The mean diameter of the square threaded screw having pitch of10 mm is 50 mm. A load of 20 kN is lifted through a distance of 170mm. Find the work done in lifting the load and the efficiency ofthe screw, when
1. The load rotates with the screw, and
2. The load rests on the loose head which does not rotate with thescrew.
The external and internal diameter of the bearing surface of theloose head are 60 mm and 10 mm respectively. The coefficient offriction for the screw and the bearing surface may be taken as0.08.
