WIPERS WORK HARD

Press, Volume CIX, Issue 31983, 9 May 1969, Page 9

WIPERS WORK HARD

Few drivers would deny that a smeared, dirty windscreen is a considerable danger, yet few think of replacing their windscreen wiper blades until they are so old that visibility , is seriously. reduced. Because wiper blades deteriorate gradually, the consequent deterioration in vision is not very noticeable until you have to drive on a busy road on a wet night, or suddenly realise that whenever it rains you are having to strain to see.

Manufacturers say wiper blades should be replaced once a year. Generally, this means after about one million wipes, or the equivalent of each wiper blade sweeping 30 acres of glass. Although many researchers have sought a better way of clearing water from vehicle windscreens, nobody has yet developed anything more satisfactory than the rubber wiper-blade. The first wiper blade used in the United States was

called a “rain rubber," and it appeared at almost the same time as the first windscreens designed to be looked through rather than over.

The “rain rubber” swept horizontally across the screen from side to side, and was moved by hand. Later another type of wiper, the “crescent cleaner,” was developed. This swept across the screen in an arc, the principle used by pre-sent-day wipers. It is interesting to note that in the search for more efficient screen-wiping, some sports-racing car manufacturers have recently gone back to a type of wiper that sweeps horizontally from side to side of. the screen.

This type of wiper has special links connecting the wiper blade backing to the wiper arm, and as the arm sweeps, the links keep the blade in a vertical position. Curved, sloping windscreens brought a particular difficulty in recent years: the air-flow tended to lift blades off the screen, so that in some cars the blades would leave

the screen completely at little more than 50 m.p.h. Motor-racing helped produce the answer to this problem—a new design of blade backing that prevented the fast-flowing airstream from lifting the blade from the screen. Only three years ago, “anti-lift" blades were successfully tested on Ford GT4O racing prototypes at speeds up to 200 miles an hour.

Apart from the changes in methods of wiper operation —from ■ manual to electric, vacuum-operated, and mech-anically-operated from a camshaft gear—the main design alterations have been aimed at coping with windscreen curvature.

When screens were flat, there was little problem, but the more screens were curved and sloped back, the more difficult it became to keep the wiper blades in even contact with the glass.

The “wrap-around” screens which appeared in the mid--1950s created particularly serious problems for wiper manufacturers, problems which in some car designs were never completely solved. But the blade manufacturers met the challenge remarkably well, and as a result today’s wiper blades follow screen contours well, clear rain and even snow efficiently, and stay in contact with-the windscreen at high speeds. For safety, wiper blades should be replaced once a year, preferably now, before the worst of the winter. When the windscreen is cleaned, the wiper blades should also be carefully cleaned, and they should never be allowed to come in contact with carbody polish, which will make them smear. A windscreen washer is a valuable aid to good visibility and most garages stock special solutions that can be added to windscreen-washer reservoirs to help remove oily road film from windscreens.