Abstract: Two mechanically identical cranes whose luffing jibs have the same maximum and minimum out-reach and which have their own slewing machinery, are mounted via respective supporting structures on a common foundation, at the same level for rotation about the same axis by bearings and an axle which provide a compact journalling of the supporting structures upon the foundation.

Abstract: An articulated crawler track comprises track links having forward and rear edges and a width dimension extending transverse to the longitudinal dimension of the track and at least two drag links provided between the forward edge of each track link and the rear edge of the adjacent track link, each drag link being articulated to each of the respective track links for movement about parallel axes which are transverse to the longitudinal dimension of the track, the drag links being spaced apart along the width dimension of the track links and being arranged within the effective width of the track links.

Abstract: Two mechanically identical cranes whose luffing jibs have the same maximum and minimum out-reach and which have their own slewing machinery, are mounted via respective supporting structures on a common foundation, at the same level for rotation about the same axis by bearings and an axle which provide a compact journalling of the supporting structures upon the foundation.

Abstract: A suspension system for a tracked vehicle has a hull provided with double crawler tracks positioned on either side of the hull. Each crawler track runs around a track drive wheel, track roller assemblies and a take-up idler. A torsion unit assembly connects each track roller assembly to the hull. The torsion unit assembly includes a plurality of torsion units mechanically connected in series, with the torsion unit at one end of the series being fixed to the hull and the torsion unit at the other end of the series being connected to and suspending the respective track roller assembly in order to obtain a large amount of suspension travel for the track roller.

Abstract: The one ends of the closing rope and holding rope of the jib or other hoisting gear-suspended grab of a winch are wrapped about a common drum and travel equivalent paths for syncronization of rope movement as the grab is raised and lowered. The opposite end of the closing rope is wrapped about an auxiliary drum or other extensible, retractible load rope anchoring device, equipped to be rotated, on command by an amount sufficient to open or close the grab.