Ball and Roller Bearings

GENERAL INFORMATION

03-7

General inspection
All components should be inspected for wear or 
damage before being reassembled.

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Never inspect a component for wear or 
dimensional check unless it is absolutely clean; 
a slight smear of grease can conceal an 
incipient failure.

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When a component is to be checked 
dimensionally against recommended values, 
use the appropriate measuring equipment 
(surface plates, micrometers, dial gauges etc.). 
Ensure the measuring equipment is calibrated 
and in good serviceable condition. 

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Reject a component if its dimensions are 
outside the specified tolerances, or if it appears 
to be damaged.

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A part may be refitted if its critical dimension is 
exactly to its tolerance limit and it appears to be 
in satisfactory condition. Use 'Plastigauge' 12 
Type PG-1 for checking bearing surface 
clearances.

Ball and Roller Bearings

General
When removing and installing bearings, ensure that 
the following practices are observed to ensure 
component serviceability.

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Remove all traces of lubricant from bearing 
under inspection by cleaning with a suitable 
degreasant; maintain absolute cleanliness 
throughout operations.

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Conduct a visual inspection for markings on 
rolling elements, raceways, outer surface of 
outer rings or inner surface of inner rings. Reject 
any bearings found to be marked, since marking 
in these areas indicates onset of wear.

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Hold inner race of bearing between finger and 
thumb of one hand and spin outer race to check 
that it revolves absolutely smoothly. Repeat, 
holding outer race and spinning inner race.

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Rotate outer ring gently with a reciprocating 
motion, while holding inner ring; feel for any 
check or obstruction to rotation. Reject bearing 
if action is not perfectly smooth.

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Lubricate bearing with generous amounts of 
lubricant appropriate to installation.

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Inspect shaft and bearing housing for 
discoloration or other markings which indicate 
movement between bearing and seatings.

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Ensure that shaft and housing are clean and 
free from burrs before fitting bearing.

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If one bearing of a pair shows an imperfection, it 
is advisable to replace both with new bearings; 
an exception could be if the faulty bearing had 
covered a low mileage, and it can be 
established that damage is confined to only one 
bearing.

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Never refit a ball or roller bearing without first 
ensuring that it is in a fully serviceable condition.

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When hub bearings are removed or displaced, 
new bearings must be fitted; do not attempt to 
refit the old hub bearings.