Historical Notes : Brakes (Part 2)
Historical Notes: Brakes (Part 2)
(Continued from the June issue)
rO OUR-WHEEL brakes first appeared in a patent granted to Mr. P. L. Benoist' of Erdington, near Birmingham, in 1904. and this was followed by a period of many similar ideas from Germany. France and Italy ; but it is to Henri Perrot that the credit is normally given for their practical introduction. At the time he was connected with the famous Argyll works at Alexandria, near Glasgow. The Argyll systeni was operated diagonally, off-side front to near-side rear, and vice versa. Another early system was the Allen-Live.rsidge. fitted to Arad-Johnston, Adams, Crossley, Spyker, Sheffield-Simplex, Thames and Newton-Bennett cars in 1910, and in this type, the main brake control-rod passed through the steering pivot.
Unfortunately, it was sometimes possible to lock the steering when the brakes were applied with this system, and all the manufacturers listed above abandoned the idea after the one year's trial. Isotta-Fraschini produced an independent four-wheel system in 1911, but it was the French Grand Prix at Lyons in 1914 that really set the ball rolling. A detailed description of this race would seriously encroach upon " 13aladeur's " territory, but suffice it to say that, so far as manufacturers were concerned, it was the continental people who first learned the lessons at that race. British designers were probably more shaken by the trends shown at the French Automobile Salon in Paris, after the war, than by the results at Lyons. Delage Hispano and Talbot-Darracq led the way in 1919, but M. De &mina of the Excelsior factory in Belgium had produced, during the war, a "cross" between the Perrot and the Isotta system, the Perrot part being the diagonal control, and the Isotta part being the mounting Of the special operating earn in the axle itself, which was one of the main claims in the Ilona Patent of 1910. During the twenties, the following were some of the main linkages. and perhaps the accompanying sketches will help to make matters
clearer. The Perrot, Fig. 1, is, of course, sufficiently well known amongst vintage folk to warrant no further description. The RuberyAlford, Fig. 2, became exceedingly popular, if only because it was the standard fitment to the Morris products of the era. The centre Pivot type, Fig. 3, Was the standard Austin system, and although it worked well on the lighter models, stopping the " Twenty" certainly required the leaden foot in no mean fashion. The BendixPerrot was an early "self-wrapping" type, and was probably the first appearance of the Bendix principle which has lasted right through to present times. But space simply does not admit of going into further details. As has been said in Part I of this article, Merhanieal Servos were sometimes added to these typical systems and the Rolls-Royce servo comprised a "driving disc " which received its positive drive from a shaft in the gearbox throngh a bevel and the propeller-shaft, and is, perhaps, typical. Ilispano had pioneered a somewhat similar idea in 1919, and another early proprietary servo was the Hallot, the conception of Capt. HaliOt of the French Army, and Chenard-Walcker and Sunbeam cars were fitted with it. Before leaving this all too brief review of the mechanical brake linkages of the vintage era, and the servos that
sometimes actuated them, the Dewandra must be mentioned. In principle it was a large vacuum cylinder which the act of pushing the brake pedal connected to the inlet manifold depression, and this idea has persisted on heavy vehicles right up to modern times. The Rolland-Pillain car was shown at the Paris Salon in 1910 with hydraulic front-wheel brakes, but again racing was responsible for bringing the system into prominence, in particular following Murphy's Duesenberg victory at Le Mans in 1921. The Duesenberga used water-operated hydraulics, and the water passed through a hollow front axle and on to the bisecting cylinders via the pivot pin. Whether the fact that an emergency stop during practice locked a brake on Murphy's car and tipped it over did anything to dissuade other people is not officially recorded, but it certainly meant a painful race in bandages for poor Murphy. Lockheed himself, whose name was destined to become one of the most famous in automotive engineering, was connected early in his career with the FleMeVeloc Engineering Co. of San Francisco, California, and in consequence the Heine-Velox Special, a I2-cylinder luxury car of 1924, was amongst the very first to be fitted with Lockheed hydraulic brakes. The idea spread rapidly in America, but took somewhat longer over here. The early American Lockheed sets were quite often laid out to suit external contracting brakes, then still quite popular. in America, and quite why this fashion persisted so long in that country is something of a major mystery. Some of the early Lockheed schemes had an arrangement whereby the brake shoes
were of uneven size, in order to " spread the load " more evenly round the circumference of the drum, but in the '30's they returned to the more normal idea of symmetrical shoes, and the later development of the system must be too well known to need description here.
To try to complete this somewhat inadequate and complicated attempt to indicate the history of brakes, it is necessary to consider the ways in which the brakes were actually connected during the vintage period. The foot brake still remained the primary control, and more and more throughout the intervening years the hand brake tended to become a parking affair, partly because it was logical, and partly because the law had something to Say. Gradually the lovely levers with ratchets that made real engineering noises disappeared and the modern irritating " brolly handle " took its place. The hand brake frequently operated a second set of shoes in the back drums, this leading to much advertising along the " 6 brakes " lines, Mr. Minchin having recently retold one such delightful story in " Under My Bonnet." Frequently too, the hand brake operated the transmission brake, a complete " swing round " from the Edwardian era. SoMetimes, too, as in the Austin " Seven " case, the hand brake operated the rear, and the foot brake the front brakes, the operator being expected to pull and push at the same time for the real emergency. Sometimes, as in the Model T Ford and Trojan, you dispensed with the brakes altogether for real stopping and Stood hard on the reversing gear. But gradually the hand brake came to work a separate linkage to the single pair of rear shoes, thus dispensing with the need for the wider rear drums previously needed-.
Data regarding the distribution of the braking effort between the front and rear brakes is difficult to come by. Undoubtedly, in the early days of popular four-wheel braking, the front brakes were there in many cases for pure advertising purposes ! The fear of the " dreaded front-wheel slide " still persisted, and the arbitrary rule seemed to be to allot the braking effort in direct proportion to the static weight On each axle, making no allowance for weight transfer. Gradually, however, holder distributions were used, and around 1928 it might be said that the front brakes were beginning to take the major portion of the load. Modern brakes sometimes came in for criticism, but, even the most rapid vintage enthusiast can hardly deny that they are incomparably better than even the best of the older systems, especially when it is home in mind that nowadays they SCC711 to receive almost no maintenance attention at all, and are used to a far greater degree than ever before.
In the author's opinion there is no component part of the motor car that has come so near to perfection as the modern brake and its lining.'Were this not so. Some of our modern motor cars really would be " lethal weapons," 6specially in the typical modern motorist's hands, hut thanks to the brake people, Mr. Foley can make no capital out of that statement !—" A. B. C."
of 1 min. 48 sfq7., or 97.57 m.p.h. On the same lap, to ensure the B.R.M. did not creep up. Farina did on identical speed. On lap four Hawthorn gave up, his engine hot. Wharton thus, took third place, some way from Fangio, with Hod:hart fourth in his smart ex-Mays 2-litre E.R.A. but at snore than '" Charterhall distance," although he drove his high car sensibly as well as fast. Farina was driving magnificently. His third lap was a new record 1 min. 46 sec.. 99.41 m.p.h. Although Fangio was not in sight, Farina continued to make the. long green Ferrari go, and on hits fifth lap got round in 1 min. 45.2 see., a speed of 100.16 m.p.h. and Silverstone's first 100 b lap record. He looked calm and under control all the time. The B.R.M.s screamed along in arrears, but with a little development they should make quite good Formula I cars! Rosier lost a place or two, suffering a bumpy ride in his 0-litre Ferrari, which had had gearbox trouble in practice. Richardson got the R.R.A. along well in sixth place, tail-sliding his corners. The rest of the field--Cooper-Bristols„ old E.R.A.s, and the H.A.R.—circulated purely as a background. Birrell kept slipping plug leads on his aged E.R.A., reappearing at intervals to confuse the amateur lap-scorers. Dutt's 'ex-de Graffenried 4CI, Maserati, Sponsored, we believe, by Redex. non-started; perhaps this was not unconnected with an oil-dropping incident in practice which caused Lyons' Connaught. to go slap into the straw bales in front of the stands, With considerable damage to the front suspension. Other
non-runners were the A.II. and Cooper-E.R.A., although both had reached the grid. Tuck's 4CI, was gradually overhauled by the more modern Cooper-Bristols, but Graham Whitehead's E.R.A. was a match for t hese. Farina won a lonesome but splendid race at nearly 97 m.p.h., the Weber carburetters, Pirelli tyres and Scintilla ignitions standing up to the sizzling speed he set.—W. B.