Positive-displacement pump

A positive-displacement pump for a viscous rubber-like material, having a body including a supply opening for introducing the material into the pump, and an outlet orifice for discharging the material from the pump, said pump including at least one delivery piston sliding in a cylinder between a bottom position and a top position, a delivery phase occurring during the stroke between the bottom position and the top position, said pump including inlet and delivery passages emerging in said cylinder or cylinders, said inlet and delivery passages being located in said body at points which are separated from one another, each inlet passage being closed off by the delivery piston during its movement from the bottom position in the direction of the top position, said pump including a rotary feed screw in a transfer chamber between the supply opening and the inlet passage or passages for filling said cylinder or cylinders with said material in the inlet phase, said pump including a rotary distributor mounted on an end of the feed screw and provided with a recess in permanent communication with the outlet orifice, the body including a bearing in which said distributor turns, the latter and said bearing having matched surfaces of revolution, the recess of said distributor including a cutout ending at the surface of revolution of said member, and in which pump the body includes as many delivery passages as cylinders, the delivery passages connecting the cylinders and the surface of revolution of said bearing at points which are uniformly spaced along said surface of revolution of said bearing, so that the cutout passes across each of said passages in succession during its rotational movement, said passages and said cutout being shaped relative to one another so that the rotation of said distributor places a cylinder in communication with said outlet orifice during delivery phases of the corresponding piston and isolates said cylinder from the outlet orifice between the delivery phases.