A mechanic uses a crowfoot wrench to loosen a bolt at E. Knowing that the mechanic applies a vertical 18-lb force at A, determine the -in. diameter shaft. (Round principal stresses and the maximum shearing stress magnitude at point located as shown on top of the the final answers to two decimal places.) E V H 10 in. 6 in. B The maximum principal stress is Omax The maximum shearing stress magnitude is ksi and the minimum principal stress is min ksi. II ksi (+ tensile; - compressive).