A volumetric dosage for containers filling machine

The present invention relates to a metering device (1) comprising: - a metering chamber (4), - a piston (10) separating said metering chamber into a feed compartment (8) and a dosing compartment (9), the piston comprising a passage between the two chambers, - a valve (20) closing this passage enabling the product to pass when in osition opening, - moving means (30) valve, the valve comprising the piston driving means arranged on either side of the piston so that movement of the valve in a flow direction (R) causes the displacement of the piston according to the flow direction and moving the valve along the cylinder body in a transfer direction (T), causes movement of the piston according to this direction.