Multi-cylinder pump for concrete

A multi-cylinder piston pump for conveying concrete, comprising two cylinders, a filling chamber casing, a respective inlet opening for each cylinder located in an end wall of the filling chamber casing at approximately equal distances from a vertical plane through the casing, said plane containing a horizontal axis which is the axis of the cylindrical wall of the casing, an outlet opening located in the other end wall, the perpendicular projection of the outlet opening on to the inlet openings partially covering said inlet openings, each cylinder being arranged to alternately suck the material through its respective inlet opening and force the material conveyed through the outlet opening, said pump further comprising a shaft containing said horizontal axis, a pivot body fixed on said shaft acting to deflect the material conveyed in the filling chamber, blades on said pivot body enclosing a pressure channel leading to the outlet opening, each blade having its edges sealed against the casing walls, and a base which is fixed to the shaft, the shape of said pressure channel being formed by the intersection of two pipe segments with the portions of the pipe segments which lie within the channel being eliminated, the line of said intersection being located substantially midway between the two end walls of the filling chamber, complementary surfaces on said pipe segments providing a smooth flow path when said pivot body is in one position only, and conical recesses on said inlet and outlet openings providing a smooth flow from said pressure channel to said openings.