Spring brake actuator with a pressure plate bearing for a caging tool

A fluid-operated diaphragm spring brake actuator comprising:

• an enclosed housing with a housing aperture in a wall thereof,
• a movable diaphragm suspended within the housing, and dividing the interior thereof into a first chamber and a second chamber,
• a pressure plate disposed within the first chamber and adjacent to the diaphragm, said pressure plate having a pressure plate aperture axially aligned with the housing aperture,
• a spring in the upper chamber between the pressure plate and the housing,
• a hollow actuator rod having an axial opening at one end thereof, said actuator rod having a portion disposed in the second chamber in a position to alternately actuate and release a brake mechanism in response to reciprocal movement of the diaphragm and pressure plate,
• a caging tool mounted to the housing and extending through the housing aperture, the pressure plate aperture and the axial opening into the hollow actuator rod, and
• a bearing mounted within the pressure plate aperture and disposed between the pressure plate and the caging tool.

A fluid-operated diaphragm spring brake comprising:

• a generally cylindrical housing with a housing aperture in a wall thereof,
• a fluid-tight dividing means suspended within the housing for dividing the interior thereof into a first chamber and a second chamber,
• a support means disposed within the first chamber and adjacent to the fluid-tight dividing means in the upper chamber, said support means having a support means aperture axially aligned with the housing aperture,
• a biasing means in the upper chamber disposed between the support means and the housing for biasing the support means toward the second chamber in response to the exhausting of fluid from the lower chamber,
• a hollow actuating means in the lower chamber for actuating a brake mechanism in response to movement of the fluid-tight dividing means and support means, said actuating means having an axial opening at one end thereof,
• a caging means mounted to the housing and extending through the housing aperture, the support means aperture and the axial opening into the actuating means for caging the biasing means between the housing and the support means, and
• a bearing means mounted between the support means and the caging means for preventing contact between the support means and the caging means.