Displacement slurry pump equipped with known piston-rod drive, in which on a piston rod expediently three pistons are arranged at a distance of at least one stroke length, they are a liquid piston moving the auxiliary liquid free of solid matter, and on both sides thereof a slurry piston each moving on one side the slurry, on the other side, however, the auxiliary liquid. The liquid piston fits sealed to the liquid cylinder provided with liquid suction valves, whereas the two slurry pistons fit by slot to the slurry cylinders provided with slurry suction valves and slurry delivery valves. The effective section of the liquid cylinder is larger than the effective section of a slurry cylinder each. The slurry pump may be of single-operation or of double-operation, of one-cylinder or two-cylinder or three-cylinder construction.
During the operation, at the delivery stroke of the slurry cylinder, auxiliary liquid is pressed from the liquid cylinder through the aperture between the slurry cylinder and slurry piston, preventing thus the slurry from flowing in between the slurry piston and the slurry cylinder, thus the life of these latters will increase.