Abstract: In the electromagnet control apparatus described herein, demagnetization of the electromagnet and a workpiece held thereby, following a period of holding, is effected by stepwise adjustment of the phase setting of a power control means such as a triggerable, semi-conductor switching device, thereby controlling the average AC voltage applied to a full wave bridge through which the electromagnet is energized. Reversing switch means are interposed between the bridge and the electromagnet for reversing the direction of the energizing current at each successive step.

Abstract: Apparatus for the magnetically lifting and tilting an elongate load, e.g., a steel beam, is disclosed. The apparatus comprises a plurality of electromagnets supported in a corresponding plurality of yokes in a linear array along a beam structure. On each yoke, a stepping motor is coupled to the respective electromagnet for controllably rotating the electromagnet around a pivotal axis which is parallel to the axis of the array. The motors are synchronously operated, thereby enabling an elongate load to be lifted by the electromagnets together and tilted around the pivotal axis. In a preferred construction, each end of each yoke is suspended on a plurality of tie elements connected to a vertically compliant spring suspension system mounted on the beam structure. The tie elements are arranged to minimize swinging or misalignment of the several electromagnetic lifting elements.

Abstract: The lifting magnet disclosed herein is adapted for lifting layered pipe. The pipe is engaged by a pair of elongate pole pieces which extend transversely to the length of the pipe, the pole pieces being energized by at least one coil disposed therebetween. The pole pieces are of essentially uniform thickness over most of their length but have substantially thicker portions adjacent each end so as to provide, to a pipe contacting the ends of the pole pieces, an approach flux path of cross-sectional area substantially equal to the cross-sectional area of the approach flux path presented to a pipe contacting the pole pieces intermediate their ends.