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MAINTENANCE & REPLACEMENTS: UNIVERSAL RAI° SERIES BLOWERS <br />A good program of consistent inspection and mainte- <br />nance is the most reliable method of minimizing repairs <br />to a blower. A simple record of services and dates will <br />help keep this work on a regular schedule. Basic <br />service needs are: <br />• Lubrication <br />• Checking for hot spots <br />• Checking for increases or changes in vibration <br />and noise <br />• Recording of operating pressures and temperatures <br />Above all, a blower must be operated within its <br />specified rating limits, to obtain satisfactory service life. <br />A newly installed blower should be checked often <br />during the first month of full-time operation. Attention <br />thereafter may be less frequent assuming satisfactory <br />performance. Lubrication is normally the most impor- <br />tant consideration and weekly checks of lubricant <br />levels in the gearbox and bearing reservoirs should <br />be customary. Complete oil change schedules are <br />discussed under LUBRICATION. <br />Driver lubrication practices should be in accordance <br />with the manufacturer's instructions. If direct connected <br />to the blower through a lubricated type coupling, the <br />coupling should be checked and greased each time <br />blower oil is changed. This will help reduce wear and <br />prevent unnecessary vibration. In a belted drive <br />system, check belt tension periodically and inspect <br />for frayed or cracked belts. <br />In a new, and properly installed, unit there is no contact <br />between the two impellers, or between the impellers <br />and cylinder or headplates. Wear is confined to the <br />bearings (which support and locate the shafts) the oil <br />seals, and the timing gears. All are lubricated and wear <br />should be minimal if clean oil of the correct grade is <br />always used. Seals are subject to deterioration as well <br />as wear, and may require replacement at varying periods. <br />Shaft bearings are designed for optimum life under <br />average conditions with proper lubrication and are <br />critical to the service life of the blower. Gradual <br />bearing wear may allow a shaft position to change <br />slightly, until rubbing develops between impeller and <br />casing. This will cause spot heating, which can be <br />detected by observing these surfaces. Sudden bearing <br />failure is usually more serious. Since the shaft and <br />impeller are no longer supported and properly located, <br />extensive general damage to the blower casing and <br />gears is likely to occur. <br />Oil seals should be considered expendable items, to <br />be replaced whenever drainage from the headplate <br />vent cavity becomes excessive or when the blower is <br />disassembled for any reason. Sealing effectiveness <br />can vary considerably from seal to seal and is also <br />affected to surprising degree by shaft finish under the <br />seal lip. Because of these normal variables, minor seal <br />leakage should not be considered as indicating <br />seal replacement. <br />Timing gear wear, when correct lubrication is main- <br />tained, should be negligible over a period of years. <br />Gear teeth are cut to provide the correct amount of <br />backlash, and gears correctly mounted on the shafts <br />will accommodate a normal amount of tooth wear <br />without permitting contact between lobes of the two <br />impellers. However, too high an oil level will cause <br />churning and excessive heating. This is indicated by <br />unusually high temperature at the bottom of the gear <br />housing. Consequent heating of the gears will result <br />in loss of tooth -clearance , backlash and rapid wear of <br />the gear teeth usually will develop. Continuation of this <br />tooth wear will eventually produce impeller contacts <br />(knocking), and from this point serious damage will be <br />unavoidable if blower operation is continued. A similar <br />situation can be produced suddenly by gear tooth <br />fracture, which is usually brought on by sustained <br />overloading or momentary shock loads. <br />Problems may also develop from causes other than <br />internal parts failure. Operating clearances within a <br />blower are only a few thousandths of an inch. This <br />makes it possible for impeller interference or casing <br />rubs to result from shifts in the blower mounting, or <br />from changes in piping support. If this type of trouble <br />is experienced, and the blower is found to be clean, try <br />removing mounting strains. Loosen blower mounting <br />bolts and reset the leveling and drive alignment. Then <br />tighten mounting again, and make sure that all piping <br />meets blower connections accurately and squarely <br />Foreign materials in the blower will also cause trouble, <br />which can only be cured by disconnecting the piping <br />and thoroughly cleaning the blower interior. <br />A wide range of causes & solutions for operating <br />troubles are covered in the TROUBLE SHOOTING <br />CHECKLIST. The remedies suggested should be <br />performed by qualified mechanics with a good <br />background, using procedures detailed in this manual. <br />Major repairs generally are to be considered beyond <br />the scope of maintenance, and should be referred <br />to ROOTS. <br />Warranty failures should not be repaired at all, unless <br />specific approval has been obtained through ROOTS <br />before starting work. Unauthorized disassembly within <br />the warranty period will void the warranty. <br />For your nearest ROOTS Office, dial our Customer Service Hot Line 1 877 363 ROOTS (7668). 10 <br />