From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
New noise regulations for vehicle horns and their impact on the Phantom and Bentley chassis.
| Identifier | ExFiles\Box 166\9\ img175 | |
| Date | 18th March 1938 | |
| F.{Mr Friese} DODD - what is the reliability of the latest Mellotone horns Rm{William Robotham - Chief Engineer}, BY/RD.1/B.18.3.38. NOISE - HORNS. Conversation between the Minister of Transport and the S.M.M.T. based on the Committee's Report of "Noise in the operation of mechanically propelled vehicles", has resulted in the members of the S.M.M.T. being requested to give an undertaking that vehicles sold by them after January 1st. 1939, will not be fitted with warning devices capable of emitting a noise greater than the maximum agreed upon. The Mellotone Horns fitted to the Phantom Chassis are approximately correct and arrangements have been made that any further deliveries will be adjusted to bring them down to 105 phons or just below. The position with regard to the High Frequency Horns on the Bentley Chassis is rather different. The twin alto horns are considerably more than 100 phons and cannot effectively be reduced to this figure either by an adjustment to the existing horns or by any simple alteration to the design. To make High Frequency Horns to be used in pairs, not exceeding 100 phons, produces horns which do not give a satisfactory warning signal, and it appears that pairs of H.F. Horns will be impracticable when the limit is introduced. The alternative would appear then, that we fit the Bentley Chassis with Mellotone Horns. -Contd- | ||