A ${1\mathrm{.}5}^{\text{'}\text{'}}$ outer diameter power screw has double square threads with a pitch of $\frac{1}{4^{\text{'}\text{'}}}.$ The nut is to move a load of $F=$

$6828$ Ibf. The frictional coefficients are $0\mathrm{.}10$ for the threads and $0\mathrm{.}15$ for the collar. The frictional diameter of the collar is $2\mathrm{.}25".$

Find the torque required to drive the power screw.