Abstract: A conveyor is located between a machine for separating articles and a machine for packing the articles, and comprises two chains linked to each other by stems, with slides mounted on each couple of stems. Each slide has a roller running in a first guide so that the slide moves transversely to the conveyor because of the changes in the path of the first guide; a panel is fixed to each slide, and two walls are located on the panel. One of these walls is mobile since it is linked to a roll running in a second guide formed by consecutive sections positioned at different distance from the first guide. The mobile wall is moved away from the other when an article is introduced between time, and then the mobile wall is moved toward the other so that the distance between them is equal to the size of the article.