$1$

A single$-$threaded power screw is $25$ mm in diameter with a pitch of $5$ mm $.$ A vertical load on the screw reaches a maximum of $6$ kN $.$ The coefficients of friction are $0\mathrm{.}150$ for the collar and $0\mathrm{.}050$ for the threads. The frictional diameter of the collar is $53\mathrm{.}0$ mm $.$ Find the overall efficiency and the torque to$-$raise and lower the load.

The overall efficiency is The torque to raise the load is $\%.$

The torque to lower the load is $q,kN*mm.$

$q,$ kN$-$mm$.$