Blow molding machine

A machine particularly useful for the blow molding of large thermoplastic articles such as cylindrical drums comprises a plurality of stations through which mold cavities are successively advanced. At a first station, containing a cart-mounted blow assembly an article is blow molded to substantially its final form in a cavity with the blow medium being introduced via a blow pin assembly operatively associated with the cavity after the blow assembly has been operatively engaged with the blow pin assembly. After the blowing operation has been completed, the blow assembly is operatively disengaged from the blow pin assembly and the cavity with the blown article is transported in a second station, the blow pin assembly traveling with the cavity. At the second station, an auxiliary blow assembly is operatively engaged with the blow pin assembly to circulate medium through the interior of the article. At the conclusion of operation at the second station, the auxiliary blow assembly is disengaged from the blow pin assembly and the cavity is transported to a further station. The disclosed embodiment has two such further stations which are identical to the second station. The cavity finally returns to the first station where the completed article is removed.