The GATE Grind

GATE 2022 AG – Question 51

Farm Power · Farm Power · 2 marks · Numerical answer

An engine crank radius is 250 mm and connecting rod length1000 mm. At100° from head dead centre, net piston force along motion is 35 kN. Find crank torque in kN m, to two decimals.

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Correct answer: 8.00 to 8.50

Explanation

Rod obliquity satisfies $\sin\beta=(r/l)\sin\theta=.25\sin100^\circ$, hence β≈14.25°. Tangential crank force is $F\sin(\theta+\beta)/\cos\beta$. Torque is $35(.25)\sin(100^\circ+\beta)/\cos\beta=\mathbf{8.23}$ kN m. Rod obliquity must be included.

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