Pneumatic pressure operated parking brake for a railway vehicle brake

Abstract

Air pressure actuated and hydraulic applied railway car parking brake system includes air source to actuate. A control valve receives air from source to initiate air communication. Pneumatic to hydraulic pressure intensifier receives air in first chamber therein from valve. A second intensifier chamber is connected at open first end thereof with partially open second end of first chamber. Hydraulic fluid is disposed in second chamber adjacent closed second end thereof. A force transmitting cylinder, in fluid communication with second chamber, exerts force on brake beam carrying brake shoes thereon which are brought and maintained in frictional engagement with a respective surface of tread portion of a pair of wheels during system operation. A piston member, disposed for reciprocal movement in first chamber, is linearly displaced when a first surface thereof is acted on by air communicated to intensifier. A first seal, around peripheral portion of piston, contains air communicated to intensifier in portion of first chamber located between the first surface and first end of first chamber. A stem member, disposed to move linearly in first and second chambers, is connected at first end thereof to second surface of piston. Such stem is linearly displaced in first and second chambers by piston movement. A second seal, around peripheral second end portion of stem, retains hydraulic fluid in second chamber between second end of stem and second end of second chamber to communicate hydraulic fluid to force transmitting cylinder, by linear displacement, and exert force on beam carrying shoes.