Arranged between pole shoes 1 and 2 of steel magnet 3 is^stationary
iron cylinder 4 which imparts a radial direction to the
lines of force of the magnet. Secured to shaft 5 are rotary
frames 6, which are coils arranged at a certain angle'with respect
to each other. When there is a current in frames 6, their own
magnetic flux interacts w ith that of magnet 3, developing a
force proportional to the current. The current is supplied by
means of three hairsprings 7, which have a very small torque in
comparison to the torque of frames 6. The angle of deflection of
hand 8, mounted rig id ly on shaft 5, is proportional to the current.
Spiral springs 9 and 10 develop a torque preventing rotation
of frames 6 and turn the hand to zero when there is no current
in the frames.
$4367$SmE,M$