21. A shaft made of 40 C 8 steel is used to drive a machine. It rotates at 1500 rp.m. The pulleys.A, B and the bearings C, D are located as shown in Fig. 14.21.

The belt tensions are also shown in the figure. 350N 165 N 330 N 135 N 45 200 300 200 200 All dimensions in mm. Fig. 14.21 Determine the diameter of the shaft. The permissible shear stress for the shaft material is 100 MPa. The combined shock and fatigue factor applied to bending and torsion are 1.5 and 1.2 respectively.

350 N 165 N 330 N A B 135 N C D 45 200 -200- 300 +200- 300 All dimensions in mm. Fig. 14.21 B.