The trains were used in the quarry to carry slates to port, and later to carry workers to their work as well. In 1848 two steam engines were running on the rails — Jenny Lind and the Fire Queen. In 1882 a strong, modern engine called Dinorwic was added to the stock. By 1895 two other large engines were travelling the line between Gilfach Ddu and Penscoins near Port Dinorwic — Amalthaea (called Pandora until 1909) and Velinheli. These drew the workers' train until 1947, and the slate train too until 1961. The train only failed once in all this time, during the great snow of 1929.

Between 1848-95, however, the workers used machines called 'velocipedes' to get to work. These could move pretty quickly with a fair wind behind them! Indeed, although they were forbidden from doing so the men would often race their cars. In 1858 two men were drowned when they lost control of their car, tipping it into Padarn Lake.

Like everything else in the quarry, these had names — some fancy, like Garibaldi, Signor Foli and the Duke of Cambridge, and some more homely, such as Y Gaseg ('The Mare'), Jennie Bach ('Little Jennie') and Y Falwoden Lwyd ('The Grey Snail'). (You can see an example of a velocipede in the Museum's collection.)

In 1895 over a thousand men were travelling back and forth every day between their homes and their work in the quarry and the workshops. Two carriages were added on Monday morning and Saturday afternoon to accommodate the workers from Anglesey, who only went home once a week.

There were all kinds of engines in the quarry; small ones used on the galleries to work drilling machines, and to draw sledges and rubble wagons, and larger engines which worked the slate run on the exit level railway. These were too large to work on the galleries.

There was also another kind of carriage on the line, a pretty remarkable one, called 'The Saloon' or 'y garej felen' (the yellow carriage). This was the Assheton Smith family's private carriage, and as well as carrying the Faenol family and their guests on their occasional visits to the quarry, it carried the workers' wages every week from the bank in Port Dinorwic, guarded by two armed men.