Adapted from compilation by Terry Martin and David Churchill
Working the DHR, with its sharp curves, severe gradients and long stretches of uphill running is a very challenging task requiring a very special locomotive. The 'B' Class steam locomotives still in service were introduced in 1889 and have not changed a great deal since as they are particularly well adapted to the line.
'Tiny' was one of the diminutive locos used by the contractor constructing DHR.
'1' Class steam locomotives
The first locomotives for DHR were the eight No. 1 Class built in 1880 by Sharp Stewart in the UK. They proved barely capable of working the line, which was constructed with much steeper gradients and sharper curves than specified.
'A' Class steam locomotives
A rapid reassessment must have followed and in 1882 Sharp Stewart delivered a radically changed design, first called the No. 2 Class, later renamed as 'A' Class. This was much better suited to the DHR, being more powerful whilst keeping the short wheelbase needed to negotiate curves. Having water in a well tank between the frames gave a lower centre of gravity, outside Walschaerts valve gear was more accessible, and a larger boiler produced more steam. Before long a small saddle tank was added (more water and better 'balance') plus a bunker in front of the cab (more coal). This gave an outline which looked recognisably similar to that of the later 'B' Class. The frames and wheels of one of the 'A' Class locos is still at Tindharia – having been found under a rubbish tip in Siliguri.