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A wiper linkage assembly is a mechanical device that transfers power from the windshield wiper motor to the wiper arms. Commonly manufactured from stamped steel components, the wiper linkage assembly is typically composed of two or three sections, with some assemblies using four sections of linkage to complete the system. The wiper linkage assembly is designed in such a manner that the linkage drives the wipers through a full sweeping motion across the windshield when in use.
While the windshield wipers in many vehicles sweep back and forth across the windshield, the typical windshield wiper motor does not work back and forth, rather it operates by spinning continually like a fan motor. A small tab or linkage arm attaches to the drive hub of the wiper motor at one end and to the wiper linkage assembly at the other. The back-and-forth motion of the wiper arms comes from the wiper linkage assembly moving in one direction when the tab is on the top of the drive hub, and in the opposite direction when the tab is on the bottom of the drive hub. This is similar to watching the second hand on a clock appear to move to the right when at the 12 o'clock position and to the left when at the six o'clock position.
The ability to rotate and pivot the different sections of the wiper linkage assembly is made possible by loosely fitted rivets and nylon bushings. Rivets hold the sections of linkage together, while the nylon bushings provide a quiet and cushioned bearing-like component to the linkage arms. The typical wiper linkage assembly is designed to outlast the average automobile. In some applications, the linkage is permanently attached to the wiper pivot towers. This mandates the replacement of both wiper towers when there is a deficiency in the wiper linkage.
Most commonly, the linkage is underneath the cowl of the vehicle. This protects the mechanism from exposure to the elements and provides quiet operation when in use. The fact that the linkage is unseen in most vehicles is the reason that a clunking or squeaking sound is the most easily detected type of signal that there may be a problem with the linkage assembly. Most vehicles will have a removable panel or screened area that will allow access to the linkage and the wiper motor. On some larger and wider vehicles, the linkage assembly may include a support in the middle of the cowl area that supports the linkage from sagging or twisting when in use.