The shaft, as shown in Fig. $(3),$ is driven by pulley $B$ from an electric motor. Another belt drive from pulley $A$ is running a compressor. The belt tensions for pulley A are $1500N$ and $600N.$ The ratio of belt tensions for pulley $B$ is $3\mathrm{.}5.$

rig. $($v$)$

The diameter of pulley $A$ is $150mm$ and the diameter of pulley $B$ is $480mm.$ The allowable tensile stress for the shaft material is $170$MPa and the allowable shear stress is $85$ MPa. Taking torsion and bending factors as $1\mathrm{.}25$ and $1\mathrm{.}75$ respectively, find the shaft diameter. Also find out the dimensions for a hollow shaft with outside diameter limited to $30mm.$ Compare the weights of the two shafts.

$[$Ans$.30mm$;$24mm$;$1\mathrm{.}82]$