Scope. This standard makes recommendations relating to limits of size of parts or components and to fits constituted by their assembly.
Symbols. Following symbols are used in this standard,
Upper deviation of a hole ES (Ecart Superieur)
Lower deviation of a hole EI (Ecart Inferieur)
Upper deviation of a shaft es
Lower deviation of a shaft ei
Fits. When the parts are to be assembled, the relation resulting from the differences between the sizes before assembly is known as Fit. Depending up on the limits of the hole or shaft, the fit may be a clearance, a transition or an interference.
Hole Basis System. In this standard, the different clearances and interferences are obtained in associating various shafts with a single hole, whose upper deviation is zero and the symbol is H.
Shaft Basis System. In this, the different interferences and clearances are obtained in associating various shafts with a single shaft, whose upper deviation is zero and the symbol is h.
Indication of Fit. A fit is indicated by the basic size common to both components followed by symbols corresponding to each component, the hole being quoted first.
Eg : 40 H7/g 6 or 40 H 7 – g 6   _{Your Comment}