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00 Index and foreword
Explanation of terms for maintenance standard
Repair limit and allowable value or allowable
dimension
The dimensions of parts change because of the
q
wear or deformation while they are used. When
the dimension changes exceeding certain value,
the parts can not be used any longer. This value
is called "repair limit".
If a part is worn to the repair limit, it must be re-
q
placed or repaired.
The performance and function of the products
q
lower while they are used. When the value of the
performance and function lowers exceeding a
certain limit and it influences the operation etc.,
this value is called the allowable value or allow-
able dimension.
A product whose dimension is out of the allow-
q
able value, must be repaired. However, since
the allowable values are generally estimated
through various tests or experiences in most
cases, the judgement must be made in consider-
ation of the operating condition and customer's
requirement.
Allowable clearance
Parts can be used until the clearance between
q
them is increased to a certain limit. The limit at
which those parts cannot be used is called the
"allowable clearance".
If the clearance between the parts exceeds the
q
allowable clearance, they must be replaced or
repaired.
Allowable interference
The allowable maximum interference between
q
the hole of a part and the shaft of another part to
be assembled is called the "allowable interfer-
ence".
The allowable interference shows the repair limit
q
of the part of smaller tolerance.
The parts whose interferences are out of the al-
q
lowable interference must be replaced or re-
paired.
00-24
WA200-7
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