GB190624569A - Improvements in or relating to Alarm Sounding Devices of the Whistle Type. - Google Patents

Abstract

24,569. Madge, P. F. Nov. 2. Whistles.-In a sound-producing device of the whistle type, applicable to motor-cars, launches, &c., an orificed diaphragm co-operates with a movable piston, whereby a sound of varying or fixed pitch is produced according as the piston is kept moving or held stationary. In the form shown in Fig. 1, the gases from the engine exhaust pipe k pass through an orifice c in the diaphragm b, and through an aperture e in the casing a, when the piston d is withdrawn by a metallic cord l. The piston is preferably formed in two parts, and serves to shut off the pressure fluid as well as to determine the pitch of the note. The orifice or orifices in the diaphragm b may be made adjustable in size so as to vary the loudness of the note. According to the Provisional Specification, a separate valve may be used to control the passage of fluid past the diaphragm, the piston being then used solely for varying the pitch. In the modification shown in Fig. 4, the inner tube is formed with an orificed diaphragm b and an aperture e, over which slides a cylinder m<1>, which is adapted to close the aperture e and also to vary the pitch of the sound produced.