Table of Contents
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FOREWORD
2.
Standard clearance and standard value
•
The clearance made when new parts are as-
sembled is called the "standard clearance",
which is indicated by the range from the min-
imum clearance to the maximum clearance.
•
When some parts are repaired, the clear-
ance is generally adjusted to the standard
clearance.
•
A value of performance and function of new
products or equivalent is called the "standard
value", which is indicated by a range or a tar-
get value.
•
When some parts are repaired, the value of
performance/function is set to the standard
value.
3.
Standard interference
•
When the diameter of a hole of a part shown
in the given standard size and tolerance ta-
ble is smaller than that of the mating shaft,
the difference between those diameters is
called the "interference".
•
The range (A – B) from the difference (A) be-
tween the minimum size of the shaft and the
maximum size of the hole to the difference
(B) between the maximum size of the shaft
and the minimum size of the hole is the
"standard interference".
•
After repairing or replacing some parts,
measure the size of their hole and shaft and
check that the interference is in the standard
range.
4.
Repair limit and allowable value or allowable
dimension
•
The size of a part changes because of wear
and deformation while it is used. The limit of
changed size is called the "repair limit".
•
If a part is worn to the repair limit, it must be
replaced or repaired.
•
The performance and function of a product
lowers while it is used. A value which the
product can be used without causing a prob-
lem is called the "allowable value" or "allow-
able dimension".
•
If a product is worn to the allowable value, it
must be checked or repaired. Since the per-
missible value is estimated from various
tests or experiences in most cases, howev-
er, it must be judged after considering the
operating condition and customer's require-
ment.
PC200/220(LC)-7
EXPLANATION OF TERMS FOR MAINTENANCE STANDARD
5.
Clearance limit
•
Parts can be used until the clearance be-
tween them is increased to a certain limit.
The limit at which those parts cannot be used
is called the "clearance limit".
•
If the clearance between the parts exceeds
the clearance limit, they must be replaced or
repaired.
6.
Interference limit
•
The allowable maximum interference be-
tween the hole of a part and the shaft of an-
other part to be assembled is called the
"interference limit".
•
The interference limit shows the repair limit
of the part of smaller tolerance.
•
If the interference between the parts ex-
ceeds the interference limit, they must be re-
placed or repaired.
00-11
(14)
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