BENDIX BW1786 User's Manual
Contents
1. ELEASE VALVE APPLY Figure 1 shows the QRN 2 valve with its port designations date code piece number and T M C identifications Figure 2is a sectional view Note that the standard QRN 2 valve which has a 1 psi maximum differential does not include a differential spring Figure 3 shows a partial air brake system schematic with a QRN 2 valve Receiving its signal from the secondary brake circuit the QRN 2 valve is controlling the front axle brake chambers OPERATION APPLY As shown in Figure 4 when air pressure enters the supply port it causes the center portion of the diaphragm to seal the exhaust Supply air pressure simultaneously forces the edges of the diaphragm away from the sealing lip in the body allowing air to flow out the delivery ports Delivery pressure will be within 1 psi of supply pressure for the standard QRN 2 valve SUPPLY DELIVERY SEALED EXHAUST EXHAUST SEALED FIGURE 5 QRN 2 QUICK RELEASE VALVE BALANCE SUPPLY DIAPHRAGM IZ Ay Ss DELIVERY FIGURE 6 QRN 2 QUICK RELEASE VALVE RELEASE BALANCE Figure 5 shows the QRN 2 valve balanced mode When air pressure beneath diaphragm is approximately 1 psi less than air pressure above the diaphragm the outer edges of the diaphragm seal against the body s sealing lip The exhaust remains sealed because air pressure bears against the center portion of the diaphragm from one side only RELEASE When air pressure2. SD 03 907 Service Dat Bendix QRN 2 Quick Release Valve SUPPLY SUPPLY PIECE NUMBER DATE CODE AND T M C IDENTIFICATIONS STAMPED HERE DELIVERY DELIVERY a BODY EXHAUST COVER n DELIVERY EXHAUST FIGURE 1 QRN 2 QUICK RELEASE VALVE Supply port 1 2 14 P T or 3 8 18 P T Delivery ports 3 8 18 P T Weight 3 Ib Material Molded black reinforced nylon 6 DESCRIPTION The Bendix QRN 2 quick release valve is a lightweight nonmetallic quick release valve It is designed to speed up the release of air from the devices it is attached to In its standard configuration the valve is designed to deliver within 1 psi of control pressure However for special applications the valve is available with zero hysteresis Port Embossed I D Operating pressure 150 psi maximum Operating temperature 40 to 180 F Za S FRONT AXLE Supply SUP 1 l ONT A Delivery DEL 2 CHAMBER Exhaust EXH3 DUAL BRAKE xw VALVE DELIVERY ORN 2 S VALVE S SUPPLY T SUPPLY BRAKE VALVE SECONDARY CIRCUIT DELIVERY se DELIVERY SECONDARY CIRCUIT DELIVERY EXHAUST FIGURE 2 QRN 2 QUICK RELEASE VALVE SECTIONAL VIEW Z SUPPLY RESERVOIR RESERVOIR FIGURE 3 PARTIAL SYSTEM SCHEMATIC WITH QRN 2 QUICK RELEASE VALVE SUPPLY N DELIVERY EXHAUST MEZ DIAPHRAGM FIGURE 4 QRN 2 QUICK R
3. is removed from the QRN 2 valve supply port the air pressure on the delivery side of the diaphragm holds the outer edge of the diaphragm against the sealing lip in the body while simultaneously moving the center portion away from the exhaust port Air from the delivery ports flows out the exhaust When delivery air pressure is fully exhausted the diaphragm will return to its natural state with its outer edges sealing the delivery and its center portion sealing the exhaust WARNING PLEASE READ AND FOLLOW THESE INSTRUCTIONS TO AVOID PERSONAL INJURY OR DEATH When working on or around a vehicle the following general precautions should be observed at all times 1 Park the vehicle on a level surface apply the parking brakes and always block the wheels Always wear safety glasses 2 Stop the engine and remove ignition key when working under or around the vehicle When working in the engine compartment the engine should be shut off and the ignition key should be removed Where circumstances require that the engine be in operation EXTREME CAUTION should be used to prevent personal injury resulting from contact with moving rotating leaking heated or electrically charged components 3 Do not attempt to install remove disassemble or assemble a component until you have read and thoroughly understand the recommended procedures Use only the proper tools and observe all precautions pertaining to use of those tools 4 If the w
4. nance procedures A warranty may be voided if intrusive maintenance is performed during the warranty period No two vehicles operate under identical conditions as a result maintenance intervals may vary Experience is a valuable guide in determining the best maintenance interval for air brake system components At a minimum the QRN 2 valve should be inspected every 12 months or 3600 operating hours whichever comes first for proper operation Should the QRN 2 valve not meet the elements of the operational tests noted in this document further investigation and service of the valve may be required SERVICE CHECKS 1 Remove any accumulated contaminants Visually inspect the valve s exterior for cracks gouges or other physical damage Replace the valve if physical damage is excessive 2 Inspect all air lines connected to the valve for signs of wear or physical damage Repair replace as necessary 3 Test air line fittings for excessive leakage and tighten or replace as necessary OPERATIONAL AND LEAKAGE TESTS 1 Block the vehicle s wheels and fully charge the air system 2 Apply and release the service brakes several times and check for prompt response of the brakes at the appropriate wheels 3 With the air system fully charged apply a soap solution to the QRN 2 valve exhaust port Leakage of a 1 bubble in 5 seconds is permissible 4 Make and hold a full brake application and again apply a soap solution
5. ork is being performed on the vehicle s air brake system or any auxiliary pressurized air systems make certain to drain the air pressure from all reservoirs before beginning ANY work on the vehicle If the vehicle is equipped with an AD IS air dryer system or a dryer reservoir module be sure to drain the purge reservoir 5 Following the vehicle manufacturer s recommended procedures deactivate the electrical system in a manner that safely removes all electrical power from the vehicle 6 Never exceed manufacturer s recommended pressures 7 Never connect or disconnect a hose or line containing pressure it may whip Never remove a component or plug unless you are certain all system pressure has been depleted 8 Use only genuine Bendix replacement parts components and kits Replacement hardware tubing hose fittings etc must be of equivalent size type and strength as original equipment and be designed specifically for such applications and systems 9 Components with stripped threads or damaged parts should be replaced rather than repaired Do not attempt repairs requiring machining or welding unless specifically stated and approved by the vehicle and component manufacturer 10 Prior to returning the vehicle to service make certain allcomponents and systems are restored to their proper operating condition PREVENTIVE MAINTENANCE Important Review the Bendix Warranty Policy before performing any intrusive mainte
6. to the QRN 2 valve exhaust Leakage of a 1 bubble in 3 seconds is permissible 5 With the brakes still applied apply a soap solution around the valve where the exhaust cover meets the body No leakage at this point is permitted If the valve does not function as described or if leakage is excessive replace it at any authorized parts outlet REMOVAL 1 Identify and mark or label all air lines and their connections to the QRN 2 valve Then disconnect the air lines 2 Remove the QRN 2 valve from the vehicle Retain the mounting hardware INSTALLATION 1 Install the QRN 2 valve on the vehicle using the mounting hardware saved during removal 2 Reconnect all air lines to the valve using the identification made during removal 3 Test all air fittings for excessive leakage and tighten as needed NOTE MAXIMUM TORQUE FOR FITTINGS IS 10 FT LBS Perform OPERATIONALAND LEAKAGE TESTS before placing the vehicle back into service NOTE THERE ARE NO DISASSEMBLY ASSEMBLY PROCEDURES FOR THE QRN 2 VALVE IT ISA REPLACE ITEM IF A VALVE DOES NOT MEET THE OPERATIONAL AND LEAKAGE TESTS IT SHOULD BE REPLACED AT ANY AUTHORIZED PARTS OUTLET BW1786 2004 Bendix Commercial Vehicle Systems LLC All rights reserved 3 2004 Printed in U S A
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