This set of Automotive Engine Components Design Questions and Answers for Freshers focuses on “IC Engine – Centre Crankshaft at Angle of Maximum Torque”

1. The maximum torque is due to which component of force on the crank pin?

a) Perpendicular

b) Parallel

c) Concentric

d) Tangential

View Answer

Explanation: The torque is maximum when the tangential component of force on the crank pin is maximum. The force is produced due to the connecting rod.

2. What is the crank angle from the TDC position for the petrol engine?

a) 30° to 40°

b) 35° to 45°

c) 25° to 35°

d) 20° to 30°

View Answer

Explanation:The crank angle from the TDC position for the petrol engine is 25° to 35° and the crank angle from the TDC position for the diesel engine is 30° to 40°.

3. What is the crank angle from the TDC position for diesel engines?

a) 35° to 45°

b) 25° to 35°

c) 30° to 40°

d) 20° to 30°

View Answer

Explanation: The crank angle from the TDC position for the petrol engine is 25° to 35° and the crank angle from the TDC position for the diesel engine is 30° to 40°.

4. The relationship between Φ and θ is given by?

a) SinΦ=\(\frac{sin\theta}{L/r}\)

b) CosΦ=\(\frac{sin\theta}{L/r}\)

c) SinΦ=\(\frac{sin\theta}{L\times r}\)

d) CosΦ=\(\frac{cos\theta}{L/r}\)

View Answer

Explanation: The relationship between Φ and θ is given by SinΦ=\(\frac{sin\theta}{L/r}\) where L is the length of the connecting rod and r is the radius of the crank.

5. In the formula SinΦ=\(\frac{sin\theta}{L/r}\), what is L?

a) Lateral shift

b) Length of connecting rod

c) Linear bending

d) Length of stroke

View Answer

Explanation: The relationship between Ф and ϴ is given by SinΦ=\(\frac{sin\theta}{L/r}\) where L is the length of the connecting rod and r is the radius of the crank.

6. In the formula P_{t}=P_{q}Sin(θ+Φ), what is P_{t}?

a) The pressure at crankpin

b) The lateral component at crankpin

c) The tangential component at crankpin

d) Power at crankpin

View Answer

Explanation: In the formula P

_{t}=P

_{q}Sin(θ+Φ), P

_{t}is the tangential component of P

_{q}at the crankpin and P

_{r}is the radial component of P

_{q}at the crank pin.

7. In the formula P_{r}=P_{q}Sin(θ+Φ), what is P_{r}?

a) The radial component at crankpin

b) Pressure component at crankpin

c) The tangential component at crankpin

d) Vector component at crankpin

View Answer

Explanation: In the formula P

_{r}=P

_{q}Sin(θ+Φ), P

_{t}is the tangential component of P

_{q}at the crankpin and P

_{r}is the radial component of P

_{q}at the crank pin.

8. Which are the two forces experienced by the crank pin?

a) Bending and shear moment

b) Two couple force

c) Force and torsional moment

d) Bending and torsional moment

View Answer

Explanation: Bending and torsional moment are the two forces experienced by the crankpin and these forces are produced by bearing 1,2 and 3.

9. In the formula M_{t}=P_{t}×r, what is M_{t}?

a) Couple

b) Bending moment

c) Torsional moment

d) Shear moment

View Answer

Explanation: In the formula M

_{t}=P

_{t}×r, M

_{t}is the torsional moment due to tangential component P

_{t}and r is the crank radius. Hence, the torsional moment is the right answer.

10. The right-hand crank web is subjected to which stress due to radial component.

a) Tensile

b) Compressive

c) Normal strain

d) Linear stress

View Answer

Explanation: The right-hand crank web is subjected to compressive stress due to the radial component and bending moment in the vertical plane due to forces in the vertical plane.

11. The maximum compressive stress should be less than which stress?

a) Allowable tensile stress

b) Allowable compressive stress

c) Allowable shear stress

d) Allowable bending moment

View Answer

Explanation: The maximum compressive stress should be less than allowable compressive stress if not the crankshaft tends to bend and wobbling takes place.

12. Calculate the width of the crank web when the diameter of crankpin is 65mm?

a) 57.3mm

b) 74.1mm

c) 63.7mm

d) 80.6mm

View Answer

Explanation: w=1.14d

_{c}

=1.14×65

=74.1mm

13. Calculate the direct compressive stress when the reaction force is 15340N and the thickness and width of the crank web are 46mm and 75mm?

a) 8.43N/mm^{2}

b) 4.44N/mm^{2}

c) 5.54N/mm^{2}

d) 3.68N/mm^{2}

View Answer

Explanation: σ

_{c}=\(\frac{(R_1)_v}{W_t}\)

\(\frac{15340}{46\times 75}\)

=4.44N/mm

^{2}

14. In the formula σ_{c}=\(\frac{(R_1)_v}{W_t}\) , what is (R_{1})_{v} ?

a) Point load

b) Eccentric load

c) UVL

d) UDL

View Answer

Explanation: In the formula σ

_{c}=\frac{(R_1)_v}{W_t}[/latex], (R

_{1})

_{v}is the eccentric load, w is the width of the crank web and t is the thickness of the crank web.

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