Abstract: An apparatus for wiping a non-planar window has a wiper and a track arrangement including a first track substantially parallel to at least a portion of the window and a second track substantially parallel to and displaced from the first track. A drive wheel assembly includes at least one motorized drive wheel. The drive wheel assembly alternately engages the first and second tracks and drives in alternate directions along the length of the track arrangement for drawing the wiper across the surface.

Abstract: An apparatus for wiping a window has a wiper, a first track substantially parallel to at least a portion of the window and a second track substantially parallel to and displaced from the first track. A first motorized drive wheel is provided for driving the wiper along the first track in a first direction and a second motorized drive wheel for driving the wiper along the second track in a second direction, opposite to the first direction, so as to wipe the window. The wiper is preferably designed to reduce drag-back of water across the window. In a preferred embodiment, curved connecting tracks connect between the ends of the first track and the second track so as to form a closed loop track. A single motorized drive wheel is used. The single motorized drive wheel may be driven by a motor rotatably associated with the wiper, or through a flexible drive cable by a remotely mounted motor. Other embodiments use a single substantially linear track in combination with a motor running unidirectionally.