Shutdown SIS Previous Screen Product: NO EQUIPMENT SELECTED Model: NO EQUIPMENT SELECTED Configuration: NO EQUIPMENT SELECTED Special Instruction Generator Bearing Service{4457} Media Number -REHS4892-02 Publication Date -20/09/2011 Date Updated -20/09/2011 i04554108 Generator Bearing Service{4457} SMCS - 4457-BD Electric Power Generation: All Generator Set: All Introduction This Special Instruction provides information about the recommended method to service generator bearings. Generators are equipped with one or two bearings depending on the application. In addition, some configurations include bearing wear sleeves that are located in the bearing bracket. Refer to Illustration 4. Bearing wear sleeves are constructed from a harder material to prevent the brackets from being worn. Some wear sleeves are insulated to prevent shaft currents. Generators are provided with many different bearing configurations. Ball bearings, roller bearings, and sleeve bearings are all common types of bearings used in generators. The type of grease, operational life, temperature limits, and method of grease containment vary throughout the many generator applications. Sleeve bearings are not used in Caterpillar generators, therefore, sleeve bearings will not be covered in this document. Ball bearings and roller bearings are commonly configured with shields to keep grease in, and contaminants out. Testing confirms that grease will pass from bearing bracket cavity through shields when the following occur: Equilibrium of grease is achieved, that is, excessive grease has purged out of the bearing • Grease in the bearing bracket cavity rises above 50% fill • In some cases, where the potential for contamination of bearing grease is minimal, ball bearings are configured without shields to minimize bearing operating temperatures. Página 1 de 16 Media Search - REHS4892 - Generator Bearing Service{4457} 24/07/2012 https://sisweb.cat.com/sisweb/sisweb/techdoc/techdoc_print_page.jsp?returnurl=/sisweb/s ...
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Special Instruction Generator Bearing Service{4457} Media Number -REHS4892-02 Publication Date -20/09/2011 Date Updated -20/09/2011
i04554108
Generator Bearing Service{4457}SMCS - 4457-BD
Electric Power Generation: All Generator Set: All
IntroductionThis Special Instruction provides information about the recommended method to service generator bearings.
Generators are equipped with one or two bearings depending on the application. In addition, some configurations include bearing wear sleeves that are located in the bearing bracket. Refer to Illustration 4. Bearing wear sleeves are constructed from a harder material to prevent the brackets from being worn. Some wear sleeves are insulated to prevent shaft currents.
Generators are provided with many different bearing configurations. Ball bearings, roller bearings, and sleeve bearings are all common types of bearings used in generators. The type of grease, operational life, temperature limits, and method of grease containment vary throughout the many generator applications.
Sleeve bearings are not used in Caterpillar generators, therefore, sleeve bearings will not be covered in this document.
Ball bearings and roller bearings are commonly configured with shields to keep grease in, and contaminants out. Testing confirms that grease will pass from bearing bracket cavity through shields when the following occur:
Equilibrium of grease is achieved, that is, excessive grease has purged out of the bearing•
Grease in the bearing bracket cavity rises above 50% fill•
In some cases, where the potential for contamination of bearing grease is minimal, ball bearings are configured without shields to minimize bearing operating temperatures.
To determine the type of bearing and generator lubrication requirements, use one of the following:
Engine serial number•
Generator arrangement number (that is found on the generator barrel)•
Generator frame size•
Use the information to look up the bearing part number that is located in the parts replacement publication. Use the information in Table 1 to determine the lubrication guidelines. Many generators that require the addition of grease are labeled with a lubrication plate or decal near the greasing ports.
The front of the generator refers to the generator drive end, that is, the end of the generator that is closest to the engine. The rear of the generator refers to the non-drive end.
Important Safety InformationDo not perform any procedure in this Special Instruction until you have read this Special Instruction and you understand this information. Use only proper tools and observe all precautions that pertain to the use of those tools. Failure to follow these procedures can result in personal injury. The following procedures should also be observed.
Work safely. Most accidents that involve product operation, maintenance, and repair are caused by failure to observe basic safety rules or precautions. An accident can often be avoided by recognizing potentially hazardous situations before an accident occurs.
A person must be alert to potential hazards. This person should also have the necessary training, skills, and tools in order to perform these functions properly.
Safety precautions and warnings are provided in this instruction and on the product. If these hazard warnings are not heeded, bodily injury or death could occur to you or to other persons. Caterpillar cannot anticipate every possible circumstance that might involve a potential hazard.
Therefore, the warnings in this publication and the warnings that are on the product are not all inclusive. Ensure that any tool, procedure, work method, or operating technique you use that is not recommended by Caterpillar is safe.
Ensure that the product will not be damaged or the product will not be made unsafe by the operation, lubrication, maintenance, or repair procedures used.
Parts KitSome generators are not factory configured with lubrication hardware (10) installed to allow grease to be added. Refer to Illustration 3. Therefore, field installation of lubrication hardware for the bearings will need to be done to allow the required maintenance lubrication.
The 342-2409 Bearing Kit has been made available for generators with pre-drilled bearing brackets. The bearing kit contains pipe extensions and grease fittings. The components allow grease to be added to a bearing. The grease must be added according to the maintenance schedule that is in Table 1.
Monitor the operating temperatures of the bearings.1.
Log the values of the ambient temperature, bearing temperatures, and generator electrical load at the time of the commissioning procedure. Log the values of the ambient temperature, bearing temperatures, and generator electrical load at periodic time intervals.
2.
Log the data for the alignment of the generator set at the time of the commissioning procedure. Log the data for the vibration level at the time of the commissioning procedure. Log the data from any subsequent alignment procedures for the generator. Log the data for the vibration level at periodic time intervals.
3.
Routinely perform a trend analysis of bearing temperature, alignment, and data for the vibration level throughout the operational life of the generator. Log the information for the bearings in order to ensure effective preventive maintenance for the bearings.
The maximum temperature at which each bearing has been designed to operate continuously is identified in Table 1. Periodically compare the temperature trending data against the value in Table 1 to evaluate the condition of the bearing. The following are typical signs that grease is deteriorating and that bearing life could be adversely affected:
Continual operation above the maximum temperature◦
A sharp rise in bearing temperature◦
If the conditions that are listed above exist, the recommendation is that the generator must be stopped and bearings inspected.
Note: Ambient temperature and break-in period are factors that must be considered.
Bearing Inspection
External inspection of the generator bearings will require the removal of external generator covers such as grills, louvers, or cover plates.
The following is a list of common causes of bearing problems:
Insufficient amount of grease•
Contaminated grease from dirty environment•
Grease deterioration•
Mixing of incompatible grease•
Excessive bearing sleeve wear•
Generator set misalignment•
Excessive generator set vibration•
Extreme high or low operating temperatures•
Bearing bracket misalignment•
Bearing retainer bar hardware loose•
Excessive electrical shaft current•
Poor ventilation•
Excessive bearing wear•
End of lifetime•
Bearing replacement is suggested if any of the following conditions are found:
(34) Polyethylene (protective) strips used during generator service, removed for operation
(35) Main rotor
(36) Main rotor leads
Illustration 7 g02707657
(40) Grease fitting for lubricant on 7000 frame generator
Procedure for Bearing ServicePerform periodic bearing lubrication at the intervals that are shown in Table 1. Use the following instructions as the suggested procedure in order to service the bearings of the generator.
Note: If the generator already has a visible grease point, go to Step 4.
Stop the generator set. Remove the required external cover plates, grills, and louvers of the generator in order to access the bearings.
1.
Remove the top grease pipe plug and the lower grease pipe plug. If no grease pipes can be found, then locate the insert for the grease pipe. The insert is located on the bearing brackets. Remove the inserts. Install the grease pipes.
2.
Install a grease fitting in the top grease pipe.3.
Use a Cat® 8F-9866 Grease Gun or equivalent grease gun to grease the bearings. Use the appropriate type of grease and the quantity that is listed in Table 1. Avoid the use of alternate types of grease. Usage of alternate types of grease could cause premature bearing failure.
4.
Note: Add only the amount of grease listed in Table 1. Do not continue to add grease until purging is observed. Purging of grease will not always be observed.
If grease fittings are permanently installed, ensure that the protective caps for the grease fittings are installed on the fittings when finished. If a grease fitting was installed in Step 2, remove the top grease fitting and install the plug that was removed. If applicable, do not install the plug on the bottom grease location yet. Wipe off the excess grease.
5.
Note: Do not allow grease to drip on the stator windings of the generator. The stator windings that are exposed to grease could suffer degraded insulation. The degraded insulation would cause a reduction in the life of the windings.
Operate the generator set at rated speed for approximately 1 hour. When running the engine more than 30 minutes, the recommended engine load to apply is a minimum of 50%. The procedure will allow the grease to expand. The expanding grease will force the excess grease from the cavity. The internal pressure will be reduced as the excess grease is forced from the cavity. Operate the generator until no grease is forced out of the cavity.
6.
Stop the generator set. Inspect the generator windings, grease tubes, and bearing housings. Wipe off any excess grease. If a grease pipe plug was removed in Step 2, install the plug in the bottom grease pipe. Wipe off any excess grease.
7.
Note: Do not allow grease to drip on the stator windings of the generator. The stator windings that are exposed to grease could suffer degraded insulation. The degraded insulation would cause a reduction in the life of the windings.
Install all of the external cover plates, grills, and louvers of the generator that were removed in order to access the bearings.
( 1 ) Indicates the alarm temperature set point that the bearing should be continuously operated at on the specified generator frame size. Shutdown set points are typically 10° C (18° F) higher.
( 2 ) 1800 frame generators and 3000 frame generators shipped before 2012 use double-shielded bearings with EA6 grease. There are no threaded holes in the bearing brackets for the grease tubes that are used to add grease. Therefore, no grease can be added to the bearings. Beginning in 2012, 1800 frame generators and 3000 frame generators that are shipped will use a single-shielded bearing with 2S-3230 grease. The front and rear brackets contain factory installed grease fittings, therefore, single-shielded bearings must be lubricated periodically. Reference the Parts Manual with package serial number to identify the bearing part number and to determine bearing lubrication requirements.
( 3 ) All 2700 and 2600 frame generators, regardless of ship date, as well as 1800 and 3000 frame generators shipped beginning in 2012, use a single-shielded bearing design. Replacement bearings received from the Parts Division will have a shield on each side of the bearing. The shield facing the outside of the generator must be removed when the new bearing is installed.
( 4 ) Grease cannot be added to this bearing. Refer to the Operation and Maintenance Manual, "Generator Bearing - Replace" article for information concerning the replacement of these bearings.
( 5 ) The generator uses a non-shielded bearing design. Although replacement bearings may have a shield on each side, both shields must be removed when the new bearing is installed. Replacement bearings are shipped as dry bearings and must be packed to 50% grease fill at time of installation.
Bearing Replacement
Refer to the appropriate publication for each specific generator for bearing replacement procedures.
Replace both bearings of a two-bearing generator.
Replace any bearing wear sleeves and lip seals when the bearings are replaced.
Except for the 341-7383 Ball Bearing , replacement bearings are pre-lubricated. The pre-lubricated bearings do not require additional grease at time of replacement. The 341-7383 Ball Bearing is shipped as a dry bearing. The 341-7383 Ball Bearing must be packed to 50% grease fill at time of installation.
Old grease must be removed at the time of bearing replacement from the bearing bracket cavity. After the bearing bracket cavity is cleaned, the bearing bracket cavity must be packed with new grease from one-third to one-half full.
Note: Generator set alignment is required after the bearings are replaced.
