How Are Those Car Brakes?—Helpful Guide By Transport Department

Chronicle (Levin), 4 November 1949, Page 4

How Are Those Car Brakes?—Helpful Guide By Transport Department

The safe speed of any vehicle in a given set of circumstances d-epends upop a number of different factors. The alertness and ability of th'e driver; the nature of the road and road surface; weather and traffic conditions are all factors, but of prime importance also are the amount of available space in which the vehicle may stop and the mechanical ability of the vehicle, particularly in braking efficiency.

This question of speed and stopping ability is once again engaging the attention of the Transport Department and for the information of the public it has issued a circular which inspectors will hand to motorists after their vehicle has been checked by them. Included in the circular is a chart indicating safe stopping distances at various speeds and a report filled in by the examining inspector on the performance of each indivi'dual car. "The law requires that your footbrake be capable of bringing the vehicle to a stop within 40 feet from 20 m.p.h.," states the circular. "Your hand brake must be capable of stopping the vehicle within 70 feetr at 20 mi.p.h. and hold it stationary on an incline of one in five." ' . Those are the main facts in the circular. Another is that the traffic inspectors are right on the job" and have already tested a number of vehicles in the Horo•whenua district. • Traffic Inspector W. Boyes told a "Chronicle" reporter yesterday that during the last fortnight he had .tested 70 vehicles. Ten per cent. of these had failed to comply with the regulaitions governing brakes. More tests will be sprung on "drivers from time to time. For the information of drivers, here are a few more hints included in the circular. "A car travelfing at 30 m.p.h. travels 44 feet in one second; at 40 m.p.h. it travels 59 feet per second." The stopping distance of the

yehicle is determined by its speed, the reaction time of the driver, the , braking efficiency of the vehicle and the friction between tyres and the road surface. The normal 'driver takes three-quarters of a second to react to an emergency so xhat at 30 m.p.h. the vehicle will have travelled 33 feet. This is before the brakes are actually applied and thus before the vehicle has started to slow down. The braking distance, i.e., the distance travelled while the car is actually coming to a standstill, increases very rapidly as speed increases. It is in fact in proportion to the square of the speed. Thus, a vehicle travelling at 40 m.p.h. takes four times the distance to stop as when travelling at 20 m.p.h. It is obviously impossible to determine a speed which would be safe for all drivers of all vehicles under all possible conditions. However, all drivers should remember the following requirements governing the speed - of vehicles: — (a) It is an offence to drive at such a speed that the vehicle cannot he stopped in half the length of the clear roadway aheac^ which is visible to the driver; (b) ■' the driver must be able to stop short of another vehicle preceding him in the event of the other vehicle stopping suddenly; (c) the driver must be able to stop to give way to another vehicle at an intersection, or to a pedestrian using a crossing, and should consequently approach. such localities at a reduced, speed.