A windscreen wiper or windshield wiper (American English) is a device used to remove rain, snow, ice, washer fluid, water, and/or debris from a vehicle’s front window so the vehicle’s operator can better see what’s ahead of them. Almost all motor vehicles, including cars, trucks, buses, train locomotives, and watercraft with a cabin—and some aircraft—are equipped with one or more such wipers, which are usually a legal requirement.
A wiper generally consists of a metal arm; one end pivots, the other end has a long rubber blade attached to it. The arm is powered by a motor, often an electric motor, although pneumatic power is also used for some vehicles. The blade is swung back and forth over the glass, pushing water, other precipitation, or any other impediments to visibility, from its surface. On vehicles made after 1969, the speed is normally adjustable, with several continuous speeds, and often one or more intermittent settings. Most personal automobiles use two synchronized radial-type arms, while many commercial vehicles use one or more pantograph arms.
On some vehicles, a windscreen washer system is also used to improve and expand the function of the wiper(s) to dry or icy conditions. This system sprays water, or an antifreeze window washer fluid, at the windscreen using several well-positioned nozzles. This system helps remove dirt or dust from the windscreen when it is used in concert with the wiper blades. When antifreeze washer fluid is used, it can help the wipers remove snow or ice. For these types of winter conditions, some vehicles have additional heaters aimed at the windows, or embedded heating wire(s) in the glass; these defroster systems help to keep snow and ice from building up on the windscreen.