blocks 29 are mounted in guides 31 suitably secured to the end framework of the gin structure at 32 and 33 we show pairs of fluid pressure cylinders for instance air cylinders to which air under pressure may be supplied from lines 34 these cylinder pairs are suitably mounted on the gin framework so that the piston rods 36 thereof engage cross members 37 forming a part of the slide system for supporting the ends of the shaft 27 thus whenever pressure is applied to the cylinders 32 and 33 the roll 18 is pressed into ginning contact with the ginning knife when pressure is released due to the upward inclination of the slide assemblies roll 18 moves by gravity downwardly and away from the knife 21 so that its surface 19 no longer engages the knife the feeder comprises a pair of feed rolls 42 these may be in the form of spiked members and they are driven by a variable speed electric motor 43 through suitable chains 43a or the like to rotate in the direction of the arrows fig1 seed cotton is delivered downwardly between these rolls at a given rate as determined by the speed of the motor 43 immediately beneath the rolls 42 is a spike cylinder 44 the tips of the spikes 46 of which pass very closely adjacent the tips of the spikes of the rollers 42 also mounted adjacent cylinder 44 is another spiked cylinder 47 and these two cylinders run over grids 48 and 49 trash falling from the grids 48 and 49 is removed from the gin by a conveyor 51 driven.