Disc Brakes Answer A Moral Question

Press, Volume XCVIII, Issue 28783, 2 January 1959, Page 11

Disc Brakes Answer A Moral Question

rjsHE eight high-performance . cars fitted with disc brakes at the Earls Court Motor Show last October—seven built in Great Britain and one in France—showed that car designers are becoming increasingly aware of the advantages of the system. It is true that none of the cars to which they were fitted could be classed as cheap, and as yet, they are Incorporated only in cars which are very powerful. However, if one of the major British companies fits disc brakes to its medium price-range models, there Is little doubt that the others will be quick to follow. With speeds becoming higher with each successive model, the problem of efficient braking is one of primary importance. There must be few drivers who have not experienced brake “fade” with conventional brake drums and linings, especially during the descent of a long hili' with hard use of the brakes. In order to reduce the unsprung weight of cars in recent years, wheels and the brake drums have become smaller, and streamlined bodies tend to keep the cooling air away from the drums. First Solution The Dunlop Aviation Division were the first to solve the problem of overheating drum brakes, when they fitted a brake In which comparatively small friction pads were pressed on to the sides of a

metal ring keyed into the aircraft wheel These brake* were first demonstrated on an aircraft at Elmdon, Birmingham, in 1946. In 1951, a team of engineers undertook the adaption of the aircraft brake to a Jaguar racing car. The strains involved in a racing car with the driver unmercilessly pulling up from 150 miles an hour were harder to predict than in an aircraft. But by the end of the year the engineers had produced their first, astonishingly simple answer. Braking Pad* A metal disc, the diameter of a soup plate, about half an inch thick, was bolted to the halfshaft Straddling the rim of the disc and attached to the axle casing was a small casting which bore the friction pads. These had a Surface area of only a few inches, ' and were forced against the revolving disc by opposed hydraulic pistons. The power of the braking was outstanding. However, when fitted to a Jaguar sports car in 1952, the brake showed up some serious defects. The engineers brought out their drawing boards again and went back to work. In 1953, when the Jaguars took to the circuit at Le Mans, they were the dark horses in one of i the strongest fields motor racing i has seen. Among the entrants i were Ferrari, Alfa Romeo, lan-

cia. Talbot, and Cunningham but 24 hours later these oar* were eliminated rather than beaten. The Jaguars cam* first, second, and fourth.

The following year, Mereedes appeared at Le Mans with an air brake in a desperate effort to counter the disc brake. But one by one since 1953, th* racing manufacturers have adopted the disc brake—the latest being Bnzo Ferrari, who has sadly canted out the advice given him by the late Peter Collins.

Already disc brake* are being mass-produced, and soon may be almost as cheap as the drum types. The latest improvement to the pads allows them to be changed in 20 minutes, a big saving on the long hours taken in renewing a set of brake linings. With today's saloon cars reaching such high speeds, the question is becoming a moral rather than an engineering one. Disc brake* are the best answer yet to high speed stopping, and can play a big part in greater road safety.