Question

A shaft of 80 mm dia is made to rotate in a bush. The tolerances for both the shaft and bush are 0.06 mm. Give a maximum clearance of 0.13 mm.
The allowance for the assembly is

• A. 0.06 mm
• B. 0.13 mm
• C. 0.012 mm
• D. 0.01 mm

Answer 1

The correct option is D 0.01 mm

U.L of hole - L.L of hole = 0.06 mm

U.L of shaft-L.L of shaft = 0.06 mm

Max clearance = U.L of hole - L.L of shaft

= 0.13 mm

As it is a hole based system,

$\text{Hole size will be}80\begin{array}{c}+0.06\\ +0.00\end{array}$

$\therefore$U.L of hole-0.13 mm = L.L of shaft

80.06 - 0.13 mm = L.L of shaft

L.L of shaft = 79.93 mm

$\therefore$U.L of shaft = L.L of shaft + 0.06mm

=79.99 mm

Allowance of assembly

= L.L of hole - U.L of shaft

=80.00- 79.99 = 0.01 mm