Measuring spindle 1 slides in fixed guide B. Two pulleys 2 and 3 make up a two-step drum. Steel band 4 runs over pulley 2 and has one end D attached to spring 5 and the other to measuring spindle 1. Steel band 6 runs over pulley 3 and has one end E attached to pulley 3 and the other F attached to fixed flat surface d. When spindle 1 is displaced, pulley 3 rolls along band 6, lying on flat surface d. This turns hand b, rigidly attached to pulley 3, so that it indicates the motion of measuring spindle 1 on scale a.
$3524$SFL,M$