Railway freight braking on the continent (UJC)

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Railway freight braking on the continent (UJC)

Roberts, H.P.

Whereas on the Continent (UIC) there are still large numbers of ordinary 80 kph freight trains, there is an ever increasing quantity of them, carrying perishable goods, travelling at speeds up to 120 kph and even 140 kph notwithstanding the constraint of comparatively short signalling distances which impose high brake rates at the higher speeds. The main braking difficulty arises from the fact that as the power source is compressed air there is an undesirable time lag between initiation of the brake at the front of the train and the build up of brake power on the rearmost vehicle. For much the same reasons, brake release also poses a problem, as does the large difference in brake power between the vehicles in a train. The manner in which brake engineers have overcome these various problems are discussed in the paper from the days of the old triple valve to the modern distributor, also pneumatic and mechanical (manual and automatic) empty/load and variable load devices. The advantages of the two pipe air brake are also indicated. Also discussed, in the context of freight train operation, are the friction media commonly used on this type of train viz on tread braking, with cast iron or composition brake blocks, and disc brakes with composition brake pads.