FOUR-WHEEL BRAKES

Wanganui Chronicle, Volume 74, Issue 114, 16 May 1931, Page 10

FOUR-WHEEL BRAKES

IMPORTANCE OF ADJUSTMENT. The importance of correct, adjustment of four-wheel automobile brakes was recently demonstrated by tests conducted at the National Physical Laboratory, London. A working model of a car was used in the experiments. 1L was found that tho model skidded perfectly straight for 4ft. with all four brakes on and the wheels locked. With tho two rear wheels locked the car skidded 9ft. forward, and deviated Ift. to one side, while with the two front wheels locked the machine skidded sft. forward and kept a straight course. With both frjni. and the right hand rear whbel locked there was a skid of 4Kt. and a >light deviation to one side. The investigation resulted in conclusion that the tendency to overturn is specially marked at hign speeds with two rear brakes only in operation, a diagonal pair of brakes, end nlso when one front and two rear brakes are applied. In the case where the front brakes lock the wheels of a car, the driver has little or no control over the direction of travel so long as those wheels are locked. On the other hand, when the rear wheels lock, the stability of tho motion is bettor un-jcr control. These experiment indicate ttie importance of cooct brake adjustment. Points for Owner Drivera. Today, with high speeds and more rumi traffic, the efficiency of automoLie brakes becomes more important than ever. The standardising of fourwheel brakes has given to motorists greater control over their vehicles, but at the same time has introduced a more intricate braking system when it calls for adjustment. The appearance of so many black smears of rubber on the suriacc of city streets is only too significant evidence of the number of automobiles that aro running with unevenly adjusted brakes. Admittedly not all brake systems are easy to adjust, anl where there is any doubt in this respect it is advisable to let, an experienced mechanic handle the job. For those who desire to handle the adjustment themselves, the best way is to jack up both axles so that all wheels are free of tho ground at tho same time; then cut a strut to press down the brake pedal from the. dash or from front of seat, whichever is Ue most convenient. Go to each wheel in turn and make the adjustment so that, you can just manage to turn fhe wheel by using the whole of your strength. Compensated brakes present the greatest difficulty, and may make it necessary to go the round of the wheels several times. This is because individual adjustments affect the other brakes. In carrying out such an ad justment it is well to remember that worn treads of tyres do not, give the same road grip, as do covers with the patterned tread in good condition; also, that tyres should bo evenly balanced as regards tread surface.