User manual BENDIX LOW PRESSURE INDICATORS

[. . . ] The nominal setting of the indicator is 60 psi; however, pressure settings may vary depending upon the vehicle. 1 SD-06-1600 OPERATION To describe the operation, we shall assume that the low pressure indicator is set for 60 psi. When air pressure at the supply port and under the diaphragm is above 60 psi, the electrical contacts remain open because the force exerted by air pressure underneath the diaphragm overcomes the force exerted by the spring above the diaphragm. When air pressure below the diaphragm drops below 60 psi, the spring exerts a force which is greater than the force exerted by the air pressure below the diaphragm. This causes the diaphragm (and the piston in the LP-3TM indicator) to move and allow the electrical contacts to close. [. . . ] Check the valve spring for cracks or corrosion. If contact points are not severely pitted, they can be dressed with a fine file. Replace all parts that were discarded and any parts not found to be serviceable during inspection, using only genuine Bendix replacement parts. TESTING FOR SERVICEABILITY OPERATING TEST 1. If possible, determine the setting of the low pressure indicator by referring to the label on the valve or the vehicle manual. Operation of the low pressure indicator may be checked with ignition switch "on" by reducing the system pressure and observing that low pressure warning occurs when system pressure drops below the setting of the low pressure indicator. The contacts will be closed when the warning device operates. If the setting of the indicator is unknown, the contacts should close between approximately 70 psi and 50 psi. With air pressure present at the supply port, coat the indicator with soap solution. No leakage permitted. ASSEMBLY NOTE: When using pipe thread sealant during assembly and installation, take particular care to prevent the sealant from entering the valve itself. Apply the sealant beginning with the second thread back from the end. Place and position the diaphragm assembly in the body. Position the spring so that it rests on the upper diaphragm follower. Place cover over the diaphragm and screw cover retainer to the body and tighten securely. (Torque to 110-130 inch pounds. ) REMOVING 1. Otherwise, secure the vehicle with other than service brakes. The ignition switch should be in the "off" position. Disconnect the electrical connections at the low pressure indicator. 2 LP-3TM INDICATOR 1. Lubricate bore of body and both sides of the o-ring diaphragm with silicone lubricant BW-650-M (Bendix piece no. (Note: o-ring portion of diaphragm should face supply port. ) 3. Flat side of piston should face o-ring diaphragm. (Always use a phenolic gasket in a two terminal switch and a metallic gasket in the single terminal. ) 5. Position contact plate over fingers of piston. [. . . ] 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. Prior to returning the vehicle to service, make certain all components and systems are restored to their proper operating condition. For vehicles with Antilock Traction Control (ATC), the ATC function must be disabled (ATC indicator lamp should be ON) prior to performing any vehicle maintenance where one or more wheels on a drive axle are lifted off the ground and moving. TEST OF REBUILT LOW PRESSURE INDICATOR After rebuilding, perform the leakage and operating tests as outlined in section "Testing for Serviceability. " WARNING! [. . . ]