Abstract: A piston pump for the transport of viscous materials and, in particular, concrete, includes a housing having defined therein an annular-shaped working space, a piston slidably mounted within the annular-shaped working space for oscillatory movement, and a pressure conduit and a suction conduit, each of which is communicative with the working space. The pump also includes control means having a member which is disposed in the annular-shaped working space for connecting the portion of the working space, which lies in front of the moving piston, to the pressure conduit and for simultaneously connecting the portion of the working space which lies back of the moving piston, to the suction conduit. In addition, the pump includes means for reversibly driving the piston so that it moves in an oscillatory manner in the annular working space, reversing its direction when it nears the member of the control means.

Abstract: A pivotable pipe slide for use in a two cylinder concrete pump includes a swing pipe which is pivotably moved in a reciprocal fashion between the two discharge openings of the pump cylinders in such a manner that it is pressed against the discharge openings in its end positions, while it is moved away therefrom during its pivotal movement between its end positions. Pivoting is effected by means of a movable joint which is coupled to an end segment of the swing pipe and which has an axis disposed normally to the pivot plane of the swing pipe, a fixed joint spaced from the movable joint and disposed centrally between the discharge openings which also has an axis disposed normally to the pviot plane and a guide joint which is coupled to the movable joint and is pivotable about the fixed joint.