BRAKE ACTUATOR HAVING SEALING STRUCTURE FOR INSIDE AIR CIRCULATION

Disclosed is an air-operated brake actuator, including: a hollow upper housing; a hollow lower housing spaced apart from the upper housing in a lower direction; a coupling housing configured to couple and restrain the upper housing and the lower housing to each other; a piston disposed in the upper housing to divide an inside of the upper housing into a spring chamber and a pressure chamber disposed below the spring chamber; a hollow actuator rod disposed in the piston; a casing bolt head disposed at a lower end of the actuator rod and having an air flow hole formed therein; a pilot lip seal fixed to an outer surface of the casing bolt head to seal an outer end of the air flow hole; a compression spring installed in the spring chamber; a diaphragm disposed in the lower housing to divide an inside of the lower housing into a service chamber and a push rod chamber disposed below the service chamber; a pressure plate configured to contact a lower end of the diaphragm and move vertically along the diaphragm; and a push rod having one end vertically coupled to a lower end of the pressure plate and the other end located in the push rod chamber through a through hole of the upper housing.