complex mechanical design of shaft

A solid steel shaft is supported on two bearings 1.8 m apart and rotates at 250

r.p.m. A 20° involute gear D, 300 mm diameter is keyed to the shaft at a distance of 150 mm to the left

on the right hand bearing. Two pulleys B and C are located on the shaft at distances of 600 mm and

1350 mm respectively to the right of the left hand bearing. The diameters of the pulleys B and C are

750 mm and 600 mm respectively. 30 kW is supplied to the gear, out of which 18.75 kW is taken off at

the pulley C and 11.25 kW from pulley B. The drive from B is vertically downward while from C the

drive is downward at an angle of 60° to the horizontal. In both cases the belt tension ratio is 2 and

the angle of lap is 180°. The combined fatigue and shock factors for torsion and bending may be

taken as 1.5 and 2 respectively.

Design a suitable shaft taking working stress to be 42 MPa in shear and 84 MPa in tension