Patent ID: 7976369

Claim:
A biomass cleaner, of a harvesting machine, comprising at least a first sieve for sieving biomass and having one or more first sieve apertures that are openable and closeable in dependence on control commands; an air fan the speed of which is adjustable in dependence on control commands; and at least one control device that generates the control commands, the first sieve defining a support for biomass that is sieveable via the sieve; and the biomass cleaner including one or more pressure sensors for generating one or more signals that are related to a pressure of air in the vicinity of the biomass, wherein at least one pressure sensor is operatively connected to supply the signals to the at least one control device that derives therefrom sieve load signals indicative of the amount of biomass on the first sieve and derives from sieve load signals estimates of sieve losses and Material Other than Grain content of cleaned biomass, during operation of the cleaner, wherein the at least one control device is programmed to compare the pressure sensor signal with a range of pressures corresponding to first sieve aperture opening values, to determine therefrom a first sieve opening equivalence, and to establish the difference between a degree of opening of the first sieve aperture on the one hand and the first sieve opening equivalence on the other, the at least one control device derives the sieve load signals from the difference.