Abstract: A method and apparatus for controlling the horizontal motion of a double articulated crane comprises determining the angle about a common axis between a base member pivotally mounted on a crane post and a head member carrying a load application point on an outer end thereof. The angle can vary from 0.degree. to 360.degree.. A desired movement direction value is then set on a direction selector movable on a direction indicator. The value corresponds to a target position for the load application point. The desired movement direction value is adjusted by small increments to reach the target however. The desired movement direction value is broken up into two components, one aligned with the axis of the head and the other aligned with a perpendicular axis. The values of these two compartments are calculated as a function of the sin or cos of an angle of misalignment between the longitudinal axis and the direction of the selector.

Abstract: A mobile truck crane having an elongated main frame that forms the carriage for the crane as well as forming a fore and aft elongated outrigger for stabilization in the crane operative position. A pair of transversely swingable outriggers are attached intermediate the length of the main frame and act to stabilize the crane in transverse directions. The main frame is formed of rectangular tubular cross section and is of such shape as to have a high strength-to-weight ratio and which is particularly rigid and capable of transmitting high, concentrated loads in an efficient manner from a revolvable upper that includes a telescoping boom. The main frame includes an intermediate tub which is fabricated to transmit loads from the upper superstructure to all four outriggers of the main frame.

Abstract: A marine crane having an upper works rotatably mounted on a pedestal adapter, includes a retainer for limiting the extent to which the upper works can be tilted, such retainer having an arcuate member secured to the upper works that extends partially around the pedestal adapter and presents a lip beneath and out of contact with a stationary circumferential member forming a part of the pedestal adapter. The arcuate member has a series of vertical, plate-like buttresses spaced along its circumferential length that have outer ends facing a machinery deck of the upper works to brace the arcuate member, so as to retain the arcuate member in place in the event of abnormal forces being applied thereto.