Abstract: The invention relates to a tracked running gear, in which two running gears are arranged parallel to one another and each running gear has a longitudinal member (1) and a running gear chain (2) which runs around the longitudinal member in the longitudinal direction thereof and forms an upper and a lower strand, and at least one traction drive, composed of a motor, transmission and a drive gearwheel which meshes into the running gear chain and also a deflecting wheel which permits chain tensioning by means of a movement relative to the fixed part of the longitudinal member, characterized in that at least one additional traction drive (3) which acts on the upper strand is provided on the longitudinal member, wherein the running gear length is changed or remains unchanged.

Abstract: The invention relates to a tracked running gear, in which two running gears are arranged parallel to one another and each running gear has a longitudinal member (1) and a running gear chain (2) which runs around the longitudinal member in the longitudinal direction thereof and forms an upper and a lower strand, and at least one traction drive, composed of a motor, transmission and a drive gearwheel which meshes into the running gear chain and also a deflecting wheel which permits chain tensioning by means of a movement relative to the fixed part of the longitudinal member, characterized in that at least one additional traction drive (3) which acts on the upper strand is provided on the longitudinal member, wherein the running gear length is changed or remains unchanged.

Abstract: The invention concerns a crane undercarriage (1) that comprises a center section (2), which is constructed for removable mounting of a rotatable crane superstructure (40), and a plurality of outriggers (4), which are pivotably supported on the center section (2) for assuming a transport configuration and at least one operational configuration. The support elements (10; 20) necessary for the operation of the crane are attachable on the outriggers (4). In addition, the invention concerns a variable crane that comprises a crane undercarriage of the above-mentioned type and selectively a set of crawlers (10) or a set of floor jacks (20) is removably mountable on the crane undercarriage (1).