SERVICE MANUALRESERVOIR AUTOMATIC DRAIN VALVEDESCRIPTIONThe DV-2 Reservoir Automatic Drain Valve ejectsmoisture and contaminants from the reservoir in which itis connected. It operates automatically and requires nomanual assistance or control lines from other sources.The reservoir automatic drain valve has a die castaluminum body and cover and is normally mountedeither in the bottom of the reservoir using the top port ofthe drain valve or in the end of an end drain reservoirusing the side port of the valve.For vehicles operating in subfreezing temperatures,the valve is also available with a heater and thermostatcast into the cover.Fig. 7 Reservoir Automatic Drain ValveOPERATIONWith no air pressure in air system, the inlet and exhaustvalves are closed (Fig. 8).Fig. 8When charging the air system, a slight pressure opensthe inlet valve which permits air and contaminants tocollect in sump (Fig. 9).The inlet valve remains open while pressure ascends inthe system until maximum governor cut-out pressure isreached. The spring action of valve guide in sump cavitycloses the inlet. The inlet valve and exhaust valve arenow closed (Fig. 10).CTS-4079Fig. 9Fig. 10When reservoir pressure drops slightly (approximately13.8 kPa - 2 psi), air pressure in the sump cavity opensexhaust valve allowing moisture and contaminants to beejected from sump cavity until pressure in sump cavitydrops sufficiently to close the exhaust valve. The lengthof time the exhaust valve remains open and the amountof moisture and contaminants ejected depends upon thesump pressure and reservoir pressure drop that occurseach time air is used from the system.Fig. 11Manual draining can be accomplished by inserting a toolin the exhaust port so that the wire in the port may bemoved up and held until draining is completed.CTS -4079-CHAPTER II -PRINTED IN UNITED STATES OF AMERICAPage 7
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