Modern windshields are generally made of laminated safety glass, which consists of two curved sheets of glass with a plastic layer laminated between them for safety, and are glued into the window frame. Earlier windshields were made of toughened glass and were fitted in the frame using a rubber or neoprene seal.
Windshields protect the vehicle's occupants from wind, temperature extremes, and flying debris such as dust, insects, and rocks. 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.
Most cars have an intermittent wiper system, which permits the driver to select a delayed wipe that operates only every few seconds. A representative wiper/washer unit is the wiper assembly, which incorporates a depressed park system that places the wiper blades below the hood line in the parked position. The relay control uses a relay coil, relay armature, and switch assembly. It controls starting and stopping of the wiper through a latching mechanism. An electric washer pump is mounted on the gear box section of the wiper. The wiper unit gear assembly drives it.
All cars use an electric pump-operated windshield washer with a positive displacement washer pump. On some, the motor is placed in the washer reservoir, while on others, it is driven by a wiper motor. When the pump is attached to the wiper motor, the four lobe cam starts a spring-loaded follower, but the pump does not operate all the time that the wiper motor is running. This is because the pumping mechanism is locked out and pumping action occurs.