A single-thread standard power screw of 30 mm mean diameter and 4 mm pitch, has a collar of 40 mm mean diameter. Thread and collar coefficients of friction are f= 0.15 and fc = 0.1, respectively. Assume that a load of F = 100 kN is acting on the power screw. For a square-thread power screw: 1) Find the torque necessary to raise and lower the load (T and T) including the collar, and efficiency of the power screw for raising the load (e). Also check the self-locking condition for the power screw during lowering. Note: A power screw is said to be self-locking during lowering the load when T> 0. For an ACME-thread power screw: 2) Find the torque necessary to raise and lower the load (TR and TL) including the collar, and efficiency of the power screw for raising the load (e). Also check the self-locking condition for the power screw during lowering.