Abstract: A pumping apparatus of the type comprising twin cylindrical pumping chambers which alternately take in and deliver material to be pumped, the taking in being via ports in a common feeding chamber and the delivery being via a delivery conduit which moves to the port of the chamber which is to deliver. The pumping is carried out by hydraulically-actuated pumping pistons in the chambers, the hydraulic circuitry being adapted to ensure that the pumping piston in that chamber taking in material arrives at the fully charged position before the delivering chamber attains the fully discharged position. In another embodiment, the pumping apparatus comprises a "push-over" facility, wherein the speed of the pumping is automatically increased to compensate for the drop in flow rate caused by the time taken by the delivery conduit to move from one port to the other. The apparatus gives an exceptionally pulsation-free flow and is especially useful in concrete spraying apparatus.