User manual BENDIX TU-FLO 750 COMPRESSOR

[. . . ] ® Bendix® Tu-Flo® 750 Air Compressor DISCHARGE VALVE STOP DISCHARGE VALVE UNLOADER COVER AIR DISCHARGE CYLINDER HEAD WATER OUTLET WATER INLET AIR INLET DISCHARGE VALVE SPRING PISTON DISCHARGE VALVE SEAT CRANKCASE PISTON RINGS CONNECTING ROD GOVERNOR MOUNTING PAD CRANKCASE CRANKSHAFT BENDIX® TU-FLO® 750 AIR COMPRESSOR (CROSS SECTION) PIECE NO. TAG DESCRIPTION The function of the air compressor is to provide and maintain air under pressure to operate devices in the air brake and/or auxiliary air systems. The Tu-Flo® 750 compressor is a two cylinder single stage, reciprocating compressor with a rated displacement of 16. 5 cubic feet per minute at 1, 250 RPM. The compressor assembly consists of two major subassemblies, the cylinder head and the crankcase. [. . . ] must be of equivalent size, type and strength as original equipment and be designed specifically for such applications and systems. 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 indication 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. 15 This troubleshooting guide obsoletes and supersedes all previous published troubleshooting information relative to Bendix air compressors. Advanced Troubleshooting Guide for Air Brake Compressors * The guide consists of an introduction to air brake charging system components, a table showing recommended vehicle maintenance schedules, and a troubleshooting symptom and remedy section with tests to diagnose most charging system problems. INDEX Symptom Air Air brake charging system: Slow build (9. 0) . 32-34 Maintenance & Usage Guidelines Maintenance Schedule and Usage Guidelines (Table A) . 18 *This guide is only for vehicles that use desiccant air dryers. 16 Introduction to the Air Brake Charging System Powered by the vehicle engine, the air compressor builds the air pressure for the air brake system. The air compressor is typically cooled by the engine coolant system and lubricated by the engine oil supply. The compressor's unloader mechanism and governor (along with a synchro valve for the Bendix® DuraFloTM 596 air compressor) control the brake system air pressure between a preset maximum and minimum pressure level by monitoring the pressure in the service (or "supply") reservoir. When the air pressure becomes greater than that of the preset "cut-out", the governor controls the unloader mechanism of the compressor to stop the compressor from building air and also causes the air dryer to purge. As the service reservoir air pressure drops to the "cut-in" setting of the governor, the governor returns the compressor back to building air and the air dryer to air drying mode. As the atmospheric air is compressed, all the water vapor originally in the air is carried along into the air system, as well as a small amount of the lubricating oil as vapor. The duty cycle is the ratio of time the compressor spends building air to the total engine running time. Air compressors are designed to build air (run "loaded") up to 25% of the time. Higher duty cycles cause conditions that affect air brake charging system performance which may require additional maintenance. Factors that add to the duty cycle are: air suspension, additional air accessories, use of an undersized compressor, frequent stops, excessive leakage from fittings, connections, lines, chambers or valves, etc. The discharge line allows the air, water-vapor and oil-vapor mixture to cool between the compressor and air dryer. The typical size of a vehicle's discharge line, (see column 2 of Table A on page 18) assumes a compressor with a normal (less than 25%) duty cycle, operating in a temperate climate. When the temperature of the compressed air that enters the air dryer is within the normal range, the air dryer can remove most of the charging system oil. If the temperature of the compressed air is above the normal range, oil as oil-vapor is able to pass through the air dryer and into the air system. Larger diameter discharge lines and/or longer discharge line lengths can help reduce the temperature. The discharge line must maintain a constant slope down from the compressor to the air dryer inlet fitting to avoid low points where ice may form and block the flow. [. . . ] These figures are approximate and assume that air system leakage is within the limits of the Bendix "Dual System Air Brake Test and Check List" (BW1279). Last but not least, begin using alcohol several weeks prior to freezing weather to ensure that the system is completely protected. Use only methanol alcohol, such as Bendix "Air Guard", in evaporators or injectors. Air Dryers Make certain air brake system leakage is within the limits stated in BW1279. [. . . ]