BRAKE DRUM COOLING

Rotorua Morning Post, Volume 2, Issue 515, 26 April 1933, Page 6

BRAKE DRUM COOLING

It is 'surprtising that cooling fins on brake drums have not been more generally adopted by car manufacturers, in view of the ancreased thermal stresises being put upon the brakes, owing to- the gneated decelerating powers of the latest cars, -states an oYerseas journal. In bringing a vehicle to a :stop, pra.ctically'all the energy absorbed by the brakes is. converted into heat, so that the temperatures to whiich the material of the drum and the linings are subjiected l may exceed the degree of heat at j which the metal is tempered,, result- . ing in distortion of the drum and i locking of the wheels. Also considerI .a.ble expansion may be caused by overheated drums, and this may seriously affect the correct functlioning of the brakes. Both pressed steel and cast brake drums, when tested, have shown decided changes in their istructure due , to over-heating, and the strength of the metal in som'e cases was reduced to :a.n unsafe limit. Ini the effort to decrease the unsp-rung weight of the vehicle, the weight of the brake drum may in some instances be Teiduced, but this (iis. not considered by leading authorities to be a safe practice. A properly ribbed brake drum, many critics declare, is no heavier than one . without ribs, and at the same time retains lits shape better. It has been stated that by providing cooling fins, the radiating surface of the drum may be increased more than twofold.