The railway used steam locomotives from the start, unlike its neighbour the horse-drawn Corris Railway. The original two locomotives, although of entirely different design, were both purchased from Fletcher, Jennings & Co. of Whitehaven in Cumbria, and both are still in service, 150 years on, although so many of their parts have been replaced down the years that much of their present-day component metal is not original. The Talyllyn's rare gauge is thought to have been adopted to match that of the Corris Railway, and the line's two original steam locomotives were among the earliest locomotives built for such a narrow gauge. No. 1 "Talyllyn" is an and No. 2 "Dolgoch" is an . The line carried slate from the quarry to the wharf at Tywyn and general goods along its length. Public passenger trains initially ran between Abergynolwyn, Dolgoch and Pendre stations only; quarrymen were carried on unofficial trains that continued on from Abergynolwyn to the foot of the Alltwyllt incline in Nant Gwernol gorge.