air horn

air horn (plural air horns)

1. Alternative form of airhorn.
   • 1944 January and February, “Chime Whistles and Horns”, in Railway Magazine, page 2:

     For use with petrol-electric, and subsequently diesel-electric, vehicles, air horns were developed about 1918, and today they vary from single-note instruments to those producing as many as five chiming pitches.

   • 1962 March, Brian Haresnape, “Design in 1961—a Retrospect”, in Modern Railways, page 191:

     At a later date in production, the Western Region requested that the two-tone air horns should be placed on the cab roof instead of behind the buffer beam, in order to increase audibility.

   • 2026 January 21, “Another Swietelsky Class 37 revived”, in RAIL, number 1053, page 12:

     37424 had been noted at Barrow Hill with its air horns moved onto the nose (in front of the cab windows) to allow it to work on certain routes where '37s' with roof-mounted horns are barred, such as to Stranraer. However, the horns have now been refitted to their normal position, with the bolts of the alternative positioning still fitted.

• “air horn”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.