that one or more combs 18 are in contact with each seed head during the entire time it is in the threshing zone the zone of controlled brushing between the brushes and the combs is illustrated in this figure by the distance between points a and b in the preferred embodiment the distance between points a and b is also approximately four inches but the present invention contemplates that the arc created by the cam mechanism could represent as much as ninety 90 degrees or one fourth of the brush surface in the preferred embodiment a comb spacing of approximately four inches ensures that each seed head is held in contact with the brush as it travels through the approximately four inch long threshing zone the harvester with cam design described in this and the parent application is superior over existing art in at least four respects first it reduces the amount of seed that falls to the ground after being stripped from the plant because the vacuum airflow created by the rotating brushes and combs captures the seed and impels it into the accumulation chamber which is depicted as reference number 50 in fig1 of the parent application second it increases the amount of seed harvested through better positioning of the seed heads.