Two railway coaches are coupled with the help of two tie rods of a turn buckle with right and left handed threads having single-start square threads. Pitch and mean diameter of the threads are 8 mm and 30 mm respectively. How much energy will be spent in bringing two coaches closer through a distance of 320 mm against a steady load of 5.0 kN. Use coefficient of friction in screw thread and coupler nut as 0.12. Determine shear stress on the tie rod due to above torque.