Abstract: An automatically adjustable brush assembly for cleaning semiconductor wafers. The brush assembly includes a first rotary brush, a brush carriage having first and second arms and a second rotary brush, and at least one pressure adjustment assembly positioned to engage at least one of the arms of the brush carriage and configured for automatically adjusting the pressure applied to the wafer surfaces by the first and second rotary brushes. The brush assembly further includes a control system coupled to the pressure adjustment assembly for controlling operation of the pressure adjustment assembly to selectively increase and decrease the pressure applied to the wafer by the first and second rotary brushes.