What device is used to prevent over travel of the aircraft elevator?

The correct answer is an electrical stopping device. In aircraft systems, over travel of the elevator can lead to dangerous situations, so effective control measures are essential. An electrical stopping device is designed to monitor the position of the elevator and can provide precise limits on its movement. This device ensures that the elevator does not move beyond its designated range, thereby preventing over travel.

The electrical stopping device typically works in tandem with sensors and control systems that detect the position of the elevator. When the elevator reaches a predetermined limit, the device will stop its movement, thereby ensuring safe operation within defined parameters.

Other devices mentioned, while they may serve various roles in mechanical control systems, do not specifically address the need for positioning and travel limitation in elevator systems as effectively as an electrical stopping device. A mechanical clutch, hydraulic limiter, and pneumatic regulator may have applications in different contexts, but they do not directly manage elevator travel in the same targeted manner as the electrical stopping device does.