EFFECTIVE BRAKES.

Shannon News, 15 February 1929, Page 4

EFFECTIVE BRAKES.

LEGAL INTERPRETATION ■/[% Every motor-car in New ir*}| respective of sue or seating capacity ,'j| is required to have a footbrake whiclh§ will bring it'to rest frpin 20 m.p.h. i'n-4 a distance .of 50ft. ,The hand brake =$ 'must' be effective within 75ft. undeipjl -the same conditions. %The relate to a test taken on "a hard, <$ dry, level road of bitumen, concrete, similar surface, free 6i loose metal." |> The braking effect of the engine; % against compression with the throttle, | closed may not be used in brake tests..* £ The Department of Highways of % Canada has just issued brake specifica* <\± tions identical with those required b£ ,'jthe 'New Zealand regulations. An in; : .? genious device which is.applied to one'- ;=' wheel is being nsc;i in great Britain '''"•• to indicate stopping ability. Some of; >j (lie local bodies iu the. Dominion may ■ fj ,\ et equip "themselves with such gear, -v Brakes are usually in* better condition { ii.'hilly cities such as Auckland than .";. they'.are'in cities' such as Christchurch. ); . The many grades encountered in : - everyday (hiving compel motorists tq '•-; look after the footbrake at least. A :<*. flying squadron which-recently exam-/ "1 iiicd 1000 cars' 'picked' af random in J New York directed repair's or prose- - 1 eutions in 700 cases ~A

The stopping ability required by th«i .c New Zealand regulations is well with* ':] n the capacity of even the older twp- t ; wheel brdke system. From 20 m.p.h.'*.; average rear wheel should bring a car '; to rest in 37ft., or 13ft., less than the •? distance required by law. Four wheel '■'- brakes should arrest a car within 17ft. ; .. t'rom. a speed of 20 m.p.h. With effici-' '•' '■.; ;-nt four-wheel brakes, it is possible ■ : to stop within 50ft. from a speed of • .. '>s m.p.h. It has actually been demon- -. Crated 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 time of the driver has •in important bearing on braking, and although it can be demonstrated that ') a car can be halted in even 25ft., from - '.!-0 m.p.h., it ik a different matter when the stop is unexpectedly "required. ' * Tests have shown that the ' time of some drivers is -as low as one third of a sceoird. Other drivers may allow fully one second to elapse before " they act in accordance with a warn- - ing. The average may be taken as slightly more than half a second. '• If a \ driver!, with a reaction time of onehalf 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 s.oft. allowed before the reaction time expired. -'