A steel shaft ABCD of circular section is 2 m long and is supported in bearings at the ends A and D. AB =0.75 m. BC= 0.5 m. CD=0.75 m. The shaft is horizontal, and two horizontal arms, rigidly connected to it at B and C. project at right angles on opposite sides. Arm B carries a vertical load of 2000 kg at 0.333 m from the shaft axis, and C carries a vertical balancing load at 0.417 m from the axis. If the shear stress is not to exceed 80 MN/m find the minimum diameter of shaft. Assume the bearings give simple support.