11 39 is open and the space within the first cylinder 2 the connector box 4 and the second cylinder 2 39 is contracted to move the material therein through the piston 11 39 into the space in front of piston 11 39 in second cylinder 2 39 while the space in front of the first piston 11 is expanded to reduce the pressure therein so that the material from the material inlet 6 is caused to flow smoothly into the first cylinder 2 it will be seen that one cycle of the operation as described is accomplished by one reciprocal stroke of the pistons which in turn is produced by one revolution of the crank wheel 22 the rate or rotation of which may be varied steplessly depending on the amount of material and the distance of transportation the mechanical valve 42 is operated by means of the cam 45 on the cam shaft 44 driven synchronously with the crank wheel 22 during the reciprocation of the pistons 11 and 11 39 for jetting the streams of the compressed air against the material within the cylinders the space within the first and second cylinders 2 and 2 39 and the connector box 4 is repeatedly contracted and expanded during the simultaneous reciprocation of pistons so that the powdery or granular material is sucked through the material inlet 6 and propelled through the first and second cylinders and into the material outlet funnel 8 and into the transport pipe 9 efficaciously depending on.