Which statement accurately describes a universal joint?

• A. It locks the shafts at a fixed angle.
• B. It increases torque exponentially.
• C. It is used only in worm gear systems.
• D. It allows angular misalignment between connected shafts.

Answer: (D)

The main idea is that a universal joint lets two shafts rotate even when their axes are not perfectly aligned, accommodating angular misalignment while transmitting rotation. It uses a cross-shaped intermediate piece connected to each shaft so the angle between the shafts can be nonzero, and rotation is transferred through that joint. This is what makes the universal joint distinctive: it enables misalignment rather than forcing and locking the shafts into a fixed alignment. It doesn’t lock the shafts at a fixed angle, it doesn’t amplify torque, and it isn’t limited to worm gear systems. So the statement that it allows angular misalignment between connected shafts is the best description.