Ball Bearing on the shaft
Driving Fit - When a plug or a shaft is made slightly larger than the hole into which it is to be inserted and the allowance is such that the parts can be assembled by driving, this is known as driving fit.
Ball bearing on the shaft is the best example for driving fit.
Cart rim on the wooden wheel
Best example for shrinkage fit is Cart rim on the wooden wheel.
Shrinkage fit A shrinkage fit is obtained by making the shaft (internal member) slightly larger than the hole (external member). In shrinkage fit, pressure is not required for assembling but instead the hole (external member) is heated and expanded sufficiently to permit the shaft (internal member) to be inserted easily. Then the hole (external member) is cooled to shrink tightly around the shaft (internal member).
The size of the hole is made constant
In Hole basic system the size of the hole is made constant, different fits is obtained by varying shaft size.
Produce the parts within the required permissible size error
It is impossible to make anything to an exact size, therefore, it is essential to allow a definite tolerance or permissible variation on every specified dimension. Hence Tolerance is given to the part size to produce the parts, within the required permissible size error.
IT01, IT0, IT1 to 16
As per BIS system of Limits and fits, there are 18 grades of tolerances represented by number symbols from IT01, IT0, IT1 to 16.