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85 Cards in this Set
- Front
- Back
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What is a friction bearing?
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Is a plain bearing that does not have any rolling element. Consists of the housing, the bearing, the lubricant and the shaft.
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What is an anti-friction bearing?
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Bearing that has some type of rolling element
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What is the main function of a bearing?
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A device that reduces friction between 2 surfaces while supporting a load. Reduces friction, provides a replaceable wear surface AND guide and support a load.
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What are three major plain bearing types?
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Journal, Thrust, Linear
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What are some typical plain bearing materials?
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Brass, Bronze, Babbitt, Steel, PTFE, Plastic, Nylon, Wood, Rubber, etc...
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Define: CLEARANCE FIT
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The fit between a bearing and a shaft or a bearing and a housing that leaves space between parts (enables clearance).
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Define: INTERFERENCE FIT
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The fit between a bearing and a shaft or a bearing and a housing that has overlap between parts.
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Why would you measure the bore of a bearing?
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To ensure it will fit onto the shaft (cold install) or expand with heat far enough to fit (thermal install).
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Why would you measure the outer race diameter of a bearing?
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To ensure it will fit inside of the housing (cold install) or shrink enough in a thermal install.
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What are the different ways to install a bearing on a shaft or in a housing?
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Cold (mechanically), Hydraulic (pressure or oil is forced between sleeves), and Thermal (heating or freezing).
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How do the load and speed characteristics of ball and roller bearings differ?
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Ball bearings have higher speed/lower load capability. Roller bearings have a higher load/lower speed capability.
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What three types of loads do bearings support?
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Radial loads, axial (thrust) loads, and combination loads.
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Contrast a static versus a dynamic load. How are they different from each other?
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A static load is a load placed on a bearing in a non-running condition. A dynamic load, generally less than the static load, occurs while the bearing is in operation.
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What specific type of load would a journal bearing support?
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Radial load
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What specific type of load would a thrust bearing support?
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An axial load in one direction
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Give an example of a radial load on a shaft in a WTG.
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The weight of the hub/rotor, or the weight of a rotor, gears on a shaft in the gearbox
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What two methods are used to preload a bearing?
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Fixed position or constant pressure
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What are four typical causes of damage to a bearing?
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Lubricant problems, improper installation, overloading, and misalignment.
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How should a brand new bearing be stored away?
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Unopened in its original packaging; in a clean, dry and temperate storage area.
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What are the four major types of roller bearings?
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Cylindrical, Spherical, Tapered, Needle
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As the temperature of a direct mount tapered roller bearing increases, what happens to the end float on the shaft?
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End float (end play) decreases
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Why must a tapered roller bearing be adjusted?
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To control the amount of clearance inside the bearing
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What is the MAX temperature to which a beariing may be heated?
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250F, 121C, unless otherwise specified b the manufacturer
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What is the function of a gasket and what are some typical gasket materials?
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Prevent leakage of gases or fluids; paper, rubber, silicone, cork, metal, plastic, teflon, nitride, fiberglass. HNBR and EPDM are common in wind.
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What is one thing that ALL rolling element bearings require?
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Lubrication
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What is the safest method for measuring temperature?
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IR: non-contact infrared thermometers
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What would cause an O-ring to become swollen or distorted?
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Harmful or improper chemicals
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What is one of the most common causes of seal failure?
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Incorrect installation
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What is the purpose of a seal in a sealed ball bearing?
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Keeps the lubrication in and contaminants out
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From what type of materials is an O-ring made?
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Elastomeric
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What is used to prevent oil from leaking between the housing and the rotating shaft?
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Lip seal
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Grease guns are used to lubricate a bearing in conjunction with what item?
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Zerk fitting
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What specific type of damage to a bearing is caused by electricity?
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Fluting
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Why are oil samples taken from a garbox?
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To monitor oil contamination, metals and wear debris
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An oil temperature sensor is used for what purpose?
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Generate alarms and controls the cooling fan
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What determines the frequency of grease delivery from an auto-lubrication system
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A pre-determined time schedule
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What four factors affect the choice of lubricant?
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Speed, load, operating temperature, open or closed housing.
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Which way does a lip seal face?
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Open side towards the lubricant
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What does a lip seal do?
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Retains the lubricant, Seperates two different media, Seals under pressure, and excludes dirt and moisture.
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On a bearing, what is the inner diameter of the inner race typically called?
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Bore
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What are the five ball bearing types?
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Deep groove, Angular contact, Self-aligning, Thrust, Max-load/Slot-filled
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What are the four types of bearing housings?
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Pillow block, flanged, built-in, machined
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With what type of preload device would a floating housing be used?
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Constant pressure
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Give three examples of preload mechanisms
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Snap ring (position), Spring (constant pressure), Wave washer (constant pressure).
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Bearings up to a size of ______ outside diameter can be cold mounted.
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4" (10.16cm)
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What methods can be used to remove ball bearings?
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Arbor press, sleeve and hammer, hydraulic, thermal
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What does each section represent in this example of a ball bearing specification.
6 - 2 - 09 - RSR - C3 |
6 - Bearing type
2 - Dimension series (indicator of bearing size) 09 - Bore size (04 and up, multiply code by 5mm) RSR - Features (shields, seals, type of retainer) C3 - Internal clearance (clearance between the balls and the inner and outer races) |
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What common type of damage to a bearing initially appears as small craters or "potholes" due to metal fatigue?
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Flaking (spalling)
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Acid formation or moisture in the lubricant can cause a bearing to ________.
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Corrode
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What type of damage can be caused by hammer blows?
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Cracks (Shock loads)
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The area of the shaft supported by the bearing is called the _______.
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Journal
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What are the two types of lubrication for plain bearings?
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- Hydrostatic: lubricated by an external pump, maintains a static amount of pressure.
- Hydrodynamic: Pressure in the oil film is maintained by the rotation of the journal, lubrication does not occur until rotation of the shaft |
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What type of bearings often have grooves to distribute lubricant?
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Plain bearings
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In hydrodynamic lubrication, what condition is often presented when a lubrication wedge fails to form?
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Oil whirl or oil whip. Leads to direct contact beween the journal and the bearing.
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What are the three stages of Hydrdynamic lubrication?
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Metal-to-metal contact, Boundary lubrication, Full-film lubrication
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In plain bearing classification, what do the letters d, D, and B represent?
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d - bore
D - outside diameter B - width |
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What are the three type of bearing fits?
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Interference, Clearance, Transition
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What are the manufacturing tolerances for ball bearings for size and roundness?
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Size - .00001" (hundred thousandth)
Roundness - .000005" (millionth) |
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What is bearing "preload"?
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An axial load on the bearing. Applied during installation. Increases stiffness of bearing alignment. Creates a "negative clearance" inside the bearing.
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What three intances are thermal fits used?
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For non-threaded components, when requiring a strong secure fit, and when shaft/bearing/housing must stay in place throughout normal operation.
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Indirect mount ______ end float
Direct mount _______ end float |
Indirect increases, Direct decreases
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What are the parts of a tapered bearing?
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Cone, Cup, Cage, Rollers
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What are the four types of roller bearings?
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Spherical, Cylindrical, Needle, Tapered
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What hardware can be used to remove a tapered roller bearing?
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Seperator + press; Puller only if you remove cup.
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What bearings do not usually have an inner race?
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Needle
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The inner race of a tapered roller bearing is called the ____ , and the outer race is called the _____.
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Cone, Cup
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______ a bearing means control the play between the cup and cone.
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Adjusting
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What does a gasket do?
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Fills the space between two mating surfaces. Prevent leakage of gases or fluids from or into the joined objects while under compression.
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What are some typical gasket materials?
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Paper, rubber, silicone, metal, cork, felt, nitrile rubber
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What is a recommended way to remove an o-ring?
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Using a pick or hook
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What are o-rings typically made out of?
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Elastomer rubber
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What is a common sign of a failing gasket or o-ring?
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Leaking, appearence, contamination
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What is the difference between a static and dynamic o-ring application?
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Static - used between mating surfaces which do not move
Dynamic - used when surfaces move relative to eachother |
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What are four purposes of a lip seal?
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Retain the lubricant, Seperate two different media from eachother, Seperate fluids under pressure, Exclude dirt moisture or other contaminents
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Where would you typically see a lip seal?
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Dynamic loads (radial, rotary)
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Where would you typically see an o-ring?
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compressional loads
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What is a common cause of seal failure?
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improper installation
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Which side of the lip seal faces the lubricant?
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Facing the side in which the lubrication is present.. garter spring toward lube.
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What can improper chemicals do to an o-ring?
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Swell or distort
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Define viscosity
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A measure of the resistance of a fluid which is being deformed by either shear stress or tensile stress.
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What are four factors when selecting lubricant for a bearing application?
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Open or closed housing, Speed, Load, Operating temperature
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What are three basic lubrication types?
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Grease, oil, dry
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What does a bearing lubricant do?
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Reduces friction, Reduces and transports heat away from points of a high load, transports foreign particles away from the conrtact surface/race of bearing.
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Examples of radial, thrust, and linear
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Radial - weight
Thrust - wind on a turbine Linear - loads that slide, moves in a line. |
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If you have a tandem tapered bearing configuration, whar needs to be done?
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Need a bearing facing in the opposite direction of th tandem bearings.
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