EFFECTIVE BRAKES

Manawatu Times, Volume LIV, Issue 6805, 8 January 1929, Page 10

EFFECTIVE BRAKES

LEGAL INTERPRETATION Every motor car in New Zealand, irrespective of size or seating capacity, is required to have a foot brake which will bring it to rest from 20 m.p.h. in a distance of 50ft. The hand brake must be effective within 75ft. under tlic same conditions. The regulations relate to a. test- taken on “a hard, dry, icvcl road of bitumen, concrete, or similar surface, free of loose metal.” The braking effect of the engine against compression with the throttle closed may not bo used in brakq, tests. The Department of Highways of Canada lias just issued brake specifications identical with those required by the New Zealand regulations. An ingenious device which, is applied to one. wheel is being used in great Britain to indicate stopping ability. Some of the local bodies in the Dominion may yet equip themselves with such gear. Brakes are usually in better condition it. 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 New York directed repairs or prosecutions in 700 cases.

The stopping ability required by the New' Zealand regulations is well within the capacity of even the older two wheel brake system. From 20 m.p.h. average roar -wheel should bring a car to rest in 37ft., or 13ft., less than the distance required by law. Pour wheel brakes should arrest a car within 17ft. from a speed, of 20 m.p.h. With efficient four-wheel brakes, it is possible to- stop within 50ft. from a speed of 35.m.p.h.- It has actually been demonstrated 7 that a car travelling at 45 m.p.h':' can be brought, to rest- in less than 50ft., but this result is well above the average. The reaction timo of the driver has an important bearing on braking, and although it can be demonstrated that a car can be halted in even 25ft., from. 30 m.p.h., it is a different matter when the stop is unexpectedly . required. Tests have showa that the reaction time of some drivers is as low as one third of a second. Other drivers may allow fully on'e second to elapse before they act in accordance with a warning. The average may be taken as slightly more than half a second. If a driver, with a. reaction time of onohalf second was travelling at 30 m.p.h., he would go approximately 22ft., before beginning to comply with a signal to - apply his brakes. A driver with a reaction as high as one and a-half seconds would traverse 66ft. From this it will be seen that with the finest brakes possible it would be possible to traverse the 50ft. allowed before tho reaction time expired.