Abstract: A drive system comprising an endless tread belt made up of identical tread belt links and a cooperating drive tumbler is disclosed. The link is formed with a ground engaging bottom face, a drive wheel engaging top face, and connecting ears along its forward and aft sides which are suitable to interdigit with the ears of other links so as to form a belt. The link also has a guiding cog rising upwardly from the central region of the top face, a bearing surface on each lateral side of the guiding cog, aligned drive surfaces on the forward and aft sides of the guiding cog located between the link bottom face and link top face, and a slot in alignment with the drive surfaces.