A combine harvester comprises an oscillating thresher pan (128228328) for conveying a chaff/grain stream rearwardly to a rear edge from where the grain/chaff stream falls under gravity into a cleaning unit (148248348). The cleaning unit, or shoe, includes at least one vibrating pan (150250350,151251351) onto which the grain/chaff stream falls. The cleaning unit comprising a fan (52) for generating a cleaning airstream which is directed through the failing grain/chaff stream. The cleaning pan, when in use, is provided with a damping surface to damp bounce of kernels falling thereupon. In one example, the damping surface is provided by a sheet of rubber (284,288).
