In a mechanical system, the transmission of torque is primarily done by which component?

• A. Key
• B. Shaft
• C. Hub
• D. Coupling

Answer: (B)

In a mechanical system, the shaft plays a crucial role in the transmission of torque. The shaft is a rotating component designed to transmit power and torque from one part of the system to another. When rotational force is applied to one end of the shaft, it rotates and delivers that same torque to connected components, such as gears or driveshafts, at the other end.

The key, hub, and coupling each serve important functions in a mechanical system, but they do not directly transmit torque in the same way that a shaft does. The key is used to lock a rotating part to a shaft, ensuring that they rotate together, while the hub connects to the shaft and may also serve as a mounting point for other components. Couplings are designed to connect two shafts together and may allow for some flexibility and misalignment but are also not the primary components through which torque is transmitted.

Therefore, the shaft is the fundamental component responsible for the effective transmission of torque in mechanical systems.