Abstract: A process and device for interpositioning the tools of a body assembly machine which includes departing from all the intermediate mechanisms for putting these tools in place, from the function of their geometric referencing, so as to impart to the tools themselves the ability to be interpositioned after temporary isolation of a part of them from their positioning mechanism. According to the process, these tools are made to have a lateral orientation.

Abstract: A unit for assembly of an approximately plane, large-sized motor vehicle body element of the type including a plurality of work stations (P1-P6) between which the element is successively transferred by a lengthwise transfer device (12), wherein at each work station the body element is located in a plane (PC) forming a predetermined angle (.alpha.) in relation to the horizontal plane on which the assembly unit rests. The lengthwise transfer device (12) includes a transfer mechanism with drive bars located in a plane (PT) forming a predetermined angle (.alpha.') in relation to the horizontal plane equal to the predetermined angle.