Which component in the radial drive shaft prevents over-torque to the AGB?

The component in the radial drive shaft that prevents over-torque to the Accessory Gear Box (AGB) is a shear pin. A shear pin is designed to break or "shear" at a specific torque level to protect more critical components of the system from damage due to excessive torque. When the torque exceeds this designated limit, the shear pin fails, effectively disconnecting the drive and preventing further transmission of excessive force. This mechanism acts as a safety feature to maintain the integrity of the AGB and its associated components, ensuring that they are not subjected to damaging conditions that could arise from over-torque situations.

In contrast, a torque limiter is also intended to prevent over-torque but operates differently—typically by slipping at a certain torque threshold instead of breaking. A safety clutch may serve a different purpose related to engagement and disengagement of components but does not directly act to break under excessive torque like a shear pin does. A disconnect coupling allows for separation of components but does not specifically prevent over-torque situations like the shear pin does. Thus, the effectiveness and design of the shear pin make it the correct answer for the function described in the question.