Improvements in or relating to electric torque motors

934,498. Electromagnets. VICKERS Inc. Dec. 16, 1959, No. 42804/59. Class 35. An electric torque motor constructed to have a flat torque/displacement curve during a long stroke comprises opposed polepiece faces forming between them a gap 18, Fig. 3, at least one face having at least one recess 28, permanent magnets 14, 16 for polarizing the polepieces 10, 12 and producing a field flux in the gap 18, a resiliently centred armature 38 pivotally mounted for restricted angular movement in the gap and having thereon at least one tooth 52 for entry into the recess 28 to produce therebetween a pulling gap which comprises both linear and inverse gaps 74, 72, Fig. 8, and electrical coils 54, 56 for producing a variable magnetic control flux in the armature. In the embodiment shown, there are two sets of polepieces and magnets at respective sides of the armature and there are several parallel-sided recesses 28 and complementary teeth 52. The armature is locked to a stationary shaft 40, Fig. 4, rendered torsionally resilient about a central rest position by the shaping shown in Fig. 6. The polepieces 10,12 &c, and frame plates 30, 32 are secured together by screws 34 and dowel pins, and the load, not shown, is connectable to a member 62 secured to the armature. Equal currents in the coils 54, 56 neutralize each other and retain the armature in its rest position, and unbalanced currents cause the armature to pivot.