Windshield

Windshield

[wind-sheeld, win-]

The windshield or windscreen of an aircraft, automobile, bus, motorcycle, or tram is the front window. Modern windshields are generally made of laminated safety glass, a type of treated glass, which consists of two (typically) curved sheets of glass with a plastic layer laminated between them for safety, and are glued into the window frame.

Motorcycle windshields are often made of high-impact acrylic plastic. As the name implies, their main function is to shield the driver from the wind, though they do not do so as totally as those of a car.

Usage

In daily use, windshields mainly protect the vehicle's occupants from wind, temperature extremes, and flying debris such as dust, insects, and rocks, as well as providing an aerodynamically formed window towards the front. UV Coating may be applied to screen out harmful ultraviolet light.

Safety

Early windshields were made of ordinary window glass, but that could lead to serious injuries in the event of a crash. They were replaced with windshields made of toughened glass and were fitted in the frame using a rubber or neoprene seal. The hardened glass shattered into many mostly harmless fragments when the windshield broke. These windshields, however, could shatter from a simple stone chip. In 1919, Henry Ford solved the problem of flying debris by using a new technology founded in France called glass laminating. Windshields made using this process were actually two layers of glass with a cellulose inner layer. This inner layer held the glass together when it fractured. Between 1919 and 1929, Ford ordered the use of laminated glass on all of his vehicles.

The modern, glued-in glass contribute to the vehicle's rigidity, but the main force in innovating the windshield has historically been the need to prevent injury from sharp glass fragments. Modern windshields, now almost universally required in all nations, do not fragment, but tend to stay in one piece even if broken, except if pierced locally by a strong force. Properly installed automobile windshields are also essential to safety; along with the roof of the car, they provide protection in the case of a roll-over accident in the vehicle.

Other aspects

In many places, laws restrict the use of heavily tinted glass in vehicle windshields; generally, laws specify the maximum level of tint permitted. Some vehicles have noticeably more tint in the uppermost part of the windshield of motor vehicles that blocks glare from the sun.

In aircraft windshields, a current is applied through a conducting layer of tin(IV) oxide to generate heat to prevent icing. A similar system for automobile windshields, introduced on Ford vehicles as "Quickclear" in Europe ("InstaClear" in North America) in the 1980s, uses very thin heating wires or conductive-film layer embedded between the two laminations.

Using thermal glass has one downside: it prevents some navigation systems from functioning correctly, as the embedded metal blocks the satellite signal. This can be resolved by using an external antenna for the navigation system.

Terminology

The term windshield is used generally throughout North America. The term windscreen is the usual term in the UK and Australia/New Zealand for all vehicles. In Japanese English, it is called "front glass". In the USA, windscreen refers to the mesh or foam screen placed over a microphone to minimize wind noise, while a windshield refers to the front window of a car. In the UK, the meaning of these terms is reversed.

Today’s windshields are a safety device just like seat belts and air bags. The installation of the auto glass is done with an automotive grade urethane designed specifically for automobiles. The adhesive creates a molecular bond between the glass and the vehicle. If the adhesive bond fails at any point on the glass it can reduce the effectiveness of the air bag and substantially compromise the structural integrity of the roof. (Raymond Clough)

Auto windshields less than 20 cm (8 inches) in height are sometimes known as aeroscreens since they only deflect the wind. The twin aeroscreen setup (often called Brooklands) was popular among older sports and modern cars in vintage style.

A wiperless windshield is a windshield that uses a mechanism other than wipers to remove snow and rain from the windshield. The concept car Acura TL features a wiperless windshield using a series of jet nozzles in the cowl to blow pressurized air onto the windshield.

Stone chip and crack damage

Many types of stone damage can be successfully repaired. Bullseyes, cracks, starbreaks or a combination of all three, can be repaired without removing the glass, eliminating the risk of leaking or bonding problems sometimes associated with replacement.

Repair

Windshield repair is a process that combines modern technology and skill to fill a damaged area on a windshield with special clear adhesive resin. The resin is then cured with an ultraviolet light. When done properly, the damaged area’s strength is restored, as is most of the clarity.

When repairing a windshield, it is important to start with a clean work area. Any dust, dirt, or contaminants in or on the glass can result in scarring or trapped particles that will permanently be visible in the final repair. Any moisture can cause future cracks when the glass cools or heats. Many chips in automotive safety glass will never grow but insurance companies in the United States often waive the deductible to ensure they do not have to pay for the replacement of the auto glass.

References

See also

External links

  • Windshields.com An online provider of windshield repair information and companies.
  • Car Windshields A website devoted to windshields, including markings.
  • Long crack repair A video of the crack repair process.
  • An online provider of windshield repair information.
  • National Glass Association
  • Auto Glass Replacement Safety Standards Council
  • Auto Safety Expert

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