SEN00056-01 00 Index and foreword Explanation of terms for maintenance standard 1 The maintenance standard values necessary for judgment of products and parts are described by the follow- ing terms. 1. Standard size and tolerance q To be accurate, the finishing size of parts is a little different from one to another. q To specify a finishing size of a part, a tem- porary standard size is set and an allow- able difference from that size is indicated. q The above size set temporarily is called the “standard size” and the range of differ- ence from the standard size is called the “tolerance”. q The tolerance with the symbols of + or – is indicated on the right side of the standard size.
Example: a The tolerance may be indicated in the text and a table as [standard size (upper limit of tolerance/lower limit of tolerance)]. Example) 120 (–0.022/–0.126) q Usually, the size of a hole and the size of the shaft to be fitted to that hole are indi- cated by the same standard size and dif- ferent tolerances of the hole and shaft. The tightness of fit is decided by the toler- ance. q Indication of size of rotating shaft and hole and relationship drawing of them Example: 8 D65EX, PX, WX-15E0 Standard size Tolerance 120 –0.022 –0.126 Standard size Tolerance Shaft Hole 60 –0.030 –0.076 +0.046 +0