[~JC~]

Windshield Wipers, Seeing Clearly


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.
Wipers can also be fitted to other vehicles, such as buses, trams, locomotives, aircraft 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 called the Monoblade 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, sweeping out a somewhat 'W'-shaped path.
Some larger cars are equipped with "hidden" (or "depressed-park") wipers. When wipers are switched off, a "parking" mechanism or circuit moves the wipers to the lower extreme of the wiped area, near the bottom of the windshield, but still in sight. To hide the wipers, the windshield extends below the rear edge of the hood, and the wipers park themselves below the wiping range at the bottom of the windshield, but out of sight.
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.
On the earlier Citroën 2CV, the windscreen wipers were powered by a purely mechanical system: a cable connected to the transmission, to reduce cost this cable powered also the speedometer. The wipers' speed was therefore variable with car speed. When the car was waiting at a crossroad, the wipers were not powered, thus a handle under the speedometer allowed to power them by hand.
Most windscreen wipers operate together with a windscreen washer; a pump that supplies water and detergent (usually a blend called windscreen wiper fluid) from a tank to the windscreen through small nozzles, mounted on the hood or on the wipers, known as a 'wet-arm' system.
Some automobiles have small 'windscreen' wipers/washers on the headlights. In more modern vehicles, these have been replaced with a powerful jet spray, without wipers.
Some vehicles are fitted with wipers (with or without washers) on the back window as well. Rear-window wipers are typically found on hatchbacks, station wagons, sport utility vehicles, minivans, and some sports cars. They were first implemented in the 1970s, but SUVs did not use them until the 1980s.
Nowadays some cars include intelligent (automatic) windscreen wipers that detect the presence and amount of rain using a rain sensor, and automatically adjusts the speed of the blades according to the amount of rain detected.

History
Inventor J. H. Apjohn came up with a method of moving two brushes up and down on a vertical plate glass windshield in 1903.
Mary Anderson is said to have invented the windshield wiper swinging arm 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, a 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, the world-famous concert pianist and Mills Munitions, Birmingham who also claimed to have been the first to patent windscreen wipers in England.
In the late 1950s, a feature common on modern vehicles first appeared, operating the wipers automatically for two or three passes when the washer button was pressed, making it unnecessary to manually turn them on as well. Today, a simple electronic timing circuit is used, but originally a small vacuum cylinder mechanically linked to a switch provided the delay as the vacuum leaked off.
In 1969, the first intermittent wipers were introduced with an adjustable delay between wipes, making it possible to select the degree of wiping action required. Robert Kearns is the recognized inventor of this system although it took years of concerted effort and legal action before he was eventually compensated.
In 1970. Saab Automobile introduced headlight wipers across the product range. These operated on a horizontal reciprocating mechanism, with a single motor. They were later superseded by a radial spindle action wiper mechanism, with individual motors on each headlamp.
In the late 20th century, rain-sensing windshield wipers appeared on various models, one of the first being Buick's Park Avenue Ultra. As of early 2006, rain-sensing wipers are standard on all Cadillacs, and are available on many other GM, Chrysler, Jeep, Peugeot, Citroën, Toyota, Mercedes, Honda and Renault as well as many other main-stream manufacturers.

The rest of the story:
Most people realize the importance of being able to see the road ahead clearly when driving in wet weather. That is why windshield wipers were invented in the first place. In 1916, a motorist struck a man on a bike during a rain storm because water on his windshield blurred his view. Soon thereafter, the first hand-operated windshield wipers appeared on motor vehicles, followed by one innovation after another as time went on: automatic vacuum-powered wipers, multi-ply wiper blades, dual wiper blades, windshield washers, winter blades, electric wipers, variable speed and intermittent wipers, airfoils on blades to resist wind lift, and so on.
The proliferation of wiper systems with different arm styles and blade designs has created a lot of confusion when it comes to replacing wiper blades today. Not only does a customer have to match the length of the blade, but also the mounting system. Universal mounting systems that come with many replacement blades have certainly made mounting easier, but it can still be confusing to some motorists - especially if someone only wants a refill and not an entire blade assembly. Different blade widths, blade designs and blade holder assemblies mean some can accept refills while others cannot.
EXACT FIT OR UNIVERSAL?
Wiper blades that fit exactly the same as the original are a snap to install because they look and fit the same as the OEM blades. Exact replacement blades have the same mounting system as the original blades and do not require any adapters. But they do require more part numbers to cover the more popular applications.
Universal blades, by comparison, have fewer part numbers and reduce your inventory requirements. Blades are packaged and sold by length. Universal blades solve the mounting issue by using adapters that can fit a wide variety of different mounting styles.
WINTER BLADES
With cold weather fast approaching, many motorists can benefit from the anti-clogging design feature of winter blades. Ordinary wiper blades can become packed with ice and snow, causing them to streak and wipe poorly. But winter blades do not have that problem because a rubber boot keeps ice and snow out of the blade superstructure to prevent it from freezing up. The result is consistent wiper performance regardless of weather conditions for safer winter driving. Winter blades are available in most common lengths and mounting styles.
HIGH-TECH WIPER BLADE MATERIALS
Blades today run the gambit from standard replacement blades made of natural or synthetic rubber to premium and ultra-premium blades made of longer-lasting materials that may include silicone, Teflon or other ingredients. Some premium blades combine several layers of different materials to improve wiping performance and longevity.
Natural rubber wipes clean and provide excellent durability, but it also hardens and cracks with age. That is why most wiper manufacturers also sell a premium line of wiper blades that are made of more exotic materials. A growing number of late-model vehicles such as Lincoln LS, Ford Navigator, Expedition and Explorer now come factory-equipped with Teflon-edged blades. Teflon is one of the slickest substances known, and it reduces wiping friction and blade wear to improve visibility and blade life.
WHEN TO REPLACE WINDSHIELD WIPERS
Recent statistics show that the average motorist only replaces their front windshield wiper blades every three years. Yet most experts recommend replacing the wiper blades once a year, and more often in hot, sunny climates if the vehicle sits outside all day.
For safe driving, wiper blades should be replaced at the first sign of trouble. Streaking, chattering and noisy operation are all clues that the wipers are nearing the end of their useful service life.
Here's another interesting statistic. According to Bosch market research, approximately 75 million registered vehicles on the road have a rear windshield wiper. Yet, only 16 percent of motorists who buy two blades for a three-blade vehicle, purchase the third blade. Furthermore, the rear wiper is replaced only once every six years on average!

Motorists should not wait until they can barely see where they are going to think about changing their blades. They should change them at the first sign of trouble. But many wait until the blades are falling apart, which is risky because the metal blade holder can permanently scratch the windshield if it rubs against the glass.
Other items that might also be needed when changing wiper blades include windshield washer fluid, an ice scraper, windshield de-icer and some glass cleaner to remove stubborn bugs and road slime.

BUYING BLADES
A good time to buy wiper blades is when a person is buying other maintenance parts such as filters, spark plugs or similar parts. If it has been more than a year since the blades were last replaced, it's time to buy a new set of wiper blades.

How well a particular set of blades performs is important. The blades are part of the windshield wiper system, which includes the wiper arms and holders. The blades ability to clean the glass depends on the slope and area of the windshield, the amount of spring tension on the wiper arm, the number of pressure points or claws that hold the blade and the material used in the blade itself.
On newer vehicles with steeply-raked windshields, wind lift at high speed can be a problem if the correct replacement blades are not installed. For these applications, anti-lift blades that incorporate aerodynamic features keep blades in firm contact with the glass at all speeds.
When buying blades, be sure to match blade length. Refills will not fit unless they are the same length as the original bladews. Replacement blades that are too long may create interference problems, while ones that are too short may not do an adequate job of clearing the windshield. And don't forget the rear wipers that are used on many cars, vans and sport utility vehicles. Rear vision is important too.