Which of the following is not a function of a mechanical system for power transmission?

• A. Transmit torque
• B. Change speed
• C. Align shafts
• D. Increase power

Answer: (D)

The key idea is what a mechanical power transmission system actually does: it moves torque from a driving shaft to a driven shaft and can adjust the speed and torque through gear ratios, belts, or shafts. It also helps keep the shafts aligned so the power can flow smoothly without excessive wear or vibration. But it does not create extra power. In a well-designed system, the output power is the input power minus small losses from friction and inefficiency, so changing speed and torque via gearing trades one for the other without increasing the total power. So the statement about increasing power isn’t a function of the transmission—it’s about delivering the existing power effectively.