Deformed by the difference in pressure inside and outside, double aneroid capsule 1 turns shaft 4 through tie-rod 2 and crank 3. Turned together with shaft 4 is segment gear 5, meshing with pinion 6. Pinion 6 is mounted on a shaft together with gears 7 and 8, and hairspring 15 which eliminates backlash. Gear 7 meshes with pinion 9 on whose shaft hand 11 is mounted. Gear 8 meshes with gear 10 on whose hollow shaft hand 12 is mounted. Hand 11 rotates ten times faster than hand 12. At a speed increase of 100 km/h, hand 11 makes one revolution and indicates a reading in tens of kilometres, while hand 12 makes 0.1 revolution and indicates a reading in hundreds of kilometres. Hands 11 and 12 indicate zero when fixed magnet 13 attracts iron rod 14. When the aircraft reaches a speed exceeding a certain minimum value, rod 14 breaks away from magnet 13, after which the instrument responds to all changes in speed. Flat spring 16, whose end a bears against the centre of aneroid capsule 1, provides for a uniformly graduated scale. Screws 17 adjust the action of spring 16.
$3937$LHP,M$