Link 1 is connected by screw pair A to the fixed link and by screw pair B to link 2 whose slot b slides along fixed pin a. Adjusting link 1 has external and internal threads of the same hand and with a slight difference in pitch. Link 3 is connected by screw pair C to link 2. A rough setting of stop d is obtained by turning link 3. Link 1 is turned for a precise setting.
$2253$LS,PS$