Wiper System

The technology relates to a wiper systems. For instance, a system may include a sensor including a sensor housing and a housing window in the sensor housing. The system may also include a rotating drive mechanism. A first portion of the rotating drive mechanism is positioned adjacent to a top of the housing window. The system also includes a plurality of pulleys, and the rotating drive mechanism may be wrapped around at least a portion of the pulleys. The system also includes a wiper attached to the rotating drive mechanism and a motor. The motor may be configured to rotate at least one of the pulleys in order to cause at least the first portion of the rotating drive mechanism to rotate in a first direction. As a result, the wiper may move across the housing window from an initial position to a second position in order to move contaminants on the housing window.