as do the Ffestiniog and Welsh Highland Railways. Most other British narrow gauge lines use the air brake: this is because these railways were not required to fit continuous braking until the last quarter of the 20th century, by which time vacuum brake equipment was no longer being produced and was difficult to obtain. High altitude Vacuum brakes are less effective at high altitude. This is because they depend upon the creation of a pressure differential; atmospheric pressure is lower at high altitudes, and so the maximum differential is also lower. See also Brake (railway) Gladhand connector Eames Vacuum Brake Railway air brake Vacuum Brake Company References British Transport Commission, London (1957:142). Handbook for Railway Steam Locomotive Enginemen. Further reading External links illustrated description of the vacuum automatic brake Railway brakes