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What function do bearings serve within a generator or motor?
They are designed to allow a rotating armature or rotor to turn freely within the motor.
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What are the two most common types of bearings found in motors and generators?
Friction and Antifriction bearings.
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What are two types of antifriction bearings?
Roller or Ball type.
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What type of bearing consists of two hardened steel rings, hardened steel rollers or balls and separators?
Antifriction bearing.
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What is the difference between a ball bearing and a roller bearing?
A ball bearing carries the load on two tiny spots diametrically opposite, while a roller carries the load on two narrow lines.
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Determining which type of ball or roller bearing to use is dependent on what factor?
By the load it was designed to carry.
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What are the three forces that can effect ball or roller bearings?
Radial, axial thrust, and angular contact.
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A load that is a result of forces applied to the bearing perpendicular to the shaft is known as what type offeree?
Radial.
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A combination of radial and thrust loads create what type offeree on a bearing?
Angular.
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What type of bearing would be installed on a vertically mounted motor?
thrust bearing.
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Horizontal motors use what type of motor bearings?
Radial bearings.
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What type offeree is the result offerees applied to the bearing parallel to the shaft?
Thrust.
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What is the easiest way to determine bearing wear on an operating motor?
By periodically feeling the bearing housing for overheating or excessive vibration.
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A simple way to sound test a bearing is by what method?
By placing one end of a screwdriver against the bearing housing and the other end against the ear.
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Motor bearings are lubricated IAW what technical guidance?
PMS.
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Most motor bearings are lubricated within what periodicity?
Annually.
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What NSTM can be used to find general information on all types of bearings?
NSTM 244.
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How do manufacturers' identify bearings?
By use of a three digit basic bearing number.
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Bearings should be stored in a dry environment and never exceed what storage temperature?
120 Deg. F.
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If a high bearing temperature is reached within the first 10 to 15 minutes of operation this can indicate what?
A serious overheating problem.
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A motor shaft that has no vertical movement is an indication of what?
Worn bearings.
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Excessive end-play on a generator can be corrected by what?
By adding shims.
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What are two methods of bearing installation?
Arbor press and heat method.
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When using the arbor press method to install a bearing onto a shaft, pressure is always applied to what part of the bearing?
To the inner ring.
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When pressing a bearing into a housing using the arbor press method, pressure is applied to what part of the bearing?
The outer ring.
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When heating a bearing in a temperature-controlled furnace, the temperature must never exceed?
203 Deg. F +-10 F.
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What are three types of friction bearings?
Right line, journal and thrust.
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Prolonged heating of a bearing in a temperature-controlled oven could have what detrimental effect?
Deterioration of the prelubrication grease.
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How can you determine bearing wear on a sleeve bearing?
By measuring the air gap at each end of the machine.
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When removing bearings from a motor using an arbor press care should taken to place the flat steel blocks in what location?
Under the inner ring.
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When renewing grease on a bearing with outer bearing caps, what type of oil is used to flush the bearing cap upon disassembly?
2190 TEP.
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Do permanently lubricated bearings require periodic grease renewal?
Never add lubricate to this type of bearing.
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How is a bearing removed that has seized to an operating shaft?
By use of a cutting wheel.
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