MODERN BRAKING

Evening Post, Volume CVII, Issue 10, 12 January 1929, Page 25

MODERN BRAKING

-TfiE EMERGENCY STOP

Each year the average speed of traffic increases,i as dbe.s the average speed of .•the car,'and alsdthe volume of cars on the congested road. Brakes, therefore, must improve equally as rapidly 'as the speed of the car; more rapidly, in fact, for brakes, have been-a long way bes hind speed for years past, and it is only since the relatively- recent arrival of four-wheel brakes 7 that, general safety has been at ; all assured. Progress has, bo.cii made with brake systems/ and, indeed, is being'made quite rapidly by those manufacturers of cars who are keen enough toy study, the performance ofi[efficient-contemporaries. ■'• : - ■■■

( -yA yearior -two ago cars with four■wheel brakes took 90 to 110 feet to pull up in emergency from 40 miles per hour. To-dax the.brake system urgently needs attention if the'vehicle cannot make an emergency; stop from that Bpeed in : 6o :to. 7p.:£eet,!"and stop, smoothly at that:. Attention'"to"effleiency"in the meclianism. has obtained these results. Men and women are capable of exerting a certain average pressure with a single foot, and there is,a limit--of only a few

inches of travel over which this pressure can .comfortably be maintained. These, two factors provido all tho leverage'for brak'o application that is avail.able.."' If "the. system of. leverages and tie-rods, leading to the brako shoes is efficiently designed arid made, then this av-;iablo force is, quite sufficient to give .adequate,control-for a car up to 20 h.p. and capable of 60' miles per hour. Larger cars of greater weight and need to have some form of mechanical, assistance, or, servo system, in order to relieve the driver :of hard,work.

Servo motor brakes of tho vacuum operating typo are ceasing to find a place on the small and medium-sized car, because detail improvement in actuating gear is making them less necessary, and partly because of price, but .on larger cars in which expense is more or less a secondary'consideration, such systems are falling into regular use,.,to say nothing of the-mechanical type of servo brake and the hydraulicall/ assisted brako. ... . -. '.. " "