Question $3$

Fig. $3$

A screw press is required to exert a force of $50$ kN when applied torque is $560$ Nm $.$ The uhisupportas length of the screw is $450$ mm and a thrust bearing of hardened steel on Cast$-$tron isprovinged athet power end.

The permissible stresses in the steel screw are:

$-$ Tension and compression $85$ MPa, Shear $55$ MPa $.$

$-$ The permissible bearing pressure is $13\mathrm{.}5$ MPa for steel screw and Cast$-$lron material

$-$ The permissible shearing stress in the Cast$-$Iron is $20$ MPa

$-$ The yield strength of steel of screw is $\backslash (\backslash$mathbf$\{260\}\backslash$mathbf$\{$~ M P a$\}\backslash )$

$-$ The coefficient of friction in screw and nut is $0\mathrm{.}15$

Determine the dimensions of screw and nut, and efficiency.