Two solid steel shafts are

connected by gears $B$ and $C.$

Knowing that for each shaft $G=$

$70$GPa and that the allowable

shearing stress is $40$MPa.

Determine

$($a$)$ the largest torque $T_0$ that may

be applied to the end of shaft

$CD,$

$($b$)$ the corresponding angle

through which end D of shaft

CD rotates