User manual BENDIX LQ-5 BOBTAIL RATIO VALVE

[. . . ] (For more information on the BP-R1TM valve, see SD-03-1067. ) OPERATION GENERAL After an initial delivery, the LQ-5TM valve limits front axle brake pressure during normal tractor-trailer operation. The LQ-5TM valve has two spring-loaded pistons: a blend back piston and a proportioning piston. The "stepped" proportioning piston determines actual air pressure reduction and the blend back piston allows the valve's delivery pressure to "blend back" and reach a 1:1 ratio during high pressure brake applications. 1 SD-03-953 BRAKE CHAMBER PP-7TM TRAILER SUPPLY VALVE SUPPLY QUICK RELEASE VALVE LQ-5TM VALVE BRAKE VALVE LP-3TM LOW PRESSURE INDICATOR GAUGE DELIVERY BRAKE CHAMBER FRONT AXLE SERVICE RESERVOIR FIGURE 2 - LQ-5TM BOBTAIL RATIO VALVE INSTALLATION The LQ-5TM valve also allows full service pressure to pass through it when the trailer supply valve (red octagonal button) is pulled out--when the tractor is running in bobtail mode. Note: LQ-5TM valve control pressure, which comes from the trailer supply line, will vary. [. . . ] Upon brake valve release, delivery air pressure flows back through the LQ-5TM valve, to the brake valve and out to atmosphere. Air from the actuators exhausts through the quick release valve. PREVENTIVE MAINTENANCE GENERAL Perform the following tests and inspections at the prescribed intervals. If the LQ-5TM valve fails to function as described or if leakage is excessive, repair the valve or replace it with a new or genuine Bendix remanufactured unit, available at any authorized parts outlet. Important: Review the Bendix Warranty Policy before performing any intrusive maintenance 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 valve should be inspected every 6 months or 1500 operating hours, whichever comes first, for proper operation. Should the valve not meet the elements of the operational tests noted in this document, further investigation and service of the valve may be required. 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. Park the vehicle on a level surface, apply the parking brakes, and always block the wheels. 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. 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. If the work 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-ISTM air dryer system or a dryer reservoir module, be sure to drain the purge reservoir. Following the vehicle manufacturer's recommended procedures, deactivate the electrical system in a manner that safely removes all electrical power from the vehicle. 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. must be of equivalent size, type and strength as original equipment and be designed specifically for such applications and systems. [. . . ] Make sure the springs are square when the cover is attached to the body. Using the Phillips head screws and their lock-washers, secure the cover to the body. Install all air line fittings, making sure thread sealing material does not enter the valve. Mount LQ-5TM valve on the vehicle and perform Operation and Leakage Tests before returning the vehicle to service. ASSEMBLY 1. [. . . ]