A clock face system is sometimes used as an alternative method of indicating the strength grade. The external chamfers or
a face of the nut is marked in a position relative to the appropriate hour mark on a clock face to indicate the strength
grade.
A dot is used to locate the 12 o'clock position and a dash to indicate the strength grade. If the grade is above 12, two
dots identify the 12 o'clock position.
When tightening a slotted or castellated nut, never loosen it to insert a split pin except where specified as part of an
adjustment procedure. If difficulty is experienced in correctly positioning the slot, alternative washers or nuts should be
selected.
Where a nut is tightened to adjust or maintain bearing pre-load, the tightening procedure must be adhered to.
Self-locking nuts
Unless stated otherwise, self-locking nuts once removed must be discarded and new nuts of the same type and strength
grade installed.
Ball and Roller Bearings
When removing and installing bearings, make sure that the following practices are observed to make sure component
serviceability:
CAUTION: Service tools have been developed for removing the majority of bearings; these must always be used
where specified.
Remove all traces from bearing under inspection by cleaning with a suitable degreasant; maintain absolute
cleanliness throughout operations.
Conduct a visual inspection for markings on rolling elements, raceways, outer surfaces of outer or inner surfaces of
inner rings. Reject any bearings found to be marked since marking in these areas indicates onset of wear.
Hold inner race of bearing between finger and thumb of one hand and rotate outer race to check that it revolves
absolutely smoothly. Repeat holding outer race and rotating inner race. DO NOT spin the bearing.
Rotate outer ring gently using a reciprocating movement whilst holding inner ring; feel for any check or obstruction
to rotation. Reject bearing if movement is not absolutely smooth.
Check bearing for blueing or signs of overheating.
Lubricate bearing with the specified lubricant.
Inspect bearing surface of shaft and bearing housing for discoloration or other markings which indicate overheating
of bearing or movement between bearing and seating.
Before installing bearing, make sure that shaft and bearing housing are clean and free from burrs.
If one bearing of a pair shows signs of wear, overheating etc., it is advisable to replace bearings as a pair unless it
is suspected that one bearing may have been faulty when installed, was installed incorrectly or the fault arose due
to oil seal failure.
Never reinstall a bearing unless it is in a fully serviceable condition.
When installing a bearing to a shaft, only apply force to the inner ring of the bearing. When installing a bearing
into a housing, only apply force to the outer ring of the bearing.