Abstract: An improved electromagnetic scanner has a substantially E-shaped core having an outer surface that is positioned, at a predetermined air-gap spacing, from a regularly grooved ferromagnetic surface of a textile machine. A pair of coils extend around the crosspiece of the core between the outer arms of the core and the middle arm thereof, such coils being connected in series and connected to a bridge circuit to generate an electrical indication that varies at the rate of movement of the grooved ferromagnetic surface past the core in a direction crossing the grooves in the surface. The plane of said core is oblique to the grooves. A pair of abrasion-resistant, non-magnetic contact elements supported in the spaces between the arms of the core, projecting outwardly into the air gap, and are urged into contact with the moving ferromagnetic surface by a spring carried in a housing in which the core and coils are mounted.

Abstract: The movement of each of a plurality jacks or rocking pressers of a ferromagnetic material a circular knitting machine between a knitting and a non-knitting position is accomplished by the cooperation of the fields of a permanent magnet and a selectively actuable electromagnet which are magnetically isolated from each other. The portion of the jack where such fields intersect may be recessed to accomplish jack positioning with minimum expenditure of magnetomotive force. The airgap in the pole structure of the permanent magnet and in the separate core of the electromagnet are coaxially disposed, with the electromagnet being suitably located either inside or outside the core of the electromagnet. Where outside mounting is used, the permanent magnet may be disposed on the periphery of the circular bed of the machine along with the jacks, while the electromagnet is radially spaced therefrom.