EFFECTIVE BRAKES.

Hawera Star, Volume XLVIII, 12 January 1929, Page 13

EFFECTIVE BRAKES.

THE LEGAL POSITION. TESTS KEQUIBED. Every motor-car in Now Zealand, irrespective of size or seating capacity,i's required .to have a foot!)rake, which wild bring it to rest from 20 m.p.h. in a distance, of 50ft. Tiro 'hand-.brake must bo effective wit him 75ft under the; same conditions. The regulations relate to. a test taken on a hard, dry, level toad of bitumen, concrete, or similar surface, free of loose metal.” The- braking effect of the engine against cotmpresskur with the. throttle closed may not be used in brake tests 1 .

The Department of Highway® of Canada has just issued 'brake specifications identical wit if those required by the Hew Zealand regulations', says an Auckland writer. An ingenious device which is applied to one wheel is being used in Great Britain to indicate stopping ability". Soane of the local bodies in the Dominion may yet equip themselves with such gear. Brakes are usually in better condition in hilly cities such as Auckland than they are in cities such as Christchurch. The many grades encountered in everyday driving compel motorists to look after the footbrake. at least. A flying squadron which recently examined 1000 cars picked at random, in Hew York, directed repairs or prosecutions' in 700 cases. The stopping ability required by the Hew Zealand regulations is well within the capacity of even the older twowheel brake systems. From 20 mjp.h. averago rear wheel brakes should bring a cair to rest in 37ft, or 13ft less than the distance, required by law". Four wheel brakes should arrest a car within 17ft from a speed of 20 in.p.h. With efficient four-wheel brakes 1 , it is possible to stop within 50ft from a speed of 35 m.p.h. It has actually been demonstrated that a. car travelling at 45 m.p.b. can be brought to rest in less than 50ft, but this result is well above the average. The reaction time of the driver has an important bearing on braking, and although it can be demonstrated that a car cad .be halted in .even 25 ft from 30 mjp.h. it is a different anatter when the stop is unexpectedly required. Test®, have shown that; the reaction time of some drivers is as' low as onethird: of a. second- Other drivers nay allow fully one second to elapse before they act in according with a .warming. The average may be taken as .slightly more than half a second. If a) driver, with a reaction l time .of onehalf a second was travelling at 30 mupJi. he would go. approximately 22ft before beginning to comply with a signal to apply his brakes. A driver with a reaction as hight as on© and a half seconds would traverse 66ft. From this it will be seen that with the finest brakes possible it would be possigle to traverse the 50ft allowed before the reaction time expired.