Pre-season concave inspection and repair: Knocking an old concave back into shape Greener crops, higher yields and greater output expectations are all plotting against the modern combine harvester’s concave, conspiring to give it a harder time. The crop flow forces exerted on this one threshing tool can be massive, and are magnified even further should extraneous objects find their way in. We look at how to breathe new crop-separating life into a tired concave