Yoke 1 : A C-shaped piece of soft magnetic material, either solid or laminated, around which is wound a coil carrying the magnetizing current. (RP 5A5)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}