Abstract: A magnetic grab has a pair of vertically elongated magnetic pole pieces each having an upper end and a lower end. The pole pieces diverge downward symmetrically with respect to a vertical symmetry plane with the upper ends substantially more closely spaced than the lower ends. A plurality of nonmagnetic elements fixed to the pole pieces secure same together and a generally cylindrical rotor engaged between the pole pieces and centered on and rotatable about a rotor axis extending horizontally parallel to and between the pole pieces is formed by a pair of soft-iron bodies one of which is substantially thicker in a direction transverse to the axis than the other. One or more permanent magnets are sandwiched between the bodies and polarized generally diametrically of the rotor axis.

Abstract: A magnetic grab has a pair of pole pieces each forming a downwardly directed pole and formed adjacent the respective poles with horizontally extending semicylindrical seats having approximately the same center of curvature and open concavely inward toward each other. One of the pieces has an upwardly directed upper surface to one side of the seats and the other piece has a lower surface directed downward at the upper surface and also to the one side of the seats. A rotor fitting in the seats is provided with a plurality of high-flux rotor magnets polarized about respective axes extending generally diametrically of the rotor axis. At least one low-flux permanent magnet having a vertical polarization axis between the upper and lower surfaces has its north pole engaging one of the surfaces and its south pole engaging the other surface.