MOTOR AND CYCLE.

Taranaki Daily News, 4 September 1920, Page 10

MOTOR AND CYCLE.

KEWS AND NOTES. SPEEDOMETERS. Considerable experience with various forms of speedometer and speedometer driving mechanics brings to light a few points about these appliances which may be of interest to other users. Few speedometers register accurately. The error is not sufficient to write home 'about; but it is there, and the fault does not lie with the speedometer makers. Every one of the well-known make* of speedometer is, in itself, accurate within limits which are of no importance in the usage of the appliance in actual road conditions. Errors invariably are due to one of two causes. Either the power-transmitting mechanism from the moving part of the ear to the times instrument is defective, or'the effective tyre diameter is not of a ratio to give a proper and accurate reading on the dial of the instrument. The tyre diameter discrepancy is the most frequent of the causes of lack of accuracy in the mileage-hour reading of the speedometer, and, speedometer makers cannot be blamed for this A tyro too big will give a. mileag* and speed less than that travelled. A slack tyre—an under-inflated tyre—will give a spesd and mileage greater than that actually attained and covered. Some speedometers when fitted on cars will give a fluctuating, vibrating, reading at the indicator hand; but this must riot be put down to the speedometer. We have seen one of the steadiest of instruments with its pointer doing jazz dances over the dial. This was due to a pinion on the drive wheel meshing deeply at one part of the rotation of the road wheel and hardly engaging its teeth at the. opposite half of rotation. The speedometer cannot be blamed for this. In one ease the speedometer was driven by a flexible metallic spring belt off a wooden pulley on the Cardan shaft, and every time the belt fastening went round the small pulley it gave a jerk to the transmission shaft which was plainly indicated at the pointer on the dial. These belt drives for speedometers are neat and effective ways of getting the power to the instrument, but when a wooden pulley is used—and even when an aluminium pulley is used—there is always a reduction of tho diameter through wears, so that after extended use the instrument registers a lower speed than that actually travorsed by tho vehicle—oven if the cui'/ration were correct when new. The toothed drive, giving always the same ratio of rotation, is undoubtedly tho better drive, but it somatimes gets noisy. If it is fitted with a fibre wheel the latter wears badly in time, and rattles and jumps, but the speed is not affected. It should be removed occasionally. Flat leather belts get slack, and do undoubtedly slip, especially if the pulleys are small.,

FLYING POPULAR. It would really seem that flying as a popular pastime and method of transport may yet be brought within the reach of the private motorist of ordinary means. Aeroplanes. «'c know, can be produced at corny atively low prices! the £250 aeroplane has several timeß been mooted in the English Press, and we should imagine that in the course of the next year or two a.really practical machine could be put on the market at a figure of less than £SOO. One would have expected, however, that the running and maintenance expenses of an aeroplane would have been excessively high, yet recently a Green-engin-ed 'plane flew from London to Turin, a distance of 650 miles, on 20 gallons of petrol. This works out to the extraordinary figure of 32J miles to the gallon —which is much better than the 15 to 25 miles a gallon—ran by the aver- | age passenger motor-car. The carburetter used was an ordinary standard car type Zenith. 'MOTOR INDUSTRY IN U.S.A. Figures showing the tremendous growth of the automobile industry in America during the. last six years have recently been compiled by the National < Automobile Chamber of Commerce of | that country. The following table is instructive:— Capita} invested, 1914, 407,730,000 dols,; 1010, 1802,302,000 idols.; .increase, 342 per cent.. Motor vehicle output, 509,000 dols.; 1,974,000 dols.; increase, 247 per cent. Value of products, 632,831,000 dols.;' 2,506,834,000 dols.; increase, 296 per cent. Persons employed, 145,000; 651,000; increase, 346 per cent. Wages and salaries, 139,453,000 dols.; 813,731,000 dols.; increase, 485 per cent. Some idea r* the present magnitude of the industry may be gathered from the fact that last year the total exports of passenger cars represented only 4 per cent of the cars produced, and motor truck exports amounted to 4.9 per cent of the output. It must he borne in mind, too, that of this 4 per cent of exported passenger cars, ia spread over Europe and many other countries including Australasia. So that all the new American cars one sees in this country represent considerably less than 1 per 1-etot of America's output. The actual number of passenger cars produced in 1019 in the U.S.A. was 1,657,652,