Abstract: An improved valve assembly providing a constant flow of semi-fluid concrete material through a concrete-pump assembly having a hopper to receive the concrete material and a plurality of hydraulically-actuated concrete pumps operably communicating with the hopper through inlet ports disposed in one wall of the hopper, the valve assembly being operably mounted within the hopper to oscillate therein. The valve comprises a main conduit for selective communication with the inlet ports, and a second conduit connected to the main conduit at one end thereof, the opposite end thereof being rotatably supported in the hopper wall and adapted to be connected to one of the hydraulic pumps. The main conduit together with the second conduit form a substantially Y-shaped configuration whereby the valve oscillates about the axis of the second conduit.