the invention relates to a modular construction system for a conveyor for conveying article carriers longitudinally or transversely , having lateral longitudinal carriers , having transverse frame elements which connect these longitudinal carriers , and having driven load - bearing conveying means for the article carriers . the object of the present invention is to provide a modular construction system which is significantly improved in relation to prior - art solutions in respect of production costs , assembly and installation costs , process costs and the delivery time for the conveyor . in order to achieve the object , it is proposed that the longitudinal carrier , which accommodates the conveying means , is a respective torsionally rigid hollow aluminum or plastic profile which can be connected in a releasable manner to the transverse frame element and is designed for optionally accommodating driven load - bearing rollers or insertable sliding plates for a load - bearing belt .