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book: vector mechanics for engineers: statics 9th ed. Question: 8.72 In the mach

ID: 2992052 • Letter: B

Question

book: vector mechanics for engineers: statics 9th ed.

Question: 8.72

In the machinists's vise shown, the movable jaw D is rigidly attached to the tongue AB that fits loosely into the fixed body of the vise. The screw is single-threaded into the fixed base and has a mean diameter of 0.75 and a pitch of 0.25. The coefficient of static friction is 0.25 between the threads and also between the tongue and the body. Neglecting bearing friction between the screw and the movable head, determine the couple that must be applied tothe andle in order to produce a clamping force of 1 kip.

Explanation / Answer

Br=540N, Qr(H comp)=,L=2p=4 mm,pi x d=12 x pi mm,

=tan-1 (4/12pi)=6 deg , s= tan-1 s=19.29 deg.

s+= 25.3466 deg

Qr=540xtan 25.3466 deg= 255.80 N

Couple= rx Q =6mm X 255.80 =1535 N mm.

M=1.535 Nm.