General view of Airchimes (4 of KM135,4 of KM165) The Chimes are air operated signals of the "Tyfon/Typhon" type where compressed air produces a sound by means of vibrating diaphragms. KM135 sounds at 135Hz KM165 sounds at 165Hz The timimg of the opening of the valves for this to give the correct character and the opening of the valves themselves is done electrically.The air is compressed using vane-type compressors. KM135 Each chime has one air pipe and two electrical cables (Heater and Solenoid) All photographs taken 2005 Hyson Airchimes discontinued 1994