A pump comprising a rotor rotatably driven about a longitudinal axis and including peripheral rotor pockets which each longitudinally extend generally spirally around only a portion of the periphery of the rotor and have their ends inwardly of the ends of the rotor. A disc, rotatably driven in timed relationship with the driven rotation of the rotor about an axis transverse to said rotor axis, is provided with peripheral lobes sealingly in the rotor pockets for discharging material from the pockets in a direction transverse to said rotor axis as the material is rotated in the rotor pockets towards the disc. Material to be pumped is supplied to the rotor pockets on one side of the disc in a direction transverse to the rotor axis, whereupon the driven rotation of the rotor moves the material to the other side of the disc where it is discharged from the rotor pockets by the disc.