Abstract: A drive chain has a plurality of pairs of link elements with the elements each pair extending longitudinally parallel to each other and having relatively widely spaced outer ends formed with transversely open and confronting blind bores and relatively closely spaced inner ends formed with axially throughgoing and transversely aligned bores. Each pair of inner ends lies between a respective pair of outer ends with the bores coaxial and receiving respective pins defining respective transverse axes, each fitting tightly in the bores of the inner ends, and having ends rotatably seated in the respective bores of the respective outer ends. Respective sleeves surround the pins between the respective inner ends. Respective outer seal rings between the outer ends and the pin ends define with the pin ends outer compartments and respective inner seal rings between the inner ends and the sleeve define between the respective pin, sleeve, and inner ends an inner compartment.

Abstract: A tracked-vehicle drive has a wheel rotatably driven about an axis and having an outer surface, an endless traction element spanned over and frictionally engaging the wheel so as to be advanced thereby when the wheel rotates and having an inner face formed with an endless row of spaced teeth, and an auxiliary drive member displaceable adjacent the traction element and formed with an endless row of spaced entrainment formations in constant mesh with the teeth so that the drive member is displaced synchronously with the traction element. A coupling body having entrainment formations in constant mesh with the drive-member entrainment formations is engageable with the wheel outer surface. The body can be coupled to the wheel for positive driving of the traction element from the wheel via the member and body and can be decoupled from the wheel for frictional coupling of the traction element by the wheel.

Abstract: A rotatable drive/support element having a support surface is used with a chain link having a hardened running surface extending in and adapted to ride in a travel direction on the support surface and a side surface also extending in the travel direction and normally out of contact with the element. The running surface has a predetermined width b and is formed of at least one edge region of an outwardly convex arcuate shape seen in the travel direction having a radius R of curvature and a respective corner region extending from the edge region to the side region and of an outwardly convex arcuate shape seen in the travel direction having a radius r of curvature. Herein r/b≅0.05 to 0.11, and preferably R/b≅2.4 to 3.1.