 The NSR coaching stock was , even until grouping , predominantly four and six wheeled vehicles . Four @-@ wheeled carriages were the norm from the start and the last were constructed in the 1880s , although by then they had progressed from the <unk> coaches of the 1840s with the introduction of the communication cord in 1869 and the simple vacuum brake in 1883 . The first bogie coaches were introduced in 1906 for use on the Derby – Llandudno service and these were followed by further examples until 1923 . By 1919 all carriages , except 13 four @-@ wheelers used on miners trains , had been fitted with steam heating and a number of vehicles had been fitted with through pipes to allow use in trains equipped with Westinghouse brakes . Most carriages were constructed at Stoke but some were purchased from companies such as the Metropolitan Carriage , Wagon and Finance Company . 
