TOUGH BRAKES

Wairarapa Times-Age, 1 June 1942, Page 4

TOUGH BRAKES

FOR BOMBING & FIGHTING AIRCRAFT MADE FROM METAL POWDER. RESISTANCE TO TREMENDOUS STRAINS. Brakes of bombing and fighting aircraft, which have to be tougher than any others, are being made in Britain from metal powders. This process, a comparatively recent development in metallurgy originally discovered by an Englishman, enables the bronze friction plates for the disc-like brakes, with which many planes are now provided, to stand up to the tremendous friction involved in bringing to a standstill a mass of some 40,0001b5. travelling at a velocity of 100 miles an hour, when in a moment or so the brake assembly may well reach a temperature of about 900 deg. Fahr. Motorists know how easy it is to burn out their brake linings under conditions much less strenuous than these; while on other forms of surface transport, such as trains, there are many wheels to each of which brakes can be applied simultaneously. But the aeroplane, as at present designed, has only two wheels to which brake assemblies can be attached. In the case of a bomber, thp brakes on each wheel have to kill about 6,000,0(10 foot-pounds of energy in a few seconds. Odd though it may seem that metal powders can provide materials capable of standing up to such conditions, they do so. The bronze is produced by mixing proportions of the component metals in fine powder form, which are then pressed in powerful hydraulic presses into the desired shape- and size. The slabs thus produced are now passed into furnaces where the heat is so controlled that the mass is sintered, that is, the low melting point component melts and alloys with the high melting point component. The heat treatment is such that as perfect an alloy is formed as if the part had been produced from cast metal; moreover, the use of powders gives infinitely greater control, over the properties of the resulting metal part and allows it to be bonded direct on to steel backing. This reinforces the strength of the part and the whole assembly is capable of standing up to the tremendous strains involved in bringing a heavy aeroplane quickly and safely to rest.