# Automotive Engine Components Design Questions and Answers – IC Engine – Centre Crankshaft at TDC Position

This set of Automotive Engine Design Question Paper focuses on “IC Engine – Centre Crankshaft at TDC Position”.

1. Which type of crankshaft is supported by three bearings?
a) Top crankshaft
b) Bottom crankshaft
c) Side crankshaft
d) Center crankshaft

Explanation: The forces acting on the centre crankshaft at the top dead centre position are three principle forces and to withstand this, the crankshaft is supported by three bearings.

2. In the design of centre crankshaft at TDC position, the driven belt is assumed to be in which direction?
a) Vertical
b) Angled
c) Horizontal
d) Perpendicular

Explanation: A crankshaft is subjected to bending and torsional moments due to the following three forces. Hence, In the design of centre crankshaft at the TDC position, the driven belt is assumed to be ina horizontal direction.

3. In the design of centre crankshaft at TDC position, the crank alone is at which position?
a) BDC position
b) ODC position
c) TDC position
d) HDF position

Explanation: A crankshaft is subjected to bending and torsional moments due to the following three forces. Hence, In the design of centre crankshaft at the TDC position, the crank alone is at the TDC position.

4. In the design of centre crankshaft at the TDC position, the engine is placed in which position?
a) Vertical
b) Horizontal
c) Parallel
d) Perpendicular

Explanation: A crankshaft is subjected to bending and torsional moments due to the following three forces. Hence, In the design of centre crankshaft at the TDC position, the engine is placed in a vertical position.

5. The reactions at the bearing 1 and 2 are due to force by which part of the crankshaft?
a) Circlip
b) Crankpin
c) Spigot
d) Key

Explanation: The reactions at the bearing 1 and 2 are due to force on the crankpin (Pp) and the reaction forces at the bearing are given R1 and R2. Hence, crankpin the right answer.

6. The reactions at the bearing 2 and 3 are due to which part of the engine?
a) Weight of camshaft
b) Weight of connecting rod
c) Weight of flywheel
d) Weight of the gears

Explanation: The reactions at the bearing 2 and 3 are due to the weight of the flywheel(W) and the sum of their belt tensions(P1+P2) and reaction forces denoted by R1 and R2.

7. The thrust in the connecting rod will be equal to the force acting on which part of the engine?
a) Piston
b) Connecting rod
c) Crankshaft
d) Gudgeon pin

Explanation: The thrust in the connecting rod will be equal to the force acting on the piston, this force is denoted by Pp. The crankshaft is simply supported by the bearings.

8. Which plane of the crankshaft is subjected to the maximum bending moment?
a) Bottom plane
b) Top plane
c) Side plane
d) Central plane

Explanation: In the central plane of the crankshaft is subjected to a maximum bending moment. This moment is due to the force produced by the weight of the flywheel.

9. The right and left-hand webs should be identified based on which consideration?
a) Unbalanced
b) Unilateral
c) Balancing
d) lateral

Explanation: The right hand and left-hand webs should be identical from balancing considerations. So, the thickness and width of the right-hand crank web are made equal to that of the left-hand crank web.

10. The bending moment in the vertical plane is due to which part of the engine?
a) Weight of piston
b) Weight of flywheel
c) Weight of engine
d) Weight of vehicle

Explanation: The bending moment in the vertical plane is due to the weight of the flywheel and The bending moment in the horizontal plane is due to resultant belt tension.

11. The central plane of the crankpin is subjected to which force?
a) Minimum bending moment
b) Maximum bending moment
c) Normal stress
d) Principle stress

Explanation:The central plane of the crankpin is subjected to maximum bending moment and the bending moment at the central plane is given by (Mb)c=(R1)vb1.

12. In the design of center crankshaft b=2D, what is D?
a) Valve diameter
b) Piston diameter
c) Gudgeon pin diameter
d) Shrinking diameter

Explanation: In the design of center crankshaft b=2D, b is the distance between bearing 1 and bearing 2 and D is the piston diameter. Hence, piston diameter is the right answer.

13. The bending moment in the horizontal plane is due to?
a) Belt compression
b) Resultant belt tension
c) Resultant tension
d) Resultant belt compression

Explanation: The bending moment in the vertical plane is due to the weight of the flywheel and the bending moment in the horizontal plane is due to resultant belt tension.

14. What is the dimension of crankweb when the diameter of crankpin is 50mm?
a) 25mm
b) 35mm
c) 40mm
d) 45mm

Explanation: Thickness of the crank web is given by t=0.7dc
t=0.7×50
=35mm

Sanfoundry Global Education & Learning Series – Automotive Engine Components Design.

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