Contact point 1, which contacts the surface of the work being checked, raises and lowers slider 2 which travels vertically along supports 3. This changes the clearance between the upper lug of the slider and the face of nozzle 4 to which compressed air is delivered. This, in turn, varies the air pressure in the system which is registered by a manometer. Screw 5 serves to set the contact point to the specified size of the work.
$3710$SHP,M$