Windshield and Windshield Wiper
Because early autos traveled at fairly slow speeds, little, if any, wind-breaking protection needed to be provided in the car design itself. As speeds increased, this type of protection became more important. The earliest "windshields" were nothing more than vertical sheets of plate glass in wooden frames.
The plate glass was an obvious source of injury to drivers and passengers. Hoping to strengthen and reinforce windshield glass, John C. Wood (in 1905) glued two sheets of glass together with a central layer of celluloid to create a type of laminated glass. Unfortunately, in addition to being difficult and expensive to produce, the celluloid tended to yellow over time, causing yet another safety hazard.
Work continued on laminated glass in efforts to eliminate the yellowing and to increase the ease of production. Although laminated glass could be curved to suit specific manufacturing needs, it most often required a frame, and this made it less desirable. In 1928, the car maker Hillman was the first to use laminated safety glass for use in windshields as well as in side and rear windows.
Toughened glass was developed as an alternative. The French glassmaking firm St. Gobain developed toughened glass for car windshields in 1929 based on previous findings of Owens-Corning, the U.S.-based company. This type of glass is super-heated and rapidly cooled in single sheets. Toughened glass was found to be more pliable than laminated glass, making it ideal for the curved slopes of the windshield. Unlike laminated glass, it could be fitted directly into the bodywork and did not need a frame. Unfortunately, the finished product was so rigid that it was hazardous. It did not yield upon impact and could severely injure individuals in the vehicle.
Further development of laminated glass continued. The Triplex company created curved laminated glass for use in streetcars. In 1956, a British car, the Vauxhall Victor, was fitted with the first wraparound, laminated windshield.
Additional features developed after World War II include window defoggers and tinting. In 1948, Rolls Royce first embedded tungsten wires in the laminations of the rear window for defogging and de-icing. Tinted glass (under the brand name Sundym), for cutting down on heat and glare, was introduced in American cars years later. Safety in window glass has also been a concern. Car makers created differential zoning, which allows windshields to crack and break in such a way that larger, undamaged sections will be left in front of the driver.
Another feature created to improve the driver's field of vision is the windshield wiper. In 1903, J. H. Apjohn invented a system of two brushes that he could move up and down the glass. Other systems based on the same principles were later developed using rubber strips rather than brushes. Until 1917, drivers had to use one hand to manipulate the wipers and the other to steer and shift. Ormand Wall, a Hawaiian dentist, recognized the danger in this practice and devised an electric motor in the middle of the windshield to oscillate a long rubber blade. Other wiper designs featured double blades with rubber on the outside to clear the windshield and a tandem, felt-lined squeegee to defog the inside. In 1929, another American, William Folberth, designed the vacuum-powered wiper that was run by suction from the engine's intake manifold. Similar versions of this system evolved, but the timing of the mechanisms was problematic. The wipers would speed up and slow down with the speed of the car.
By the 1930s, wipers propelled by an electric motor were refined and became the standard. Blower vents were added to the dashboard to defrost windshields. With the introduction of a curved windshield, the British car company Vauxhall, in 1933, produced a blade made of a number of short blades all controlled by a main curved arm. By the late 1930's, the American car manufacturer Nash introduced automobile air conditioning, and defrosting and defogging methods were incorporated in this system.The intermittent wiper was invented in 1962 by Bob Kearns, and microsensors in windshields of the 1990s can sense rain on the windshield and adjust intermittent wipers for showers or downpours.
This is the complete article, containing 681 words
(approx. 2 pages at 300 words per page).
