Installed in the body of snap gauge 1 are three pins: fixed back-stop 2 and gauging anvil 3, and movable anvil 4. The movable anvil is actuated by the deviations in the diameter of work 5, which contacts the outer ends of the three pins. A definite clearance is set up between the rear end of movable anvil (pin) 4 and nozzle 6, to which compressed air is delivered, to suit the nominal size of work 5. The variation in clearance affects the air pressure in the system. This pressure is measured by a pressure gauge which thereby indicates the deviations in the size of the work. The positions of pins 2 and 3 are adjustable with setscrews.
$3708$SHP,M$