Question:medium
The stresses in a shaft are:
(i) Shear stress due to torsion
(ii) Normal stress due to bending moments
(iii) Axial stress
Which ONE of the following options lists the stresses that are considered while designing a circular propeller shaft?
The stresses in a shaft are:
(i) Shear stress due to torsion
(ii) Normal stress due to bending moments
(iii) Axial stress
Which ONE of the following options lists the stresses that are considered while designing a circular propeller shaft?
(i) Shear stress due to torsion
(ii) Normal stress due to bending moments
(iii) Axial stress
Which ONE of the following options lists the stresses that are considered while designing a circular propeller shaft?
Show Hint
Think about every load a propeller shaft carries: torque from the engine, its own bending, and the propeller's thrust.
Updated On: Jul 28, 2026
- (i) and (ii) only
- (ii) and (iii) only
- (i) and (iii) only
- (i), (ii) and (iii)
Show Solution
The Correct Option is D
Solution and Explanation
Step 1: List every load path into the shaft.
A propeller shaft sits between the engine and the propeller. The engine side feeds in torque, the propeller side feeds in thrust and a rotating weight. Check torsion, axial load, and bending separately.
Step 2: Check torsion.
Torque delivered by the engine to spin the propeller sets up a shear stress that varies with radius, largest at the outer surface of the circular shaft. So item (i) must be kept.
Step 3: Check bending.
The propeller overhangs the last bearing and has its own weight, and shaft misalignment adds further bending. This gives a bending moment along the shaft and a normal bending stress. So item (ii) must be kept.
Step 4: Check axial stress.
Thrust generated by the propeller to push the ship is carried by the shaft to the thrust bearing, loading the shaft axially in compression. So item (iii) must be kept too.
Final Answer:
All three stress types act together on a propeller shaft, so a safe design must combine them. \[ \boxed{\text{(i), (ii) and (iii)}} \]
A propeller shaft sits between the engine and the propeller. The engine side feeds in torque, the propeller side feeds in thrust and a rotating weight. Check torsion, axial load, and bending separately.
Step 2: Check torsion.
Torque delivered by the engine to spin the propeller sets up a shear stress that varies with radius, largest at the outer surface of the circular shaft. So item (i) must be kept.
Step 3: Check bending.
The propeller overhangs the last bearing and has its own weight, and shaft misalignment adds further bending. This gives a bending moment along the shaft and a normal bending stress. So item (ii) must be kept.
Step 4: Check axial stress.
Thrust generated by the propeller to push the ship is carried by the shaft to the thrust bearing, loading the shaft axially in compression. So item (iii) must be kept too.
Final Answer:
All three stress types act together on a propeller shaft, so a safe design must combine them. \[ \boxed{\text{(i), (ii) and (iii)}} \]
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