The first window wipers were operated manually by moving a lever inside the car back and forth. Can you imagine having to do that nowadays? Today, most of us take our electric wind shield wipers for granted. The wipers keep the window clear, moving back and forth across the wind shield countless times as they sweep the water away. Wind shield wipers are found on car wind shields and some car headlights. The wipers combine two mechanical technologies to perform their task: A combination electric motor and worm gear (a gear consisting of a spirally threaded shaft and a wheel with marginal teeth that mesh into it) reduction provides power to the wipers. A neat linkage converts the rotational output of the motor into the back-and-forth motion of the wipers. It takes a lot of force to accelerate the wiper blades back and forth across the window so quickly. In order to generate this type of force, a worm gear is used on the output of a small electric motor. The output of the gear reduction operates a linkage that moves the wipers back and forth. Inside the motor/gear assembly is an electronic circuit that senses when the wipers are in their down position. The circuit maintains power to the wipers until they are stopped at the bottom of the wind shield, and then cuts the power to the motor. This circuit also stops the wipers between wipes when they are on their intermittent setting. The wiper blades are like squeegees. The arms of the wiper drag a thin rubber strip across the wind shield to clear away the water. When the blade is new, the rubber is clean and has no nicks or cracks. It wipes the water away without leaving streaks. When the wiper blades age or crack, road grime builds up on the edge and it doesn’t make as tight a seal against the window, so it leaves streaks. Wiper blades are designed to attach in a single point in the middle, but a series of arms branch out from the middle like a tree, so the blade is actually connected in six to eight places. If ice or snow forms on these arms, it can make the distribution of pressure uneven, causing streaks under part of the blade. If the wipers do not clean the window properly restricting the drivers view then this can be a failure on an MOT. Some wiper manufacturers make a special winter blade with a rubber boot covering the arm assembly to keep snow and ice out. Here at AE Services in Sutton we stock a wide range of wiper blades so if you are in need of replacement blades then book in now. For further details go to www.autoexpressservices.com.