Abstract: A piston pump for conveying fragile particulate food products without damaging the product. The pump includes a filler and a discharge conduit containing piston valves actuated by hydraulic cylinders. The pumping chamber in which the product is compressed is equipped with a linear displacement transducer/magnet sensor which senses not only the position, but the speed of the piston. In response to the sensor, a proportioning valve releases hydraulic fluid at increasing pressure to a desired maximum, to the hydraulic cylinder actuating the piston in the pumping chamber of a second pump operating in tandem with the first pump. The product is expelled alternatively from the two pumps at the maximum desired pressure appropriate for the character of the product. The pump also includes means for flushing the pump without dismantling.