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The method of screen wipers work is really fascinating

  • October 26, 2017

You may not notice this, however there’s associate degree elaborate linkage slightly below the bottom of your screen that permits your car’s windshield wiper  to maneuver back and forth and, in some cases, up and down—and it's fascinating.

windshield wiper

The primary mechanism for any wiper blade transmission is an electric motor whose output shaft is a worm gear. That worm gear spins a ring gear seen in the picture above (this gear-mesh multiplies the motor’s torque), which sits on a shaft that goes through the bottom of the casing.

That shaft has a small metal link bolted to it, so as the motor’s worm gear spins the ring gear, the latter’s shaft actually rotates the link like a propeller blade on an airplane engine.

At the end of that “propeller” is a rod attached to a pin or revolute joint; that One Degree Of Freedom-joint restricts translation of that rod in any direction relative to the attachment at the end of the link, but allows for rotation about a single axis (into the screen in the picture above). What this means is that as the ring gear shaft spins its link, that pushes and pulls the rod, but because that link is free to rotate about its joint, the other end of the rod does not necessarily have to move up and down as the ring gear link rotates—it can just move left and right.

Then there’s the opposed style wiper system, whose windshield wiper  pivot about shafts located in the lower corners of the windshield. These systems are great, because they clean a lot of the window (including the corners) and the only part left un-wiped is behind the rear-view mirror—a part of the windscreen that you don’t really need to look through anyhow.