In: Mechanical Engineering
The mean diameter of the square threaded screw having pitch of
10 mm is 50 mm. A load of 20 kN is lifted through a distance of 170
mm. Find the work done in lifting the load and the efficiency of
the screw, when
1. The load rotates with the screw, and
2. The load rests on the loose head which does not rotate with the
screw.
The external and internal diameter of the bearing surface of the
loose head are 60 mm and 10 mm respectively. The coefficient of
friction for the screw and the bearing surface may be taken as
0.08.