Abstract: This disclosure relates to an air brake system for a vehicle having a front set of wheels having a front air brake and a rear set of wheels having a rear air brake. The air brake system comprises a front air brake cylinder included in the front air brake, and a rear air brake cylinder included in the rear air brake. A foot valve having a first side and a second side is included. A primary air tank is pneumatically connected with the second side of the foot valve, and a secondary air tank is pneumatically connected with the first side of the foot valve. A rear relay valve is pneumatically connected with second side of the foot valve and is pneumatically connected with the rear brake cylinder. A front relay valve is pneumatically connected with the first side of the foot valve and pneumatically connected with the front brake cylinder.

Abstract: A service brake inspection system engages service brake air lines downstream of a foot operated activation valve thereof to provide continuous engagement of the service brakes during inspection. The system includes a manually controlled air line which supplies air to a source port of an inversion valve. The inversion valve further includes an outlet port which is engaged to air lines supplying the vehicle service brake system via a double check valve in each of the primary and secondary service brake air lines, each being downstream of the foot operated valve. A third control port is connected to an air line disposed between a hand operated valve for exhausting the air lines to the spring parking brakes to set the parking brakes of the vehicle on. When the hand operated exhaust valve is set on, the pathway from the source to the outlet port in the inversion valve is opened to cause the service brakes to be continuously engaged for inspection.