BENDIX R-12DC Manuals

1 Figure 1 – Bendix® R-12DC® Relay Valve Exploded View *Crack Pressure is the amount of control pressure required by the valve to initiate air delivery. For Crack pressures other than 4 psi, a differential spring is used in the assembly to produce the required valve response. (Models designed to have a 4 psi crack pressure do not require a differential spring.) Primary Control Port 1/4 NPT Secondary Control Port 1/4 NPT Cap Screw Torx® Screw Differential Spring (Controls Crack Pressure*) (Not required for Most Models. See Below.) Vertical Delivery Ports Supply Port Horizontal Delivery Ports Differential Springs BENDIX® R-12DC® RELAY VALVE MAJOR MAINTENANCE KIT Kit Contents Item No. Description Qty. 1 Valve Spring 1 2 Check Valve Guide 1 3 Check Valve 1 4 O-Ring 1 5 O-Ring 1 6 O-Ring 1 7 Inlet & Exhaust Valve 1 8 Valve Retainer 1 9 Spring 1 10 O-Ring 1 11 O-Ring 1 12 Exhaust Cover 1 13 Retaining Ring 1 14 Lubricant (Not Shown) 1 6 7 8 2 3 4 5 1 9 13 12 11 10 Valve Cover Double Check Cover Relay Piston Valve Body

1 Bendix® R-12DC® Relay Valve with Biased Double-Check DESCRIPTION The relay valve in an air brake system functions as a relay station to speed up the application and release of the brakes. The valve is normally mounted at the rear of the vehicle in proximity to the chambers it serves. The valve operates as a remote controlled brake valve that delivers or releases air to the chambers in response to the control air delivered to it from the foot brake valve. Figure 1 – Exterior Views EXTERIOR BENDIX® R-12DC® VALVE (MODEL WITH 2 HORIZONTAL PORTS) PRIMARY SERVICE DELIVERY SUPPLY (2) SD-03-1068 SECONDARY SERVICE EXTERIOR R-12DC® VALVE (MODEL WITH 4 VERTICAL DELIVERY PORTS) EXTERIOR R-12DC® VALVE (MODEL WITH 2 HORIZONTAL AND 2 VERTICAL DELIVERY PORTS) PRIMARY SERVICE PORT Figure 2 – Bendix® R-12DC® Relay Valve with Biased Double-Check Sectional View RELAY PISTON VALVE RETAINER EXHAUST SEAT RETAINING RING EXHAUST PORT SECONDARY SERVICE PORT DOUBLE-CHECK DIAPHRAGM GUIDE SPRING CAP SCREW SEALING RING COVER RELAY PISTON O-RING SPRING O-RINGS INLET EXHAUST VALVE Bendix® R-12DC® relay valves are designed for either reservoir or frame mounting. (See Figure 1). For ease of servicing, the inlet/exhaust valve can be replaced without the need for line removal.