MOTORING NOTES

Te Aroha News, Volume XLI, Issue 6409, 1 November 1923, Page 7

MOTORING NOTES

(By an Expert.) * BITUMEN SURFACING. SOME WELL-TESTED SURFACES.—SMALL MAINTENANCE COSTS. A correspondent has forwarded a list of borough streets surfaced with bitumen on the penetration method which have been done a good number of years in each case, and have cost little for maintenance. The cost of the actual bitumen work by this method is stated to be from 1/5 to 1/8 per square yard, which covers the cost of the bitumen and the spraying. Brougham Street, New Plymouth, laid in 1918. No cost for maintenance up to 1922, when it was still in firstclass order, and received only a light top-dressing. Main Street, Ellerslie, laid in 1915. No cost for maintenance up to April of this year, 1923, when it received a light topdressing, at a cost of 5d pel 1 square yard. This street carries heavy through traffic. > Victoria Street, Cambridge, laid in 1916. No cost for maintenance up to date. This street carries heavy traffic. Main Street, Te Awamutu, laid in 1916. No maintenance ' ( cost up to date. The street is still in first-class order, and carries fairly heavy traffic. High Street, Dannevirke, laid in 1916. No maintenance cost to date. Street s*till in good order and carries fairly heavy traffic. Main Street, Waiuku, laid in 1916. No maintenance cost to date. The street is in first-class order, and carries very heavy traffic. , Lake Road, Takapuna, laid in 1916. No maintenance cost up to April of this year, 1923, when it received a light top-dressing at a cost of 5d per square yard. There is rather an unfortunate tendency, says “The Motor” (Eng.) to assume that four-wheel braking systems are only really required on large and heavy cars, and this misconception arises from the erroneous idea that the stopping distance is greater for large cars than for small ones. As a matter of fact the stopping distances are much the same, and in either case a great reduction can be effected if front-wheel brakes be adopted. The advantage of safe control on slippery surfaces applies, of cpurse, to any car. Taking the case of a car fitted with rear-wheel brakes only it is a eomparativly easy matter to design the brakes that the wheels are almost locked when the full pressure is applied. This means that the full retarding force is being utilized, and the magnitude of hte force depends upon the weight on the wheels and the state of the road and tyres. To quote definite figures: in most cars of orthodox design 60 per cent of the weight is applied to the rear wheels. Under normal conditions the retarding force amounts to about half this weight, so that, with rear wheel brakes this forceps about 30 per cent of the weight for any size of car. Now, the stopping distance depends on this retarding force and also on the energy which the cas possesses at the instant the brakes are applied. For a given speed this energy is proportional to the total weight of the car. We, therefore, get the following result: that both the energy to be dissipated and the retarding force depend on the weight. It is, therefore, easy to see that because the energy and the retarding force both increase with the weight, the distance in which the car can be brought to a standstill from any giv/en speed is not dependant on the weight. Roughly speaking, owing to the additional weight thrown on the front wheels when the brakes are applied, the addition of brakes to the front wheels doubles the retarding force and so halves the pulling up distance for any weight of car. This statement i robsiappldeveryklr|alaf-a statement is borne out by many practical tests. • Lastly it is worthy of noti’.e that although the stopping distance is altered when the car is ascending or descending a hill, £he distances are once more independent of the weight benefit by the adoption of front wheel of the car, so that all types would brakes. We are pleased to note that our Borough Council has made a start with repairing the main Te ArohaPaeroa road. This portion of the road, through Ruakaka, was becoming very rough, and motorists will be pleased to note that the pot-holes are receiving attention. Motorcyclists will be interested to know that Percy Coleman is now riding Harley-D'avidson motors in the championship.