Topic: Machine Design
The power is transmitted through a spur gear with 20 deg pressure angle mounted at the mid span of shaft supported on bearings at the ends. The nature of stress induced in the shaft is
- A. Normal stress due to bending only.
- B. Normal stress due to bending and shear stress due to torsion.
- C. Normal stress due to bending, axial loading and shear stress due to torsion
- D. Normal stress due to axial loading and shear stress due to torsion
Answer: B. Normal stress due to bending and shear stress due to torsion.
Explanation: A spur gear transmits both a tangential force component (which causes torsional shear stress in the shaft) and a radial force component (which causes bending moment, hence normal bending stress). Unlike helical gears, spur gears do not produce axial/thrust forces.