The cast-iron bell-crank lever depicted in the figure is acted upon by forces F1 of 2.36 kN and F2 of 3.48 kN. The section A-A at the central pivot has a curved inner surface with a radius of r;= 25 mm. Estimate the stresses at the inner and outer surfaces of the curved portion of the lever. Take D₁ = 200 mm and D2 = 150 mm. D1 mm 87 60° 25 Nylon bushing 9 25 R. D2 mm 31 28 F₂ 47 Section A-A The stresses at the inner and outer surfaces of the curved portion of the lever are estimated to be respectively. MPa and MPa,