforth for overhaul and main line charters; these are 37706, 37710, 37712 and 37717. 37717 has since been sold for scrap while 37712 returned to traffic before a serious internal fire. 37706 is now the only operational 37/7 in the UK. The number ranges were:
37701 - 37719
37796 - 37803
37883 - 37899
Keywords:37/7, Class 37, Co-Co, Electric, English, diesel, locomotive