the material being dewatered the speed of the cylinders 166 will be ramped down from 8 fpm to 2 fpm by slowly closing the orifice opening in the flow control valve 152 which will constantly increase the pressure drop resulting in a reduced flow output from the pump 150 as the flow throttling is taking place the pressure is increasing due to compaction to the point of high pressure low flow however the horsepower requirements will remain somewhat constant to the needs at low pressure high flow when the degree of compaction has been obtained by reaching the hydraulic pressure setting p s 1 the flow control valve 152 will shift to the center position resulting in the dissipation of pressure in the compression area since the a and b ports drain to tank and the directional valve 174a will shift to the b position and cause cylinder 47 to raise the channel member 42 as cylinder 47 raised the channel member 42 knife gate 12 was raised by cam surface 69 raising cam bar 70 during the compression portion of the stroke after a short time delay the flow valve 152 will again shift to the a position to pass maximum flow for maximum ram speed low pressure high flow another electrically operated limit switch activated by the ram cylinder will register the end of the stroke and cause the flow valve 152 to shift completely to position b causing the ram cylinders to reverse directions and retract at high speed low pressure high flow instantaneous with the reversal of cylinders 166 the cam bar 70 drops.