US Patent 8424142 Pool cleaning robot

A pool cleaning robot is provided for cleaning a surface of a swimming pool. The robot comprises a main housing, a pair of main wheels disposed at opposite ends of a bottom panel of the housing spanning along a majority of its width and carrying a pair of continuous tracks spanning between edges thereof, the main wheels being configured for rotating at a first angular velocity, at least one inlet being formed in the bottom panel between the main wheels and being configured for intake of water and debris, and at least one auxiliary brushwheel disposed between the main wheels. The robot is configured for rotating the auxiliary brushwheel about an axis of rotation at a second angular velocity which is substantially greater than the first angular velocity.