A conveyor system comprising an endless conveyor belt (5) having a plurality of mechanical conveyor means (12) projecting from a top surface thereof and a delivery tube (1) having an intake end and a discharge end for receiving a delivery portion of the endless belt and a return tube (10) extending along the delivery tube for receiving a return portion of the endless belt. A drive assembly (6, 7) is mechanically connected to the endless belt for rotating it for moving it in the tubes. Means (9) are arranged to guide the endless belt into the return tube with a bottom surface (14) of the belt following at least the upper portion of the return tube when moving through the return tube. The return tube is designed and dimensioned with respect to the width of said belt so as to support transversal end portions of the belt by return tube portions from below when the belt moves through the return tube while following the upper portion thereof.