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 used to cool the cylinders.
The main part of the system is piping and regulation of atmospheric air drawn into the cylinders, into which cooling water and oil is injected.
Water injected into the incoming air evaporates during compression, carrying away much of the heat generated.
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.