apparatus for conveying article carriers through a series of processing stations in the form of tanks into which articles supported by the carriers are to be dipped has a row of lifting devices , each including an article carrier support which defines a section of a horizontal processing track along which the article carriers are movable in succession . the article carrier supports are individually displaceable vertically between an upper position and a lower position . when adjacent article carrier supports are simultaneously in the upper position , an article carrier on one of the article carrier supports can be fed over to the other . a sensor triggers lowering of said other article carrier support to the lower position in response to the reception of the article carrier by that article carrier support . when supported by the article carrier support provided at the downstream end of the processing track , the article carrier is displaced , together with the article carrier support generally horizontally transversly of the processing track to a return track on which the article carrier is returned to a position opposite the processing track .