Abstract: A machine for transferring metered quantities of viscous materials from a source of such materials into successive receptacles has a tubular housing with inlets and outlets disposed diametrically opposite each other. The housing confines a rotary metering device having an axially extending chamber and an opening which communicates with the inlet in one angular position and with the outlet in another angular position of the metering device. A piston in the metering device draws flowable material from the source into the chamber in the first angular position and expels such material from the chamber into a receptacle in the second angular position of the metering device. The housing and the metering device have adjacent frustoconical surfaces and the metering device is movable axially to establish between such surfaces a frustoconical clearance for admission of a liquid or gaseous cleaning fluid while the metering device remains in the interior of the housing.