SPEEDOMETERS

New Zealand Times, Volume LIII, Issue 12453, 22 May 1926, Page 18

SPEEDOMETERS

RELIABILITY DOUBTFUL.

A* couple of_ motoring pals were discussing the rival performances of two people who, on their own confession could and did habitually drive at 50 miles an hour on wellinown roads. Whether the cars in question art capable of such speed is another matter, but their speedometers no doubt showed over-speeding. I Many speedometers to-day overestimate tho speed of the car, and are ; n °t always correct as has been shown 'on several occasions recently. The i error can bo easily discovered, liowover, if the odometer is checked ovei I a known distance or against a series ,of milestones, as the mileage recording part of the instrument is that which regulates the speedometer. Or it can bo exposed by the aid of a good I watch and a level stretch of milejstoned road. A chat with an expert motorist disclosed that the hairspring of ,\ magneto is very delicate, and if anything goes wrong with this the car !is more likely to under-register than over-register. When a soeedometer is first put out it is possible that it may over-register, as manufacturers are more likely to err in this direction in order that motorists may b» on tho right side.