Abstract: A crane, and a boom assembly for a crane, include an outermost boom portion having the area between its front chord members being substantially open. Inner lacing members extend in intersecting pairs between diagonally opposing pairs of chord members for strengthening the boom. The various lacing members in the latticework construction for a crane are connected to the chord members using reusable clevis pin assemblies of a predetermined tolerance. This enables it to be easily assembled and to be readily disassembled for ease of transport and storage in a compact state. It also produces a rigid structure having substantially no internal residual stress.

Abstract: A windlock for selectively preventing relative pivotal movement between a mobile platform and a horizontal interconnecting stinger at the base of an elevated crane. The stinger is normally interconnected to one load platform for relative pivotal movement about the stinger central axis. Outer horizontal surfaces on the stinger structure are longitudinally movable relative to the platform to a position between adjustable screws which engage them to lock the stinger against rotational movement. This locking arrangement applies the heavy weight of a remote counterweight unit to assist in preventing lateral tipping of the load platform on which the elevated boom is supported. Outboard jacks on the platform further stabilize it against lateral tipping movements.

Abstract: A counterbalanced crane structure having an upright boom and diverging staymast mounted to a ground supported mobile crane base. An independent mobile counterweight unit has a vertical counterweight strut connected to the outer end of the staymast. The counterweight unit is interconnected with the crane base by an elongated horizontal stinger assembly. The counterweight unit is powered to move in an arc, the center of which is determined by the crane base. Turning motion is transmitted from the moving counterweight unit to the main boom and staymast by the stinger. Movable connections on the stinger permit pivotal movement of the counterweight unit about an axis that is substantially radial with the center turning axis of the mainboom and staymast and another pivot axis that is transverse to the radial axis. Limited movement of the counterweight unit toward or away from the crane base is permitted to eliminate direct transfer of tension and compressive stresses through the stinger.

Abstract: A vertical tower and lifting boom are counterbalanced by a separately supported counterweight unit. The counterweight unit is self-propelled and connected to a mobile tower platform by a horizontal stinger. A diagonal tower brace extends between the outer end of the stinger and the upper end of the tower for transmission of rotational forces about the vertical tower axis. A vertical counterweight strut is connected between the counterweight unit and the outer end of a pivoted staymast that extends rearwardly in opposition to the boom.

Abstract: A vertical tower and pivoted upper boom are counterbalanced by a mobile counterweight member mounted on a self-propelled earthborn unit spaced a substantial distance from the tower in diametric opposition to the boom. The tower, which is pivotable about a vertical pivot axis, is connected to the counterweight by a first horizontal rigid spreader link and by a second diagonal rigid spreader link. The two links are respectively connected to the lower and upper ends of the tower. In this manner, rotational torque is transmitted directly to both the lower and upper ends of the tower. Both the tower and the boom can therefore be turned about the vertical pivot axis by operation of the self-propelled counterweight unit without the usual problems of having the tower "winding up" due to the rotational forces applied to it during turning of large loads.