Apparatus and methods are provided for pumping concrete using a pumping
apparatus including first and second drive cylinders, a valve, and a pump. Fluid
is delivered into the cylinders from the pump to reciprocate pistons within the
cylinders. Pressure within the cylinders is monitored, and a direction of flow
of the fluid is switched based upon the pressure within the cylinders. For example,
during rod-side operation, the valve is set to deliver fluid into a head side of
the cylinders. When the pressure exceeds a predetermined threshold, the valve switches
to head-side operation, and fluid is delivered into a rod side of the cylinders.
If the pressure falls below the threshold, the valve switches the cylinders back
to rod-side operation.