A machine vice whose length of the handle is 150mm and the coefficient of friction for thread and collar are 0.15 and 0.17 respectively has a force applied at handle of 125N. Also the outer and inner diameters of collar are 55mm and 45mm respectively. Find the screw torque in terms of clamping force W if nominal diameter=22mm and pitch=5mm.

Correct Answer: 2.286W N-mm
M₁=Wd x tan(Ǿ+ἀ)/2 or M₁=W x (22-0.5×2.5)x tan(4.66’+8.531’)/2 as tan(ἀ)=l/πd and tanǾ=0.15.