Abstract: In a pump, a piston rod is mounted for lost motion on a piston head so that when the piston rod 31 is advanced by a full stroke in a forward direction from a fully retracted position, only the piston rod moves for an initial stroke portion S2, then a piston head is also advanced with the piston rod for a final stroke portion which is equivalent to a difference between the full stroke S1 and initial stroke portion S2 (S3=S1-S2), and a liquid inside said cylinder is expelled from the exhaust port by a quantity corresponding the final stroke portion S3. When the piston rod is being withdrawn in the return direction, only the piston rod is moved during the initial stroke portion causing residual liquid in a passageway from the cylinder to the exhaust port to be sucked back to the cylinder.

Abstract: A vacuum cast molding apparatus includes a plurality of vacuum chambers which can be brought into communication with each other, a plurality of depressurizing devices to evacuate each of the vacuum chambers respectively, a plurality of mixing and injecting devices installed in each of the vacuum chambers, to mix, agitate and inject molding materials into dies installed in each of the vacuum chambers, and separators installed removably between the vacuum chambers for partitioning each of the vacuum chambers. The vacuum chambers can be used independently when the separators are installed to partition them from each other. The vacuum chambers can also be used as one large vacuum chamber when the separators are removed bringing the chambers into communication with each other.