Subtopic: Overload safety devices used in farm machinery
Question Statement:
A shear bolt used as an overload release device in a rotary tiller driveline is designed primarily to fail under:
Options:
(A) Direct transverse shear stress exceeding the yield limit
(B) High cyclic bending fatigue
(C) Excessive torsional bucking of the bolt shank
(D) Compressive crushing along the bolt head
Answer Key:
A
Step-by-Step Solution & Explanation
Shear bolts are calibrated sacrificial elements designed with known cross-sectional area and material shear strength $\tau_{\text{allow}}$. When torque spikes exceed safe limits, direct transverse shear causes instantaneous rupture of the bolt, isolating the tractor PTO from shock overloads.