Windscreen wiper
From Free net encyclopedia
A windscreen wiper (windshield wiper in North America) is a device used to wipe rain and dirt from a windscreen. Almost all automobiles are equipped with windscreen wipers, often by legal requirement. Though confusing, some legal systems require wipers without requiring a windscreen.
Wipers can also be fitted to other vehicles, such as buses, trams, locomotives and ships.
A wiper generally consists of an arm, pivoting at one end and with a long rubber blade attached to the other. The blade is swung back and forth over the glass, pushing water from its surface. The speed is normally adjustable, with several continuous speeds and often one or more "intermittent" settings. Most automobiles use two synchronized radial type arms, while many commercial vehicles use one or more pantograph arms. Mercedes-Benz pioneered a system in which a single wiper extends outward to get closer to the top corners, and pulls in at the ends and middle of the stroke.
Wipers may be powered by a variety of means, although most in existence today are powered by an electric motor through a series of mechanical components, typically two 4-bar linkages in series or parallel. Vehicles with air operated brakes sometimes use air operated wipers, run by bleeding a small amount of air pressure from the brake system to a small air operated motor mounted just above the windscreen. These wipers are activated by opening a valve which allows pressurized air to enter the motor.
Early wipers were often powered by manifold vacuum, but this had the drawback that manifold vacuum alters depending on throttle position and is almost non-existent under wide-open throttle; the wipers would slow down or even stop. This problem was overcome somewhat by using a combined fuel/vacuum booster pump. Some cars, mostly from the 1960s and 1970s, had hydraulically driven wipers.
Most all windscreen wipers operate together with a windscreen washer; a pump that supplies water and detergent from a tank to the windscreen through small nozzles, mounted on the hood/bonnet or on the wipers.
Some automobiles have small 'windscreen' wipers/washers on the headlights or wipers on the back window as well. Rear-window wipers are typically found on hatchbacks, station wagons, sport utility vehicles, and some sports cars. They were first implemented in the 1970s, and SUVs did not use them until the 1980s.
History
Mary Anderson is said to have invented the windshield wiper in the United States, where she patented the idea in 1905. The idea was initially met with resistance, but was a standard feature on all American cars by 1916.
In April 1911 the first British patent for windscreen wipers was registered by Sloan & Lloyd Barnes, patent agents of Liverpool, England, for Gladstone Adams of Whitley Bay. The first designs for the windscreen wiper are also credited to Józef Hofmann, better known as a pianist.
In the early part of the 21st century, rain-sensing windshield wipers appeared. An infrared light is beamed at a 45-degree angle into the windshield—if the glass is wet, less light makes it back to the sensor, and the wipers turn on. As of early 2006, rain-sensing wipers are standard on all Cadillacs, and are available on many other GM models.
See also
External link and references
- http://www.madeinbirmingham.org
- Howstuffworks - [1]de:Scheibenwischer