The counter-pressure brake (German: Gegendruckbremse), also named the Riggenbach counter-pressure brake after its inventor, Niklaus Riggenbach, is a dynamic railway brake on steam locomotives that, through a combination of means, brakes the locomotive in the driving cylinders. In doing so it prevents wear and tear and overheating of the driving wheel tyres and brake blocks and enables a continuously high brake force to be applied. The brake works by using the cylinders as air compressors and converting kinetic energy into heat. Steam is emitted during braking but this does not come from the boiler. It is produced by evaporation of water, which is used to cool the cylinders.
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Counter-pressure brakes were found especially on steam engines that worked long inclines and on rack railway locomotives (e.g. on the Vienna Kahlenberg Railway (Kahlenbergbahn), relieving brake blocks and tyres from high levels of wear and tear that they would otherwise be subjected to[1].
For operation on ramps its availability was indispensable because these dynamic brakes on steam locomotives provided the required third independent set of brakes.
A further area of use was in measurement and testing on braking locomotives to provide continuous braking on railway vehicles being tested in normal running. Here a number of steam engines survived in this niche activity in Germany until the middle of the 1970s.
Counter-pressure brakes are used on the steam locomotives of the Snowdon Mountain Railway.
The counter-pressure brake should not be confused with the countersteam brake (German:Gegendampfbremse), which cannot be used as an auxiliary braking system.
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