User manual BENDIX TW-12 CONTROL VALVE

[. . . ] Refer to the following chart and figure one. Connection Supply Delivery Vent Body Ident. Thread Sizex SUP DEL NONE 1/4" P. T. xx OPERATION SYSTEM CONNECTIONS Although the TW-12TM valve can be used in a variety of different systems and connected in different ways, figure 2 illustrates a typical hydraulic parking brake system. In this system the TW-12TM valve controls an HR-1TM hydraulic relay that in turn applies and releases hydraulic spring brakes. VALVE OPERATION Parking Brakes Applied With hydraulic fluid flowing to the supply port (Figure 1) and the piston in the upward position, fluid flow into the TW-12TM control valve is stopped at the closed inlet valve. SD-03-3625 1 IN POWER STEERING GEAR OUT IN OUT HYDRAULIC BRAKE BOOSTER IN TW-12TM CONTROL VALVE MASTER CYLINDER RETURN TO SERVICE BRAKES DELIVERY SUPPLY SUPPLY CONTROL HYDRAULIC SPRING BRAKE ACTUATOR DELIVERY DELIVERY HYDRAULIC RESERVOIR RETURN RETURN HR-1TM HYDRAULIC RELAY HYDRAULIC SPRING BRAKE ACTUATOR IN RETURN POWER STEERING PUMP OUT FIGURE 2 - TW-12TM CONTROL VALVE HYDRAULIC PARK SYSTEM The TW-12TM valve delivery port is open to its return port through a passage in the center of the piston. [. . . ] With 120psi applied to the supply and return ports simultaneously, apply a soap solution around the plunger and cam follower in the yoke assembly. Leakage should not exceed a 1" bubble in less than 5 seconds (100 SCCM). If the TW-12TM valve does not function as described or if excessive leakage is detected, it is recommended that it be replaced with a genuine Bendix® service replacement. PREVENTIVE MAINTENANCE 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 system components. At a minimum the TW-12TM valves should be inspected every 6 months or 1500 operating hours, whichever comes first. Check the TW-12TM control valve for proper operation. Inspect the exterior of the valve for signs of leakage and any apparent physical damage. Inspect the control cable and its connection point to the lever cam for damage and wear. If the TW-12TM control valve does not function as required or if leakage excessive, wear, or damage is noted during inspection, replace the valve with a genuine Bendix® service replacement unit. 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 the use of those tools. Following the vehicle manufacturer's recommended procedures, deactivate the electrical system in a manner that safely removes all electrical power from the vehicle. If the vehicle is equipped with an air over hydraulic brake system or any auxiliary pressurized air system, 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. Never connect or disconnect a hose or line containing pressure; it may whip. Never remove a component or pipe plug unless you are certain all system pressure has been depleted. Never exceed manufacturer's recommended pressure. Never attempt to disassemble a component until you have read and understand all recommended procedures. Some components contain powerful springs and injury can result if not properly disassembled. Use only proper tools and observe all precautions pertaining to use of those tools. [. . . ] Identify and mark or label all lines and their respective connections on the valve to facilitate ease of installation. 3 4. Disconnect all lines and the control cable from the lever cam. Remove the valve from the vehicle. VALVE INSTALLATION 1. Install all line fittings and plugs making certain thread sealing material, if used, does not enter the valve. [. . . ]