Beer & Johnston — Torsion: Problem 3.23

3.23 Under normal operating conditions a motor exerts a torque of magnitude \( T_F \) at \( F \). The shafts are made of a steel for which the allowable shearing stress is \( 12 \text{ ksi} \) and have diameters \( d_{CDE} = 0.900 \text{ in.} \) and \( d_{FGH} = 0.800 \text{ in.} \) Knowing that \( r_D = 6.5 \text{ in.} \) and \( r_G = 4.5 \text{ in.} \), determine the largest allowable value of \( T_F \).